1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * altera_jtaguart.c -- Altera JTAG 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/bitfield.h>
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/interrupt.h>
16#include <linux/module.h>
17#include <linux/console.h>
18#include <linux/of.h>
19#include <linux/tty.h>
20#include <linux/tty_flip.h>
21#include <linux/serial.h>
22#include <linux/serial_core.h>
23#include <linux/platform_device.h>
24#include <linux/io.h>
25#include <linux/altera_jtaguart.h>
26
27#define DRV_NAME "altera_jtaguart"
28
29/*
30 * Altera JTAG UART register definitions according to the Altera JTAG UART
31 * datasheet: https://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf
32 */
33
34#define ALTERA_JTAGUART_SIZE 8
35
36#define ALTERA_JTAGUART_DATA_REG 0
37
38#define ALTERA_JTAGUART_DATA_DATA_MSK 0x000000FF
39#define ALTERA_JTAGUART_DATA_RVALID_MSK 0x00008000
40#define ALTERA_JTAGUART_DATA_RAVAIL_MSK 0xFFFF0000
41#define ALTERA_JTAGUART_DATA_RAVAIL_OFF 16
42
43#define ALTERA_JTAGUART_CONTROL_REG 4
44
45#define ALTERA_JTAGUART_CONTROL_RE_MSK 0x00000001
46#define ALTERA_JTAGUART_CONTROL_WE_MSK 0x00000002
47#define ALTERA_JTAGUART_CONTROL_RI_MSK 0x00000100
48#define ALTERA_JTAGUART_CONTROL_RI_OFF 8
49#define ALTERA_JTAGUART_CONTROL_WI_MSK 0x00000200
50#define ALTERA_JTAGUART_CONTROL_AC_MSK 0x00000400
51#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK 0xFFFF0000
52
53static unsigned int altera_jtaguart_tx_space(struct uart_port *port, u32 *ctlp)
54{
55 u32 ctl = readl(addr: port->membase + ALTERA_JTAGUART_CONTROL_REG);
56
57 if (ctlp)
58 *ctlp = ctl;
59
60 return FIELD_GET(ALTERA_JTAGUART_CONTROL_WSPACE_MSK, ctl);
61}
62
63static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
64{
65 return altera_jtaguart_tx_space(port, NULL) ? TIOCSER_TEMT : 0;
66}
67
68static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
69{
70 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
71}
72
73static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
74{
75}
76
77static void altera_jtaguart_start_tx(struct uart_port *port)
78{
79 port->read_status_mask |= ALTERA_JTAGUART_CONTROL_WE_MSK;
80 writel(val: port->read_status_mask,
81 addr: port->membase + ALTERA_JTAGUART_CONTROL_REG);
82}
83
84static void altera_jtaguart_stop_tx(struct uart_port *port)
85{
86 port->read_status_mask &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
87 writel(val: port->read_status_mask,
88 addr: port->membase + ALTERA_JTAGUART_CONTROL_REG);
89}
90
91static void altera_jtaguart_stop_rx(struct uart_port *port)
92{
93 port->read_status_mask &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
94 writel(val: port->read_status_mask,
95 addr: port->membase + ALTERA_JTAGUART_CONTROL_REG);
96}
97
98static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
99{
100}
101
102static void altera_jtaguart_set_termios(struct uart_port *port,
103 struct ktermios *termios,
104 const struct ktermios *old)
105{
106 /* Just copy the old termios settings back */
107 if (old)
108 tty_termios_copy_hw(new: termios, old);
109}
110
111static void altera_jtaguart_rx_chars(struct uart_port *port)
112{
113 u32 status;
114 u8 ch;
115
116 while ((status = readl(addr: port->membase + ALTERA_JTAGUART_DATA_REG)) &
117 ALTERA_JTAGUART_DATA_RVALID_MSK) {
118 ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
119 port->icount.rx++;
120
121 if (uart_handle_sysrq_char(port, ch))
122 continue;
123 uart_insert_char(port, status: 0, overrun: 0, ch, TTY_NORMAL);
124 }
125
126 tty_flip_buffer_push(port: &port->state->port);
127}
128
129static void altera_jtaguart_tx_chars(struct uart_port *port)
130{
131 unsigned int count;
132 u8 ch;
133
134 count = altera_jtaguart_tx_space(port, NULL);
135
136 uart_port_tx_limited(port, ch, count,
137 true,
138 writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG),
139 ({}));
140}
141
142static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
143{
144 struct uart_port *port = data;
145 unsigned int isr;
146
147 isr = (readl(addr: port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
148 ALTERA_JTAGUART_CONTROL_RI_OFF) & port->read_status_mask;
149
150 uart_port_lock(up: port);
151
152 if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
153 altera_jtaguart_rx_chars(port);
154 if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
155 altera_jtaguart_tx_chars(port);
156
157 uart_port_unlock(up: port);
158
159 return IRQ_RETVAL(isr);
160}
161
162static void altera_jtaguart_config_port(struct uart_port *port, int flags)
163{
