1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * altera_uart.c -- Altera UART driver
4 *
5 * Based on mcf.c -- Freescale ColdFire UART driver
6 *
7 * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
8 * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
9 * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
10 */
11
12#include <linux/kernel.h>
13#include <linux/init.h>
14#include <linux/timer.h>
15#include <linux/interrupt.h>
16#include <linux/module.h>
17#include <linux/console.h>
18#include <linux/tty.h>
19#include <linux/tty_flip.h>
20#include <linux/serial.h>
21#include <linux/serial_core.h>
22#include <linux/platform_device.h>
23#include <linux/of.h>
24#include <linux/io.h>
25#include <linux/altera_uart.h>
26
27#define DRV_NAME "altera_uart"
28#define SERIAL_ALTERA_MAJOR 204
29#define SERIAL_ALTERA_MINOR 213
30
31/*
32 * Altera UART register definitions according to the Nios UART datasheet:
33 * http://www.altera.com/literature/ds/ds_nios_uart.pdf
34 */
35
36#define ALTERA_UART_SIZE 32
37
38#define ALTERA_UART_RXDATA_REG 0
39#define ALTERA_UART_TXDATA_REG 4
40#define ALTERA_UART_STATUS_REG 8
41#define ALTERA_UART_CONTROL_REG 12
42#define ALTERA_UART_DIVISOR_REG 16
43#define ALTERA_UART_EOP_REG 20
44
45#define ALTERA_UART_STATUS_PE_MSK 0x0001 /* parity error */
46#define ALTERA_UART_STATUS_FE_MSK 0x0002 /* framing error */
47#define ALTERA_UART_STATUS_BRK_MSK 0x0004 /* break */
48#define ALTERA_UART_STATUS_ROE_MSK 0x0008 /* RX overrun error */
49#define ALTERA_UART_STATUS_TOE_MSK 0x0010 /* TX overrun error */
50#define ALTERA_UART_STATUS_TMT_MSK 0x0020 /* TX shift register state */
51#define ALTERA_UART_STATUS_TRDY_MSK 0x0040 /* TX ready */
52#define ALTERA_UART_STATUS_RRDY_MSK 0x0080 /* RX ready */
53#define ALTERA_UART_STATUS_E_MSK 0x0100 /* exception condition */
54#define ALTERA_UART_STATUS_DCTS_MSK 0x0400 /* CTS logic-level change */
55#define ALTERA_UART_STATUS_CTS_MSK 0x0800 /* CTS logic state */
56#define ALTERA_UART_STATUS_EOP_MSK 0x1000 /* EOP written/read */
57
58 /* Enable interrupt on... */
59#define ALTERA_UART_CONTROL_PE_MSK 0x0001 /* ...parity error */
60#define ALTERA_UART_CONTROL_FE_MSK 0x0002 /* ...framing error */
61#define ALTERA_UART_CONTROL_BRK_MSK 0x0004 /* ...break */
62#define ALTERA_UART_CONTROL_ROE_MSK 0x0008 /* ...RX overrun */
63#define ALTERA_UART_CONTROL_TOE_MSK 0x0010 /* ...TX overrun */
64#define ALTERA_UART_CONTROL_TMT_MSK 0x0020 /* ...TX shift register empty */
65#define ALTERA_UART_CONTROL_TRDY_MSK 0x0040 /* ...TX ready */
66#define ALTERA_UART_CONTROL_RRDY_MSK 0x0080 /* ...RX ready */
67#define ALTERA_UART_CONTROL_E_MSK 0x0100 /* ...exception*/
68
69#define ALTERA_UART_CONTROL_TRBK_MSK 0x0200 /* TX break */
70#define ALTERA_UART_CONTROL_DCTS_MSK 0x0400 /* Interrupt on CTS change */
71#define ALTERA_UART_CONTROL_RTS_MSK 0x0800 /* RTS signal */
72#define ALTERA_UART_CONTROL_EOP_MSK 0x1000 /* Interrupt on EOP */
73
74/*
75 * Local per-uart structure.
