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/kernel.h>
13 #include <linux/init.h>
14 #include <linux/interrupt.h>
15 #include <linux/module.h>
16 #include <linux/console.h>
17 #include <linux/of.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/io.h>
24 #include <linux/altera_jtaguart.h>
25
26 #define DRV_NAME "altera_jtaguart"
27
28 /*
29 * Altera JTAG UART register definitions according to the Altera JTAG UART
30 * datasheet: http://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf
31 */
32
33 #define ALTERA_JTAGUART_SIZE 8
34
35 #define ALTERA_JTAGUART_DATA_REG 0
36
37 #define ALTERA_JTAGUART_DATA_DATA_MSK 0x000000FF
38 #define ALTERA_JTAGUART_DATA_RVALID_MSK 0x00008000
39 #define ALTERA_JTAGUART_DATA_RAVAIL_MSK 0xFFFF0000
40 #define ALTERA_JTAGUART_DATA_RAVAIL_OFF 16
41
42 #define ALTERA_JTAGUART_CONTROL_REG 4
43
44 #define ALTERA_JTAGUART_CONTROL_RE_MSK 0x00000001
45 #define ALTERA_JTAGUART_CONTROL_WE_MSK 0x00000002
46 #define ALTERA_JTAGUART_CONTROL_RI_MSK 0x00000100
47 #define ALTERA_JTAGUART_CONTROL_RI_OFF 8
48 #define ALTERA_JTAGUART_CONTROL_WI_MSK 0x00000200
49 #define ALTERA_JTAGUART_CONTROL_AC_MSK 0x00000400
50 #define ALTERA_JTAGUART_CONTROL_WSPACE_MSK 0xFFFF0000
51 #define ALTERA_JTAGUART_CONTROL_WSPACE_OFF 16
52
53 /*
54 * Local per-uart structure.
55 */
56 struct altera_jtaguart {
57 struct uart_port port;
58 unsigned int sigs; /* Local copy of line sigs */
59 unsigned long imr; /* Local IMR mirror */
60 };
61
altera_jtaguart_tx_empty(struct uart_port * port)62 static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
63 {
64 return (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
65 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) ? TIOCSER_TEMT : 0;
66 }
67
altera_jtaguart_get_mctrl(struct uart_port * port)68 static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
69 {
70 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
71 }
72
altera_jtaguart_set_mctrl(struct uart_port * port,unsigned int sigs)73 static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
74 {
75 }
76
altera_jtaguart_start_tx(struct uart_port * port)77 static void altera_jtaguart_start_tx(struct uart_port *port)
78 {
79 struct altera_jtaguart *pp =
80 container_of(port, struct altera_jtaguart, port);
81
82 pp->imr |= ALTERA_JTAGUART_CONTROL_WE_MSK;
83 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
84 }
85
altera_jtaguart_stop_tx(struct uart_port * port)86 static void altera_jtaguart_stop_tx(struct uart_port *port)
87 {
88 struct altera_jtaguart *pp =
89 container_of(port, struct altera_jtaguart, port);
90
91 pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
92 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
93 }
94
altera_jtaguart_stop_rx(struct uart_port * port)95 static void altera_jtaguart_stop_rx(struct uart_port *port)
96 {
97 struct altera_jtaguart *pp =
98 container_of(port, struct altera_jtaguart, port);
99
100 pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
101 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
102 }
103
altera_jtaguart_break_ctl(struct uart_port * port,int break_state)104 static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
105 {
106 }
107
altera_jtaguart_set_termios(struct uart_port * port,struct ktermios * termios,struct ktermios * old)108 static void altera_jtaguart_set_termios(struct uart_port *port,
109 struct ktermios *termios,
110 struct ktermios *old)
111 {
112 /* Just copy the old termios settings back */
113 if (old)
114 tty_termios_copy_hw(termios, old);
115 }
116
altera_jtaguart_rx_chars(struct altera_jtaguart * pp)117 static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
118 {
119 struct uart_port *port = &pp->port;
120 unsigned char ch, flag;
121 unsigned long status;
122
123 while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) &
124 ALTERA_JTAGUART_DATA_RVALID_MSK) {
125 ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
126 flag = TTY_NORMAL;
127 port->icount.rx++;
128
129 if (uart_handle_sysrq_char(port, ch))
130 continue;
131 uart_insert_char(port, 0, 0, ch, flag);
132 }
133
134 spin_unlock(&port->lock);
135 tty_flip_buffer_push(&port->state->port);
136 spin_lock(&port->lock);
137 }
138
altera_jtaguart_tx_chars(struct altera_jtaguart * pp)139 static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
