xref: /openbmc/linux/drivers/tty/serial/clps711x.c (revision b8265621) 
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 #include <linux/module.h>
12 #include <linux/device.h>
13 #include <linux/console.h>
14 #include <linux/serial_core.h>
15 #include <linux/serial.h>
16 #include <linux/clk.h>
17 #include <linux/io.h>
18 #include <linux/tty.h>
19 #include <linux/tty_flip.h>
20 #include <linux/ioport.h>
21 #include <linux/of.h>
22 #include <linux/platform_device.h>
23 #include <linux/regmap.h>
24 
25 #include <linux/mfd/syscon.h>
26 #include <linux/mfd/syscon/clps711x.h>
27 
28 #include "serial_mctrl_gpio.h"
29 
30 #define UART_CLPS711X_DEVNAME	"ttyCL"
31 #define UART_CLPS711X_NR	2
32 #define UART_CLPS711X_MAJOR	204
33 #define UART_CLPS711X_MINOR	40
34 
35 #define UARTDR_OFFSET		(0x00)
36 #define UBRLCR_OFFSET		(0x40)
37 
38 #define UARTDR_FRMERR		(1 << 8)
39 #define UARTDR_PARERR		(1 << 9)
40 #define UARTDR_OVERR		(1 << 10)
41 
42 #define UBRLCR_BAUD_MASK	((1 << 12) - 1)
43 #define UBRLCR_BREAK		(1 << 12)
44 #define UBRLCR_PRTEN		(1 << 13)
45 #define UBRLCR_EVENPRT		(1 << 14)
46 #define UBRLCR_XSTOP		(1 << 15)
47 #define UBRLCR_FIFOEN		(1 << 16)
48 #define UBRLCR_WRDLEN5		(0 << 17)
49 #define UBRLCR_WRDLEN6		(1 << 17)
50 #define UBRLCR_WRDLEN7		(2 << 17)
51 #define UBRLCR_WRDLEN8		(3 << 17)
52 #define UBRLCR_WRDLEN_MASK	(3 << 17)
53 
54 struct clps711x_port {
55 	struct uart_port	port;
56 	unsigned int		tx_enabled;
57 	int			rx_irq;
58 	struct regmap		*syscon;
59 	struct mctrl_gpios	*gpios;
60 };
61 
62 static struct uart_driver clps711x_uart = {
63 	.owner		= THIS_MODULE,
64 	.driver_name	= UART_CLPS711X_DEVNAME,
65 	.dev_name	= UART_CLPS711X_DEVNAME,
66 	.major		= UART_CLPS711X_MAJOR,
67 	.minor		= UART_CLPS711X_MINOR,
68 	.nr		= UART_CLPS711X_NR,
69 };
70 
71 static void uart_clps711x_stop_tx(struct uart_port *port)
72 {
73 	struct clps711x_port *s = dev_get_drvdata(port->dev);
74 
75 	if (s->tx_enabled) {
76 		disable_irq(port->irq);
77 		s->tx_enabled = 0;
78 	}
79 }
80 
81 static void uart_clps711x_start_tx(struct uart_port *port)
82 {
83 	struct clps711x_port *s = dev_get_drvdata(port->dev);
84 
85 	if (!s->tx_enabled) {
86 		s->tx_enabled = 1;
87 		enable_irq(port->irq);
88 	}
89 }
90 
91 static irqreturn_t uart_clps711x_int_rx(int irq, void *dev_id)
92 {
93 	struct uart_port *port = dev_id;
94 	struct clps711x_port *s = dev_get_drvdata(port->dev);
95 	unsigned int status, flg;
96 	u16 ch;
97 
98 	for (;;) {
99 		u32 sysflg = 0;
100 
101 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
102 		if (sysflg & SYSFLG_URXFE)
103 			break;
104 
105 		ch = readw(port->membase + UARTDR_OFFSET);
106 		status = ch & (UARTDR_FRMERR | UARTDR_PARERR | UARTDR_OVERR);
107 		ch &= 0xff;
108 
109 		port->icount.rx++;
110 		flg = TTY_NORMAL;
111 
112 		if (unlikely(status)) {
113 			if (status & UARTDR_PARERR)
114 				port->icount.parity++;
115 			else if (status & UARTDR_FRMERR)
116 				port->icount.frame++;
117 			else if (status & UARTDR_OVERR)
118 				port->icount.overrun++;
119 
120 			status &= port->read_status_mask;
121 
122 			if (status & UARTDR_PARERR)
123 				flg = TTY_PARITY;
