1	// SPDX-License-Identifier: GPL-2.0+
2	/*
3	* Driver core for serial ports
4	*
5	* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6	*
7	* Copyright 1999 ARM Limited
8	* Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
9	*/
10	#include <linux/module.h>
11	#include <linux/tty.h>
12	#include <linux/tty_flip.h>
13	#include <linux/slab.h>
14	#include <linux/sched/signal.h>
15	#include <linux/init.h>
16	#include <linux/console.h>
17	#include <linux/gpio/consumer.h>
18	#include <linux/kernel.h>
19	#include <linux/of.h>
20	#include <linux/pm_runtime.h>
21	#include <linux/proc_fs.h>
22	#include <linux/seq_file.h>
23	#include <linux/device.h>
24	#include <linux/serial.h> /* for serial_state and serial_icounter_struct */
25	#include <linux/serial_core.h>
26	#include <linux/sysrq.h>
27	#include <linux/delay.h>
28	#include <linux/mutex.h>
29	#include <linux/math64.h>
30	#include <linux/security.h>
31
32	#include <linux/irq.h>
33	#include <linux/uaccess.h>
34
35	#include "serial_base.h"
36
37	/*
38	* This is used to lock changes in serial line configuration.
39	*/
40	static DEFINE_MUTEX(port_mutex);
41
42	/*
43	* lockdep: port->lock is initialized in two places, but we
44	* want only one lock-class:
45	*/
46	static struct lock_class_key port_lock_key;
47
48	#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)
49
50	/*
51	* Max time with active RTS before/after data is sent.
52	*/
53	#define RS485_MAX_RTS_DELAY 100 /* msecs */
54
55	static void uart_change_pm(struct uart_state *state,
56	enum uart_pm_state pm_state);
57
58	static void uart_port_shutdown(struct tty_port *port);
59
60	static int uart_dcd_enabled(struct uart_port *uport)
61	{
62	return !!(uport->status & UPSTAT_DCD_ENABLE);
63	}
64
65	static inline struct uart_port *uart_port_ref(struct uart_state *state)
66	{
67	if (atomic_add_unless(v: &state->refcount, a: 1, u: 0))
68	return state->uart_port;
69	return NULL;
70	}
71
72	static inline void uart_port_deref(struct uart_port *uport)
73	{
74	if (atomic_dec_and_test(v: &uport->state->refcount))
75	wake_up(&uport->state->remove_wait);
76	}
77
78	#define uart_port_lock(state, flags) \
79	({ \
80	struct uart_port *__uport = uart_port_ref(state); \
81	if (__uport) \
82	uart_port_lock_irqsave(__uport, &flags); \
83	__uport; \
84	})
85
86	#define uart_port_unlock(uport, flags) \
87	({ \
88	struct uart_port *__uport = uport; \
89	if (__uport) { \
90	uart_port_unlock_irqrestore(__uport, flags); \
91	uart_port_deref(__uport); \
92	} \
93	})
94
95	static inline struct uart_port *uart_port_check(struct uart_state *state)
96	{
97	lockdep_assert_held(&state->port.mutex);
98	return state->uart_port;
99	}
100
101	/**
102	* uart_write_wakeup - schedule write processing
103	* @port: port to be processed
104	*
105	* This routine is used by the interrupt handler to schedule processing in the
106	* software interrupt portion of the driver. A driver is expected to call this
107	* function when the number of characters in the transmit buffer have dropped
108	* below a threshold.
109	*
110	* Locking: @port->lock should be held
111	*/
112	void uart_write_wakeup(struct uart_port *port)
113	{
114	struct uart_state *state = port->state;
115	/*
116	* This means you called this function _after_ the port was
117	* closed. No cookie for you.
118	*/
119	BUG_ON(!state);
120	tty_port_tty_wakeup(port: &state->port);
121	}
122	EXPORT_SYMBOL(uart_write_wakeup);
123
124	static void uart_stop(struct tty_struct *tty)
125	{
126	struct uart_state *state = tty->driver_data;
127	struct uart_port *port;
128	unsigned long flags;
129
130	port = uart_port_lock(state, flags);
131	if (port)
132	port->ops->stop_tx(port);
133	uart_port_unlock(port, flags);
134	}
135
136	static void __uart_start(struct uart_state *state)
137	{
138	struct uart_port *port = state->uart_port;
139	struct serial_port_device *port_dev;
140	int err;
141
142	if (!port || port->flags & UPF_DEAD || uart_tx_stopped(port))
143	return;
144
145	port_dev = port->port_dev;
146
147	/* Increment the runtime PM usage count for the active check below */
148	err = pm_runtime_get(dev: &port_dev->dev);
149	if (err < 0 && err != -EINPROGRESS) {
150	pm_runtime_put_noidle(dev: &port_dev->dev);
151	return;
152	}
153
154	/*
155	* Start TX if enabled, and kick runtime PM. If the device is not
156	* enabled, serial_port_runtime_resume() calls start_tx() again
157	* after enabling the device.
158	*/
159	if (!pm_runtime_enabled(dev: port->dev) || pm_runtime_active(dev: port->dev))
160	port->ops->start_tx(port);
161	pm_runtime_mark_last_busy(dev: &port_dev->dev);
162	pm_runtime_put_autosuspend(dev: &port_dev->dev);
163	}
164
165	static void uart_start(struct tty_struct *tty)
166	{
167	struct uart_state *state = tty->driver_data;
168	struct uart_port *port;
169	unsigned long flags;
170
171	port = uart_port_lock(state, flags);
172	__uart_start(state);
173	uart_port_unlock(port, flags);
174	}
175
176	static void
177	uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
178	{
179	unsigned long flags;
180	unsigned int old;
181
182	uart_port_lock_irqsave(up: port, flags: &flags);
183	old = port->mctrl;
184	port->mctrl = (old & ~clear) | set;
185	if (old != port->mctrl && !(port->rs485.flags & SER_RS485_ENABLED))
186	port->ops->set_mctrl(port, port->mctrl);
187	uart_port_unlock_irqrestore(up: port, flags);
188	}
189
190	#define uart_set_mctrl(port, set) uart_update_mctrl(port, set, 0)
191	#define uart_clear_mctrl(port, clear) uart_update_mctrl(port, 0, clear)
192
193	static void uart_port_dtr_rts(struct uart_port *uport, bool active)
194	{
195	if (active)
196	uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
197	else
198	uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
199	}
200
201	/* Caller holds port mutex */
202	static void uart_change_line_settings(struct tty_struct *tty, struct uart_state *state,
203	const struct ktermios *old_termios)
204	{
205	struct uart_port *uport = uart_port_check(state);
206	struct ktermios *termios;
207	bool old_hw_stopped;
208
209	/*
210	* If we have no tty, termios, or the port does not exist,
211	* then we can't set the parameters for this port.
212	*/
213	if (!tty || uport->type == PORT_UNKNOWN)
214	return;
215
216	termios = &tty->termios;
217	uport->ops->set_termios(uport, termios, old_termios);
218
219	/*
220	* Set modem status enables based on termios cflag
221	*/
222	uart_port_lock_irq(up: uport);
223	if (termios->c_cflag & CRTSCTS)
224	uport->status |= UPSTAT_CTS_ENABLE;
225	else
226	uport->status &= ~UPSTAT_CTS_ENABLE;
227
228	if (termios->c_cflag & CLOCAL)
229	uport->status &= ~UPSTAT_DCD_ENABLE;
230	else
231	uport->status |= UPSTAT_DCD_ENABLE;
232
233	/* reset sw-assisted CTS flow control based on (possibly) new mode */
234	old_hw_stopped = uport->hw_stopped;
235	uport->hw_stopped = uart_softcts_mode(uport) &&
236	!(uport->ops->get_mctrl(uport) & TIOCM_CTS);
237	if (uport->hw_stopped != old_hw_stopped) {
238	if (!old_hw_stopped)
239	uport->ops->stop_tx(uport);
240	else
241	__uart_start(state);
242	}
243	uart_port_unlock_irq(up: uport);
244	}
245
246	/*
247	* Startup the port. This will be called once per open. All calls
248	* will be serialised by the per-port mutex.
249	*/
250	static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
251	bool init_hw)
252	{
253	struct uart_port *uport = uart_port_check(state);
254	unsigned long flags;
255	unsigned long page;
256	int retval = 0;
257
258	if (uport->type == PORT_UNKNOWN)
259	return 1;
260
261	/*
262	* Make sure the device is in D0 state.
263	*/
264	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
265
266	/*
267	* Initialise and allocate the transmit and temporary
268	* buffer.
269	*/
270	page = get_zeroed_page(GFP_KERNEL);
271	if (!page)
272	return -ENOMEM;
273
274	uart_port_lock(state, flags);
275	if (!state->xmit.buf) {
276	state->xmit.buf = (unsigned char *) page;
277	uart_circ_clear(&state->xmit);
278	uart_port_unlock(uport, flags);
279	} else {
280	uart_port_unlock(uport, flags);
281	/*
282	* Do not free() the page under the port lock, see
283	* uart_shutdown().
284	*/
285	free_page(page);
286	}
287
288	retval = uport->ops->startup(uport);
289	if (retval == 0) {
290	if (uart_console(uport) && uport->cons->cflag) {
291	tty->termios.c_cflag = uport->cons->cflag;
292	tty->termios.c_ispeed = uport->cons->ispeed;
293	tty->termios.c_ospeed = uport->cons->ospeed;
294	uport->cons->cflag = 0;
295	uport->cons->ispeed = 0;
296	uport->cons->ospeed = 0;
297	}
298	/*
299	* Initialise the hardware port settings.
300	*/
301	uart_change_line_settings(tty, state, NULL);
302
303	/*
304	* Setup the RTS and DTR signals once the
305	* port is open and ready to respond.
306	*/
307	if (init_hw && C_BAUD(tty))
308	uart_port_dtr_rts(uport, active: true);
309	}
310
311	/*
312	* This is to allow setserial on this port. People may want to set
313	* port/irq/type and then reconfigure the port properly if it failed
314	* now.
315	*/
316	if (retval && capable(CAP_SYS_ADMIN))
317	return 1;
318
319	return retval;
320	}
321
322	static int uart_startup(struct tty_struct *tty, struct uart_state *state,
323	bool init_hw)
324	{
325	struct tty_port *port = &state->port;
326	int retval;
327
328	if (tty_port_initialized(port))
329	return 0;
330
331	retval = uart_port_startup(tty, state, init_hw);
332	if (retval)
333	set_bit(TTY_IO_ERROR, addr: &tty->flags);
334
335	return retval;
336	}
337
338	/*
339	* This routine will shutdown a serial port; interrupts are disabled, and
340	* DTR is dropped if the hangup on close termio flag is on. Calls to
341	* uart_shutdown are serialised by the per-port semaphore.
342	*
343	* uport == NULL if uart_port has already been removed
344	*/
345	static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
346	{
347	struct uart_port *uport = uart_port_check(state);
348	struct tty_port *port = &state->port;
349	unsigned long flags;
350	char *xmit_buf = NULL;
351
352	/*
353	* Set the TTY IO error marker
354	*/
355	if (tty)
356	set_bit(TTY_IO_ERROR, addr: &tty->flags);
357
358	if (tty_port_initialized(port)) {
359	tty_port_set_initialized(port, val: false);
360
361	/*
362	* Turn off DTR and RTS early.
363	*/
364	if (uport && uart_console(uport) && tty) {
365	uport->cons->cflag = tty->termios.c_cflag;
366	uport->cons->ispeed = tty->termios.c_ispeed;
367	uport->cons->ospeed = tty->termios.c_ospeed;
368	}
369
370	if (!tty || C_HUPCL(tty))
371	uart_port_dtr_rts(uport, active: false);
372
373	uart_port_shutdown(port);
374	}
375
376	/*
377	* It's possible for shutdown to be called after suspend if we get
378	* a DCD drop (hangup) at just the right time. Clear suspended bit so
379	* we don't try to resume a port that has been shutdown.
380	*/
381	tty_port_set_suspended(port, val: false);
382
383	/*
384	* Do not free() the transmit buffer page under the port lock since
385	* this can create various circular locking scenarios. For instance,
386	* console driver may need to allocate/free a debug object, which
387	* can endup in printk() recursion.
388	*/
389	uart_port_lock(state, flags);
390	xmit_buf = state->xmit.buf;
391	state->xmit.buf = NULL;
392	uart_port_unlock(uport, flags);
393
394	free_page((unsigned long)xmit_buf);
395	}
396
397	/**
398	* uart_update_timeout - update per-port frame timing information
399	* @port: uart_port structure describing the port
400	* @cflag: termios cflag value
401	* @baud: speed of the port
402	*
403	* Set the @port frame timing information from which the FIFO timeout value is
404	* derived. The @cflag value should reflect the actual hardware settings as
405	* number of bits, parity, stop bits and baud rate is taken into account here.
406	*
407	* Locking: caller is expected to take @port->lock
408	*/
409	void
410	uart_update_timeout(struct uart_port *port, unsigned int cflag,
411	unsigned int baud)
412	{
413	unsigned int size = tty_get_frame_size(cflag);
414	u64 frame_time;
415
416	frame_time = (u64)size * NSEC_PER_SEC;
417	port->frame_time = DIV64_U64_ROUND_UP(frame_time, baud);
418	}
419	EXPORT_SYMBOL(uart_update_timeout);
420
421	/**
422	* uart_get_baud_rate - return baud rate for a particular port
423	* @port: uart_port structure describing the port in question.
424	* @termios: desired termios settings
425	* @old: old termios (or %NULL)
426	* @min: minimum acceptable baud rate
427	* @max: maximum acceptable baud rate
428	*
429	* Decode the termios structure into a numeric baud rate, taking account of the
430	* magic 38400 baud rate (with spd_* flags), and mapping the %B0 rate to 9600
431	* baud.
432	*
433	* If the new baud rate is invalid, try the @old termios setting. If it's still
434	* invalid, we try 9600 baud. If that is also invalid 0 is returned.
435	*
436	* The @termios structure is updated to reflect the baud rate we're actually
437	* going to be using. Don't do this for the case where B0 is requested ("hang
438	* up").
439	*
440	* Locking: caller dependent
441	*/
442	unsigned int
443	uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
444	const struct ktermios *old, unsigned int min, unsigned int max)
445	{
446	unsigned int try;
447	unsigned int baud;
448	unsigned int altbaud;
449	int hung_up = 0;
450	upf_t flags = port->flags & UPF_SPD_MASK;
451
452	switch (flags) {
453	case UPF_SPD_HI:
454	altbaud = 57600;
455	break;
456	case UPF_SPD_VHI:
457	altbaud = 115200;
458	break;
459	case UPF_SPD_SHI:
460	altbaud = 230400;
461	break;
462	case UPF_SPD_WARP:
463	altbaud = 460800;
464	break;
465	default:
466	altbaud = 38400;
467	break;
468	}
469
470	for (try = 0; try < 2; try++) {
471	baud = tty_termios_baud_rate(termios);
472
473	/*
474	* The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
475	* Die! Die! Die!
476	*/
477	if (try == 0 && baud == 38400)
478	baud = altbaud;
479
480	/*
481	* Special case: B0 rate.
482	*/
483	if (baud == 0) {
484	hung_up = 1;
485	baud = 9600;
486	}
487
488	if (baud >= min && baud <= max)
489	return baud;
490
491	/*
492	* Oops, the quotient was zero. Try again with
493	* the old baud rate if possible.
