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
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_space(struct uart_port * port,u32 * ctlp)62 static unsigned int altera_jtaguart_tx_space(struct uart_port *port, u32 *ctlp)
63 {
64 u32 ctl = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG);
65
66 if (ctlp)
67 *ctlp = ctl;
68
69 return FIELD_GET(ALTERA_JTAGUART_CONTROL_WSPACE_MSK, ctl);
70 }
71
altera_jtaguart_tx_empty(struct uart_port * port)72 static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
73 {
74 return altera_jtaguart_tx_space(port, NULL) ? TIOCSER_TEMT : 0;
75 }
76
altera_jtaguart_get_mctrl(struct uart_port * port)77 static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
78 {
79 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
80 }
81
altera_jtaguart_set_mctrl(struct uart_port * port,unsigned int sigs)82 static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
83 {
84 }
85
altera_jtaguart_start_tx(struct uart_port * port)86 static void altera_jtaguart_start_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_tx(struct uart_port * port)95 static void altera_jtaguart_stop_tx(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_WE_MSK;
101 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
102 }
103
altera_jtaguart_stop_rx(struct uart_port * port)104 static void altera_jtaguart_stop_rx(struct uart_port *port)
105 {
106 struct altera_jtaguart *pp =
107 container_of(port, struct altera_jtaguart, port);
108
109 pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
110 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
111 }
112
altera_jtaguart_break_ctl(struct uart_port * port,int break_state)113 static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
114 {
115 }
116
altera_jtaguart_set_termios(struct uart_port * port,struct ktermios * termios,const struct ktermios * old)117 static void altera_jtaguart_set_termios(struct uart_port *port,
118 struct ktermios *termios,
119 const struct ktermios *old)
120 {
121 /* Just copy the old termios settings back */
122 if (old)
123 tty_termios_copy_hw(termios, old);
124 }
125
altera_jtaguart_rx_chars(struct altera_jtaguart * pp)126 static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
127 {
128 struct uart_port *port = &pp->port;
129 unsigned char ch, flag;
130 unsigned long status;
131
132 while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) &
133 ALTERA_JTAGUART_DATA_RVALID_MSK) {
134 ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
135 flag = TTY_NORMAL;
136 port->icount.rx++;
137
138 if (uart_handle_sysrq_char(port, ch))
139 continue;
140 uart_insert_char(port, 0, 0, ch, flag);
141 }
142
143 tty_flip_buffer_push(&port->state->port);
144 }
145
altera_jtaguart_tx_chars(struct altera_jtaguart * pp)146 static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
147 {
148 struct uart_port *port = &pp->port;
149 struct circ_buf *xmit = &port->state->xmit;
150 unsigned int pending, count;
151
152 if (port->x_char) {
153 /* Send special char - probably flow control */
154 writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
155 port->x_char = 0;
156 port->icount.tx++;
157 return;
158 }
159
160 pending = uart_circ_chars_pending(xmit);
161 if (pending > 0) {
162 count = altera_jtaguart_tx_space(port, NULL);
163 if (count > pending)
164 count = pending;
165 if (count > 0) {
166 pending -= count;
167 while (count--) {
168 writel(xmit->buf[xmit->tail],
169 port->membase + ALTERA_JTAGUART_DATA_REG);
170 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
171 port->icount.tx++;
172 }
173 if (pending < WAKEUP_CHARS)
174 uart_write_wakeup(port);
175 }
176 }
177
178 if (pending == 0)
179 altera_jtaguart_stop_tx(port);
180 }
181
altera_jtaguart_interrupt(int irq,void * data)182 static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
183 {
184 struct uart_port *port = data;
185 struct altera_jtaguart *pp =
186 container_of(port, struct altera_jtaguart, port);
187 unsigned int isr;
188
189 isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
190 ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;
191
192 spin_lock(&port->lock);
193
194 if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
195 altera_jtaguart_rx_chars(pp);
196 if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
197 altera_jtaguart_tx_chars(pp);
198
199 spin_unlock(&port->lock);
200
201 return IRQ_RETVAL(isr);
202 }
203
altera_jtaguart_config_port(struct uart_port * port,int flags)204 static void altera_jtaguart_config_port(struct uart_port *port, int flags)
205 {
206 port->type = PORT_ALTERA_JTAGUART;
207
208 /* Clear mask, so no surprise interrupts. */
209 writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
210 }
211
altera_jtaguart_startup(struct uart_port * port)212 static int altera_jtaguart_startup(struct uart_port *port)
213 {
214 struct altera_jtaguart *pp =
215 container_of(port, struct altera_jtaguart, port);
216 unsigned long flags;
217 int ret;
218
219 ret = request_irq(port->irq, altera_jtaguart_interrupt, 0,
220 DRV_NAME, port);
221 if (ret) {
222 pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d "
223 "interrupt vector=%d\n", port->line, port->irq);
224 return ret;
225 }
226
227 spin_lock_irqsave(&port->lock, flags);
228
229 /* Enable RX interrupts now */
230 pp->imr = ALTERA_JTAGUART_CONTROL_RE_MSK;
231 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
232
233 spin_unlock_irqrestore(&port->lock, flags);
234
235 return 0;
236 }
237
altera_jtaguart_shutdown(struct uart_port * port)238 static void altera_jtaguart_shutdown(struct uart_port *port)
239 {
240 struct altera_jtaguart *pp =
241 container_of(port, struct altera_jtaguart, port);
242 unsigned long flags;
243
244 spin_lock_irqsave(&port->lock, flags);
245
246 /* Disable all interrupts now */
247 pp->imr = 0;
248 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
249
250 spin_unlock_irqrestore(&port->lock, flags);
251
252 free_irq(port->irq, port);
253 }
254
altera_jtaguart_type(struct uart_port * port)255 static const char *altera_jtaguart_type(struct uart_port *port)
256 {
257 return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
258 }
259
altera_jtaguart_request_port(struct uart_port * port)260 static int altera_jtaguart_request_port(struct uart_port *port)
261 {
262 /* UARTs always present */
263 return 0;
264 }
265
altera_jtaguart_release_port(struct uart_port * port)266 static void altera_jtaguart_release_port(struct uart_port *port)
267 {
268 /* Nothing to release... */
269 }
270
altera_jtaguart_verify_port(struct uart_port * port,struct serial_struct * ser)271 static int altera_jtaguart_verify_port(struct uart_port *port,
272 struct serial_struct *ser)
273 {
274 if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
275 return -EINVAL;
276 return 0;
277 }
278
279 /*
280 * Define the basic serial functions we support.