124 			else if (status & UARTDR_FRMERR)
125 				flg = TTY_FRAME;
126 			else if (status & UARTDR_OVERR)
127 				flg = TTY_OVERRUN;
128 		}
129 
130 		if (uart_handle_sysrq_char(port, ch))
131 			continue;
132 
133 		if (status & port->ignore_status_mask)
134 			continue;
135 
136 		uart_insert_char(port, status, UARTDR_OVERR, ch, flg);
137 	}
138 
139 	tty_flip_buffer_push(&port->state->port);
140 
141 	return IRQ_HANDLED;
142 }
143 
144 static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
145 {
146 	struct uart_port *port = dev_id;
147 	struct clps711x_port *s = dev_get_drvdata(port->dev);
148 	struct circ_buf *xmit = &port->state->xmit;
149 
150 	if (port->x_char) {
151 		writew(port->x_char, port->membase + UARTDR_OFFSET);
152 		port->icount.tx++;
153 		port->x_char = 0;
154 		return IRQ_HANDLED;
155 	}
156 
157 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
158 		if (s->tx_enabled) {
159 			disable_irq_nosync(port->irq);
160 			s->tx_enabled = 0;
161 		}
162 		return IRQ_HANDLED;
163 	}
164 
165 	while (!uart_circ_empty(xmit)) {
166 		u32 sysflg = 0;
167 
168 		writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
169 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
170 		port->icount.tx++;
171 
172 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
173 		if (sysflg & SYSFLG_UTXFF)
174 			break;
175 	}
176 
177 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
178 		uart_write_wakeup(port);
179 
180 	return IRQ_HANDLED;
181 }
182 
183 static unsigned int uart_clps711x_tx_empty(struct uart_port *port)
184 {
185 	struct clps711x_port *s = dev_get_drvdata(port->dev);
186 	u32 sysflg = 0;
187 
188 	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
189 
190 	return (sysflg & SYSFLG_UBUSY) ? 0 : TIOCSER_TEMT;
191 }
192 
193 static unsigned int uart_clps711x_get_mctrl(struct uart_port *port)
194 {
195 	unsigned int result = TIOCM_DSR | TIOCM_CTS | TIOCM_CAR;
196 	struct clps711x_port *s = dev_get_drvdata(port->dev);
197 
198 	return mctrl_gpio_get(s->gpios, &result);
199 }
200 
201 static void uart_clps711x_set_mctrl(struct uart_port *port, unsigned int mctrl)
202 {
203 	struct clps711x_port *s = dev_get_drvdata(port->dev);
204 
205 	mctrl_gpio_set(s->gpios, mctrl);
206 }
207 
208 static void uart_clps711x_break_ctl(struct uart_port *port, int break_state)
209 {
210 	unsigned int ubrlcr;
211 
212 	ubrlcr = readl(port->membase + UBRLCR_OFFSET);
213 	if (break_state)
214 		ubrlcr |= UBRLCR_BREAK;
215 	else
216 		ubrlcr &= ~UBRLCR_BREAK;
217 	writel(ubrlcr, port->membase + UBRLCR_OFFSET);
218 }
219 
220 static void uart_clps711x_set_ldisc(struct uart_port *port,
221 				    struct ktermios *termios)
222 {
223 	if (!port->line) {
224 		struct clps711x_port *s = dev_get_drvdata(port->dev);
225 
226 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON1_SIREN,
227 				   (termios->c_line == N_IRDA) ? SYSCON1_SIREN : 0);
228 	}
229 }
230 
231 static int uart_clps711x_startup(struct uart_port *port)
232 {
233 	struct clps711x_port *s = dev_get_drvdata(port->dev);
234 
235 	/* Disable break */
236 	writel(readl(port->membase + UBRLCR_OFFSET) & ~UBRLCR_BREAK,