494	*/
495	termios->c_cflag &= ~CBAUD;
496	if (old) {
497	baud = tty_termios_baud_rate(termios: old);
498	if (!hung_up)
499	tty_termios_encode_baud_rate(termios,
500	ibaud: baud, obaud: baud);
501	old = NULL;
502	continue;
503	}
504
505	/*
506	* As a last resort, if the range cannot be met then clip to
507	* the nearest chip supported rate.
508	*/
509	if (!hung_up) {
510	if (baud <= min)
511	tty_termios_encode_baud_rate(termios,
512	ibaud: min + 1, obaud: min + 1);
513	else
514	tty_termios_encode_baud_rate(termios,
515	ibaud: max - 1, obaud: max - 1);
516	}
517	}
518	return 0;
519	}
520	EXPORT_SYMBOL(uart_get_baud_rate);
521
522	/**
523	* uart_get_divisor - return uart clock divisor
524	* @port: uart_port structure describing the port
525	* @baud: desired baud rate
526	*
527	* Calculate the divisor (baud_base / baud) for the specified @baud,
528	* appropriately rounded.
529	*
530	* If 38400 baud and custom divisor is selected, return the custom divisor
531	* instead.
532	*
533	* Locking: caller dependent
534	*/
535	unsigned int
536	uart_get_divisor(struct uart_port *port, unsigned int baud)
537	{
538	unsigned int quot;
539
540	/*
541	* Old custom speed handling.
542	*/
543	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
544	quot = port->custom_divisor;
545	else
546	quot = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);
547
548	return quot;
549	}
550	EXPORT_SYMBOL(uart_get_divisor);
551
552	static int uart_put_char(struct tty_struct *tty, u8 c)
553	{
554	struct uart_state *state = tty->driver_data;
555	struct uart_port *port;
556	struct circ_buf *circ;
557	unsigned long flags;
558	int ret = 0;
559
560	circ = &state->xmit;
561	port = uart_port_lock(state, flags);
562	if (!circ->buf) {
563	uart_port_unlock(port, flags);
564	return 0;
565	}
566
567	if (port && uart_circ_chars_free(circ) != 0) {
568	circ->buf[circ->head] = c;
569	circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
570	ret = 1;
571	}
572	uart_port_unlock(port, flags);
573	return ret;
574	}
575
576	static void uart_flush_chars(struct tty_struct *tty)
577	{
578	uart_start(tty);
579	}
580
581	static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count)
582	{
583	struct uart_state *state = tty->driver_data;
584	struct uart_port *port;
585	struct circ_buf *circ;
586	unsigned long flags;
587	int c, ret = 0;
588
589	/*
590	* This means you called this function _after_ the port was
591	* closed. No cookie for you.
592	*/
593	if (WARN_ON(!state))
594	return -EL3HLT;
595
596	port = uart_port_lock(state, flags);
597	circ = &state->xmit;
598	if (!circ->buf) {
599	uart_port_unlock(port, flags);
600	return 0;
601	}
602
603	while (port) {
604	c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
605	if (count < c)
606	c = count;
607	if (c <= 0)
608	break;
609	memcpy(circ->buf + circ->head, buf, c);
610	circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
611	buf += c;
612	count -= c;
613	ret += c;
614	}
615
616	__uart_start(state);
617	uart_port_unlock(port, flags);
618	return ret;
619	}
620
621	static unsigned int uart_write_room(struct tty_struct *tty)
622	{
623	struct uart_state *state = tty->driver_data;
624	struct uart_port *port;
625	unsigned long flags;
626	unsigned int ret;
627
628	port = uart_port_lock(state, flags);
629	ret = uart_circ_chars_free(&state->xmit);
630	uart_port_unlock(port, flags);
631	return ret;
632	}
633
634	static unsigned int uart_chars_in_buffer(struct tty_struct *tty)
635	{
636	struct uart_state *state = tty->driver_data;
637	struct uart_port *port;
638	unsigned long flags;
639	unsigned int ret;
640
641	port = uart_port_lock(state, flags);
642	ret = uart_circ_chars_pending(&state->xmit);
643	uart_port_unlock(port, flags);
644	return ret;
645	}
646
647	static void uart_flush_buffer(struct tty_struct *tty)
648	{
649	struct uart_state *state = tty->driver_data;
650	struct uart_port *port;
651	unsigned long flags;
652
653	/*
654	* This means you called this function _after_ the port was
655	* closed. No cookie for you.
656	*/
657	if (WARN_ON(!state))
658	return;
659
660	pr_debug("uart_flush_buffer(%d) called\n", tty->index);
661
662	port = uart_port_lock(state, flags);
663	if (!port)
664	return;
665	uart_circ_clear(&state->xmit);
666	if (port->ops->flush_buffer)
667	port->ops->flush_buffer(port);
668	uart_port_unlock(port, flags);
669	tty_port_tty_wakeup(port: &state->port);
670	}
671
672	/*
673	* This function performs low-level write of high-priority XON/XOFF
674	* character and accounting for it.
675	*
676	* Requires uart_port to implement .serial_out().
677	*/
678	void uart_xchar_out(struct uart_port *uport, int offset)
679	{
680	serial_port_out(up: uport, offset, value: uport->x_char);
681	uport->icount.tx++;
682	uport->x_char = 0;
683	}
684	EXPORT_SYMBOL_GPL(uart_xchar_out);
685
686	/*
687	* This function is used to send a high-priority XON/XOFF character to
688	* the device
689	*/
690	static void uart_send_xchar(struct tty_struct *tty, char ch)
691	{
692	struct uart_state *state = tty->driver_data;
693	struct uart_port *port;
694	unsigned long flags;
695
696	port = uart_port_ref(state);
697	if (!port)
698	return;
699
700	if (port->ops->send_xchar)
701	port->ops->send_xchar(port, ch);
702	else {
703	uart_port_lock_irqsave(up: port, flags: &flags);
704	port->x_char = ch;
705	if (ch)
706	port->ops->start_tx(port);
707	uart_port_unlock_irqrestore(up: port, flags);
708	}
709	uart_port_deref(uport: port);
710	}
711
712	static void uart_throttle(struct tty_struct *tty)
713	{
714	struct uart_state *state = tty->driver_data;
715	upstat_t mask = UPSTAT_SYNC_FIFO;
716	struct uart_port *port;
717
718	port = uart_port_ref(state);
719	if (!port)
720	return;
721
722	if (I_IXOFF(tty))
723	mask |= UPSTAT_AUTOXOFF;
724	if (C_CRTSCTS(tty))
725	mask |= UPSTAT_AUTORTS;
726
727	if (port->status & mask) {
728	port->ops->throttle(port);
729	mask &= ~port->status;
730	}
731
732	if (mask & UPSTAT_AUTORTS)
733	uart_clear_mctrl(port, TIOCM_RTS);
734
735	if (mask & UPSTAT_AUTOXOFF)
736	uart_send_xchar(tty, STOP_CHAR(tty));
737
738	uart_port_deref(uport: port);
739	}
740
741	static void uart_unthrottle(struct tty_struct *tty)
742	{
743	struct uart_state *state = tty->driver_data;
744	upstat_t mask = UPSTAT_SYNC_FIFO;
745	struct uart_port *port;
746
747	port = uart_port_ref(state);
748	if (!port)
749	return;
750
751	if (I_IXOFF(tty))
752	mask |= UPSTAT_AUTOXOFF;
753	if (C_CRTSCTS(tty))
754	mask |= UPSTAT_AUTORTS;
755
756	if (port->status & mask) {
757	port->ops->unthrottle(port);
758	mask &= ~port->status;
759	}
760
761	if (mask & UPSTAT_AUTORTS)
762	uart_set_mctrl(port, TIOCM_RTS);
763
764	if (mask & UPSTAT_AUTOXOFF)
765	uart_send_xchar(tty, START_CHAR(tty));
766
767	uart_port_deref(uport: port);
768	}
769
770	static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
771	{
772	struct uart_state *state = container_of(port, struct uart_state, port);
773	struct uart_port *uport;
774	int ret = -ENODEV;
775
776	/* Initialize structure in case we error out later to prevent any stack info leakage. */
777	*retinfo = (struct serial_struct){};
778
779	/*
780	* Ensure the state we copy is consistent and no hardware changes
781	* occur as we go
782	*/
783	mutex_lock(&port->mutex);
784	uport = uart_port_check(state);
785	if (!uport)
786	goto out;
787
788	retinfo->type = uport->type;
789	retinfo->line = uport->line;
790	retinfo->port = uport->iobase;
791	if (HIGH_BITS_OFFSET)
792	retinfo->port_high = (long) uport->iobase >> HIGH_BITS_OFFSET;
793	retinfo->irq = uport->irq;
794	retinfo->flags = (__force int)uport->flags;
795	retinfo->xmit_fifo_size = uport->fifosize;
796	retinfo->baud_base = uport->uartclk / 16;
797	retinfo->close_delay = jiffies_to_msecs(j: port->close_delay) / 10;
798	retinfo->closing_wait = port->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
799	ASYNC_CLOSING_WAIT_NONE :
800	jiffies_to_msecs(j: port->closing_wait) / 10;
801	retinfo->custom_divisor = uport->custom_divisor;
802	retinfo->hub6 = uport->hub6;
803	retinfo->io_type = uport->iotype;
804	retinfo->iomem_reg_shift = uport->regshift;
805	retinfo->iomem_base = (void *)(unsigned long)uport->mapbase;
806
807	ret = 0;
808	out:
809	mutex_unlock(lock: &port->mutex);
810	return ret;
811	}
812
813	static int uart_get_info_user(struct tty_struct *tty,
814	struct serial_struct *ss)
815	{
816	struct uart_state *state = tty->driver_data;
817	struct tty_port *port = &state->port;
818
819	return uart_get_info(port, retinfo: ss) < 0 ? -EIO : 0;
820	}
821
822	static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
823	struct uart_state *state,
824	struct serial_struct *new_info)
825	{
826	struct uart_port *uport = uart_port_check(state);
827	unsigned long new_port;
828	unsigned int change_irq, change_port, closing_wait;
829	unsigned int old_custom_divisor, close_delay;
830	upf_t old_flags, new_flags;
831	int retval = 0;
832
833	if (!uport)
834	return -EIO;
835
836	new_port = new_info->port;
837	if (HIGH_BITS_OFFSET)
838	new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;
839
840	new_info->irq = irq_canonicalize(irq: new_info->irq);
841	close_delay = msecs_to_jiffies(m: new_info->close_delay * 10);
842	closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
843	ASYNC_CLOSING_WAIT_NONE :
844	msecs_to_jiffies(m: new_info->closing_wait * 10);
845
846
847	change_irq = !(uport->flags & UPF_FIXED_PORT)
848	&& new_info->irq != uport->irq;
849
850	/*
851	* Since changing the 'type' of the port changes its resource
852	* allocations, we should treat type changes the same as
853	* IO port changes.
854	*/
855	change_port = !(uport->flags & UPF_FIXED_PORT)
856	&& (new_port != uport->iobase ||
857	(unsigned long)new_info->iomem_base != uport->mapbase ||
858	new_info->hub6 != uport->hub6 ||
859	new_info->io_type != uport->iotype ||
860	new_info->iomem_reg_shift != uport->regshift ||
861	new_info->type != uport->type);
862
863	old_flags = uport->flags;
864	new_flags = (__force upf_t)new_info->flags;
865	old_custom_divisor = uport->custom_divisor;
866
867	if (!capable(CAP_SYS_ADMIN)) {
868	retval = -EPERM;
869	if (change_irq || change_port ||
870	(new_info->baud_base != uport->uartclk / 16) ||
871	(close_delay != port->close_delay) ||
872	(closing_wait != port->closing_wait) ||
873	(new_info->xmit_fifo_size &&
874	new_info->xmit_fifo_size != uport->fifosize) ||
875	(((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
876	goto exit;
877	uport->flags = ((uport->flags & ~UPF_USR_MASK) |
878	(new_flags & UPF_USR_MASK));
879	uport->custom_divisor = new_info->custom_divisor;
880	goto check_and_exit;
881	}
882
883	if (change_irq || change_port) {
884	retval = security_locked_down(what: LOCKDOWN_TIOCSSERIAL);
885	if (retval)
886	goto exit;
887	}
888
889	/*
890	* Ask the low level driver to verify the settings.
891	*/
892	if (uport->ops->verify_port)
893	retval = uport->ops->verify_port(uport, new_info);
894
895	if ((new_info->irq >= nr_irqs) || (new_info->irq < 0) ||
896	(new_info->baud_base < 9600))
897	retval = -EINVAL;
898
899	if (retval)
900	goto exit;
901
902	if (change_port || change_irq) {
903	retval = -EBUSY;
904
905	/*
906	* Make sure that we are the sole user of this port.
907	*/
908	if (tty_port_users(port) > 1)
909	goto exit;
910
911	/*
912	* We need to shutdown the serial port at the old
913	* port/type/irq combination.
914	*/
915	uart_shutdown(tty, state);
916	}
917
918	if (change_port) {
919	unsigned long old_iobase, old_mapbase;
920	unsigned int old_type, old_iotype, old_hub6, old_shift;
921
922	old_iobase = uport->iobase;
923	old_mapbase = uport->mapbase;
924	old_type = uport->type;
925	old_hub6 = uport->hub6;
926	old_iotype = uport->iotype;
927	old_shift = uport->regshift;
928
929	/*
930	* Free and release old regions
931	*/
932	if (old_type != PORT_UNKNOWN && uport->ops->release_port)
933	uport->ops->release_port(uport);
934
935	uport->iobase = new_port;
936	uport->type = new_info->type;
937	uport->hub6 = new_info->hub6;
938	uport->iotype = new_info->io_type;
939	uport->regshift = new_info->iomem_reg_shift;
940	uport->mapbase = (unsigned long)new_info->iomem_base;
941
942	/*
943	* Claim and map the new regions
944	*/
945	if (uport->type != PORT_UNKNOWN && uport->ops->request_port) {
946	retval = uport->ops->request_port(uport);
947	} else {
948	/* Always success - Jean II */
949	retval = 0;
950	}
951
952	/*
953	* If we fail to request resources for the
954	* new port, try to restore the old settings.
955	*/
956	if (retval) {
957	uport->iobase = old_iobase;
958	uport->type = old_type;
959	uport->hub6 = old_hub6;
960	uport->iotype = old_iotype;
961	uport->regshift = old_shift;
962	uport->mapbase = old_mapbase;
963
964	if (old_type != PORT_UNKNOWN) {
965	retval = uport->ops->request_port(uport);
966	/*
967	* If we failed to restore the old settings,
968	* we fail like this.
969	*/
970	if (retval)
971	uport->type = PORT_UNKNOWN;
972
973	/*
974	* We failed anyway.
975	*/
976	retval = -EBUSY;
977	}
978
979	/* Added to return the correct error -Ram Gupta */
980	goto exit;
981	}
982	}
983
984	if (change_irq)
985	uport->irq = new_info->irq;
986	if (!(uport->flags & UPF_FIXED_PORT))
987	uport->uartclk = new_info->baud_base * 16;
988	uport->flags = (uport->flags & ~UPF_CHANGE_MASK) |
989	(new_flags & UPF_CHANGE_MASK);
990	uport->custom_divisor = new_info->custom_divisor;
991	port->close_delay = close_delay;
992	port->closing_wait = closing_wait;
993	if (new_info->xmit_fifo_size)
994	uport->fifosize = new_info->xmit_fifo_size;
995
996	check_and_exit:
997	retval = 0;
998	if (uport->type == PORT_UNKNOWN)
999	goto exit;
1000	if (tty_port_initialized(port)) {
1001	if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
1002	old_custom_divisor != uport->custom_divisor) {
1003	/*
1004	* If they're setting up a custom divisor or speed,
1005	* instead of clearing it, then bitch about it.