281 */
282 static const struct uart_ops altera_jtaguart_ops = {
283 .tx_empty = altera_jtaguart_tx_empty,
284 .get_mctrl = altera_jtaguart_get_mctrl,
285 .set_mctrl = altera_jtaguart_set_mctrl,
286 .start_tx = altera_jtaguart_start_tx,
287 .stop_tx = altera_jtaguart_stop_tx,
288 .stop_rx = altera_jtaguart_stop_rx,
289 .break_ctl = altera_jtaguart_break_ctl,
290 .startup = altera_jtaguart_startup,
291 .shutdown = altera_jtaguart_shutdown,
292 .set_termios = altera_jtaguart_set_termios,
293 .type = altera_jtaguart_type,
294 .request_port = altera_jtaguart_request_port,
295 .release_port = altera_jtaguart_release_port,
296 .config_port = altera_jtaguart_config_port,
297 .verify_port = altera_jtaguart_verify_port,
298 };
299
300 #define ALTERA_JTAGUART_MAXPORTS 1
301 static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
302
303 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
304
305 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
altera_jtaguart_console_putc(struct uart_port * port,unsigned char c)306 static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c)
307 {
308 unsigned long flags;
309 u32 status;
310
311 spin_lock_irqsave(&port->lock, flags);
312 while (!altera_jtaguart_tx_space(port, &status)) {
313 spin_unlock_irqrestore(&port->lock, flags);
314
315 if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
316 return; /* no connection activity */
317 }
318
319 cpu_relax();
320 spin_lock_irqsave(&port->lock, flags);
321 }
322 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
323 spin_unlock_irqrestore(&port->lock, flags);
324 }
325 #else
altera_jtaguart_console_putc(struct uart_port * port,unsigned char c)326 static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c)
327 {
328 unsigned long flags;
329
330 spin_lock_irqsave(&port->lock, flags);
331 while (!altera_jtaguart_tx_space(port, NULL)) {
332 spin_unlock_irqrestore(&port->lock, flags);
333 cpu_relax();
334 spin_lock_irqsave(&port->lock, flags);
335 }
336 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
337 spin_unlock_irqrestore(&port->lock, flags);
338 }
339 #endif
340
altera_jtaguart_console_write(struct console * co,const char * s,unsigned int count)341 static void altera_jtaguart_console_write(struct console *co, const char *s,
342 unsigned int count)
343 {
344 struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
345
346 uart_console_write(port, s, count, altera_jtaguart_console_putc);
347 }
348
altera_jtaguart_console_setup(struct console * co,char * options)349 static int __init altera_jtaguart_console_setup(struct console *co,
350 char *options)
351 {
352 struct uart_port *port;
353
354 if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
355 return -EINVAL;
356 port = &altera_jtaguart_ports[co->index].port;
357 if (port->membase == NULL)
358 return -ENODEV;
359 return 0;
360 }
361
362 static struct uart_driver altera_jtaguart_driver;
363
364 static struct console altera_jtaguart_console = {
365 .name = "ttyJ",
366 .write = altera_jtaguart_console_write,
367 .device = uart_console_device,
368 .setup = altera_jtaguart_console_setup,
369 .flags = CON_PRINTBUFFER,
370 .index = -1,
371 .data = &altera_jtaguart_driver,
372 };
373
altera_jtaguart_console_init(void)374 static int __init altera_jtaguart_console_init(void)
375 {
376 register_console(&altera_jtaguart_console);
377 return 0;
378 }
379
380 console_initcall(altera_jtaguart_console_init);
381
382 #define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console)
383
altera_jtaguart_earlycon_write(struct console * co,const char * s,unsigned int count)384 static void altera_jtaguart_earlycon_write(struct console *co, const char *s,
385 unsigned int count)
386 {
387 struct earlycon_device *dev = co->data;
388
389 uart_console_write(&dev->port, s, count, altera_jtaguart_console_putc);
390 }
391