237 	       port->membase + UBRLCR_OFFSET);
238 
239 	/* Enable the port */
240 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
241 				  SYSCON_UARTEN, SYSCON_UARTEN);
242 }
243 
244 static void uart_clps711x_shutdown(struct uart_port *port)
245 {
246 	struct clps711x_port *s = dev_get_drvdata(port->dev);
247 
248 	/* Disable the port */
249 	regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
250 }
251 
252 static void uart_clps711x_set_termios(struct uart_port *port,
253 				      struct ktermios *termios,
254 				      struct ktermios *old)
255 {
256 	u32 ubrlcr;
257 	unsigned int baud, quot;
258 
259 	/* Mask termios capabilities we don't support */
260 	termios->c_cflag &= ~CMSPAR;
261 	termios->c_iflag &= ~(BRKINT | IGNBRK);
262 
263 	/* Ask the core to calculate the divisor for us */
264 	baud = uart_get_baud_rate(port, termios, old, port->uartclk / 4096,
265 						      port->uartclk / 16);
266 	quot = uart_get_divisor(port, baud);
267 
268 	switch (termios->c_cflag & CSIZE) {
269 	case CS5:
270 		ubrlcr = UBRLCR_WRDLEN5;
271 		break;
272 	case CS6:
273 		ubrlcr = UBRLCR_WRDLEN6;
274 		break;
275 	case CS7:
276 		ubrlcr = UBRLCR_WRDLEN7;
277 		break;
278 	case CS8:
279 	default:
280 		ubrlcr = UBRLCR_WRDLEN8;
281 		break;
282 	}
283 
284 	if (termios->c_cflag & CSTOPB)
285 		ubrlcr |= UBRLCR_XSTOP;
286 
287 	if (termios->c_cflag & PARENB) {
288 		ubrlcr |= UBRLCR_PRTEN;
289 		if (!(termios->c_cflag & PARODD))
290 			ubrlcr |= UBRLCR_EVENPRT;
291 	}
292 
293 	/* Enable FIFO */
294 	ubrlcr |= UBRLCR_FIFOEN;
295 
296 	/* Set read status mask */
297 	port->read_status_mask = UARTDR_OVERR;
298 	if (termios->c_iflag & INPCK)
299 		port->read_status_mask |= UARTDR_PARERR | UARTDR_FRMERR;
300 
301 	/* Set status ignore mask */
302 	port->ignore_status_mask = 0;
303 	if (!(termios->c_cflag & CREAD))
304 		port->ignore_status_mask |= UARTDR_OVERR | UARTDR_PARERR |
305 					    UARTDR_FRMERR;
306 
307 	uart_update_timeout(port, termios->c_cflag, baud);
308 
309 	writel(ubrlcr | (quot - 1), port->membase + UBRLCR_OFFSET);
310 }
311 
312 static const char *uart_clps711x_type(struct uart_port *port)
313 {
314 	return (port->type == PORT_CLPS711X) ? "CLPS711X" : NULL;
315 }
316 
317 static void uart_clps711x_config_port(struct uart_port *port, int flags)
318 {
319 	if (flags & UART_CONFIG_TYPE)
320 		port->type = PORT_CLPS711X;
321 }
322 
323 static void uart_clps711x_nop_void(struct uart_port *port)
324 {
325 }
326 
327 static int uart_clps711x_nop_int(struct uart_port *port)
328 {
329 	return 0;
330 }
331 
332 static const struct uart_ops uart_clps711x_ops = {
333 	.tx_empty	= uart_clps711x_tx_empty,
334 	.set_mctrl	= uart_clps711x_set_mctrl,
335 	.get_mctrl	= uart_clps711x_get_mctrl,
336 	.stop_tx	= uart_clps711x_stop_tx,
337 	.start_tx	= uart_clps711x_start_tx,
338 	.stop_rx	= uart_clps711x_nop_void,
339 	.break_ctl	= uart_clps711x_break_ctl,
340 	.set_ldisc	= uart_clps711x_set_ldisc,
341 	.startup	= uart_clps711x_startup,
342 	.shutdown	= uart_clps711x_shutdown,
343 	.set_termios	= uart_clps711x_set_termios,
344 	.type		= uart_clps711x_type,
345 	.config_port	= uart_clps711x_config_port,