76 */
77struct altera_uart {
78 struct uart_port port;
79 struct timer_list tmr;
80 unsigned int sigs; /* Local copy of line sigs */
81 unsigned short imr; /* Local IMR mirror */
82};
83
84static u32 altera_uart_readl(struct uart_port *port, int reg)
85{
86 return readl(addr: port->membase + (reg << port->regshift));
87}
88
89static void altera_uart_writel(struct uart_port *port, u32 dat, int reg)
90{
91 writel(val: dat, addr: port->membase + (reg << port->regshift));
92}
93
94static unsigned int altera_uart_tx_empty(struct uart_port *port)
95{
96 return (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
97 ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
98}
99
100static unsigned int altera_uart_get_mctrl(struct uart_port *port)
101{
102 struct altera_uart *pp = container_of(port, struct altera_uart, port);
103 unsigned int sigs;
104
105 sigs = (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
106 ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
107 sigs |= (pp->sigs & TIOCM_RTS);
108
109 return sigs;
110}
111
112static void altera_uart_update_ctrl_reg(struct altera_uart *pp)
113{
114 unsigned short imr = pp->imr;
115
116 /*
117 * If the device doesn't have an irq, ensure that the irq bits are
118 * masked out to keep the irq line inactive.
119 */
120 if (!pp->port.irq)
121 imr &= ALTERA_UART_CONTROL_TRBK_MSK | ALTERA_UART_CONTROL_RTS_MSK;
122
123 altera_uart_writel(port: &pp->port, dat: imr, ALTERA_UART_CONTROL_REG);
124}
125
126static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
127{
128 struct altera_uart *pp = container_of(port, struct altera_uart, port);
129
130 pp->sigs = sigs;
131 if (sigs & TIOCM_RTS)
132 pp->imr |= ALTERA_UART_CONTROL_RTS_MSK;
133 else
134 pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
135 altera_uart_update_ctrl_reg(pp);
136}
137
138static void altera_uart_start_tx(struct uart_port *port)
139{
140 struct altera_uart *pp = container_of(port, struct altera_uart, port);
141
142 pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
143 altera_uart_update_ctrl_reg(pp);
144}
145
146static void altera_uart_stop_tx(struct uart_port *port)
147{
148 struct altera_uart *pp = container_of(port, struct altera_uart, port);
149
150 pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
151 altera_uart_update_ctrl_reg(pp);
152}
153
154static void altera_uart_stop_rx(struct uart_port *port)
155{
156 struct altera_uart *pp = container_of(port, struct altera_uart, port);
157
158 pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
159 altera_uart_update_ctrl_reg(pp);
160}
161
162static void altera_uart_break_ctl(struct uart_port *port, int break_state)
163{
164 struct altera_uart *pp = container_of(port, struct altera_uart, port);
165 unsigned long flags;
166
167 uart_port_lock_irqsave(up: port, flags: &flags);
168 if (break_state == -1)
169 pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK;
170 else
171 pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
172 altera_uart_update_ctrl_reg(pp);
173 uart_port_unlock_irqrestore(up: port, flags);
174}
175
176static void altera_uart_set_termios(struct uart_port *port,
177 struct ktermios *termios,
178 const struct ktermios *old)
179{
180 unsigned long flags;
181 unsigned int baud, baudclk;
182
183 baud = uart_get_baud_rate(port, termios, old, min: 0, max: 4000000);
184 baudclk = port->uartclk / baud;
185
186 if (old)
187 tty_termios_copy_hw(new: termios, old);
188 tty_termios_encode_baud_rate(termios, ibaud: baud, obaud: baud);
189
190 uart_port_lock_irqsave(up: port, flags: &flags);
191 uart_update_timeout(port, cflag: termios->c_cflag, baud);
192 altera_uart_writel(port, dat: baudclk, ALTERA_UART_DIVISOR_REG);
193 uart_port_unlock_irqrestore(up: port, flags);
194
195 /*
196 * FIXME: port->read_status_mask and port->ignore_status_mask
197 * need to be initialized based on termios settings for
198 * INPCK, IGNBRK, IGNPAR, PARMRK, BRKINT
199 */
200}
201
202static void altera_uart_rx_chars(struct uart_port *port)
203{
204 unsigned short status;
205 u8 ch, flag;
206
207 while ((status = altera_uart_readl(port, ALTERA_UART_STATUS_REG)) &
208 ALTERA_UART_STATUS_RRDY_MSK) {
209 ch = altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
210 flag = TTY_NORMAL;
211 port->icount.rx++;
212
213 if (status & ALTERA_UART_STATUS_E_MSK) {
214 altera_uart_writel(port, dat: status,
215 ALTERA_UART_STATUS_REG);
216
217 if (status & ALTERA_UART_STATUS_BRK_MSK) {
218 port->icount.brk++;
219 if (uart_handle_break(port))
220 continue;
221 } else if (status & ALTERA_UART_STATUS_PE_MSK) {
222 port->icount.parity++;
223 } else if (status & ALTERA_UART_STATUS_ROE_MSK) {