140 {
141 struct uart_port *port = &pp->port;
142 struct circ_buf *xmit = &port->state->xmit;
143 unsigned int pending, count;
144
145 if (port->x_char) {
146 /* Send special char - probably flow control */
147 writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
148 port->x_char = 0;
149 port->icount.tx++;
150 return;
151 }
152
153 pending = uart_circ_chars_pending(xmit);
154 if (pending > 0) {
155 count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
156 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
157 ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
158 if (count > pending)
159 count = pending;
160 if (count > 0) {
161 pending -= count;
162 while (count--) {
163 writel(xmit->buf[xmit->tail],
164 port->membase + ALTERA_JTAGUART_DATA_REG);
165 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
166 port->icount.tx++;
167 }
168 if (pending < WAKEUP_CHARS)
169 uart_write_wakeup(port);
170 }
171 }
172
173 if (pending == 0) {
174 pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
175 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
176 }
177 }
178
altera_jtaguart_interrupt(int irq,void * data)179 static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
180 {
181 struct uart_port *port = data;
182 struct altera_jtaguart *pp =
183 container_of(port, struct altera_jtaguart, port);
184 unsigned int isr;
185
186 isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
187 ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;
188
189 spin_lock(&port->lock);
190
191 if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
192 altera_jtaguart_rx_chars(pp);
193 if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
194 altera_jtaguart_tx_chars(pp);
195
196 spin_unlock(&port->lock);
197
198 return IRQ_RETVAL(isr);
199 }
200
altera_jtaguart_config_port(struct uart_port * port,int flags)201 static void altera_jtaguart_config_port(struct uart_port *port, int flags)
202 {
203 port->type = PORT_ALTERA_JTAGUART;
204
205 /* Clear mask, so no surprise interrupts. */
206 writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
207 }
208
altera_jtaguart_startup(struct uart_port * port)209 static int altera_jtaguart_startup(struct uart_port *port)
210 {
211 struct altera_jtaguart *pp =
212 container_of(port, struct altera_jtaguart, port);
213 unsigned long flags;
214 int ret;
215
216 ret = request_irq(port->irq, altera_jtaguart_interrupt, 0,
217 DRV_NAME, port);
218 if (ret) {
219 pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d "
220 "interrupt vector=%d\n", port->line, port->irq);
221 return ret;
222 }
223
224 spin_lock_irqsave(&port->lock, flags);
225
226 /* Enable RX interrupts now */
227 pp->imr = ALTERA_JTAGUART_CONTROL_RE_MSK;
228 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
229
230 spin_unlock_irqrestore(&port->lock, flags);
231
232 return 0;
233 }
234
altera_jtaguart_shutdown(struct uart_port * port)235 static void altera_jtaguart_shutdown(struct uart_port *port)
236 {
237 struct altera_jtaguart *pp =
238 container_of(port, struct altera_jtaguart, port);
239 unsigned long flags;
240
241 spin_lock_irqsave(&port->lock, flags);
242
243 /* Disable all interrupts now */
244 pp->imr = 0;
245 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
246
247 spin_unlock_irqrestore(&port->lock, flags);
248
249 free_irq(port->irq, port);
250 }
251
altera_jtaguart_type(struct uart_port * port)252 static const char *altera_jtaguart_type(struct uart_port *port)
253 {
254 return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
255 }
256
altera_jtaguart_request_port(struct uart_port * port)257 static int altera_jtaguart_request_port(struct uart_port *port)
258 {
259 /* UARTs always present */
260 return 0;
261 }
262
altera_jtaguart_release_port(struct uart_port * port)263 static void altera_jtaguart_release_port(struct uart_port *port)
264 {
265 /* Nothing to release... */
266 }
267
altera_jtaguart_verify_port(struct uart_port * port,struct serial_struct * ser)268 static int altera_jtaguart_verify_port(struct uart_port *port,
269 struct serial_struct *ser)
270 {
271 if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
272 return -EINVAL;
273 return 0;
274 }
275
276 /*
277 * Define the basic serial functions we support.
