xref: /openbmc/linux/drivers/tty/serial/clps711x.c (revision 9a8f3203) 
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  Driver for CLPS711x serial ports
4  *
5  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6  *
7  *  Copyright 1999 ARM Limited
8  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
9  */
10 
11 #if defined(CONFIG_SERIAL_CLPS711X_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
12 #define SUPPORT_SYSRQ
13 #endif
14 
15 #include <linux/module.h>
16 #include <linux/device.h>
17 #include <linux/console.h>
18 #include <linux/serial_core.h>
19 #include <linux/serial.h>
20 #include <linux/clk.h>
21 #include <linux/io.h>
22 #include <linux/tty.h>
23 #include <linux/tty_flip.h>
24 #include <linux/ioport.h>
25 #include <linux/of.h>
26 #include <linux/platform_device.h>
27 #include <linux/regmap.h>
28 
29 #include <linux/mfd/syscon.h>
30 #include <linux/mfd/syscon/clps711x.h>
31 
32 #include "serial_mctrl_gpio.h"
33 
34 #define UART_CLPS711X_DEVNAME	"ttyCL"
35 #define UART_CLPS711X_NR	2
36 #define UART_CLPS711X_MAJOR	204
37 #define UART_CLPS711X_MINOR	40
38 
39 #define UARTDR_OFFSET		(0x00)
40 #define UBRLCR_OFFSET		(0x40)
41 
42 #define UARTDR_FRMERR		(1 << 8)
43 #define UARTDR_PARERR		(1 << 9)
44 #define UARTDR_OVERR		(1 << 10)
45 
46 #define UBRLCR_BAUD_MASK	((1 << 12) - 1)
47 #define UBRLCR_BREAK		(1 << 12)
48 #define UBRLCR_PRTEN		(1 << 13)
49 #define UBRLCR_EVENPRT		(1 << 14)
50 #define UBRLCR_XSTOP		(1 << 15)
51 #define UBRLCR_FIFOEN		(1 << 16)
52 #define UBRLCR_WRDLEN5		(0 << 17)
53 #define UBRLCR_WRDLEN6		(1 << 17)
54 #define UBRLCR_WRDLEN7		(2 << 17)
55 #define UBRLCR_WRDLEN8		(3 << 17)
56 #define UBRLCR_WRDLEN_MASK	(3 << 17)
57 
58 struct clps711x_port {
59 	struct uart_port	port;
60 	unsigned int		tx_enabled;
61 	int			rx_irq;
62 	struct regmap		*syscon;
63 	struct mctrl_gpios	*gpios;
64 };
65 
66 static struct uart_driver clps711x_uart = {
67 	.owner		= THIS_MODULE,
68 	.driver_name	= UART_CLPS711X_DEVNAME,
69 	.dev_name	= UART_CLPS711X_DEVNAME,
70 	.major		= UART_CLPS711X_MAJOR,
71 	.minor		= UART_CLPS711X_MINOR,
72 	.nr		= UART_CLPS711X_NR,
73 };
74 
75 static void uart_clps711x_stop_tx(struct uart_port *port)
76 {
77 	struct clps711x_port *s = dev_get_drvdata(port->dev);
78 
79 	if (s->tx_enabled) {
80 		disable_irq(port->irq);
81 		s->tx_enabled = 0;
82 	}
83 }
84 
85 static void uart_clps711x_start_tx(struct uart_port *port)
86 {
87 	struct clps711x_port *s = dev_get_drvdata(port->dev);
88 
89 	if (!s->tx_enabled) {
90 		s->tx_enabled = 1;
91 		enable_irq(port->irq);
92 	}
93 }
94 
95 static irqreturn_t uart_clps711x_int_rx(int irq, void *dev_id)
96 {
97 	struct uart_port *port = dev_id;
98 	struct clps711x_port *s = dev_get_drvdata(port->dev);
99 	unsigned int status, flg;
100 	u16 ch;
101 
102 	for (;;) {
103 		u32 sysflg = 0;
104 
105 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
106 		if (sysflg & SYSFLG_URXFE)
107 			break;
108 
109 		ch = readw(port->membase + UARTDR_OFFSET);
110 		status = ch & (UARTDR_FRMERR | UARTDR_PARERR | UARTDR_OVERR);
111 		ch &= 0xff;
112 
113 		port->icount.rx++;
114 		flg = TTY_NORMAL;
115 
116 		if (unlikely(status)) {
117 			if (status & UARTDR_PARERR)