224 port->icount.overrun++;
225 } else if (status & ALTERA_UART_STATUS_FE_MSK) {
226 port->icount.frame++;
227 }
228
229 status &= port->read_status_mask;
230
231 if (status & ALTERA_UART_STATUS_BRK_MSK)
232 flag = TTY_BREAK;
233 else if (status & ALTERA_UART_STATUS_PE_MSK)
234 flag = TTY_PARITY;
235 else if (status & ALTERA_UART_STATUS_FE_MSK)
236 flag = TTY_FRAME;
237 }
238
239 if (uart_handle_sysrq_char(port, ch))
240 continue;
241 uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
242 flag);
243 }
244
245 tty_flip_buffer_push(port: &port->state->port);
246}
247
248static void altera_uart_tx_chars(struct uart_port *port)
249{
250 u8 ch;
251
252 uart_port_tx(port, ch,
253 altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
254 ALTERA_UART_STATUS_TRDY_MSK,
255 altera_uart_writel(port, ch, ALTERA_UART_TXDATA_REG));
256}
257
258static irqreturn_t altera_uart_interrupt(int irq, void *data)
259{
260 struct uart_port *port = data;
261 struct altera_uart *pp = container_of(port, struct altera_uart, port);
262 unsigned long flags;
263 unsigned int isr;
264
265 isr = altera_uart_readl(port, ALTERA_UART_STATUS_REG) & pp->imr;
266
267 uart_port_lock_irqsave(up: port, flags: &flags);
268 if (isr & ALTERA_UART_STATUS_RRDY_MSK)
269 altera_uart_rx_chars(port);
270 if (isr & ALTERA_UART_STATUS_TRDY_MSK)
271 altera_uart_tx_chars(port);
272 uart_port_unlock_irqrestore(up: port, flags);
273
274 return IRQ_RETVAL(isr);
275}
276
277static void altera_uart_timer(struct timer_list *t)
278{
279 struct altera_uart *pp = from_timer(pp, t, tmr);
280 struct uart_port *port = &pp->port;
281
282 altera_uart_interrupt(irq: 0, data: port);
283 mod_timer(timer: &pp->tmr, expires: jiffies + uart_poll_timeout(port));
284}
285
286static void altera_uart_config_port(struct uart_port *port, int flags)
287{
288 port->type = PORT_ALTERA_UART;
289
290 /* Clear mask, so no surprise interrupts. */
291 altera_uart_writel(port, dat: 0, ALTERA_UART_CONTROL_REG);
292 /* Clear status register */
293 altera_uart_writel(port, dat: 0, ALTERA_UART_STATUS_REG);
294}
295
296static int altera_uart_startup(struct uart_port *port)
297{
298 struct altera_uart *pp = container_of(port, struct altera_uart, port);
299 unsigned long flags;
300
301 if (!port->irq) {
302 timer_setup(&pp->tmr, altera_uart_timer, 0);
303 mod_timer(timer: &pp->tmr, expires: jiffies + uart_poll_timeout(port));
304 } else {
305 int ret;
306
307 ret = request_irq(irq: port->irq, handler: altera_uart_interrupt, flags: 0,
308 DRV_NAME, dev: port);
309 if (ret) {
310 pr_err(DRV_NAME ": unable to attach Altera UART %d "
311 "interrupt vector=%d\n", port->line, port->irq);
312 return ret;
313 }
314 }
315
316 uart_port_lock_irqsave(up: port, flags: &flags);
317
318 /* Enable RX interrupts now */
319 pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
320 altera_uart_update_ctrl_reg(pp);
321
322 uart_port_unlock_irqrestore(up: port, flags);
323
324 return 0;
325}
326
327static void altera_uart_shutdown(struct uart_port *port)
328{
329 struct altera_uart *pp = container_of(port, struct altera_uart, port);
330 unsigned long flags;
331
332 uart_port_lock_irqsave(up: port, flags: &flags);
333
334 /* Disable all interrupts now */
335 pp->imr = 0;
336 altera_uart_update_ctrl_reg(pp);
337
338 uart_port_unlock_irqrestore(up: port, flags);
339
340 if (port->irq)
341 free_irq(port->irq, port);
342 else
343 del_timer_sync(timer: &pp->tmr);
344}
345
346static const char *altera_uart_type(struct uart_port *port)
347{
348 return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
349}
350
351static int altera_uart_request_port(struct uart_port *port)
352{
353 /* UARTs always present */
354 return 0;
355}
356
357static void altera_uart_release_port(struct uart_port *port)
358{
359 /* Nothing to release... */
360}
361
362static int altera_uart_verify_port(struct uart_port *port,
363 struct serial_struct *ser)
364{
365 if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
366 return -EINVAL;
367 return 0;
368}
369
370#ifdef CONFIG_CONSOLE_POLL
371static int altera_uart_poll_get_char(struct uart_port *port)
372{
373 while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
374 ALTERA_UART_STATUS_RRDY_MSK))
375 cpu_relax();
376
377 return altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
378}
379
380static void altera_uart_poll_put_char(struct uart_port *port, unsigned char c)
381{
382 while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
383 ALTERA_UART_STATUS_TRDY_MSK))
384 cpu_relax();
385
386 altera_uart_writel(port, dat: c, ALTERA_UART_TXDATA_REG);
387}
388#endif
389
390/*
391 * Define the basic serial functions we support.
