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