164 port->type = PORT_ALTERA_JTAGUART;
165
166 /* Clear mask, so no surprise interrupts. */
167 writel(val: 0, addr: port->membase + ALTERA_JTAGUART_CONTROL_REG);
168}
169
170static int altera_jtaguart_startup(struct uart_port *port)
171{
172 unsigned long flags;
173 int ret;
174
175 ret = request_irq(irq: port->irq, handler: altera_jtaguart_interrupt, flags: 0,
176 DRV_NAME, dev: port);
177 if (ret) {
178 pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d "
179 "interrupt vector=%d\n", port->line, port->irq);
180 return ret;
181 }
182
183 uart_port_lock_irqsave(up: port, flags: &flags);
184
185 /* Enable RX interrupts now */
186 port->read_status_mask = ALTERA_JTAGUART_CONTROL_RE_MSK;
187 writel(val: port->read_status_mask,
188 addr: port->membase + ALTERA_JTAGUART_CONTROL_REG);
189
190 uart_port_unlock_irqrestore(up: port, flags);
191
192 return 0;
193}
194
195static void altera_jtaguart_shutdown(struct uart_port *port)
196{
197 unsigned long flags;
198
199 uart_port_lock_irqsave(up: port, flags: &flags);
200
201 /* Disable all interrupts now */
202 port->read_status_mask = 0;
203 writel(val: port->read_status_mask,
204 addr: port->membase + ALTERA_JTAGUART_CONTROL_REG);
205
206 uart_port_unlock_irqrestore(up: port, flags);
207
208 free_irq(port->irq, port);
209}
210
211static const char *altera_jtaguart_type(struct uart_port *port)
212{
213 return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
214}
215
216static int altera_jtaguart_request_port(struct uart_port *port)
217{
218 /* UARTs always present */
219 return 0;
220}
221
222static void altera_jtaguart_release_port(struct uart_port *port)
223{
224 /* Nothing to release... */
225}
226
227static int altera_jtaguart_verify_port(struct uart_port *port,
228 struct serial_struct *ser)
229{
230 if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
231 return -EINVAL;
232 return 0;
233}
234
235/*
236 * Define the basic serial functions we support.
237 */
238static const struct uart_ops altera_jtaguart_ops = {
239 .tx_empty = altera_jtaguart_tx_empty,
240 .get_mctrl = altera_jtaguart_get_mctrl,
241 .set_mctrl = altera_jtaguart_set_mctrl,
242 .start_tx = altera_jtaguart_start_tx,
243 .stop_tx = altera_jtaguart_stop_tx,
244 .stop_rx = altera_jtaguart_stop_rx,
245 .break_ctl = altera_jtaguart_break_ctl,
246 .startup = altera_jtaguart_startup,
247 .shutdown = altera_jtaguart_shutdown,
248 .set_termios = altera_jtaguart_set_termios,
249 .type = altera_jtaguart_type,
250 .request_port = altera_jtaguart_request_port,
251 .release_port = altera_jtaguart_release_port,
252 .config_port = altera_jtaguart_config_port,
253 .verify_port = altera_jtaguart_verify_port,
254};
255
256#define ALTERA_JTAGUART_MAXPORTS 1
257static struct uart_port altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
258
259#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
260
261#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
262static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c)
263{
264 unsigned long flags;
265 u32 status;
266
267 uart_port_lock_irqsave(up: port, flags: &flags);
268 while (!altera_jtaguart_tx_space(port, ctlp: &status)) {
269 uart_port_unlock_irqrestore(up: port, flags);
270
271 if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
272 return; /* no connection activity */
273 }
274
275 cpu_relax();
276 uart_port_lock_irqsave(up: port, flags: &flags);
277 }
278 writel(val: c, addr: port->membase + ALTERA_JTAGUART_DATA_REG);
279 uart_port_unlock_irqrestore(up: port, flags);
280}
281#else
282static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c)
283{
284 unsigned long flags;
285
286 uart_port_lock_irqsave(port, &flags);
287 while (!altera_jtaguart_tx_space(port, NULL)) {
288 uart_port_unlock_irqrestore(port, flags);
289 cpu_relax();
290 uart_port_lock_irqsave(port, &flags);
291 }
292 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
293 uart_port_unlock_irqrestore(port, flags);
294}
295#endif
296
297static void altera_jtaguart_console_write(struct console *co, const char *s,
298 unsigned int count)
299{
300 struct uart_port *port = &altera_jtaguart_ports[co->index];
301
302 uart_console_write(port, s, count, putchar: altera_jtaguart_console_putc);
303}
304
305static int __init altera_jtaguart_console_setup(struct console *co,
306 char *options)
307{
308 struct uart_port *port;
309
310 if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
311 return -EINVAL;
312 port = &altera_jtaguart_ports[co->index];
313 if (port->membase == NULL)
314 return -ENODEV;
315 return 0;
316}
317
318static struct uart_driver altera_jtaguart_driver;