1006	*/
1007	if (uport->flags & UPF_SPD_MASK) {
1008	dev_notice_ratelimited(uport->dev,
1009	"%s sets custom speed on %s. This is deprecated.\n",
1010	current->comm,
1011	tty_name(port->tty));
1012	}
1013	uart_change_line_settings(tty, state, NULL);
1014	}
1015	} else {
1016	retval = uart_startup(tty, state, init_hw: true);
1017	if (retval == 0)
1018	tty_port_set_initialized(port, val: true);
1019	if (retval > 0)
1020	retval = 0;
1021	}
1022	exit:
1023	return retval;
1024	}
1025
1026	static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
1027	{
1028	struct uart_state *state = tty->driver_data;
1029	struct tty_port *port = &state->port;
1030	int retval;
1031
1032	down_write(sem: &tty->termios_rwsem);
1033	/*
1034	* This semaphore protects port->count. It is also
1035	* very useful to prevent opens. Also, take the
1036	* port configuration semaphore to make sure that a
1037	* module insertion/removal doesn't change anything
1038	* under us.
1039	*/
1040	mutex_lock(&port->mutex);
1041	retval = uart_set_info(tty, port, state, new_info: ss);
1042	mutex_unlock(lock: &port->mutex);
1043	up_write(sem: &tty->termios_rwsem);
1044	return retval;
1045	}
1046
1047	/**
1048	* uart_get_lsr_info - get line status register info
1049	* @tty: tty associated with the UART
1050	* @state: UART being queried
1051	* @value: returned modem value
1052	*/
1053	static int uart_get_lsr_info(struct tty_struct *tty,
1054	struct uart_state *state, unsigned int __user *value)
1055	{
1056	struct uart_port *uport = uart_port_check(state);
1057	unsigned int result;
1058
1059	result = uport->ops->tx_empty(uport);
1060
1061	/*
1062	* If we're about to load something into the transmit
1063	* register, we'll pretend the transmitter isn't empty to
1064	* avoid a race condition (depending on when the transmit
1065	* interrupt happens).
1066	*/
1067	if (uport->x_char ||
1068	((uart_circ_chars_pending(&state->xmit) > 0) &&
1069	!uart_tx_stopped(port: uport)))
1070	result &= ~TIOCSER_TEMT;
1071
1072	return put_user(result, value);
1073	}
1074
1075	static int uart_tiocmget(struct tty_struct *tty)
1076	{
1077	struct uart_state *state = tty->driver_data;
1078	struct tty_port *port = &state->port;
1079	struct uart_port *uport;
1080	int result = -EIO;
1081
1082	mutex_lock(&port->mutex);
1083	uport = uart_port_check(state);
1084	if (!uport)
1085	goto out;
1086
1087	if (!tty_io_error(tty)) {
1088	result = uport->mctrl;
1089	uart_port_lock_irq(up: uport);
1090	result |= uport->ops->get_mctrl(uport);
1091	uart_port_unlock_irq(up: uport);
1092	}
1093	out:
1094	mutex_unlock(lock: &port->mutex);
1095	return result;
1096	}
1097
1098	static int
1099	uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
1100	{
1101	struct uart_state *state = tty->driver_data;
1102	struct tty_port *port = &state->port;
1103	struct uart_port *uport;
1104	int ret = -EIO;
1105
1106	mutex_lock(&port->mutex);
1107	uport = uart_port_check(state);
1108	if (!uport)
1109	goto out;
1110
1111	if (!tty_io_error(tty)) {
1112	uart_update_mctrl(port: uport, set, clear);
1113	ret = 0;
1114	}
1115	out:
1116	mutex_unlock(lock: &port->mutex);
1117	return ret;
1118	}
1119
1120	static int uart_break_ctl(struct tty_struct *tty, int break_state)
1121	{
1122	struct uart_state *state = tty->driver_data;
1123	struct tty_port *port = &state->port;
1124	struct uart_port *uport;
1125	int ret = -EIO;
1126
1127	mutex_lock(&port->mutex);
1128	uport = uart_port_check(state);
1129	if (!uport)
1130	goto out;
1131
1132	if (uport->type != PORT_UNKNOWN && uport->ops->break_ctl)
1133	uport->ops->break_ctl(uport, break_state);
1134	ret = 0;
1135	out:
1136	mutex_unlock(lock: &port->mutex);
1137	return ret;
1138	}
1139
1140	static int uart_do_autoconfig(struct tty_struct *tty, struct uart_state *state)
1141	{
1142	struct tty_port *port = &state->port;
1143	struct uart_port *uport;
1144	int flags, ret;
1145
1146	if (!capable(CAP_SYS_ADMIN))
1147	return -EPERM;
1148
1149	/*
1150	* Take the per-port semaphore. This prevents count from
1151	* changing, and hence any extra opens of the port while
1152	* we're auto-configuring.
1153	*/
1154	if (mutex_lock_interruptible(&port->mutex))
1155	return -ERESTARTSYS;
1156
1157	uport = uart_port_check(state);
1158	if (!uport) {
1159	ret = -EIO;
1160	goto out;
1161	}
1162
1163	ret = -EBUSY;
1164	if (tty_port_users(port) == 1) {
1165	uart_shutdown(tty, state);
1166
1167	/*
1168	* If we already have a port type configured,
1169	* we must release its resources.
1170	*/
1171	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
1172	uport->ops->release_port(uport);
1173
1174	flags = UART_CONFIG_TYPE;
1175	if (uport->flags & UPF_AUTO_IRQ)
1176	flags |= UART_CONFIG_IRQ;
1177
1178	/*
1179	* This will claim the ports resources if
1180	* a port is found.
1181	*/
1182	uport->ops->config_port(uport, flags);
1183
1184	ret = uart_startup(tty, state, init_hw: true);
1185	if (ret == 0)
1186	tty_port_set_initialized(port, val: true);
1187	if (ret > 0)
1188	ret = 0;
1189	}
1190	out:
1191	mutex_unlock(lock: &port->mutex);
1192	return ret;
1193	}
1194
1195	static void uart_enable_ms(struct uart_port *uport)
1196	{
1197	/*
1198	* Force modem status interrupts on
1199	*/
1200	if (uport->ops->enable_ms)
1201	uport->ops->enable_ms(uport);
1202	}
1203
1204	/*
1205	* Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
1206	* - mask passed in arg for lines of interest
1207	* (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
1208	* Caller should use TIOCGICOUNT to see which one it was
1209	*
1210	* FIXME: This wants extracting into a common all driver implementation
1211	* of TIOCMWAIT using tty_port.
1212	*/
1213	static int uart_wait_modem_status(struct uart_state *state, unsigned long arg)
1214	{
1215	struct uart_port *uport;
1216	struct tty_port *port = &state->port;
1217	DECLARE_WAITQUEUE(wait, current);
1218	struct uart_icount cprev, cnow;
1219	int ret;
1220
1221	/*
1222	* note the counters on entry
1223	*/
1224	uport = uart_port_ref(state);
1225	if (!uport)
1226	return -EIO;
1227	uart_port_lock_irq(up: uport);
1228	memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));
1229	uart_enable_ms(uport);
1230	uart_port_unlock_irq(up: uport);
1231
1232	add_wait_queue(wq_head: &port->delta_msr_wait, wq_entry: &wait);
1233	for (;;) {
1234	uart_port_lock_irq(up: uport);
1235	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1236	uart_port_unlock_irq(up: uport);
1237
1238	set_current_state(TASK_INTERRUPTIBLE);
1239
1240	if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
1241	((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
1242	((arg & TIOCM_CD) && (cnow.dcd != cprev.dcd)) ||
1243	((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
1244	ret = 0;
1245	break;
1246	}
1247
1248	schedule();
1249
1250	/* see if a signal did it */
1251	if (signal_pending(current)) {
1252	ret = -ERESTARTSYS;
1253	break;
1254	}
1255
1256	cprev = cnow;
1257	}
1258	__set_current_state(TASK_RUNNING);
1259	remove_wait_queue(wq_head: &port->delta_msr_wait, wq_entry: &wait);
1260	uart_port_deref(uport);
1261
1262	return ret;
1263	}
1264
1265	/*
1266	* Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
1267	* Return: write counters to the user passed counter struct
1268	* NB: both 1->0 and 0->1 transitions are counted except for
1269	* RI where only 0->1 is counted.
1270	*/
1271	static int uart_get_icount(struct tty_struct *tty,
1272	struct serial_icounter_struct *icount)
1273	{
1274	struct uart_state *state = tty->driver_data;
1275	struct uart_icount cnow;
1276	struct uart_port *uport;
1277
1278	uport = uart_port_ref(state);
1279	if (!uport)
1280	return -EIO;
1281	uart_port_lock_irq(up: uport);
1282	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1283	uart_port_unlock_irq(up: uport);
1284	uart_port_deref(uport);
1285
1286	icount->cts = cnow.cts;
1287	icount->dsr = cnow.dsr;
1288	icount->rng = cnow.rng;
1289	icount->dcd = cnow.dcd;
1290	icount->rx = cnow.rx;
1291	icount->tx = cnow.tx;
1292	icount->frame = cnow.frame;
1293	icount->overrun = cnow.overrun;
1294	icount->parity = cnow.parity;
1295	icount->brk = cnow.brk;
1296	icount->buf_overrun = cnow.buf_overrun;
1297
1298	return 0;
1299	}
1300
1301	#define SER_RS485_LEGACY_FLAGS (SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
1302	SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
1303	SER_RS485_TERMINATE_BUS)
1304
1305	static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485)
1306	{
1307	u32 flags = rs485->flags;
1308
1309	/* Don't return -EINVAL for unsupported legacy flags */
1310	flags &= ~SER_RS485_LEGACY_FLAGS;
1311
1312	/*
1313	* For any bit outside of the legacy ones that is not supported by
1314	* the driver, return -EINVAL.
1315	*/
1316	if (flags & ~port->rs485_supported.flags)
1317	return -EINVAL;
1318
1319	/* Asking for address w/o addressing mode? */
1320	if (!(rs485->flags & SER_RS485_ADDRB) &&
1321	(rs485->flags & (SER_RS485_ADDR_RECV|SER_RS485_ADDR_DEST)))
1322	return -EINVAL;
1323
1324	/* Address given but not enabled? */
1325	if (!(rs485->flags & SER_RS485_ADDR_RECV) && rs485->addr_recv)
1326	return -EINVAL;
1327	if (!(rs485->flags & SER_RS485_ADDR_DEST) && rs485->addr_dest)
1328	return -EINVAL;
1329
1330	return 0;
1331	}
1332
1333	static void uart_sanitize_serial_rs485_delays(struct uart_port *port,
1334	struct serial_rs485 *rs485)
1335	{
1336	if (!port->rs485_supported.delay_rts_before_send) {
1337	if (rs485->delay_rts_before_send) {
1338	dev_warn_ratelimited(port->dev,
1339	"%s (%d): RTS delay before sending not supported\n",
1340	port->name, port->line);
1341	}
1342	rs485->delay_rts_before_send = 0;
1343	} else if (rs485->delay_rts_before_send > RS485_MAX_RTS_DELAY) {
1344	rs485->delay_rts_before_send = RS485_MAX_RTS_DELAY;
1345	dev_warn_ratelimited(port->dev,
1346	"%s (%d): RTS delay before sending clamped to %u ms\n",
1347	port->name, port->line, rs485->delay_rts_before_send);
1348	}
1349
1350	if (!port->rs485_supported.delay_rts_after_send) {
1351	if (rs485->delay_rts_after_send) {
1352	dev_warn_ratelimited(port->dev,
1353	"%s (%d): RTS delay after sending not supported\n",
1354	port->name, port->line);
1355	}
1356	rs485->delay_rts_after_send = 0;
1357	} else if (rs485->delay_rts_after_send > RS485_MAX_RTS_DELAY) {
1358	rs485->delay_rts_after_send = RS485_MAX_RTS_DELAY;
1359	dev_warn_ratelimited(port->dev,
1360	"%s (%d): RTS delay after sending clamped to %u ms\n",
1361	port->name, port->line, rs485->delay_rts_after_send);
1362	}
1363	}
1364
1365	static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs485 *rs485)
1366	{
1367	u32 supported_flags = port->rs485_supported.flags;
1368
1369	if (!(rs485->flags & SER_RS485_ENABLED)) {
1370	memset(rs485, 0, sizeof(*rs485));
1371	return;
1372	}
1373
1374	/* Pick sane settings if the user hasn't */
1375	if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
1376	!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
1377	!(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
1378	dev_warn_ratelimited(port->dev,
1379	"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
1380	port->name, port->line);
1381	rs485->flags |= SER_RS485_RTS_ON_SEND;
1382	rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
1383	supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND;
1384	}
1385
1386	rs485->flags &= supported_flags;
1387
1388	uart_sanitize_serial_rs485_delays(port, rs485);
1389
1390	/* Return clean padding area to userspace */
1391	memset(rs485->padding0, 0, sizeof(rs485->padding0));
1392	memset(rs485->padding1, 0, sizeof(rs485->padding1));
1393	}
1394
1395	static void uart_set_rs485_termination(struct uart_port *port,
1396	const struct serial_rs485 *rs485)
1397	{
1398	if (!(rs485->flags & SER_RS485_ENABLED))
1399	return;
1400
1401	gpiod_set_value_cansleep(desc: port->rs485_term_gpio,
1402	value: !!(rs485->flags & SER_RS485_TERMINATE_BUS));
1403	}
1404
1405	static int uart_rs485_config(struct uart_port *port)
1406	{
1407	struct serial_rs485 *rs485 = &port->rs485;
1408	unsigned long flags;
1409	int ret;
1410
1411	if (!(rs485->flags & SER_RS485_ENABLED))
1412	return 0;
1413
1414	uart_sanitize_serial_rs485(port, rs485);
1415	uart_set_rs485_termination(port, rs485);
1416
1417	uart_port_lock_irqsave(up: port, flags: &flags);
1418	ret = port->rs485_config(port, NULL, rs485);
1419	uart_port_unlock_irqrestore(up: port, flags);
1420	if (ret)
1421	memset(rs485, 0, sizeof(*rs485));
1422
1423	return ret;
1424	}
1425
1426	static int uart_get_rs485_config(struct uart_port *port,
1427	struct serial_rs485 __user *rs485)
1428	{
1429	unsigned long flags;
1430	struct serial_rs485 aux;
1431
1432	uart_port_lock_irqsave(up: port, flags: &flags);
1433	aux = port->rs485;
1434	uart_port_unlock_irqrestore(up: port, flags);
1435
1436	if (copy_to_user(to: rs485, from: &aux, n: sizeof(aux)))
1437	return -EFAULT;
1438
1439	return 0;
1440	}
1441
1442	static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
1443	struct serial_rs485 __user *rs485_user)
1444	{
1445	struct serial_rs485 rs485;
1446	int ret;
1447	unsigned long flags;
1448
1449	if (!port->rs485_config)
1450	return -ENOTTY;
1451
1452	if (copy_from_user(to: &rs485, from: rs485_user, n: sizeof(*rs485_user)))
1453	return -EFAULT;
1454
1455	ret = uart_check_rs485_flags(port, rs485: &rs485);
1456	if (ret)
1457	return ret;
1458	uart_sanitize_serial_rs485(port, rs485: &rs485);
1459	uart_set_rs485_termination(port, rs485: &rs485);
1460
1461	uart_port_lock_irqsave(up: port, flags: &flags);
1462	ret = port->rs485_config(port, &tty->termios, &rs485);
1463	if (!ret) {
1464	port->rs485 = rs485;
1465
1466	/* Reset RTS and other mctrl lines when disabling RS485 */
1467	if (!(rs485.flags & SER_RS485_ENABLED))
1468	port->ops->set_mctrl(port, port->mctrl);
1469	}
1470	uart_port_unlock_irqrestore(up: port, flags);
1471	if (ret)
1472	return ret;
1473
1474	if (copy_to_user(to: rs485_user, from: &port->rs485, n: sizeof(port->rs485)))
1475	return -EFAULT;
1476
1477	return 0;
1478	}
1479
1480	static int uart_get_iso7816_config(struct uart_port *port,
1481	struct serial_iso7816 __user *iso7816)
1482	{
1483	unsigned long flags;
1484	struct serial_iso7816 aux;
1485
1486	if (!port->iso7816_config)
1487	return -ENOTTY;
1488
1489	uart_port_lock_irqsave(up: port, flags: &flags);
1490	aux = port->iso7816;
1491	uart_port_unlock_irqrestore(up: port, flags);
1492
1493	if (copy_to_user(to: iso7816, from: &aux, n: sizeof(aux)))
1494	return -EFAULT;
1495
1496	return 0;
1497	}
1498
1499	static int uart_set_iso7816_config(struct uart_port *port,
1500	struct serial_iso7816 __user *iso7816_user)
1501	{
1502	struct serial_iso7816 iso7816;
1503	int i, ret;
1504	unsigned long flags;
1505
1506	if (!port->iso7816_config)
1507	return -ENOTTY;
1508
1509	if (copy_from_user(to: &iso7816, from: iso7816_user, n: sizeof(*iso7816_user)))
1510	return -EFAULT;
1511
1512	/*
1513	* There are 5 words reserved for future use. Check that userspace
1514	* doesn't put stuff in there to prevent breakages in the future.