278 */
279 static const struct uart_ops altera_jtaguart_ops = {
280 .tx_empty = altera_jtaguart_tx_empty,
281 .get_mctrl = altera_jtaguart_get_mctrl,
282 .set_mctrl = altera_jtaguart_set_mctrl,
283 .start_tx = altera_jtaguart_start_tx,
284 .stop_tx = altera_jtaguart_stop_tx,
285 .stop_rx = altera_jtaguart_stop_rx,
286 .break_ctl = altera_jtaguart_break_ctl,
287 .startup = altera_jtaguart_startup,
288 .shutdown = altera_jtaguart_shutdown,
289 .set_termios = altera_jtaguart_set_termios,
290 .type = altera_jtaguart_type,
291 .request_port = altera_jtaguart_request_port,
292 .release_port = altera_jtaguart_release_port,
293 .config_port = altera_jtaguart_config_port,
294 .verify_port = altera_jtaguart_verify_port,
295 };
296
297 #define ALTERA_JTAGUART_MAXPORTS 1
298 static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
299
300 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
301
302 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
altera_jtaguart_console_putc(struct uart_port * port,int c)303 static void altera_jtaguart_console_putc(struct uart_port *port, int c)
304 {
305 unsigned long status;
306 unsigned long flags;
307
308 spin_lock_irqsave(&port->lock, flags);
309 while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) &
310 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
311 if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
312 spin_unlock_irqrestore(&port->lock, flags);
313 return; /* no connection activity */
314 }
315 spin_unlock_irqrestore(&port->lock, flags);
316 cpu_relax();
317 spin_lock_irqsave(&port->lock, flags);
318 }
319 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
320 spin_unlock_irqrestore(&port->lock, flags);
321 }
322 #else
altera_jtaguart_console_putc(struct uart_port * port,int c)323 static void altera_jtaguart_console_putc(struct uart_port *port, int c)
324 {
325 unsigned long flags;
326
327 spin_lock_irqsave(&port->lock, flags);
328 while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
329 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
330 spin_unlock_irqrestore(&port->lock, flags);
331 cpu_relax();
332 spin_lock_irqsave(&port->lock, flags);
333 }
334 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
335 spin_unlock_irqrestore(&port->lock, flags);
336 }
337 #endif
338
altera_jtaguart_console_write(struct console * co,const char * s,unsigned int count)339 static void altera_jtaguart_console_write(struct console *co, const char *s,
340 unsigned int count)
341 {
342 struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
343
344 uart_console_write(port, s, count, altera_jtaguart_console_putc);
345 }
346
altera_jtaguart_console_setup(struct console * co,char * options)347 static int __init altera_jtaguart_console_setup(struct console *co,
348 char *options)
349 {
350 struct uart_port *port;
351
352 if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
353 return -EINVAL;
354 port = &altera_jtaguart_ports[co->index].port;
355 if (port->membase == NULL)
356 return -ENODEV;
357 return 0;
358 }
359
360 static struct uart_driver altera_jtaguart_driver;
361
362 static struct console altera_jtaguart_console = {
363 .name = "ttyJ",
364 .write = altera_jtaguart_console_write,
365 .device = uart_console_device,
366 .setup = altera_jtaguart_console_setup,
367 .flags = CON_PRINTBUFFER,
368 .index = -1,
369 .data = &altera_jtaguart_driver,
370 };
371
altera_jtaguart_console_init(void)372 static int __init altera_jtaguart_console_init(void)
373 {
374 register_console(&altera_jtaguart_console);
375 return 0;
376 }
377
378 console_initcall(altera_jtaguart_console_init);
379
380 #define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console)
381
altera_jtaguart_earlycon_write(struct console * co,const char * s,unsigned int count)382 static void altera_jtaguart_earlycon_write(struct console *co, const char *s,
383 unsigned int count)
384 {
385 struct earlycon_device *dev = co->data;
386