346 	.release_port	= uart_clps711x_nop_void,
347 	.request_port	= uart_clps711x_nop_int,
348 };
349 
350 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
351 static void uart_clps711x_console_putchar(struct uart_port *port, int ch)
352 {
353 	struct clps711x_port *s = dev_get_drvdata(port->dev);
354 	u32 sysflg = 0;
355 
356 	/* Wait for FIFO is not full */
357 	do {
358 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
359 	} while (sysflg & SYSFLG_UTXFF);
360 
361 	writew(ch, port->membase + UARTDR_OFFSET);
362 }
363 
364 static void uart_clps711x_console_write(struct console *co, const char *c,
365 					unsigned n)
366 {
367 	struct uart_port *port = clps711x_uart.state[co->index].uart_port;
368 	struct clps711x_port *s = dev_get_drvdata(port->dev);
369 	u32 sysflg = 0;
370 
371 	uart_console_write(port, c, n, uart_clps711x_console_putchar);
372 
373 	/* Wait for transmitter to become empty */
374 	do {
375 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
376 	} while (sysflg & SYSFLG_UBUSY);
377 }
378 
379 static int uart_clps711x_console_setup(struct console *co, char *options)
380 {
381 	int baud = 38400, bits = 8, parity = 'n', flow = 'n';
382 	int ret, index = co->index;
383 	struct clps711x_port *s;
384 	struct uart_port *port;
385 	unsigned int quot;
386 	u32 ubrlcr;
387 
388 	if (index < 0 || index >= UART_CLPS711X_NR)
389 		return -EINVAL;
390 
391 	port = clps711x_uart.state[index].uart_port;
392 	if (!port)
393 		return -ENODEV;
394 
395 	s = dev_get_drvdata(port->dev);
396 
397 	if (!options) {
398 		u32 syscon = 0;
399 
400 		regmap_read(s->syscon, SYSCON_OFFSET, &syscon);
401 		if (syscon & SYSCON_UARTEN) {
402 			ubrlcr = readl(port->membase + UBRLCR_OFFSET);
403 
404 			if (ubrlcr & UBRLCR_PRTEN) {
405 				if (ubrlcr & UBRLCR_EVENPRT)
406 					parity = 'e';
407 				else
408 					parity = 'o';
409 			}
410 
411 			if ((ubrlcr & UBRLCR_WRDLEN_MASK) == UBRLCR_WRDLEN7)
412 				bits = 7;
413 
414 			quot = ubrlcr & UBRLCR_BAUD_MASK;
415 			baud = port->uartclk / (16 * (quot + 1));
416 		}
417 	} else
418 		uart_parse_options(options, &baud, &parity, &bits, &flow);
419 
420 	ret = uart_set_options(port, co, baud, parity, bits, flow);
421 	if (ret)
422 		return ret;
423 
424 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
425 				  SYSCON_UARTEN, SYSCON_UARTEN);
426 }
427 
428 static struct console clps711x_console = {
429 	.name	= UART_CLPS711X_DEVNAME,
430 	.device	= uart_console_device,
431 	.write	= uart_clps711x_console_write,
432 	.setup	= uart_clps711x_console_setup,
433 	.flags	= CON_PRINTBUFFER,
434 	.index	= -1,
435 };
436 #endif
437 
438 static int uart_clps711x_probe(struct platform_device *pdev)
439 {
440 	struct device_node *np = pdev->dev.of_node;
441 	struct clps711x_port *s;
442 	struct resource *res;
443 	struct clk *uart_clk;
444 	int irq, ret;
445 
446 	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
447 	if (!s)
448 		return -ENOMEM;
449 
450 	uart_clk = devm_clk_get(&pdev->dev, NULL);
451 	if (IS_ERR(uart_clk))
452 		return PTR_ERR(uart_clk);
453 
454 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
455 	s->port.membase = devm_ioremap_resource(&pdev->dev, res);