1515	*/
1516	for (i = 0; i < ARRAY_SIZE(iso7816.reserved); i++)
1517	if (iso7816.reserved[i])
1518	return -EINVAL;
1519
1520	uart_port_lock_irqsave(up: port, flags: &flags);
1521	ret = port->iso7816_config(port, &iso7816);
1522	uart_port_unlock_irqrestore(up: port, flags);
1523	if (ret)
1524	return ret;
1525
1526	if (copy_to_user(to: iso7816_user, from: &port->iso7816, n: sizeof(port->iso7816)))
1527	return -EFAULT;
1528
1529	return 0;
1530	}
1531
1532	/*
1533	* Called via sys_ioctl. We can use spin_lock_irq() here.
1534	*/
1535	static int
1536	uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
1537	{
1538	struct uart_state *state = tty->driver_data;
1539	struct tty_port *port = &state->port;
1540	struct uart_port *uport;
1541	void __user *uarg = (void __user *)arg;
1542	int ret = -ENOIOCTLCMD;
1543
1544
1545	/*
1546	* These ioctls don't rely on the hardware to be present.
1547	*/
1548	switch (cmd) {
1549	case TIOCSERCONFIG:
1550	down_write(sem: &tty->termios_rwsem);
1551	ret = uart_do_autoconfig(tty, state);
1552	up_write(sem: &tty->termios_rwsem);
1553	break;
1554	}
1555
1556	if (ret != -ENOIOCTLCMD)
1557	goto out;
1558
1559	if (tty_io_error(tty)) {
1560	ret = -EIO;
1561	goto out;
1562	}
1563
1564	/*
1565	* The following should only be used when hardware is present.
1566	*/
1567	switch (cmd) {
1568	case TIOCMIWAIT:
1569	ret = uart_wait_modem_status(state, arg);
1570	break;
1571	}
1572
1573	if (ret != -ENOIOCTLCMD)
1574	goto out;
1575
1576	/* rs485_config requires more locking than others */
1577	if (cmd == TIOCSRS485)
1578	down_write(sem: &tty->termios_rwsem);
1579
1580	mutex_lock(&port->mutex);
1581	uport = uart_port_check(state);
1582
1583	if (!uport || tty_io_error(tty)) {
1584	ret = -EIO;
1585	goto out_up;
1586	}
1587
1588	/*
1589	* All these rely on hardware being present and need to be
1590	* protected against the tty being hung up.
1591	*/
1592
1593	switch (cmd) {
1594	case TIOCSERGETLSR: /* Get line status register */
1595	ret = uart_get_lsr_info(tty, state, value: uarg);
1596	break;
1597
1598	case TIOCGRS485:
1599	ret = uart_get_rs485_config(port: uport, rs485: uarg);
1600	break;
1601
1602	case TIOCSRS485:
1603	ret = uart_set_rs485_config(tty, port: uport, rs485_user: uarg);
1604	break;
1605
1606	case TIOCSISO7816:
1607	ret = uart_set_iso7816_config(port: state->uart_port, iso7816_user: uarg);
1608	break;
1609
1610	case TIOCGISO7816:
1611	ret = uart_get_iso7816_config(port: state->uart_port, iso7816: uarg);
1612	break;
1613	default:
1614	if (uport->ops->ioctl)
1615	ret = uport->ops->ioctl(uport, cmd, arg);
1616	break;
1617	}
1618	out_up:
1619	mutex_unlock(lock: &port->mutex);
1620	if (cmd == TIOCSRS485)
1621	up_write(sem: &tty->termios_rwsem);
1622	out:
1623	return ret;
1624	}
1625
1626	static void uart_set_ldisc(struct tty_struct *tty)
1627	{
1628	struct uart_state *state = tty->driver_data;
1629	struct uart_port *uport;
1630	struct tty_port *port = &state->port;
1631
1632	if (!tty_port_initialized(port))
1633	return;
1634
1635	mutex_lock(&state->port.mutex);
1636	uport = uart_port_check(state);
1637	if (uport && uport->ops->set_ldisc)
1638	uport->ops->set_ldisc(uport, &tty->termios);
1639	mutex_unlock(lock: &state->port.mutex);
1640	}
1641
1642	static void uart_set_termios(struct tty_struct *tty,
1643	const struct ktermios *old_termios)
1644	{
1645	struct uart_state *state = tty->driver_data;
1646	struct uart_port *uport;
1647	unsigned int cflag = tty->termios.c_cflag;
1648	unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
1649	bool sw_changed = false;
1650
1651	mutex_lock(&state->port.mutex);
1652	uport = uart_port_check(state);
1653	if (!uport)
1654	goto out;
1655
1656	/*
1657	* Drivers doing software flow control also need to know
1658	* about changes to these input settings.
1659	*/
1660	if (uport->flags & UPF_SOFT_FLOW) {
1661	iflag_mask |= IXANY|IXON|IXOFF;
1662	sw_changed =
1663	tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
1664	tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
1665	}
1666
1667	/*
1668	* These are the bits that are used to setup various
1669	* flags in the low level driver. We can ignore the Bfoo
1670	* bits in c_cflag; c_[io]speed will always be set
1671	* appropriately by set_termios() in tty_ioctl.c
1672	*/
1673	if ((cflag ^ old_termios->c_cflag) == 0 &&
1674	tty->termios.c_ospeed == old_termios->c_ospeed &&
1675	tty->termios.c_ispeed == old_termios->c_ispeed &&
1676	((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
1677	!sw_changed) {
1678	goto out;
1679	}
1680
1681	uart_change_line_settings(tty, state, old_termios);
1682	/* reload cflag from termios; port driver may have overridden flags */
1683	cflag = tty->termios.c_cflag;
1684
1685	/* Handle transition to B0 status */
1686	if (((old_termios->c_cflag & CBAUD) != B0) && ((cflag & CBAUD) == B0))
1687	uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
1688	/* Handle transition away from B0 status */
1689	else if (((old_termios->c_cflag & CBAUD) == B0) && ((cflag & CBAUD) != B0)) {
1690	unsigned int mask = TIOCM_DTR;
1691
1692	if (!(cflag & CRTSCTS) || !tty_throttled(tty))
1693	mask |= TIOCM_RTS;
1694	uart_set_mctrl(uport, mask);
1695	}
1696	out:
1697	mutex_unlock(lock: &state->port.mutex);
1698	}
1699
1700	/*
1701	* Calls to uart_close() are serialised via the tty_lock in
1702	* drivers/tty/tty_io.c:tty_release()
1703	* drivers/tty/tty_io.c:do_tty_hangup()
1704	*/
1705	static void uart_close(struct tty_struct *tty, struct file *filp)
1706	{
1707	struct uart_state *state = tty->driver_data;
1708
1709	if (!state) {
1710	struct uart_driver *drv = tty->driver->driver_state;
1711	struct tty_port *port;
1712
1713	state = drv->state + tty->index;
1714	port = &state->port;
1715	spin_lock_irq(lock: &port->lock);
1716	--port->count;
1717	spin_unlock_irq(lock: &port->lock);
1718	return;
1719	}
1720
1721	pr_debug("uart_close(%d) called\n", tty->index);
1722
1723	tty_port_close(port: tty->port, tty, filp);
1724	}
1725
1726	static void uart_tty_port_shutdown(struct tty_port *port)
1727	{
1728	struct uart_state *state = container_of(port, struct uart_state, port);
1729	struct uart_port *uport = uart_port_check(state);
1730	char *buf;
1731
1732	/*
1733	* At this point, we stop accepting input. To do this, we
1734	* disable the receive line status interrupts.
1735	*/
1736	if (WARN(!uport, "detached port still initialized!\n"))
1737	return;
1738
1739	uart_port_lock_irq(up: uport);
1740	uport->ops->stop_rx(uport);
1741	uart_port_unlock_irq(up: uport);
1742
1743	uart_port_shutdown(port);
1744
1745	/*
1746	* It's possible for shutdown to be called after suspend if we get
1747	* a DCD drop (hangup) at just the right time. Clear suspended bit so
1748	* we don't try to resume a port that has been shutdown.
1749	*/
1750	tty_port_set_suspended(port, val: false);
1751
1752	/*
1753	* Free the transmit buffer.
1754	*/
1755	uart_port_lock_irq(up: uport);
1756	buf = state->xmit.buf;
1757	state->xmit.buf = NULL;
1758	uart_port_unlock_irq(up: uport);
1759
1760	free_page((unsigned long)buf);
1761
1762	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
1763	}
1764
1765	static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
1766	{
1767	struct uart_state *state = tty->driver_data;
1768	struct uart_port *port;
1769	unsigned long char_time, expire, fifo_timeout;
1770
1771	port = uart_port_ref(state);
1772	if (!port)
1773	return;
1774
1775	if (port->type == PORT_UNKNOWN || port->fifosize == 0) {
1776	uart_port_deref(uport: port);
1777	return;
1778	}
1779
1780	/*
1781	* Set the check interval to be 1/5 of the estimated time to
1782	* send a single character, and make it at least 1. The check
1783	* interval should also be less than the timeout.
1784	*
1785	* Note: we have to use pretty tight timings here to satisfy
1786	* the NIST-PCTS.
1787	*/
1788	char_time = max(nsecs_to_jiffies(port->frame_time / 5), 1UL);
1789
1790	if (timeout && timeout < char_time)
1791	char_time = timeout;
1792
1793	if (!uart_cts_enabled(uport: port)) {
1794	/*
1795	* If the transmitter hasn't cleared in twice the approximate
1796	* amount of time to send the entire FIFO, it probably won't
1797	* ever clear. This assumes the UART isn't doing flow
1798	* control, which is currently the case. Hence, if it ever
1799	* takes longer than FIFO timeout, this is probably due to a
1800	* UART bug of some kind. So, we clamp the timeout parameter at
1801	* 2 * FIFO timeout.
1802	*/
1803	fifo_timeout = uart_fifo_timeout(port);
1804	if (timeout == 0 || timeout > 2 * fifo_timeout)
1805	timeout = 2 * fifo_timeout;
1806	}
1807
1808	expire = jiffies + timeout;
1809
1810	pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
1811	port->line, jiffies, expire);
1812
1813	/*
1814	* Check whether the transmitter is empty every 'char_time'.
1815	* 'timeout' / 'expire' give us the maximum amount of time
1816	* we wait.
1817	*/
1818	while (!port->ops->tx_empty(port)) {
1819	msleep_interruptible(msecs: jiffies_to_msecs(j: char_time));
1820	if (signal_pending(current))
1821	break;
1822	if (timeout && time_after(jiffies, expire))
1823	break;
1824	}
1825	uart_port_deref(uport: port);
1826	}
1827
1828	/*
1829	* Calls to uart_hangup() are serialised by the tty_lock in
1830	* drivers/tty/tty_io.c:do_tty_hangup()
1831	* This runs from a workqueue and can sleep for a _short_ time only.
1832	*/
1833	static void uart_hangup(struct tty_struct *tty)
1834	{
1835	struct uart_state *state = tty->driver_data;
1836	struct tty_port *port = &state->port;
1837	struct uart_port *uport;
1838	unsigned long flags;
1839
1840	pr_debug("uart_hangup(%d)\n", tty->index);
1841
1842	mutex_lock(&port->mutex);
1843	uport = uart_port_check(state);
1844	WARN(!uport, "hangup of detached port!\n");
1845
1846	if (tty_port_active(port)) {
1847	uart_flush_buffer(tty);
1848	uart_shutdown(tty, state);
1849	spin_lock_irqsave(&port->lock, flags);
1850	port->count = 0;
1851	spin_unlock_irqrestore(lock: &port->lock, flags);
1852	tty_port_set_active(port, val: false);
1853	tty_port_tty_set(port, NULL);
1854	if (uport && !uart_console(uport))
1855	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
1856	wake_up_interruptible(&port->open_wait);
1857	wake_up_interruptible(&port->delta_msr_wait);
1858	}
1859	mutex_unlock(lock: &port->mutex);
1860	}
1861
1862	/* uport == NULL if uart_port has already been removed */
1863	static void uart_port_shutdown(struct tty_port *port)
1864	{
1865	struct uart_state *state = container_of(port, struct uart_state, port);
1866	struct uart_port *uport = uart_port_check(state);
1867
1868	/*
1869	* clear delta_msr_wait queue to avoid mem leaks: we may free
1870	* the irq here so the queue might never be woken up. Note
1871	* that we won't end up waiting on delta_msr_wait again since
1872	* any outstanding file descriptors should be pointing at
1873	* hung_up_tty_fops now.