387 uart_console_write(&dev->port, s, count, altera_jtaguart_console_putc);
388 }
389
altera_jtaguart_earlycon_setup(struct earlycon_device * dev,const char * options)390 static int __init altera_jtaguart_earlycon_setup(struct earlycon_device *dev,
391 const char *options)
392 {
393 if (!dev->port.membase)
394 return -ENODEV;
395
396 dev->con->write = altera_jtaguart_earlycon_write;
397 return 0;
398 }
399
400 OF_EARLYCON_DECLARE(juart, "altr,juart-1.0", altera_jtaguart_earlycon_setup);
401
402 #else
403
404 #define ALTERA_JTAGUART_CONSOLE NULL
405
406 #endif /* CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE */
407
408 static struct uart_driver altera_jtaguart_driver = {
409 .owner = THIS_MODULE,
410 .driver_name = "altera_jtaguart",
411 .dev_name = "ttyJ",
412 .major = ALTERA_JTAGUART_MAJOR,
413 .minor = ALTERA_JTAGUART_MINOR,
414 .nr = ALTERA_JTAGUART_MAXPORTS,
415 .cons = ALTERA_JTAGUART_CONSOLE,
416 };
417
altera_jtaguart_probe(struct platform_device * pdev)418 static int altera_jtaguart_probe(struct platform_device *pdev)
419 {
420 struct altera_jtaguart_platform_uart *platp =
421 dev_get_platdata(&pdev->dev);
422 struct uart_port *port;
423 struct resource *res_irq, *res_mem;
424 int i = pdev->id;
425
426 /* -1 emphasizes that the platform must have one port, no .N suffix */
427 if (i == -1)
428 i = 0;
429
430 if (i >= ALTERA_JTAGUART_MAXPORTS)
431 return -EINVAL;
432
433 port = &altera_jtaguart_ports[i].port;
434
435 res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
436 if (res_mem)
437 port->mapbase = res_mem->start;
438 else if (platp)
439 port->mapbase = platp->mapbase;
440 else
441 return -ENODEV;
442
443 res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
444 if (res_irq)
445 port->irq = res_irq->start;
446 else if (platp)
447 port->irq = platp->irq;
448 else
449 return -ENODEV;
450
451 port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
452 if (!port->membase)
453 return -ENOMEM;
454
455 port->line = i;
456 port->type = PORT_ALTERA_JTAGUART;
457 port->iotype = SERIAL_IO_MEM;
458 port->ops = &altera_jtaguart_ops;
459 port->flags = UPF_BOOT_AUTOCONF;
460 port->dev = &pdev->dev;
461
462 uart_add_one_port(&altera_jtaguart_driver, port);
463
464 return 0;
465 }
466
altera_jtaguart_remove(struct platform_device * pdev)467 static int altera_jtaguart_remove(struct platform_device *pdev)
468 {
469 struct uart_port *port;
470 int i = pdev->id;
471
472 if (i == -1)
473 i = 0;
474
475 port = &altera_jtaguart_ports[i].port;
476 uart_remove_one_port(&altera_jtaguart_driver, port);
477 iounmap(port->membase);
478
479 return 0;
480 }
481
482 #ifdef CONFIG_OF
483 static const struct of_device_id altera_jtaguart_match[] = {
484 { .compatible = "ALTR,juart-1.0", },
485 { .compatible = "altr,juart-1.0", },
486 {},
487 };
488 MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
489 #endif /* CONFIG_OF */
490
491 static struct platform_driver altera_jtaguart_platform_driver = {
492 .probe = altera_jtaguart_probe,
493 .remove = altera_jtaguart_remove,
494 .driver = {
495 .name = DRV_NAME,
496 .of_match_table = of_match_ptr(altera_jtaguart_match),
497 },
498 };
499
altera_jtaguart_init(void)500 static int __init altera_jtaguart_init(void)
501 {
502 int rc;
503
504 rc = uart_register_driver(&altera_jtaguart_driver);
505 if (rc)
506 return rc;
507 rc = platform_driver_register(&altera_jtaguart_platform_driver);
508 if (rc)
509 uart_unregister_driver(&altera_jtaguart_driver);
510 return rc;
511 }
512
altera_jtaguart_exit(void)513 static void __exit altera_jtaguart_exit(void)
514 {
515 platform_driver_unregister(&altera_jtaguart_platform_driver);
516 uart_unregister_driver(&altera_jtaguart_driver);
517 }
518
519 module_init(altera_jtaguart_init);
520 module_exit(altera_jtaguart_exit);
521
522 MODULE_DESCRIPTION("Altera JTAG UART driver");
523 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
524 MODULE_LICENSE("GPL");
525 MODULE_ALIAS("platform:" DRV_NAME);
526