319
320static struct console altera_jtaguart_console = {
321 .name = "ttyJ",
322 .write = altera_jtaguart_console_write,
323 .device = uart_console_device,
324 .setup = altera_jtaguart_console_setup,
325 .flags = CON_PRINTBUFFER,
326 .index = -1,
327 .data = &altera_jtaguart_driver,
328};
329
330static int __init altera_jtaguart_console_init(void)
331{
332 register_console(&altera_jtaguart_console);
333 return 0;
334}
335
336console_initcall(altera_jtaguart_console_init);
337
338#define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console)
339
340static void altera_jtaguart_earlycon_write(struct console *co, const char *s,
341 unsigned int count)
342{
343 struct earlycon_device *dev = co->data;
344
345 uart_console_write(port: &dev->port, s, count, putchar: altera_jtaguart_console_putc);
346}
347
348static int __init altera_jtaguart_earlycon_setup(struct earlycon_device *dev,
349 const char *options)
350{
351 if (!dev->port.membase)
352 return -ENODEV;
353
354 dev->con->write = altera_jtaguart_earlycon_write;
355 return 0;
356}
357
358OF_EARLYCON_DECLARE(juart, "altr,juart-1.0", altera_jtaguart_earlycon_setup);
359
360#else
361
362#define ALTERA_JTAGUART_CONSOLE NULL
363
364#endif /* CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE */
365
366static struct uart_driver altera_jtaguart_driver = {
367 .owner = THIS_MODULE,
368 .driver_name = "altera_jtaguart",
369 .dev_name = "ttyJ",
370 .major = ALTERA_JTAGUART_MAJOR,
371 .minor = ALTERA_JTAGUART_MINOR,
372 .nr = ALTERA_JTAGUART_MAXPORTS,
373 .cons = ALTERA_JTAGUART_CONSOLE,
374};
375
376static int altera_jtaguart_probe(struct platform_device *pdev)
377{
378 struct altera_jtaguart_platform_uart *platp =
379 dev_get_platdata(dev: &pdev->dev);
380 struct uart_port *port;
381 struct resource *res_mem;
382 int i = pdev->id;
383 int irq;
384
385 /* -1 emphasizes that the platform must have one port, no .N suffix */
386 if (i == -1)
387 i = 0;
388
389 if (i >= ALTERA_JTAGUART_MAXPORTS)
390 return -EINVAL;
391
392 port = &altera_jtaguart_ports[i];
393
394 res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
395 if (res_mem)
396 port->mapbase = res_mem->start;
397 else if (platp)
398 port->mapbase = platp->mapbase;
399 else
400 return -ENODEV;
401
402 irq = platform_get_irq_optional(pdev, 0);
403 if (irq < 0 && irq != -ENXIO)
404 return irq;
405 if (irq > 0)
406 port->irq = irq;
407 else if (platp)
408 port->irq = platp->irq;
409 else
410 return -ENODEV;
411
412 port->membase = ioremap(offset: port->mapbase, ALTERA_JTAGUART_SIZE);
413 if (!port->membase)
414 return -ENOMEM;
415
416 port->line = i;
417 port->type = PORT_ALTERA_JTAGUART;
418 port->iotype = SERIAL_IO_MEM;
419 port->ops = &altera_jtaguart_ops;
420 port->flags = UPF_BOOT_AUTOCONF;
421 port->dev = &pdev->dev;
422
423 uart_add_one_port(reg: &altera_jtaguart_driver, port);
424
425 return 0;
426}
427
428static int altera_jtaguart_remove(struct platform_device *pdev)
429{
430 struct uart_port *port;
431 int i = pdev->id;
432
433 if (i == -1)
434 i = 0;
435
436 port = &altera_jtaguart_ports[i];
437 uart_remove_one_port(reg: &altera_jtaguart_driver, port);
438 iounmap(addr: port->membase);
439
440 return 0;
441}
442
443#ifdef CONFIG_OF
444static const struct of_device_id altera_jtaguart_match[] = {
445 { .compatible = "ALTR,juart-1.0", },
446 { .compatible = "altr,juart-1.0", },
447 {},
448};
449MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
450#endif /* CONFIG_OF */
451
452static struct platform_driver altera_jtaguart_platform_driver = {
453 .probe = altera_jtaguart_probe,
454 .remove = altera_jtaguart_remove,
455 .driver = {
456 .name = DRV_NAME,
457 .of_match_table = of_match_ptr(altera_jtaguart_match),
458 },
459};
460
461static int __init altera_jtaguart_init(void)
462{
463 int rc;
464
465 rc = uart_register_driver(uart: &altera_jtaguart_driver);
466 if (rc)
467 return rc;
468 rc = platform_driver_register(&altera_jtaguart_platform_driver);
469 if (rc)
470 uart_unregister_driver(uart: &altera_jtaguart_driver);
471 return rc;
472}
473
474static void __exit altera_jtaguart_exit(void)
475{
476 platform_driver_unregister(&altera_jtaguart_platform_driver);
477 uart_unregister_driver(uart: &altera_jtaguart_driver);
478}
479
480module_init(altera_jtaguart_init);
481module_exit(altera_jtaguart_exit);
482
483MODULE_DESCRIPTION("Altera JTAG UART driver");
484MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
485MODULE_LICENSE("GPL");
486MODULE_ALIAS("platform:" DRV_NAME);
487

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