392 */
393static const struct uart_ops altera_uart_ops = {
394 .tx_empty = altera_uart_tx_empty,
395 .get_mctrl = altera_uart_get_mctrl,
396 .set_mctrl = altera_uart_set_mctrl,
397 .start_tx = altera_uart_start_tx,
398 .stop_tx = altera_uart_stop_tx,
399 .stop_rx = altera_uart_stop_rx,
400 .break_ctl = altera_uart_break_ctl,
401 .startup = altera_uart_startup,
402 .shutdown = altera_uart_shutdown,
403 .set_termios = altera_uart_set_termios,
404 .type = altera_uart_type,
405 .request_port = altera_uart_request_port,
406 .release_port = altera_uart_release_port,
407 .config_port = altera_uart_config_port,
408 .verify_port = altera_uart_verify_port,
409#ifdef CONFIG_CONSOLE_POLL
410 .poll_get_char = altera_uart_poll_get_char,
411 .poll_put_char = altera_uart_poll_put_char,
412#endif
413};
414
415static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];
416
417#if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
418
419static void altera_uart_console_putc(struct uart_port *port, unsigned char c)
420{
421 while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
422 ALTERA_UART_STATUS_TRDY_MSK))
423 cpu_relax();
424
425 altera_uart_writel(port, dat: c, ALTERA_UART_TXDATA_REG);
426}
427
428static void altera_uart_console_write(struct console *co, const char *s,
429 unsigned int count)
430{
431 struct uart_port *port = &(altera_uart_ports + co->index)->port;
432
433 uart_console_write(port, s, count, putchar: altera_uart_console_putc);
434}
435
436static int __init altera_uart_console_setup(struct console *co, char *options)
437{
438 struct uart_port *port;
439 int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
440 int bits = 8;
441 int parity = 'n';
442 int flow = 'n';
443
444 if (co->index < 0 || co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
445 return -EINVAL;
446 port = &altera_uart_ports[co->index].port;
447 if (!port->membase)
448 return -ENODEV;
449
450 if (options)
451 uart_parse_options(options, baud: &baud, parity: &parity, bits: &bits, flow: &flow);
452
453 return uart_set_options(port, co, baud, parity, bits, flow);
454}
455
456static struct uart_driver altera_uart_driver;
457
458static struct console altera_uart_console = {
459 .name = "ttyAL",
460 .write = altera_uart_console_write,
461 .device = uart_console_device,
462 .setup = altera_uart_console_setup,
463 .flags = CON_PRINTBUFFER,
464 .index = -1,
465 .data = &altera_uart_driver,
466};
467
468static int __init altera_uart_console_init(void)
469{
470 register_console(&altera_uart_console);
471 return 0;
472}
473
474console_initcall(altera_uart_console_init);
475
476#define ALTERA_UART_CONSOLE (&altera_uart_console)
477
478static void altera_uart_earlycon_write(struct console *co, const char *s,
479 unsigned int count)
480{
481 struct earlycon_device *dev = co->data;
482
483 uart_console_write(port: &dev->port, s, count, putchar: altera_uart_console_putc);
484}
485
486static int __init altera_uart_earlycon_setup(struct earlycon_device *dev,
487 const char *options)
488{
489 struct uart_port *port = &dev->port;
490
491 if (!port->membase)
492 return -ENODEV;
493
494 /* Enable RX interrupts now */
495 altera_uart_writel(port, ALTERA_UART_CONTROL_RRDY_MSK,
496 ALTERA_UART_CONTROL_REG);
497
498 if (dev->baud) {
499 unsigned int baudclk = port->uartclk / dev->baud;
500
501 altera_uart_writel(port, dat: baudclk, ALTERA_UART_DIVISOR_REG);
502 }
503
504 dev->con->write = altera_uart_earlycon_write;
505 return 0;
506}
507
508OF_EARLYCON_DECLARE(uart, "altr,uart-1.0", altera_uart_earlycon_setup);
509
510#else
511
512#define ALTERA_UART_CONSOLE NULL
513
514#endif /* CONFIG_SERIAL_ALTERA_UART_CONSOLE */
515
516/*
517 * Define the altera_uart UART driver structure.