118 				port->icount.parity++;
119 			else if (status & UARTDR_FRMERR)
120 				port->icount.frame++;
121 			else if (status & UARTDR_OVERR)
122 				port->icount.overrun++;
123 
124 			status &= port->read_status_mask;
125 
126 			if (status & UARTDR_PARERR)
127 				flg = TTY_PARITY;
128 			else if (status & UARTDR_FRMERR)
129 				flg = TTY_FRAME;
130 			else if (status & UARTDR_OVERR)
131 				flg = TTY_OVERRUN;
132 		}
133 
134 		if (uart_handle_sysrq_char(port, ch))
135 			continue;
136 
137 		if (status & port->ignore_status_mask)
138 			continue;
139 
140 		uart_insert_char(port, status, UARTDR_OVERR, ch, flg);
141 	}
142 
143 	tty_flip_buffer_push(&port->state->port);
144 
145 	return IRQ_HANDLED;
146 }
147 
148 static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
149 {
150 	struct uart_port *port = dev_id;
151 	struct clps711x_port *s = dev_get_drvdata(port->dev);
152 	struct circ_buf *xmit = &port->state->xmit;
153 
154 	if (port->x_char) {
155 		writew(port->x_char, port->membase + UARTDR_OFFSET);
156 		port->icount.tx++;
157 		port->x_char = 0;
158 		return IRQ_HANDLED;
159 	}
160 
161 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
162 		if (s->tx_enabled) {
163 			disable_irq_nosync(port->irq);
164 			s->tx_enabled = 0;
165 		}
166 		return IRQ_HANDLED;
167 	}
168 
169 	while (!uart_circ_empty(xmit)) {
170 		u32 sysflg = 0;
171 
172 		writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
173 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
174 		port->icount.tx++;
175 
176 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
177 		if (sysflg & SYSFLG_UTXFF)
178 			break;
179 	}
180 
181 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
182 		uart_write_wakeup(port);
183 
184 	return IRQ_HANDLED;
185 }
186 
187 static unsigned int uart_clps711x_tx_empty(struct uart_port *port)
188 {
189 	struct clps711x_port *s = dev_get_drvdata(port->dev);
190 	u32 sysflg = 0;
191 
192 	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
193 
194 	return (sysflg & SYSFLG_UBUSY) ? 0 : TIOCSER_TEMT;
195 }
196 
197 static unsigned int uart_clps711x_get_mctrl(struct uart_port *port)
198 {
199 	unsigned int result = TIOCM_DSR | TIOCM_CTS | TIOCM_CAR;
200 	struct clps711x_port *s = dev_get_drvdata(port->dev);
201 
202 	return mctrl_gpio_get(s->gpios, &result);
203 }
204 
205 static void uart_clps711x_set_mctrl(struct uart_port *port, unsigned int mctrl)
206 {
207 	struct clps711x_port *s = dev_get_drvdata(port->dev);
208 
209 	mctrl_gpio_set(s->gpios, mctrl);
210 }
211 
212 static void uart_clps711x_break_ctl(struct uart_port *port, int break_state)
213 {
214 	unsigned int ubrlcr;
215 
216 	ubrlcr = readl(port->membase + UBRLCR_OFFSET);
217 	if (break_state)
218 		ubrlcr |= UBRLCR_BREAK;
219 	else
220 		ubrlcr &= ~UBRLCR_BREAK;
221 	writel(ubrlcr, port->membase + UBRLCR_OFFSET);
222 }
223 
224 static void uart_clps711x_set_ldisc(struct uart_port *port,
225 				    struct ktermios *termios)
226 {
227 	if (!port->line) {
228 		struct clps711x_port *s = dev_get_drvdata(port->dev);
229 
230 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON1_SIREN,
231 				   (termios->c_line == N_IRDA) ? SYSCON1_SIREN : 0);
232 	}
233 }
234 