1874	*/
1875	wake_up_interruptible(&port->delta_msr_wait);
1876
1877	if (uport) {
1878	/* Free the IRQ and disable the port. */
1879	uport->ops->shutdown(uport);
1880
1881	/* Ensure that the IRQ handler isn't running on another CPU. */
1882	synchronize_irq(irq: uport->irq);
1883	}
1884	}
1885
1886	static bool uart_carrier_raised(struct tty_port *port)
1887	{
1888	struct uart_state *state = container_of(port, struct uart_state, port);
1889	struct uart_port *uport;
1890	int mctrl;
1891
1892	uport = uart_port_ref(state);
1893	/*
1894	* Should never observe uport == NULL since checks for hangup should
1895	* abort the tty_port_block_til_ready() loop before checking for carrier
1896	* raised -- but report carrier raised if it does anyway so open will
1897	* continue and not sleep
1898	*/
1899	if (WARN_ON(!uport))
1900	return true;
1901	uart_port_lock_irq(up: uport);
1902	uart_enable_ms(uport);
1903	mctrl = uport->ops->get_mctrl(uport);
1904	uart_port_unlock_irq(up: uport);
1905	uart_port_deref(uport);
1906
1907	return mctrl & TIOCM_CAR;
1908	}
1909
1910	static void uart_dtr_rts(struct tty_port *port, bool active)
1911	{
1912	struct uart_state *state = container_of(port, struct uart_state, port);
1913	struct uart_port *uport;
1914
1915	uport = uart_port_ref(state);
1916	if (!uport)
1917	return;
1918	uart_port_dtr_rts(uport, active);
1919	uart_port_deref(uport);
1920	}
1921
1922	static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
1923	{
1924	struct uart_driver *drv = driver->driver_state;
1925	struct uart_state *state = drv->state + tty->index;
1926
1927	tty->driver_data = state;
1928
1929	return tty_standard_install(driver, tty);
1930	}
1931
1932	/*
1933	* Calls to uart_open are serialised by the tty_lock in
1934	* drivers/tty/tty_io.c:tty_open()
1935	* Note that if this fails, then uart_close() _will_ be called.
1936	*
1937	* In time, we want to scrap the "opening nonpresent ports"
1938	* behaviour and implement an alternative way for setserial
1939	* to set base addresses/ports/types. This will allow us to
1940	* get rid of a certain amount of extra tests.
1941	*/
1942	static int uart_open(struct tty_struct *tty, struct file *filp)
1943	{
1944	struct uart_state *state = tty->driver_data;
1945	int retval;
1946
1947	retval = tty_port_open(port: &state->port, tty, filp);
1948	if (retval > 0)
1949	retval = 0;
1950
1951	return retval;
1952	}
1953
1954	static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
1955	{
1956	struct uart_state *state = container_of(port, struct uart_state, port);
1957	struct uart_port *uport;
1958	int ret;
1959
1960	uport = uart_port_check(state);
1961	if (!uport || uport->flags & UPF_DEAD)
1962	return -ENXIO;
1963
1964	/*
1965	* Start up the serial port.
1966	*/
1967	ret = uart_startup(tty, state, init_hw: false);
1968	if (ret > 0)
1969	tty_port_set_active(port, val: true);
1970
1971	return ret;
1972	}
1973
1974	static const char *uart_type(struct uart_port *port)
1975	{
1976	const char *str = NULL;
1977
1978	if (port->ops->type)
1979	str = port->ops->type(port);
1980
1981	if (!str)
1982	str = "unknown";
1983
1984	return str;
1985	}
1986
1987	#ifdef CONFIG_PROC_FS
1988
1989	static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
1990	{
1991	struct uart_state *state = drv->state + i;
1992	struct tty_port *port = &state->port;
1993	enum uart_pm_state pm_state;
1994	struct uart_port *uport;
1995	char stat_buf[32];
1996	unsigned int status;
1997	int mmio;
1998
1999	mutex_lock(&port->mutex);
2000	uport = uart_port_check(state);
2001	if (!uport)
2002	goto out;
2003
2004	mmio = uport->iotype >= UPIO_MEM;
2005	seq_printf(m, fmt: "%d: uart:%s %s%08llX irq:%d",
2006	uport->line, uart_type(port: uport),
2007	mmio ? "mmio:0x" : "port:",
2008	mmio ? (unsigned long long)uport->mapbase
2009	: (unsigned long long)uport->iobase,
2010	uport->irq);
2011
2012	if (uport->type == PORT_UNKNOWN) {
2013	seq_putc(m, c: '\n');
2014	goto out;
2015	}
2016
2017	if (capable(CAP_SYS_ADMIN)) {
2018	pm_state = state->pm_state;
2019	if (pm_state != UART_PM_STATE_ON)
2020	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2021	uart_port_lock_irq(up: uport);
2022	status = uport->ops->get_mctrl(uport);
2023	uart_port_unlock_irq(up: uport);
2024	if (pm_state != UART_PM_STATE_ON)
2025	uart_change_pm(state, pm_state);
2026
2027	seq_printf(m, fmt: " tx:%d rx:%d",
2028	uport->icount.tx, uport->icount.rx);
2029	if (uport->icount.frame)
2030	seq_printf(m, fmt: " fe:%d", uport->icount.frame);
2031	if (uport->icount.parity)
2032	seq_printf(m, fmt: " pe:%d", uport->icount.parity);
2033	if (uport->icount.brk)
2034	seq_printf(m, fmt: " brk:%d", uport->icount.brk);
2035	if (uport->icount.overrun)
2036	seq_printf(m, fmt: " oe:%d", uport->icount.overrun);
2037	if (uport->icount.buf_overrun)
2038	seq_printf(m, fmt: " bo:%d", uport->icount.buf_overrun);
2039
2040	#define INFOBIT(bit, str) \
2041	if (uport->mctrl & (bit)) \
2042	strncat(stat_buf, (str), sizeof(stat_buf) - \
2043	strlen(stat_buf) - 2)
2044	#define STATBIT(bit, str) \
2045	if (status & (bit)) \
2046	strncat(stat_buf, (str), sizeof(stat_buf) - \
2047	strlen(stat_buf) - 2)
2048
2049	stat_buf[0] = '\0';
2050	stat_buf[1] = '\0';
2051	INFOBIT(TIOCM_RTS, "|RTS");
2052	STATBIT(TIOCM_CTS, "|CTS");
2053	INFOBIT(TIOCM_DTR, "|DTR");
2054	STATBIT(TIOCM_DSR, "|DSR");
2055	STATBIT(TIOCM_CAR, "|CD");
2056	STATBIT(TIOCM_RNG, "|RI");
2057	if (stat_buf[0])
2058	stat_buf[0] = ' ';
2059
2060	seq_puts(m, s: stat_buf);
2061	}
2062	seq_putc(m, c: '\n');
2063	#undef STATBIT
2064	#undef INFOBIT
2065	out:
2066	mutex_unlock(lock: &port->mutex);
2067	}
2068
2069	static int uart_proc_show(struct seq_file *m, void *v)
2070	{
2071	struct tty_driver *ttydrv = m->private;
2072	struct uart_driver *drv = ttydrv->driver_state;
2073	int i;
2074
2075	seq_printf(m, fmt: "serinfo:1.0 driver%s%s revision:%s\n", "", "", "");
2076	for (i = 0; i < drv->nr; i++)
2077	uart_line_info(m, drv, i);
2078	return 0;
2079	}
2080	#endif
2081
2082	static void uart_port_spin_lock_init(struct uart_port *port)
2083	{
2084	spin_lock_init(&port->lock);
2085	lockdep_set_class(&port->lock, &port_lock_key);
2086	}
2087
2088	#if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
2089	/**
2090	* uart_console_write - write a console message to a serial port
2091	* @port: the port to write the message
2092	* @s: array of characters
2093	* @count: number of characters in string to write
2094	* @putchar: function to write character to port
2095	*/
2096	void uart_console_write(struct uart_port *port, const char *s,
2097	unsigned int count,
2098	void (*putchar)(struct uart_port *, unsigned char))
2099	{
2100	unsigned int i;
2101
2102	for (i = 0; i < count; i++, s++) {
2103	if (*s == '\n')
2104	putchar(port, '\r');
2105	putchar(port, *s);
2106	}
2107	}
2108	EXPORT_SYMBOL_GPL(uart_console_write);
2109
2110	/**
2111	* uart_get_console - get uart port for console
2112	* @ports: ports to search in
2113	* @nr: number of @ports
2114	* @co: console to search for
2115	* Returns: uart_port for the console @co
2116	*
2117	* Check whether an invalid uart number has been specified (as @co->index), and
2118	* if so, search for the first available port that does have console support.
2119	*/
2120	struct uart_port * __init
2121	uart_get_console(struct uart_port *ports, int nr, struct console *co)
2122	{
2123	int idx = co->index;
2124
2125	if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
2126	ports[idx].membase == NULL))
2127	for (idx = 0; idx < nr; idx++)
2128	if (ports[idx].iobase != 0 ||
2129	ports[idx].membase != NULL)
2130	break;
2131
2132	co->index = idx;
2133
2134	return ports + idx;
2135	}
2136
2137	/**
2138	* uart_parse_earlycon - Parse earlycon options
2139	* @p: ptr to 2nd field (ie., just beyond '<name>,')
2140	* @iotype: ptr for decoded iotype (out)
2141	* @addr: ptr for decoded mapbase/iobase (out)
2142	* @options: ptr for <options> field; %NULL if not present (out)
2143	*
2144	* Decodes earlycon kernel command line parameters of the form:
2145	* * earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2146	* * console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2147	*
2148	* The optional form:
2149	* * earlycon=<name>,0x<addr>,<options>
2150	* * console=<name>,0x<addr>,<options>
2151	*
2152	* is also accepted; the returned @iotype will be %UPIO_MEM.
2153	*
2154	* Returns: 0 on success or -%EINVAL on failure
2155	*/
2156	int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
2157	char **options)
2158	{
2159	if (strncmp(p, "mmio,", 5) == 0) {
2160	*iotype = UPIO_MEM;
2161	p += 5;
2162	} else if (strncmp(p, "mmio16,", 7) == 0) {
2163	*iotype = UPIO_MEM16;
2164	p += 7;
2165	} else if (strncmp(p, "mmio32,", 7) == 0) {
2166	*iotype = UPIO_MEM32;
2167	p += 7;
2168	} else if (strncmp(p, "mmio32be,", 9) == 0) {
2169	*iotype = UPIO_MEM32BE;
2170	p += 9;
2171	} else if (strncmp(p, "mmio32native,", 13) == 0) {
2172	*iotype = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ?
2173	UPIO_MEM32BE : UPIO_MEM32;
2174	p += 13;
2175	} else if (strncmp(p, "io,", 3) == 0) {
2176	*iotype = UPIO_PORT;
2177	p += 3;
2178	} else if (strncmp(p, "0x", 2) == 0) {
2179	*iotype = UPIO_MEM;
2180	} else {
2181	return -EINVAL;
2182	}
2183
2184	/*
2185	* Before you replace it with kstrtoull(), think about options separator
2186	* (',') it will not tolerate
2187	*/
2188	*addr = simple_strtoull(p, NULL, 0);
2189	p = strchr(p, ',');
2190	if (p)
2191	p++;
2192
2193	*options = p;
2194	return 0;
2195	}
2196	EXPORT_SYMBOL_GPL(uart_parse_earlycon);
2197
2198	/**
2199	* uart_parse_options - Parse serial port baud/parity/bits/flow control.
2200	* @options: pointer to option string
2201	* @baud: pointer to an 'int' variable for the baud rate.
2202	* @parity: pointer to an 'int' variable for the parity.
2203	* @bits: pointer to an 'int' variable for the number of data bits.
2204	* @flow: pointer to an 'int' variable for the flow control character.
2205	*
2206	* uart_parse_options() decodes a string containing the serial console
2207	* options. The format of the string is <baud><parity><bits><flow>,
2208	* eg: 115200n8r
2209	*/
2210	void
2211	uart_parse_options(const char *options, int *baud, int *parity,
2212	int *bits, int *flow)
2213	{
2214	const char *s = options;
2215
2216	*baud = simple_strtoul(s, NULL, 10);
2217	while (*s >= '0' && *s <= '9')
2218	s++;
2219	if (*s)
2220	*parity = *s++;
2221	if (*s)
2222	*bits = *s++ - '0';
2223	if (*s)
2224	*flow = *s;
2225	}
2226	EXPORT_SYMBOL_GPL(uart_parse_options);
2227
2228	/**
2229	* uart_set_options - setup the serial console parameters
2230	* @port: pointer to the serial ports uart_port structure
2231	* @co: console pointer
2232	* @baud: baud rate
2233	* @parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
2234	* @bits: number of data bits
2235	* @flow: flow control character - 'r' (rts)
2236	*
2237	* Locking: Caller must hold console_list_lock in order to serialize
2238	* early initialization of the serial-console lock.
2239	*/
2240	int
2241	uart_set_options(struct uart_port *port, struct console *co,
2242	int baud, int parity, int bits, int flow)
2243	{
2244	struct ktermios termios;
2245	static struct ktermios dummy;
2246
2247	/*
2248	* Ensure that the serial-console lock is initialised early.
2249	*
2250	* Note that the console-registered check is needed because
2251	* kgdboc can call uart_set_options() for an already registered
2252	* console via tty_find_polling_driver() and uart_poll_init().
2253	*/
2254	if (!uart_console_registered_locked(port) && !port->console_reinit)
2255	uart_port_spin_lock_init(port);
2256
2257	memset(&termios, 0, sizeof(struct ktermios));
2258
2259	termios.c_cflag |= CREAD | HUPCL | CLOCAL;
2260	tty_termios_encode_baud_rate(termios: &termios, ibaud: baud, obaud: baud);
2261
2262	if (bits == 7)
2263	termios.c_cflag |= CS7;
2264	else
2265	termios.c_cflag |= CS8;
2266
2267	switch (parity) {
2268	case 'o': case 'O':
2269	termios.c_cflag |= PARODD;
2270	fallthrough;
2271	case 'e': case 'E':
2272	termios.c_cflag |= PARENB;
2273	break;
2274	}
2275
2276	if (flow == 'r')
2277	termios.c_cflag |= CRTSCTS;
2278
2279	/*
2280	* some uarts on other side don't support no flow control.
2281	* So we set * DTR in host uart to make them happy
2282	*/
2283	port->mctrl |= TIOCM_DTR;
2284
2285	port->ops->set_termios(port, &termios, &dummy);
2286	/*
2287	* Allow the setting of the UART parameters with a NULL console
2288	* too:
2289	*/
2290	if (co) {
2291	co->cflag = termios.c_cflag;
2292	co->ispeed = termios.c_ispeed;
2293	co->ospeed = termios.c_ospeed;
2294	}
2295
2296	return 0;
2297	}
2298	EXPORT_SYMBOL_GPL(uart_set_options);
2299	#endif /* CONFIG_SERIAL_CORE_CONSOLE */
2300
2301	/**
2302	* uart_change_pm - set power state of the port
2303	*
2304	* @state: port descriptor
2305	* @pm_state: new state
2306	*
2307	* Locking: port->mutex has to be held
2308	*/
2309	static void uart_change_pm(struct uart_state *state,
2310	enum uart_pm_state pm_state)
2311	{
2312	struct uart_port *port = uart_port_check(state);
2313
2314	if (state->pm_state != pm_state) {
2315	if (port && port->ops->pm)
2316	port->ops->pm(port, pm_state, state->pm_state);
2317	state->pm_state = pm_state;
2318	}
2319	}
2320
2321	struct uart_match {
2322	struct uart_port *port;
2323	struct uart_driver *driver;
2324	};
2325
2326	static int serial_match_port(struct device *dev, void *data)
2327	{
2328	struct uart_match *match = data;
2329	struct tty_driver *tty_drv = match->driver->tty_driver;
2330	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
2331	match->port->line;
2332
2333	return dev->devt == devt; /* Actually, only one tty per port */
2334	}
2335
2336	int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
2337	{
2338	struct uart_state *state = drv->state + uport->line;
2339	struct tty_port *port = &state->port;
2340	struct device *tty_dev;
2341	struct uart_match match = {uport, drv};
2342
2343	mutex_lock(&port->mutex);
2344
2345	tty_dev = device_find_child(dev: uport->dev, data: &match, match: serial_match_port);
2346	if (tty_dev && device_may_wakeup(dev: tty_dev)) {
2347	enable_irq_wake(irq: uport->irq);
2348	put_device(dev: tty_dev);
2349	mutex_unlock(lock: &port->mutex);
2350	return 0;
2351	}
2352	put_device(dev: tty_dev);
2353
2354	/*
2355	* Nothing to do if the console is not suspending
2356	* except stop_rx to prevent any asynchronous data
2357	* over RX line. However ensure that we will be
2358	* able to Re-start_rx later.