altera_jtaguart_earlycon_setup(struct earlycon_device * dev,const char * options)392 static int __init altera_jtaguart_earlycon_setup(struct earlycon_device *dev,
393 const char *options)
394 {
395 if (!dev->port.membase)
396 return -ENODEV;
397
398 dev->con->write = altera_jtaguart_earlycon_write;
399 return 0;
400 }
401
402 OF_EARLYCON_DECLARE(juart, "altr,juart-1.0", altera_jtaguart_earlycon_setup);
403
404 #else
405
406 #define ALTERA_JTAGUART_CONSOLE NULL
407
408 #endif /* CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE */
409
410 static struct uart_driver altera_jtaguart_driver = {
411 .owner = THIS_MODULE,
412 .driver_name = "altera_jtaguart",
413 .dev_name = "ttyJ",
414 .major = ALTERA_JTAGUART_MAJOR,
415 .minor = ALTERA_JTAGUART_MINOR,
416 .nr = ALTERA_JTAGUART_MAXPORTS,
417 .cons = ALTERA_JTAGUART_CONSOLE,
418 };
419
altera_jtaguart_probe(struct platform_device * pdev)420 static int altera_jtaguart_probe(struct platform_device *pdev)
421 {
422 struct altera_jtaguart_platform_uart *platp =
423 dev_get_platdata(&pdev->dev);
424 struct uart_port *port;
425 struct resource *res_mem;
426 int i = pdev->id;
427 int irq;
428
429 /* -1 emphasizes that the platform must have one port, no .N suffix */
430 if (i == -1)
431 i = 0;
432
433 if (i >= ALTERA_JTAGUART_MAXPORTS)
434 return -EINVAL;
435
436 port = &altera_jtaguart_ports[i].port;
437
438 res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
439 if (res_mem)
440 port->mapbase = res_mem->start;
441 else if (platp)
442 port->mapbase = platp->mapbase;
443 else
444 return -ENODEV;
445
446 irq = platform_get_irq_optional(pdev, 0);
447 if (irq < 0 && irq != -ENXIO)
448 return irq;
449 if (irq > 0)
450 port->irq = irq;
451 else if (platp)
452 port->irq = platp->irq;
453 else
454 return -ENODEV;
455
456 port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
457 if (!port->membase)
458 return -ENOMEM;
459
460 port->line = i;
461 port->type = PORT_ALTERA_JTAGUART;
462 port->iotype = SERIAL_IO_MEM;
463 port->ops = &altera_jtaguart_ops;
464 port->flags = UPF_BOOT_AUTOCONF;
465 port->dev = &pdev->dev;
466
467 uart_add_one_port(&altera_jtaguart_driver, port);
468
469 return 0;
470 }
471
altera_jtaguart_remove(struct platform_device * pdev)472 static int altera_jtaguart_remove(struct platform_device *pdev)
473 {
474 struct uart_port *port;
475 int i = pdev->id;
476
477 if (i == -1)
478 i = 0;
479
480 port = &altera_jtaguart_ports[i].port;
481 uart_remove_one_port(&altera_jtaguart_driver, port);
482 iounmap(port->membase);
483
484 return 0;
485 }
486
487 #ifdef CONFIG_OF
488 static const struct of_device_id altera_jtaguart_match[] = {
489 { .compatible = "ALTR,juart-1.0", },
490 { .compatible = "altr,juart-1.0", },
491 {},
492 };
493 MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
494 #endif /* CONFIG_OF */
495
496 static struct platform_driver altera_jtaguart_platform_driver = {
497 .probe = altera_jtaguart_probe,
498 .remove = altera_jtaguart_remove,
499 .driver = {
500 .name = DRV_NAME,
501 .of_match_table = of_match_ptr(altera_jtaguart_match),
502 },
503 };
504
altera_jtaguart_init(void)505 static int __init altera_jtaguart_init(void)
506 {
507 int rc;
508
509 rc = uart_register_driver(&altera_jtaguart_driver);
510 if (rc)
511 return rc;
512 rc = platform_driver_register(&altera_jtaguart_platform_driver);
513 if (rc)
514 uart_unregister_driver(&altera_jtaguart_driver);
515 return rc;
516 }
517
altera_jtaguart_exit(void)518 static void __exit altera_jtaguart_exit(void)
519 {
520 platform_driver_unregister(&altera_jtaguart_platform_driver);
521 uart_unregister_driver(&altera_jtaguart_driver);
522 }
523
524 module_init(altera_jtaguart_init);
525 module_exit(altera_jtaguart_exit);
526
527 MODULE_DESCRIPTION("Altera JTAG UART driver");
528 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
529 MODULE_LICENSE("GPL");
530 MODULE_ALIAS("platform:" DRV_NAME);
531