235 static int uart_clps711x_startup(struct uart_port *port)
236 {
237 	struct clps711x_port *s = dev_get_drvdata(port->dev);
238 
239 	/* Disable break */
240 	writel(readl(port->membase + UBRLCR_OFFSET) & ~UBRLCR_BREAK,
241 	       port->membase + UBRLCR_OFFSET);
242 
243 	/* Enable the port */
244 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
245 				  SYSCON_UARTEN, SYSCON_UARTEN);
246 }
247 
248 static void uart_clps711x_shutdown(struct uart_port *port)
249 {
250 	struct clps711x_port *s = dev_get_drvdata(port->dev);
251 
252 	/* Disable the port */
253 	regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
254 }
255 
256 static void uart_clps711x_set_termios(struct uart_port *port,
257 				      struct ktermios *termios,
258 				      struct ktermios *old)
259 {
260 	u32 ubrlcr;
261 	unsigned int baud, quot;
262 
263 	/* Mask termios capabilities we don't support */
264 	termios->c_cflag &= ~CMSPAR;
265 	termios->c_iflag &= ~(BRKINT | IGNBRK);
266 
267 	/* Ask the core to calculate the divisor for us */
268 	baud = uart_get_baud_rate(port, termios, old, port->uartclk / 4096,
269 						      port->uartclk / 16);
270 	quot = uart_get_divisor(port, baud);
271 
272 	switch (termios->c_cflag & CSIZE) {
273 	case CS5:
274 		ubrlcr = UBRLCR_WRDLEN5;
275 		break;
276 	case CS6:
277 		ubrlcr = UBRLCR_WRDLEN6;
278 		break;
279 	case CS7:
280 		ubrlcr = UBRLCR_WRDLEN7;
281 		break;
282 	case CS8:
283 	default:
284 		ubrlcr = UBRLCR_WRDLEN8;
285 		break;
286 	}
287 
288 	if (termios->c_cflag & CSTOPB)
289 		ubrlcr |= UBRLCR_XSTOP;
290 
291 	if (termios->c_cflag & PARENB) {
292 		ubrlcr |= UBRLCR_PRTEN;
293 		if (!(termios->c_cflag & PARODD))
294 			ubrlcr |= UBRLCR_EVENPRT;
295 	}
296 
297 	/* Enable FIFO */
298 	ubrlcr |= UBRLCR_FIFOEN;
299 
300 	/* Set read status mask */
301 	port->read_status_mask = UARTDR_OVERR;
302 	if (termios->c_iflag & INPCK)
303 		port->read_status_mask |= UARTDR_PARERR | UARTDR_FRMERR;
304 
305 	/* Set status ignore mask */
306 	port->ignore_status_mask = 0;
307 	if (!(termios->c_cflag & CREAD))
308 		port->ignore_status_mask |= UARTDR_OVERR | UARTDR_PARERR |
309 					    UARTDR_FRMERR;
310 
311 	uart_update_timeout(port, termios->c_cflag, baud);
312 
313 	writel(ubrlcr | (quot - 1), port->membase + UBRLCR_OFFSET);
314 }
315 
316 static const char *uart_clps711x_type(struct uart_port *port)
317 {
318 	return (port->type == PORT_CLPS711X) ? "CLPS711X" : NULL;
319 }
320 
321 static void uart_clps711x_config_port(struct uart_port *port, int flags)
322 {
323 	if (flags & UART_CONFIG_TYPE)
324 		port->type = PORT_CLPS711X;
325 }
326 
327 static void uart_clps711x_nop_void(struct uart_port *port)
328 {
329 }
330 
331 static int uart_clps711x_nop_int(struct uart_port *port)
332 {
333 	return 0;
334 }
335 
336 static const struct uart_ops uart_clps711x_ops = {
337 	.tx_empty	= uart_clps711x_tx_empty,
338 	.set_mctrl	= uart_clps711x_set_mctrl,
339 	.get_mctrl	= uart_clps711x_get_mctrl,
340 	.stop_tx	= uart_clps711x_stop_tx,
341 	.start_tx	= uart_clps711x_start_tx,
342 	.stop_rx	= uart_clps711x_nop_void,
343 	.break_ctl	= uart_clps711x_break_ctl,
344 	.set_ldisc	= uart_clps711x_set_ldisc,
345 	.startup	= uart_clps711x_startup,