2359	*/
2360	if (!console_suspend_enabled && uart_console(uport)) {
2361	if (uport->ops->start_rx) {
2362	uart_port_lock_irq(up: uport);
2363	uport->ops->stop_rx(uport);
2364	uart_port_unlock_irq(up: uport);
2365	}
2366	goto unlock;
2367	}
2368
2369	uport->suspended = 1;
2370
2371	if (tty_port_initialized(port)) {
2372	const struct uart_ops *ops = uport->ops;
2373	int tries;
2374	unsigned int mctrl;
2375
2376	tty_port_set_suspended(port, val: true);
2377	tty_port_set_initialized(port, val: false);
2378
2379	uart_port_lock_irq(up: uport);
2380	ops->stop_tx(uport);
2381	if (!(uport->rs485.flags & SER_RS485_ENABLED))
2382	ops->set_mctrl(uport, 0);
2383	/* save mctrl so it can be restored on resume */
2384	mctrl = uport->mctrl;
2385	uport->mctrl = 0;
2386	ops->stop_rx(uport);
2387	uart_port_unlock_irq(up: uport);
2388
2389	/*
2390	* Wait for the transmitter to empty.
2391	*/
2392	for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
2393	msleep(msecs: 10);
2394	if (!tries)
2395	dev_err(uport->dev, "%s: Unable to drain transmitter\n",
2396	uport->name);
2397
2398	ops->shutdown(uport);
2399	uport->mctrl = mctrl;
2400	}
2401
2402	/*
2403	* Disable the console device before suspending.
2404	*/
2405	if (uart_console(uport))
2406	console_stop(uport->cons);
2407
2408	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
2409	unlock:
2410	mutex_unlock(lock: &port->mutex);
2411
2412	return 0;
2413	}
2414	EXPORT_SYMBOL(uart_suspend_port);
2415
2416	int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
2417	{
2418	struct uart_state *state = drv->state + uport->line;
2419	struct tty_port *port = &state->port;
2420	struct device *tty_dev;
2421	struct uart_match match = {uport, drv};
2422	struct ktermios termios;
2423
2424	mutex_lock(&port->mutex);
2425
2426	tty_dev = device_find_child(dev: uport->dev, data: &match, match: serial_match_port);
2427	if (!uport->suspended && device_may_wakeup(dev: tty_dev)) {
2428	if (irqd_is_wakeup_set(d: irq_get_irq_data(irq: (uport->irq))))
2429	disable_irq_wake(irq: uport->irq);
2430	put_device(dev: tty_dev);
2431	mutex_unlock(lock: &port->mutex);
2432	return 0;
2433	}
2434	put_device(dev: tty_dev);
2435	uport->suspended = 0;
2436
2437	/*
2438	* Re-enable the console device after suspending.
2439	*/
2440	if (uart_console(uport)) {
2441	/*
2442	* First try to use the console cflag setting.
2443	*/
2444	memset(&termios, 0, sizeof(struct ktermios));
2445	termios.c_cflag = uport->cons->cflag;
2446	termios.c_ispeed = uport->cons->ispeed;
2447	termios.c_ospeed = uport->cons->ospeed;
2448
2449	/*
2450	* If that's unset, use the tty termios setting.
2451	*/
2452	if (port->tty && termios.c_cflag == 0)
2453	termios = port->tty->termios;
2454
2455	if (console_suspend_enabled)
2456	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2457	uport->ops->set_termios(uport, &termios, NULL);
2458	if (!console_suspend_enabled && uport->ops->start_rx) {
2459	uart_port_lock_irq(up: uport);
2460	uport->ops->start_rx(uport);
2461	uart_port_unlock_irq(up: uport);
2462	}
2463	if (console_suspend_enabled)
2464	console_start(uport->cons);
2465	}
2466
2467	if (tty_port_suspended(port)) {
2468	const struct uart_ops *ops = uport->ops;
2469	int ret;
2470
2471	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2472	uart_port_lock_irq(up: uport);
2473	if (!(uport->rs485.flags & SER_RS485_ENABLED))
2474	ops->set_mctrl(uport, 0);
2475	uart_port_unlock_irq(up: uport);
2476	if (console_suspend_enabled || !uart_console(uport)) {
2477	/* Protected by port mutex for now */
2478	struct tty_struct *tty = port->tty;
2479
2480	ret = ops->startup(uport);
2481	if (ret == 0) {
2482	if (tty)
2483	uart_change_line_settings(tty, state, NULL);
2484	uart_rs485_config(port: uport);
2485	uart_port_lock_irq(up: uport);
2486	if (!(uport->rs485.flags & SER_RS485_ENABLED))
2487	ops->set_mctrl(uport, uport->mctrl);
2488	ops->start_tx(uport);
2489	uart_port_unlock_irq(up: uport);
2490	tty_port_set_initialized(port, val: true);
2491	} else {
2492	/*
2493	* Failed to resume - maybe hardware went away?
2494	* Clear the "initialized" flag so we won't try
2495	* to call the low level drivers shutdown method.
2496	*/
2497	uart_shutdown(tty, state);
2498	}
2499	}
2500
2501	tty_port_set_suspended(port, val: false);
2502	}
2503
2504	mutex_unlock(lock: &port->mutex);
2505
2506	return 0;
2507	}
2508	EXPORT_SYMBOL(uart_resume_port);
2509
2510	static inline void
2511	uart_report_port(struct uart_driver *drv, struct uart_port *port)
2512	{
2513	char address[64];
2514
2515	switch (port->iotype) {
2516	case UPIO_PORT:
2517	snprintf(buf: address, size: sizeof(address), fmt: "I/O 0x%lx", port->iobase);
2518	break;
2519	case UPIO_HUB6:
2520	snprintf(buf: address, size: sizeof(address),
2521	fmt: "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
2522	break;
2523	case UPIO_MEM:
2524	case UPIO_MEM16:
2525	case UPIO_MEM32:
2526	case UPIO_MEM32BE:
2527	case UPIO_AU:
2528	case UPIO_TSI:
2529	snprintf(buf: address, size: sizeof(address),
2530	fmt: "MMIO 0x%llx", (unsigned long long)port->mapbase);
2531	break;
2532	default:
2533	strscpy(p: address, q: "*unknown*", size: sizeof(address));
2534	break;
2535	}
2536
2537	pr_info("%s%s%s at %s (irq = %d, base_baud = %d) is a %s\n",
2538	port->dev ? dev_name(port->dev) : "",
2539	port->dev ? ": " : "",
2540	port->name,
2541	address, port->irq, port->uartclk / 16, uart_type(port));
2542
2543	/* The magic multiplier feature is a bit obscure, so report it too. */
2544	if (port->flags & UPF_MAGIC_MULTIPLIER)
2545	pr_info("%s%s%s extra baud rates supported: %d, %d",
2546	port->dev ? dev_name(port->dev) : "",
2547	port->dev ? ": " : "",
2548	port->name,
2549	port->uartclk / 8, port->uartclk / 4);
2550	}
2551
2552	static void
2553	uart_configure_port(struct uart_driver *drv, struct uart_state *state,
2554	struct uart_port *port)
2555	{
2556	unsigned int flags;
2557
2558	/*
2559	* If there isn't a port here, don't do anything further.
2560	*/
2561	if (!port->iobase && !port->mapbase && !port->membase)
2562	return;
2563
2564	/*
2565	* Now do the auto configuration stuff. Note that config_port
2566	* is expected to claim the resources and map the port for us.
2567	*/
2568	flags = 0;
2569	if (port->flags & UPF_AUTO_IRQ)
2570	flags |= UART_CONFIG_IRQ;
2571	if (port->flags & UPF_BOOT_AUTOCONF) {
2572	if (!(port->flags & UPF_FIXED_TYPE)) {
2573	port->type = PORT_UNKNOWN;
2574	flags |= UART_CONFIG_TYPE;
2575	}
2576	port->ops->config_port(port, flags);
2577	}
2578
2579	if (port->type != PORT_UNKNOWN) {
2580	unsigned long flags;
2581
2582	uart_report_port(drv, port);
2583
2584	/* Power up port for set_mctrl() */
2585	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2586
2587	/*
2588	* Ensure that the modem control lines are de-activated.
2589	* keep the DTR setting that is set in uart_set_options()
2590	* We probably don't need a spinlock around this, but
2591	*/
2592	uart_port_lock_irqsave(up: port, flags: &flags);
2593	port->mctrl &= TIOCM_DTR;
2594	if (!(port->rs485.flags & SER_RS485_ENABLED))
2595	port->ops->set_mctrl(port, port->mctrl);
2596	uart_port_unlock_irqrestore(up: port, flags);
2597
2598	uart_rs485_config(port);
2599
2600	/*
2601	* If this driver supports console, and it hasn't been
2602	* successfully registered yet, try to re-register it.
2603	* It may be that the port was not available.
2604	*/
2605	if (port->cons && !console_is_registered(con: port->cons))
2606	register_console(port->cons);
2607
2608	/*
2609	* Power down all ports by default, except the
2610	* console if we have one.
2611	*/
2612	if (!uart_console(port))
2613	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
2614	}
2615	}
2616
2617	#ifdef CONFIG_CONSOLE_POLL
2618
2619	static int uart_poll_init(struct tty_driver *driver, int line, char *options)
2620	{
2621	struct uart_driver *drv = driver->driver_state;
2622	struct uart_state *state = drv->state + line;
2623	enum uart_pm_state pm_state;
2624	struct tty_port *tport;
2625	struct uart_port *port;
2626	int baud = 9600;
2627	int bits = 8;
2628	int parity = 'n';
2629	int flow = 'n';
2630	int ret = 0;
2631
2632	tport = &state->port;
2633	mutex_lock(&tport->mutex);
2634
2635	port = uart_port_check(state);
2636	if (!port || !(port->ops->poll_get_char && port->ops->poll_put_char)) {
2637	ret = -1;
2638	goto out;
2639	}
2640
2641	pm_state = state->pm_state;
2642	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2643
2644	if (port->ops->poll_init) {
2645	/*
2646	* We don't set initialized as we only initialized the hw,
2647	* e.g. state->xmit is still uninitialized.
2648	*/
2649	if (!tty_port_initialized(port: tport))
2650	ret = port->ops->poll_init(port);
2651	}
2652
2653	if (!ret && options) {
2654	uart_parse_options(options, &baud, &parity, &bits, &flow);
2655	console_list_lock();
2656	ret = uart_set_options(port, NULL, baud, parity, bits, flow);
2657	console_list_unlock();
2658	}
2659	out:
2660	if (ret)
2661	uart_change_pm(state, pm_state);
2662	mutex_unlock(lock: &tport->mutex);
2663	return ret;
2664	}
2665
2666	static int uart_poll_get_char(struct tty_driver *driver, int line)
2667	{
2668	struct uart_driver *drv = driver->driver_state;
2669	struct uart_state *state = drv->state + line;
2670	struct uart_port *port;
2671	int ret = -1;
2672
2673	port = uart_port_ref(state);
2674	if (port) {
2675	ret = port->ops->poll_get_char(port);
2676	uart_port_deref(uport: port);
2677	}
2678
2679	return ret;
2680	}
2681
2682	static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
2683	{
2684	struct uart_driver *drv = driver->driver_state;
2685	struct uart_state *state = drv->state + line;
2686	struct uart_port *port;
2687
2688	port = uart_port_ref(state);
2689	if (!port)
2690	return;
2691
2692	if (ch == '\n')
2693	port->ops->poll_put_char(port, '\r');
2694	port->ops->poll_put_char(port, ch);
2695	uart_port_deref(uport: port);
2696	}
2697	#endif
2698
2699	static const struct tty_operations uart_ops = {
2700	.install = uart_install,
2701	.open = uart_open,
2702	.close = uart_close,
2703	.write = uart_write,
2704	.put_char = uart_put_char,
2705	.flush_chars = uart_flush_chars,
2706	.write_room = uart_write_room,
2707	.chars_in_buffer= uart_chars_in_buffer,
2708	.flush_buffer = uart_flush_buffer,
2709	.ioctl = uart_ioctl,
2710	.throttle = uart_throttle,
2711	.unthrottle = uart_unthrottle,
2712	.send_xchar = uart_send_xchar,
2713	.set_termios = uart_set_termios,
2714	.set_ldisc = uart_set_ldisc,
2715	.stop = uart_stop,
2716	.start = uart_start,
2717	.hangup = uart_hangup,
2718	.break_ctl = uart_break_ctl,
2719	.wait_until_sent= uart_wait_until_sent,
2720	#ifdef CONFIG_PROC_FS
2721	.proc_show = uart_proc_show,
2722	#endif
2723	.tiocmget = uart_tiocmget,
2724	.tiocmset = uart_tiocmset,
2725	.set_serial = uart_set_info_user,
2726	.get_serial = uart_get_info_user,
2727	.get_icount = uart_get_icount,
2728	#ifdef CONFIG_CONSOLE_POLL
2729	.poll_init = uart_poll_init,
2730	.poll_get_char = uart_poll_get_char,
2731	.poll_put_char = uart_poll_put_char,
2732	#endif
2733	};
2734
2735	static const struct tty_port_operations uart_port_ops = {
2736	.carrier_raised = uart_carrier_raised,
2737	.dtr_rts = uart_dtr_rts,
2738	.activate = uart_port_activate,
2739	.shutdown = uart_tty_port_shutdown,
2740	};
2741
2742	/**
2743	* uart_register_driver - register a driver with the uart core layer
2744	* @drv: low level driver structure
2745	*
2746	* Register a uart driver with the core driver. We in turn register with the
2747	* tty layer, and initialise the core driver per-port state.
2748	*
2749	* We have a proc file in /proc/tty/driver which is named after the normal
2750	* driver.
2751	*
2752	* @drv->port should be %NULL, and the per-port structures should be registered
2753	* using uart_add_one_port() after this call has succeeded.
2754	*
2755	* Locking: none, Interrupts: enabled
2756	*/
2757	int uart_register_driver(struct uart_driver *drv)
2758	{
2759	struct tty_driver *normal;
2760	int i, retval = -ENOMEM;
2761
2762	BUG_ON(drv->state);
2763
2764	/*
2765	* Maybe we should be using a slab cache for this, especially if
2766	* we have a large number of ports to handle.
2767	*/
2768	drv->state = kcalloc(n: drv->nr, size: sizeof(struct uart_state), GFP_KERNEL);
2769	if (!drv->state)
2770	goto out;
2771
2772	normal = tty_alloc_driver(drv->nr, TTY_DRIVER_REAL_RAW |
2773	TTY_DRIVER_DYNAMIC_DEV);
2774	if (IS_ERR(ptr: normal)) {
2775	retval = PTR_ERR(ptr: normal);
2776	goto out_kfree;
2777	}
2778
2779	drv->tty_driver = normal;
2780
2781	normal->driver_name = drv->driver_name;
2782	normal->name = drv->dev_name;
2783	normal->major = drv->major;
2784	normal->minor_start = drv->minor;
2785	normal->type = TTY_DRIVER_TYPE_SERIAL;
2786	normal->subtype = SERIAL_TYPE_NORMAL;
2787	normal->init_termios = tty_std_termios;
2788	normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
2789	normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
2790	normal->driver_state = drv;
2791	tty_set_operations(driver: normal, op: &uart_ops);
2792
2793	/*
2794	* Initialise the UART state(s).