456 	if (IS_ERR(s->port.membase))
457 		return PTR_ERR(s->port.membase);
458 
459 	irq = platform_get_irq(pdev, 0);
460 	if (irq < 0)
461 		return irq;
462 	s->port.irq = irq;
463 
464 	s->rx_irq = platform_get_irq(pdev, 1);
465 	if (s->rx_irq < 0)
466 		return s->rx_irq;
467 
468 	s->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
469 	if (IS_ERR(s->syscon))
470 		return PTR_ERR(s->syscon);
471 
472 	s->port.line		= of_alias_get_id(np, "serial");
473 	s->port.dev		= &pdev->dev;
474 	s->port.iotype		= UPIO_MEM32;
475 	s->port.mapbase		= res->start;
476 	s->port.type		= PORT_CLPS711X;
477 	s->port.fifosize	= 16;
478 	s->port.has_sysrq	= IS_ENABLED(CONFIG_SERIAL_CLPS711X_CONSOLE);
479 	s->port.flags		= UPF_SKIP_TEST | UPF_FIXED_TYPE;
480 	s->port.uartclk		= clk_get_rate(uart_clk);
481 	s->port.ops		= &uart_clps711x_ops;
482 
483 	platform_set_drvdata(pdev, s);
484 
485 	s->gpios = mctrl_gpio_init_noauto(&pdev->dev, 0);
486 	if (IS_ERR(s->gpios))
487 	    return PTR_ERR(s->gpios);
488 
489 	ret = uart_add_one_port(&clps711x_uart, &s->port);
490 	if (ret)
491 		return ret;
492 
493 	/* Disable port */
494 	if (!uart_console(&s->port))
495 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
496 
497 	s->tx_enabled = 1;
498 
499 	ret = devm_request_irq(&pdev->dev, s->port.irq, uart_clps711x_int_tx, 0,
500 			       dev_name(&pdev->dev), &s->port);
501 	if (ret) {
502 		uart_remove_one_port(&clps711x_uart, &s->port);
503 		return ret;
504 	}
505 
506 	ret = devm_request_irq(&pdev->dev, s->rx_irq, uart_clps711x_int_rx, 0,
507 			       dev_name(&pdev->dev), &s->port);
508 	if (ret)
509 		uart_remove_one_port(&clps711x_uart, &s->port);
510 
511 	return ret;
512 }
513 
514 static int uart_clps711x_remove(struct platform_device *pdev)
515 {
516 	struct clps711x_port *s = platform_get_drvdata(pdev);
517 
518 	return uart_remove_one_port(&clps711x_uart, &s->port);
519 }
520 
521 static const struct of_device_id __maybe_unused clps711x_uart_dt_ids[] = {
522 	{ .compatible = "cirrus,ep7209-uart", },
523 	{ }
524 };
525 MODULE_DEVICE_TABLE(of, clps711x_uart_dt_ids);
526 
527 static struct platform_driver clps711x_uart_platform = {
528 	.driver = {
529 		.name		= "clps711x-uart",
530 		.of_match_table	= of_match_ptr(clps711x_uart_dt_ids),
531 	},
532 	.probe	= uart_clps711x_probe,
533 	.remove	= uart_clps711x_remove,
534 };
535 
536 static int __init uart_clps711x_init(void)
537 {
538 	int ret;
539 
540 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
541 	clps711x_uart.cons = &clps711x_console;
542 	clps711x_console.data = &clps711x_uart;
543 #endif
544 
545 	ret = uart_register_driver(&clps711x_uart);
546 	if (ret)
547 		return ret;
548 
549 	return platform_driver_register(&clps711x_uart_platform);
550 }
551 module_init(uart_clps711x_init);
552 
553 static void __exit uart_clps711x_exit(void)
554 {
555 	platform_driver_unregister(&clps711x_uart_platform);
556 	uart_unregister_driver(&clps711x_uart);
557 }
558 module_exit(uart_clps711x_exit);
559 
560 MODULE_AUTHOR("Deep Blue Solutions Ltd");
561 MODULE_DESCRIPTION("CLPS711X serial driver");
562 MODULE_LICENSE("GPL");
563