346 	.shutdown	= uart_clps711x_shutdown,
347 	.set_termios	= uart_clps711x_set_termios,
348 	.type		= uart_clps711x_type,
349 	.config_port	= uart_clps711x_config_port,
350 	.release_port	= uart_clps711x_nop_void,
351 	.request_port	= uart_clps711x_nop_int,
352 };
353 
354 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
355 static void uart_clps711x_console_putchar(struct uart_port *port, int ch)
356 {
357 	struct clps711x_port *s = dev_get_drvdata(port->dev);
358 	u32 sysflg = 0;
359 
360 	/* Wait for FIFO is not full */
361 	do {
362 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
363 	} while (sysflg & SYSFLG_UTXFF);
364 
365 	writew(ch, port->membase + UARTDR_OFFSET);
366 }
367 
368 static void uart_clps711x_console_write(struct console *co, const char *c,
369 					unsigned n)
370 {
371 	struct uart_port *port = clps711x_uart.state[co->index].uart_port;
372 	struct clps711x_port *s = dev_get_drvdata(port->dev);
373 	u32 sysflg = 0;
374 
375 	uart_console_write(port, c, n, uart_clps711x_console_putchar);
376 
377 	/* Wait for transmitter to become empty */
378 	do {
379 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
380 	} while (sysflg & SYSFLG_UBUSY);
381 }
382 
383 static int uart_clps711x_console_setup(struct console *co, char *options)
384 {
385 	int baud = 38400, bits = 8, parity = 'n', flow = 'n';
386 	int ret, index = co->index;
387 	struct clps711x_port *s;
388 	struct uart_port *port;
389 	unsigned int quot;
390 	u32 ubrlcr;
391 
392 	if (index < 0 || index >= UART_CLPS711X_NR)
393 		return -EINVAL;
394 
395 	port = clps711x_uart.state[index].uart_port;
396 	if (!port)
397 		return -ENODEV;
398 
399 	s = dev_get_drvdata(port->dev);
400 
401 	if (!options) {
402 		u32 syscon = 0;
403 
404 		regmap_read(s->syscon, SYSCON_OFFSET, &syscon);
405 		if (syscon & SYSCON_UARTEN) {
406 			ubrlcr = readl(port->membase + UBRLCR_OFFSET);
407 
408 			if (ubrlcr & UBRLCR_PRTEN) {
409 				if (ubrlcr & UBRLCR_EVENPRT)
410 					parity = 'e';
411 				else
412 					parity = 'o';
413 			}
414 
415 			if ((ubrlcr & UBRLCR_WRDLEN_MASK) == UBRLCR_WRDLEN7)
416 				bits = 7;
417 
418 			quot = ubrlcr & UBRLCR_BAUD_MASK;
419 			baud = port->uartclk / (16 * (quot + 1));
420 		}
421 	} else
422 		uart_parse_options(options, &baud, &parity, &bits, &flow);
423 
424 	ret = uart_set_options(port, co, baud, parity, bits, flow);
425 	if (ret)
426 		return ret;
427 
428 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
429 				  SYSCON_UARTEN, SYSCON_UARTEN);
430 }
431 
432 static struct console clps711x_console = {
433 	.name	= UART_CLPS711X_DEVNAME,
434 	.device	= uart_console_device,
435 	.write	= uart_clps711x_console_write,
436 	.setup	= uart_clps711x_console_setup,
437 	.flags	= CON_PRINTBUFFER,
438 	.index	= -1,
439 };
440 #endif
441 
442 static int uart_clps711x_probe(struct platform_device *pdev)
443 {
444 	struct device_node *np = pdev->dev.of_node;
445 	struct clps711x_port *s;
446 	struct resource *res;
447 	struct clk *uart_clk;
448 	int irq, ret;
449 
450 	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
451 	if (!s)
452 		return -ENOMEM;
453 
454 	uart_clk = devm_clk_get(&pdev->dev, NULL);
455 	if (IS_ERR(uart_clk))