2795	*/
2796	for (i = 0; i < drv->nr; i++) {
2797	struct uart_state *state = drv->state + i;
2798	struct tty_port *port = &state->port;
2799
2800	tty_port_init(port);
2801	port->ops = &uart_port_ops;
2802	}
2803
2804	retval = tty_register_driver(driver: normal);
2805	if (retval >= 0)
2806	return retval;
2807
2808	for (i = 0; i < drv->nr; i++)
2809	tty_port_destroy(port: &drv->state[i].port);
2810	tty_driver_kref_put(driver: normal);
2811	out_kfree:
2812	kfree(objp: drv->state);
2813	out:
2814	return retval;
2815	}
2816	EXPORT_SYMBOL(uart_register_driver);
2817
2818	/**
2819	* uart_unregister_driver - remove a driver from the uart core layer
2820	* @drv: low level driver structure
2821	*
2822	* Remove all references to a driver from the core driver. The low level
2823	* driver must have removed all its ports via the uart_remove_one_port() if it
2824	* registered them with uart_add_one_port(). (I.e. @drv->port is %NULL.)
2825	*
2826	* Locking: none, Interrupts: enabled
2827	*/
2828	void uart_unregister_driver(struct uart_driver *drv)
2829	{
2830	struct tty_driver *p = drv->tty_driver;
2831	unsigned int i;
2832
2833	tty_unregister_driver(driver: p);
2834	tty_driver_kref_put(driver: p);
2835	for (i = 0; i < drv->nr; i++)
2836	tty_port_destroy(port: &drv->state[i].port);
2837	kfree(objp: drv->state);
2838	drv->state = NULL;
2839	drv->tty_driver = NULL;
2840	}
2841	EXPORT_SYMBOL(uart_unregister_driver);
2842
2843	struct tty_driver *uart_console_device(struct console *co, int *index)
2844	{
2845	struct uart_driver *p = co->data;
2846	*index = co->index;
2847	return p->tty_driver;
2848	}
2849	EXPORT_SYMBOL_GPL(uart_console_device);
2850
2851	static ssize_t uartclk_show(struct device *dev,
2852	struct device_attribute *attr, char *buf)
2853	{
2854	struct serial_struct tmp;
2855	struct tty_port *port = dev_get_drvdata(dev);
2856
2857	uart_get_info(port, retinfo: &tmp);
2858	return sprintf(buf, fmt: "%d\n", tmp.baud_base * 16);
2859	}
2860
2861	static ssize_t type_show(struct device *dev,
2862	struct device_attribute *attr, char *buf)
2863	{
2864	struct serial_struct tmp;
2865	struct tty_port *port = dev_get_drvdata(dev);
2866
2867	uart_get_info(port, retinfo: &tmp);
2868	return sprintf(buf, fmt: "%d\n", tmp.type);
2869	}
2870
2871	static ssize_t line_show(struct device *dev,
2872	struct device_attribute *attr, char *buf)
2873	{
2874	struct serial_struct tmp;
2875	struct tty_port *port = dev_get_drvdata(dev);
2876
2877	uart_get_info(port, retinfo: &tmp);
2878	return sprintf(buf, fmt: "%d\n", tmp.line);
2879	}
2880
2881	static ssize_t port_show(struct device *dev,
2882	struct device_attribute *attr, char *buf)
2883	{
2884	struct serial_struct tmp;
2885	struct tty_port *port = dev_get_drvdata(dev);
2886	unsigned long ioaddr;
2887
2888	uart_get_info(port, retinfo: &tmp);
2889	ioaddr = tmp.port;
2890	if (HIGH_BITS_OFFSET)
2891	ioaddr |= (unsigned long)tmp.port_high << HIGH_BITS_OFFSET;
2892	return sprintf(buf, fmt: "0x%lX\n", ioaddr);
2893	}
2894
2895	static ssize_t irq_show(struct device *dev,
2896	struct device_attribute *attr, char *buf)
2897	{
2898	struct serial_struct tmp;
2899	struct tty_port *port = dev_get_drvdata(dev);
2900
2901	uart_get_info(port, retinfo: &tmp);
2902	return sprintf(buf, fmt: "%d\n", tmp.irq);
2903	}
2904
2905	static ssize_t flags_show(struct device *dev,
2906	struct device_attribute *attr, char *buf)
2907	{
2908	struct serial_struct tmp;
2909	struct tty_port *port = dev_get_drvdata(dev);
2910
2911	uart_get_info(port, retinfo: &tmp);
2912	return sprintf(buf, fmt: "0x%X\n", tmp.flags);
2913	}
2914
2915	static ssize_t xmit_fifo_size_show(struct device *dev,
2916	struct device_attribute *attr, char *buf)
2917	{
2918	struct serial_struct tmp;
2919	struct tty_port *port = dev_get_drvdata(dev);
2920
2921	uart_get_info(port, retinfo: &tmp);
2922	return sprintf(buf, fmt: "%d\n", tmp.xmit_fifo_size);
2923	}
2924
2925	static ssize_t close_delay_show(struct device *dev,
2926	struct device_attribute *attr, char *buf)
2927	{
2928	struct serial_struct tmp;
2929	struct tty_port *port = dev_get_drvdata(dev);
2930
2931	uart_get_info(port, retinfo: &tmp);
2932	return sprintf(buf, fmt: "%d\n", tmp.close_delay);
2933	}
2934
2935	static ssize_t closing_wait_show(struct device *dev,
2936	struct device_attribute *attr, char *buf)
2937	{
2938	struct serial_struct tmp;
2939	struct tty_port *port = dev_get_drvdata(dev);
2940
2941	uart_get_info(port, retinfo: &tmp);
2942	return sprintf(buf, fmt: "%d\n", tmp.closing_wait);
2943	}
2944
2945	static ssize_t custom_divisor_show(struct device *dev,
2946	struct device_attribute *attr, char *buf)
2947	{
2948	struct serial_struct tmp;
2949	struct tty_port *port = dev_get_drvdata(dev);
2950
2951	uart_get_info(port, retinfo: &tmp);
2952	return sprintf(buf, fmt: "%d\n", tmp.custom_divisor);
2953	}
2954
2955	static ssize_t io_type_show(struct device *dev,
2956	struct device_attribute *attr, char *buf)
2957	{
2958	struct serial_struct tmp;
2959	struct tty_port *port = dev_get_drvdata(dev);
2960
2961	uart_get_info(port, retinfo: &tmp);
2962	return sprintf(buf, fmt: "%d\n", tmp.io_type);
2963	}
2964
2965	static ssize_t iomem_base_show(struct device *dev,
2966	struct device_attribute *attr, char *buf)
2967	{
2968	struct serial_struct tmp;
2969	struct tty_port *port = dev_get_drvdata(dev);
2970
2971	uart_get_info(port, retinfo: &tmp);
2972	return sprintf(buf, fmt: "0x%lX\n", (unsigned long)tmp.iomem_base);
2973	}
2974
2975	static ssize_t iomem_reg_shift_show(struct device *dev,
2976	struct device_attribute *attr, char *buf)
2977	{
2978	struct serial_struct tmp;
2979	struct tty_port *port = dev_get_drvdata(dev);
2980
2981	uart_get_info(port, retinfo: &tmp);
2982	return sprintf(buf, fmt: "%d\n", tmp.iomem_reg_shift);
2983	}
2984
2985	static ssize_t console_show(struct device *dev,
2986	struct device_attribute *attr, char *buf)
2987	{
2988	struct tty_port *port = dev_get_drvdata(dev);
2989	struct uart_state *state = container_of(port, struct uart_state, port);
2990	struct uart_port *uport;
2991	bool console = false;
2992
2993	mutex_lock(&port->mutex);
2994	uport = uart_port_check(state);
2995	if (uport)
2996	console = uart_console_registered(port: uport);
2997	mutex_unlock(lock: &port->mutex);
2998
2999	return sprintf(buf, fmt: "%c\n", console ? 'Y' : 'N');
3000	}
3001
3002	static ssize_t console_store(struct device *dev,
3003	struct device_attribute *attr, const char *buf, size_t count)
3004	{
3005	struct tty_port *port = dev_get_drvdata(dev);
3006	struct uart_state *state = container_of(port, struct uart_state, port);
3007	struct uart_port *uport;
3008	bool oldconsole, newconsole;
3009	int ret;
3010
3011	ret = kstrtobool(s: buf, res: &newconsole);
3012	if (ret)
3013	return ret;
3014
3015	mutex_lock(&port->mutex);
3016	uport = uart_port_check(state);
3017	if (uport) {
3018	oldconsole = uart_console_registered(port: uport);
3019	if (oldconsole && !newconsole) {
3020	ret = unregister_console(uport->cons);
3021	} else if (!oldconsole && newconsole) {
3022	if (uart_console(uport)) {
3023	uport->console_reinit = 1;
3024	register_console(uport->cons);
3025	} else {
3026	ret = -ENOENT;
3027	}
3028	}
3029	} else {
3030	ret = -ENXIO;
3031	}
3032	mutex_unlock(lock: &port->mutex);
3033
3034	return ret < 0 ? ret : count;
3035	}
3036
3037	static DEVICE_ATTR_RO(uartclk);
3038	static DEVICE_ATTR_RO(type);
3039	static DEVICE_ATTR_RO(line);
3040	static DEVICE_ATTR_RO(port);
3041	static DEVICE_ATTR_RO(irq);
3042	static DEVICE_ATTR_RO(flags);
3043	static DEVICE_ATTR_RO(xmit_fifo_size);
3044	static DEVICE_ATTR_RO(close_delay);
3045	static DEVICE_ATTR_RO(closing_wait);
3046	static DEVICE_ATTR_RO(custom_divisor);
3047	static DEVICE_ATTR_RO(io_type);
3048	static DEVICE_ATTR_RO(iomem_base);
3049	static DEVICE_ATTR_RO(iomem_reg_shift);
3050	static DEVICE_ATTR_RW(console);
3051
3052	static struct attribute *tty_dev_attrs[] = {
3053	&dev_attr_uartclk.attr,
3054	&dev_attr_type.attr,
3055	&dev_attr_line.attr,
3056	&dev_attr_port.attr,
3057	&dev_attr_irq.attr,
3058	&dev_attr_flags.attr,
3059	&dev_attr_xmit_fifo_size.attr,
3060	&dev_attr_close_delay.attr,
3061	&dev_attr_closing_wait.attr,
3062	&dev_attr_custom_divisor.attr,
3063	&dev_attr_io_type.attr,
3064	&dev_attr_iomem_base.attr,
3065	&dev_attr_iomem_reg_shift.attr,
3066	&dev_attr_console.attr,
3067	NULL
3068	};
3069
3070	static const struct attribute_group tty_dev_attr_group = {
3071	.attrs = tty_dev_attrs,
3072	};
3073
3074	/**
3075	* serial_core_add_one_port - attach a driver-defined port structure
3076	* @drv: pointer to the uart low level driver structure for this port
3077	* @uport: uart port structure to use for this port.
3078	*
3079	* Context: task context, might sleep
3080	*
3081	* This allows the driver @drv to register its own uart_port structure with the
3082	* core driver. The main purpose is to allow the low level uart drivers to
3083	* expand uart_port, rather than having yet more levels of structures.
3084	* Caller must hold port_mutex.
3085	*/
3086	static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *uport)
3087	{
3088	struct uart_state *state;
3089	struct tty_port *port;
3090	int ret = 0;
3091	struct device *tty_dev;
3092	int num_groups;
3093
3094	if (uport->line >= drv->nr)
3095	return -EINVAL;
3096
3097	state = drv->state + uport->line;
3098	port = &state->port;
3099
3100	mutex_lock(&port->mutex);
3101	if (state->uart_port) {
3102	ret = -EINVAL;
3103	goto out;
3104	}
3105
3106	/* Link the port to the driver state table and vice versa */
3107	atomic_set(v: &state->refcount, i: 1);
3108	init_waitqueue_head(&state->remove_wait);
3109	state->uart_port = uport;
3110	uport->state = state;
3111
3112	state->pm_state = UART_PM_STATE_UNDEFINED;
3113	uport->cons = drv->cons;
3114	uport->minor = drv->tty_driver->minor_start + uport->line;
3115	uport->name = kasprintf(GFP_KERNEL, fmt: "%s%d", drv->dev_name,
3116	drv->tty_driver->name_base + uport->line);
3117	if (!uport->name) {
3118	ret = -ENOMEM;
3119	goto out;
3120	}
3121
3122	/*
3123	* If this port is in use as a console then the spinlock is already
3124	* initialised.
3125	*/
3126	if (!uart_console_registered(port: uport))
3127	uart_port_spin_lock_init(port: uport);
3128
3129	if (uport->cons && uport->dev)
3130	of_console_check(dn: uport->dev->of_node, name: uport->cons->name, index: uport->line);
3131
3132	tty_port_link_device(port, driver: drv->tty_driver, index: uport->line);
3133	uart_configure_port(drv, state, port: uport);
3134
3135	port->console = uart_console(uport);
3136
3137	num_groups = 2;
3138	if (uport->attr_group)
3139	num_groups++;
3140
3141	uport->tty_groups = kcalloc(n: num_groups, size: sizeof(*uport->tty_groups),
3142	GFP_KERNEL);
3143	if (!uport->tty_groups) {
3144	ret = -ENOMEM;
3145	goto out;
3146	}
3147	uport->tty_groups[0] = &tty_dev_attr_group;
3148	if (uport->attr_group)
3149	uport->tty_groups[1] = uport->attr_group;
3150
3151	/*
3152	* Register the port whether it's detected or not. This allows
3153	* setserial to be used to alter this port's parameters.
3154	*/
3155	tty_dev = tty_port_register_device_attr_serdev(port, driver: drv->tty_driver,
3156	index: uport->line, device: uport->dev, drvdata: port, attr_grp: uport->tty_groups);
3157	if (!IS_ERR(ptr: tty_dev)) {
3158	device_set_wakeup_capable(dev: tty_dev, capable: 1);
3159	} else {
3160	dev_err(uport->dev, "Cannot register tty device on line %d\n",
3161	uport->line);
3162	}
3163
3164	out:
3165	mutex_unlock(lock: &port->mutex);
3166
3167	return ret;
3168	}
3169
3170	/**
3171	* serial_core_remove_one_port - detach a driver defined port structure
3172	* @drv: pointer to the uart low level driver structure for this port
3173	* @uport: uart port structure for this port
3174	*
3175	* Context: task context, might sleep
3176	*
3177	* This unhooks (and hangs up) the specified port structure from the core
3178	* driver. No further calls will be made to the low-level code for this port.
3179	* Caller must hold port_mutex.
3180	*/
3181	static void serial_core_remove_one_port(struct uart_driver *drv,
3182	struct uart_port *uport)
3183	{
3184	struct uart_state *state = drv->state + uport->line;
3185	struct tty_port *port = &state->port;
3186	struct uart_port *uart_port;
3187	struct tty_struct *tty;
3188
3189	mutex_lock(&port->mutex);
3190	uart_port = uart_port_check(state);
3191	if (uart_port != uport)
3192	dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
3193	uart_port, uport);
3194
3195	if (!uart_port) {
3196	mutex_unlock(lock: &port->mutex);
3197	return;
3198	}
3199	mutex_unlock(lock: &port->mutex);
3200
3201	/*
3202	* Remove the devices from the tty layer
3203	*/
3204	tty_port_unregister_device(port, driver: drv->tty_driver, index: uport->line);
3205
3206	tty = tty_port_tty_get(port);
3207	if (tty) {
3208	tty_vhangup(tty: port->tty);
3209	tty_kref_put(tty);
3210	}
3211
3212	/*
3213	* If the port is used as a console, unregister it
3214	*/
3215	if (uart_console(uport))
3216	unregister_console(uport->cons);
3217
3218	/*
3219	* Free the port IO and memory resources, if any.