518 */
519static struct uart_driver altera_uart_driver = {
520 .owner = THIS_MODULE,
521 .driver_name = DRV_NAME,
522 .dev_name = "ttyAL",
523 .major = SERIAL_ALTERA_MAJOR,
524 .minor = SERIAL_ALTERA_MINOR,
525 .nr = CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
526 .cons = ALTERA_UART_CONSOLE,
527};
528
529static int altera_uart_probe(struct platform_device *pdev)
530{
531 struct altera_uart_platform_uart *platp = dev_get_platdata(dev: &pdev->dev);
532 struct uart_port *port;
533 struct resource *res_mem;
534 int i = pdev->id;
535 int ret;
536
537 /* if id is -1 scan for a free id and use that one */
538 if (i == -1) {
539 for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS; i++)
540 if (altera_uart_ports[i].port.mapbase == 0)
541 break;
542 }
543
544 if (i < 0 || i >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
545 return -EINVAL;
546
547 port = &altera_uart_ports[i].port;
548
549 res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
550 if (res_mem)
551 port->mapbase = res_mem->start;
552 else if (platp)
553 port->mapbase = platp->mapbase;
554 else
555 return -EINVAL;
556
557 ret = platform_get_irq_optional(pdev, 0);
558 if (ret < 0 && ret != -ENXIO)
559 return ret;
560 if (ret > 0)
561 port->irq = ret;
562 else if (platp)
563 port->irq = platp->irq;
564
565 /* Check platform data first so we can override device node data */
566 if (platp)
567 port->uartclk = platp->uartclk;
568 else {
569 ret = of_property_read_u32(np: pdev->dev.of_node, propname: "clock-frequency",
570 out_value: &port->uartclk);
571 if (ret)
572 return ret;
573 }
574
575 port->membase = ioremap(offset: port->mapbase, ALTERA_UART_SIZE);
576 if (!port->membase)
577 return -ENOMEM;
578
579 if (platp)
580 port->regshift = platp->bus_shift;
581 else
582 port->regshift = 0;
583
584 port->line = i;
585 port->type = PORT_ALTERA_UART;
586 port->iotype = SERIAL_IO_MEM;
587 port->ops = &altera_uart_ops;
588 port->flags = UPF_BOOT_AUTOCONF;
589 port->dev = &pdev->dev;
590
591 platform_set_drvdata(pdev, data: port);
592
593 uart_add_one_port(reg: &altera_uart_driver, port);
594
595 return 0;
596}
597
598static int altera_uart_remove(struct platform_device *pdev)
599{
600 struct uart_port *port = platform_get_drvdata(pdev);
601
602 if (port) {
603 uart_remove_one_port(reg: &altera_uart_driver, port);
604 port->mapbase = 0;
605 iounmap(addr: port->membase);
606 }
607
608 return 0;
609}
610
611#ifdef CONFIG_OF
612static const struct of_device_id altera_uart_match[] = {
613 { .compatible = "ALTR,uart-1.0", },
614 { .compatible = "altr,uart-1.0", },
615 {},
616};
617MODULE_DEVICE_TABLE(of, altera_uart_match);
618#endif /* CONFIG_OF */
619
620static struct platform_driver altera_uart_platform_driver = {
621 .probe = altera_uart_probe,
622 .remove = altera_uart_remove,
623 .driver = {
624 .name = DRV_NAME,
625 .of_match_table = of_match_ptr(altera_uart_match),
626 },
627};
628
629static int __init altera_uart_init(void)
630{
631 int rc;
632
633 rc = uart_register_driver(uart: &altera_uart_driver);
634 if (rc)
635 return rc;
636 rc = platform_driver_register(&altera_uart_platform_driver);
637 if (rc)
638 uart_unregister_driver(uart: &altera_uart_driver);
639 return rc;
640}
641
642static void __exit altera_uart_exit(void)
643{
644 platform_driver_unregister(&altera_uart_platform_driver);
645 uart_unregister_driver(uart: &altera_uart_driver);
646}
647
648module_init(altera_uart_init);
649module_exit(altera_uart_exit);
650
651MODULE_DESCRIPTION("Altera UART driver");
652MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
653MODULE_LICENSE("GPL");
654MODULE_ALIAS("platform:" DRV_NAME);
655MODULE_ALIAS_CHARDEV_MAJOR(SERIAL_ALTERA_MAJOR);
656

source code of linux/drivers/tty/serial/altera_uart.c