456 		return PTR_ERR(uart_clk);
457 
458 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
459 	s->port.membase = devm_ioremap_resource(&pdev->dev, res);
460 	if (IS_ERR(s->port.membase))
461 		return PTR_ERR(s->port.membase);
462 
463 	irq = platform_get_irq(pdev, 0);
464 	if (irq < 0)
465 		return irq;
466 	s->port.irq = irq;
467 
468 	s->rx_irq = platform_get_irq(pdev, 1);
469 	if (s->rx_irq < 0)
470 		return s->rx_irq;
471 
472 	s->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
473 	if (IS_ERR(s->syscon))
474 		return PTR_ERR(s->syscon);
475 
476 	s->port.line		= of_alias_get_id(np, "serial");
477 	s->port.dev		= &pdev->dev;
478 	s->port.iotype		= UPIO_MEM32;
479 	s->port.mapbase		= res->start;
480 	s->port.type		= PORT_CLPS711X;
481 	s->port.fifosize	= 16;
482 	s->port.flags		= UPF_SKIP_TEST | UPF_FIXED_TYPE;
483 	s->port.uartclk		= clk_get_rate(uart_clk);
484 	s->port.ops		= &uart_clps711x_ops;
485 
486 	platform_set_drvdata(pdev, s);
487 
488 	s->gpios = mctrl_gpio_init_noauto(&pdev->dev, 0);
489 	if (IS_ERR(s->gpios))
490 	    return PTR_ERR(s->gpios);
491 
492 	ret = uart_add_one_port(&clps711x_uart, &s->port);
493 	if (ret)
494 		return ret;
495 
496 	/* Disable port */
497 	if (!uart_console(&s->port))
498 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
499 
500 	s->tx_enabled = 1;
501 
502 	ret = devm_request_irq(&pdev->dev, s->port.irq, uart_clps711x_int_tx, 0,
503 			       dev_name(&pdev->dev), &s->port);
504 	if (ret) {
505 		uart_remove_one_port(&clps711x_uart, &s->port);
506 		return ret;
507 	}
508 
509 	ret = devm_request_irq(&pdev->dev, s->rx_irq, uart_clps711x_int_rx, 0,
510 			       dev_name(&pdev->dev), &s->port);
511 	if (ret)
512 		uart_remove_one_port(&clps711x_uart, &s->port);
513 
514 	return ret;
515 }
516 
517 static int uart_clps711x_remove(struct platform_device *pdev)
518 {
519 	struct clps711x_port *s = platform_get_drvdata(pdev);
520 
521 	return uart_remove_one_port(&clps711x_uart, &s->port);
522 }
523 
524 static const struct of_device_id __maybe_unused clps711x_uart_dt_ids[] = {
525 	{ .compatible = "cirrus,ep7209-uart", },
526 	{ }
527 };
528 MODULE_DEVICE_TABLE(of, clps711x_uart_dt_ids);
529 
530 static struct platform_driver clps711x_uart_platform = {
531 	.driver = {
532 		.name		= "clps711x-uart",
533 		.of_match_table	= of_match_ptr(clps711x_uart_dt_ids),
534 	},
535 	.probe	= uart_clps711x_probe,
536 	.remove	= uart_clps711x_remove,
537 };
538 
539 static int __init uart_clps711x_init(void)
540 {
541 	int ret;
542 
543 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
544 	clps711x_uart.cons = &clps711x_console;
545 	clps711x_console.data = &clps711x_uart;
546 #endif
547 
548 	ret = uart_register_driver(&clps711x_uart);
549 	if (ret)
550 		return ret;
551 
552 	return platform_driver_register(&clps711x_uart_platform);
553 }
554 module_init(uart_clps711x_init);
555 
556 static void __exit uart_clps711x_exit(void)
557 {
558 	platform_driver_unregister(&clps711x_uart_platform);
559 	uart_unregister_driver(&clps711x_uart);
560 }
561 module_exit(uart_clps711x_exit);
562 
563 MODULE_AUTHOR("Deep Blue Solutions Ltd");
564 MODULE_DESCRIPTION("CLPS711X serial driver");
565 MODULE_LICENSE("GPL");
566