3220	*/
3221	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
3222	uport->ops->release_port(uport);
3223	kfree(objp: uport->tty_groups);
3224	kfree(objp: uport->name);
3225
3226	/*
3227	* Indicate that there isn't a port here anymore.
3228	*/
3229	uport->type = PORT_UNKNOWN;
3230	uport->port_dev = NULL;
3231
3232	mutex_lock(&port->mutex);
3233	WARN_ON(atomic_dec_return(&state->refcount) < 0);
3234	wait_event(state->remove_wait, !atomic_read(&state->refcount));
3235	state->uart_port = NULL;
3236	mutex_unlock(lock: &port->mutex);
3237	}
3238
3239	/**
3240	* uart_match_port - are the two ports equivalent?
3241	* @port1: first port
3242	* @port2: second port
3243	*
3244	* This utility function can be used to determine whether two uart_port
3245	* structures describe the same port.
3246	*/
3247	bool uart_match_port(const struct uart_port *port1,
3248	const struct uart_port *port2)
3249	{
3250	if (port1->iotype != port2->iotype)
3251	return false;
3252
3253	switch (port1->iotype) {
3254	case UPIO_PORT:
3255	return port1->iobase == port2->iobase;
3256	case UPIO_HUB6:
3257	return port1->iobase == port2->iobase &&
3258	port1->hub6 == port2->hub6;
3259	case UPIO_MEM:
3260	case UPIO_MEM16:
3261	case UPIO_MEM32:
3262	case UPIO_MEM32BE:
3263	case UPIO_AU:
3264	case UPIO_TSI:
3265	return port1->mapbase == port2->mapbase;
3266	}
3267
3268	return false;
3269	}
3270	EXPORT_SYMBOL(uart_match_port);
3271
3272	static struct serial_ctrl_device *
3273	serial_core_get_ctrl_dev(struct serial_port_device *port_dev)
3274	{
3275	struct device *dev = &port_dev->dev;
3276
3277	return to_serial_base_ctrl_device(dev->parent);
3278	}
3279
3280	/*
3281	* Find a registered serial core controller device if one exists. Returns
3282	* the first device matching the ctrl_id. Caller must hold port_mutex.
3283	*/
3284	static struct serial_ctrl_device *serial_core_ctrl_find(struct uart_driver *drv,
3285	struct device *phys_dev,
3286	int ctrl_id)
3287	{
3288	struct uart_state *state;
3289	int i;
3290
3291	lockdep_assert_held(&port_mutex);
3292
3293	for (i = 0; i < drv->nr; i++) {
3294	state = drv->state + i;
3295	if (!state->uart_port || !state->uart_port->port_dev)
3296	continue;
3297
3298	if (state->uart_port->dev == phys_dev &&
3299	state->uart_port->ctrl_id == ctrl_id)
3300	return serial_core_get_ctrl_dev(port_dev: state->uart_port->port_dev);
3301	}
3302
3303	return NULL;
3304	}
3305
3306	static struct serial_ctrl_device *serial_core_ctrl_device_add(struct uart_port *port)
3307	{
3308	return serial_base_ctrl_add(port, parent: port->dev);
3309	}
3310
3311	static int serial_core_port_device_add(struct serial_ctrl_device *ctrl_dev,
3312	struct uart_port *port)
3313	{
3314	struct serial_port_device *port_dev;
3315
3316	port_dev = serial_base_port_add(port, parent: ctrl_dev);
3317	if (IS_ERR(ptr: port_dev))
3318	return PTR_ERR(ptr: port_dev);
3319
3320	port->port_dev = port_dev;
3321
3322	return 0;
3323	}
3324
3325	/*
3326	* Initialize a serial core port device, and a controller device if needed.
3327	*/
3328	int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
3329	{
3330	struct serial_ctrl_device *ctrl_dev, *new_ctrl_dev = NULL;
3331	int ret;
3332
3333	mutex_lock(&port_mutex);
3334
3335	/*
3336	* Prevent serial_port_runtime_resume() from trying to use the port
3337	* until serial_core_add_one_port() has completed
3338	*/
3339	port->flags |= UPF_DEAD;
3340
3341	/* Inititalize a serial core controller device if needed */
3342	ctrl_dev = serial_core_ctrl_find(drv, phys_dev: port->dev, ctrl_id: port->ctrl_id);
3343	if (!ctrl_dev) {
3344	new_ctrl_dev = serial_core_ctrl_device_add(port);
3345	if (IS_ERR(ptr: new_ctrl_dev)) {
3346	ret = PTR_ERR(ptr: new_ctrl_dev);
3347	goto err_unlock;
3348	}
3349	ctrl_dev = new_ctrl_dev;
3350	}
3351
3352	/*
3353	* Initialize a serial core port device. Tag the port dead to prevent
3354	* serial_port_runtime_resume() trying to do anything until port has
3355	* been registered. It gets cleared by serial_core_add_one_port().
3356	*/
3357	ret = serial_core_port_device_add(ctrl_dev, port);
3358	if (ret)
3359	goto err_unregister_ctrl_dev;
3360
3361	ret = serial_core_add_one_port(drv, uport: port);
3362	if (ret)
3363	goto err_unregister_port_dev;
3364
3365	port->flags &= ~UPF_DEAD;
3366
3367	mutex_unlock(lock: &port_mutex);
3368
3369	return 0;
3370
3371	err_unregister_port_dev:
3372	serial_base_port_device_remove(port_dev: port->port_dev);
3373
3374	err_unregister_ctrl_dev:
3375	serial_base_ctrl_device_remove(ctrl_dev: new_ctrl_dev);
3376
3377	err_unlock:
3378	mutex_unlock(lock: &port_mutex);
3379
3380	return ret;
3381	}
3382
3383	/*
3384	* Removes a serial core port device, and the related serial core controller
3385	* device if the last instance.
3386	*/
3387	void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port)
3388	{
3389	struct device *phys_dev = port->dev;
3390	struct serial_port_device *port_dev = port->port_dev;
3391	struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev);
3392	int ctrl_id = port->ctrl_id;
3393
3394	mutex_lock(&port_mutex);
3395
3396	port->flags |= UPF_DEAD;
3397
3398	serial_core_remove_one_port(drv, uport: port);
3399
3400	/* Note that struct uart_port *port is no longer valid at this point */
3401	serial_base_port_device_remove(port_dev);
3402
3403	/* Drop the serial core controller device if no ports are using it */
3404	if (!serial_core_ctrl_find(drv, phys_dev, ctrl_id))
3405	serial_base_ctrl_device_remove(ctrl_dev);
3406
3407	mutex_unlock(lock: &port_mutex);
3408	}
3409
3410	/**
3411	* uart_handle_dcd_change - handle a change of carrier detect state
3412	* @uport: uart_port structure for the open port
3413	* @active: new carrier detect status
3414	*
3415	* Caller must hold uport->lock.
3416	*/
3417	void uart_handle_dcd_change(struct uart_port *uport, bool active)
3418	{
3419	struct tty_port *port = &uport->state->port;
3420	struct tty_struct *tty = port->tty;
3421	struct tty_ldisc *ld;
3422
3423	lockdep_assert_held_once(&uport->lock);
3424
3425	if (tty) {
3426	ld = tty_ldisc_ref(tty);
3427	if (ld) {
3428	if (ld->ops->dcd_change)
3429	ld->ops->dcd_change(tty, active);
3430	tty_ldisc_deref(ld);
3431	}
3432	}
3433
3434	uport->icount.dcd++;
3435
3436	if (uart_dcd_enabled(uport)) {
3437	if (active)
3438	wake_up_interruptible(&port->open_wait);
3439	else if (tty)
3440	tty_hangup(tty);
3441	}
3442	}
3443	EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
3444
3445	/**
3446	* uart_handle_cts_change - handle a change of clear-to-send state
3447	* @uport: uart_port structure for the open port
3448	* @active: new clear-to-send status
3449	*
3450	* Caller must hold uport->lock.
3451	*/
3452	void uart_handle_cts_change(struct uart_port *uport, bool active)
3453	{
3454	lockdep_assert_held_once(&uport->lock);
3455
3456	uport->icount.cts++;
3457
3458	if (uart_softcts_mode(uport)) {
3459	if (uport->hw_stopped) {
3460	if (active) {
3461	uport->hw_stopped = false;
3462	uport->ops->start_tx(uport);
3463	uart_write_wakeup(uport);
3464	}
3465	} else {
3466	if (!active) {
3467	uport->hw_stopped = true;
3468	uport->ops->stop_tx(uport);
3469	}
3470	}
3471
3472	}
3473	}
3474	EXPORT_SYMBOL_GPL(uart_handle_cts_change);
3475
3476	/**
3477	* uart_insert_char - push a char to the uart layer
3478	*
3479	* User is responsible to call tty_flip_buffer_push when they are done with
3480	* insertion.
3481	*
3482	* @port: corresponding port
3483	* @status: state of the serial port RX buffer (LSR for 8250)
3484	* @overrun: mask of overrun bits in @status
3485	* @ch: character to push
3486	* @flag: flag for the character (see TTY_NORMAL and friends)
3487	*/
3488	void uart_insert_char(struct uart_port *port, unsigned int status,
3489	unsigned int overrun, u8 ch, u8 flag)
3490	{
3491	struct tty_port *tport = &port->state->port;
3492
3493	if ((status & port->ignore_status_mask & ~overrun) == 0)
3494	if (tty_insert_flip_char(port: tport, ch, flag) == 0)
3495	++port->icount.buf_overrun;
3496
3497	/*
3498	* Overrun is special. Since it's reported immediately,
3499	* it doesn't affect the current character.
3500	*/
3501	if (status & ~port->ignore_status_mask & overrun)
3502	if (tty_insert_flip_char(port: tport, ch: 0, TTY_OVERRUN) == 0)
3503	++port->icount.buf_overrun;
3504	}
3505	EXPORT_SYMBOL_GPL(uart_insert_char);
3506
3507	#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
3508	static const u8 sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
3509
3510	static void uart_sysrq_on(struct work_struct *w)
3511	{
3512	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3513
3514	sysrq_toggle_support(enable_mask: 1);
3515	pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
3516	sysrq_toggle_seq_len, sysrq_toggle_seq);
3517	}
3518	static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
3519
3520	/**
3521	* uart_try_toggle_sysrq - Enables SysRq from serial line
3522	* @port: uart_port structure where char(s) after BREAK met
3523	* @ch: new character in the sequence after received BREAK
3524	*
3525	* Enables magic SysRq when the required sequence is met on port
3526	* (see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
3527	*
3528	* Returns: %false if @ch is out of enabling sequence and should be
3529	* handled some other way, %true if @ch was consumed.
3530	*/
3531	bool uart_try_toggle_sysrq(struct uart_port *port, u8 ch)
3532	{
3533	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3534
3535	if (!sysrq_toggle_seq_len)
3536	return false;
3537
3538	BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX);
3539	if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
3540	port->sysrq_seq = 0;
3541	return false;
3542	}
3543
3544	if (++port->sysrq_seq < sysrq_toggle_seq_len) {
3545	port->sysrq = jiffies + SYSRQ_TIMEOUT;
3546	return true;
3547	}
3548
3549	schedule_work(work: &sysrq_enable_work);
3550
3551	port->sysrq = 0;
3552	return true;
3553	}
3554	EXPORT_SYMBOL_GPL(uart_try_toggle_sysrq);
3555	#endif
3556
3557	/**
3558	* uart_get_rs485_mode() - retrieve rs485 properties for given uart
3559	* @port: uart device's target port
3560	*
3561	* This function implements the device tree binding described in
3562	* Documentation/devicetree/bindings/serial/rs485.txt.
3563	*/
3564	int uart_get_rs485_mode(struct uart_port *port)
3565	{
3566	struct serial_rs485 *rs485conf = &port->rs485;
3567	struct device *dev = port->dev;
3568	enum gpiod_flags dflags;
3569	struct gpio_desc *desc;
3570	u32 rs485_delay[2];
3571	int ret;
3572
3573	ret = device_property_read_u32_array(dev, propname: "rs485-rts-delay",
3574	val: rs485_delay, nval: 2);
3575	if (!ret) {
3576	rs485conf->delay_rts_before_send = rs485_delay[0];
3577	rs485conf->delay_rts_after_send = rs485_delay[1];
3578	} else {
3579	rs485conf->delay_rts_before_send = 0;
3580	rs485conf->delay_rts_after_send = 0;
3581	}
3582
3583	uart_sanitize_serial_rs485_delays(port, rs485: rs485conf);
3584
3585	/*
3586	* Clear full-duplex and enabled flags, set RTS polarity to active high
3587	* to get to a defined state with the following properties:
3588	*/
3589	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
3590	SER_RS485_TERMINATE_BUS |
3591	SER_RS485_RTS_AFTER_SEND);
3592	rs485conf->flags |= SER_RS485_RTS_ON_SEND;
3593
3594	if (device_property_read_bool(dev, propname: "rs485-rx-during-tx"))
3595	rs485conf->flags |= SER_RS485_RX_DURING_TX;
3596
3597	if (device_property_read_bool(dev, propname: "linux,rs485-enabled-at-boot-time"))
3598	rs485conf->flags |= SER_RS485_ENABLED;
3599
3600	if (device_property_read_bool(dev, propname: "rs485-rts-active-low")) {
3601	rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
3602	rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
3603	}
3604
3605	/*
3606	* Disabling termination by default is the safe choice: Else if many
3607	* bus participants enable it, no communication is possible at all.
3608	* Works fine for short cables and users may enable for longer cables.
3609	*/
3610	desc = devm_gpiod_get_optional(dev, con_id: "rs485-term", flags: GPIOD_OUT_LOW);
3611	if (IS_ERR(ptr: desc))
3612	return dev_err_probe(dev, err: PTR_ERR(ptr: desc), fmt: "Cannot get rs485-term-gpios\n");
3613	port->rs485_term_gpio = desc;
3614	if (port->rs485_term_gpio)
3615	port->rs485_supported.flags |= SER_RS485_TERMINATE_BUS;
3616
3617	dflags = (rs485conf->flags & SER_RS485_RX_DURING_TX) ?
3618	GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
3619	desc = devm_gpiod_get_optional(dev, con_id: "rs485-rx-during-tx", flags: dflags);
3620	if (IS_ERR(ptr: desc))
3621	return dev_err_probe(dev, err: PTR_ERR(ptr: desc), fmt: "Cannot get rs485-rx-during-tx-gpios\n");
3622	port->rs485_rx_during_tx_gpio = desc;
3623
3624	return 0;
3625	}
3626	EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
3627
3628	/* Compile-time assertions for serial_rs485 layout */
3629	static_assert(offsetof(struct serial_rs485, padding) ==
3630	(offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
3631	static_assert(offsetof(struct serial_rs485, padding1) ==
3632	offsetof(struct serial_rs485, padding[1]));
3633	static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
3634	sizeof(struct serial_rs485));
3635
3636	MODULE_DESCRIPTION("Serial driver core");
3637	MODULE_LICENSE("GPL");
3638