xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision c8ec3743) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Driver for GRLIB serial ports (APBUART)
4  *
5  *  Based on linux/drivers/serial/amba.c
6  *
7  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
8  *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
9  *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
10  *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
11  *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
12  */
13 
14 #if defined(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
15 #define SUPPORT_SYSRQ
16 #endif
17 
18 #include <linux/module.h>
19 #include <linux/tty.h>
20 #include <linux/tty_flip.h>
21 #include <linux/ioport.h>
22 #include <linux/init.h>
23 #include <linux/serial.h>
24 #include <linux/console.h>
25 #include <linux/sysrq.h>
26 #include <linux/kthread.h>
27 #include <linux/device.h>
28 #include <linux/of.h>
29 #include <linux/of_device.h>
30 #include <linux/of_platform.h>
31 #include <linux/of_irq.h>
32 #include <linux/platform_device.h>
33 #include <linux/io.h>
34 #include <linux/serial_core.h>
35 #include <asm/irq.h>
36 
37 #include "apbuart.h"
38 
39 #define SERIAL_APBUART_MAJOR	TTY_MAJOR
40 #define SERIAL_APBUART_MINOR	64
41 #define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
42 
43 static void apbuart_tx_chars(struct uart_port *port);
44 
45 static void apbuart_stop_tx(struct uart_port *port)
46 {
47 	unsigned int cr;
48 
49 	cr = UART_GET_CTRL(port);
50 	cr &= ~UART_CTRL_TI;
51 	UART_PUT_CTRL(port, cr);
52 }
53 
54 static void apbuart_start_tx(struct uart_port *port)
55 {
56 	unsigned int cr;
57 
58 	cr = UART_GET_CTRL(port);
59 	cr |= UART_CTRL_TI;
60 	UART_PUT_CTRL(port, cr);
61 
62 	if (UART_GET_STATUS(port) & UART_STATUS_THE)
63 		apbuart_tx_chars(port);
64 }
65 
66 static void apbuart_stop_rx(struct uart_port *port)
67 {
68 	unsigned int cr;
69 
70 	cr = UART_GET_CTRL(port);
71 	cr &= ~(UART_CTRL_RI);
72 	UART_PUT_CTRL(port, cr);
73 }
74 
75 static void apbuart_rx_chars(struct uart_port *port)
76 {
77 	unsigned int status, ch, rsr, flag;
78 	unsigned int max_chars = port->fifosize;
79 
80 	status = UART_GET_STATUS(port);
81 
82 	while (UART_RX_DATA(status) && (max_chars--)) {
83 
84 		ch = UART_GET_CHAR(port);
85 		flag = TTY_NORMAL;
86 
87 		port->icount.rx++;
88 
89 		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
90 		UART_PUT_STATUS(port, 0);
91 		if (rsr & UART_STATUS_ERR) {
92 
93 			if (rsr & UART_STATUS_BR) {
94 				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
95 				port->icount.brk++;
96 				if (uart_handle_break(port))
97 					goto ignore_char;
98 			} else if (rsr & UART_STATUS_PE) {
99 				port->icount.parity++;
100 			} else if (rsr & UART_STATUS_FE) {
101 				port->icount.frame++;
102 			}
103 			if (rsr & UART_STATUS_OE)
104 				port->icount.overrun++;
105 
106 			rsr &= port->read_status_mask;
107 
108 			if (rsr & UART_STATUS_PE)
109 				flag = TTY_PARITY;
110 			else if (rsr & UART_STATUS_FE)
111 				flag = TTY_FRAME;
112 		}
113 
114 		if (uart_handle_sysrq_char(port, ch))
115 			goto ignore_char;
116 
117 		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
118 
119 
120 	      ignore_char:
121 		status = UART_GET_STATUS(port);
122 	}
123 
124 	spin_unlock(&port->lock);
125 	tty_flip_buffer_push(&port->state->port);
126 	spin_lock(&port->lock);
127 }
128 
129 static void apbuart_tx_chars(struct uart_port *port)
130 {
131 	struct circ_buf *xmit = &port->state->xmit;
132 	int count;
133 
134 	if (port->x_char) {
135 		UART_PUT_CHAR(port, port->x_char);
136 		port->icount.tx++;
137 		port->x_char = 0;
138 		return;
139 	}
140 
141 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
142 		apbuart_stop_tx(port);
143 		return;
144 	}
145 
146 	/* amba: fill FIFO */
147 	count = port->fifosize >> 1;
148 	do {
149 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
150 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
151 		port->icount.tx++;
152 		if (uart_circ_empty(xmit))
153 			break;
154 	} while (--count > 0);
155 
156 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
157 		uart_write_wakeup(port);
158 
159 	if (uart_circ_empty(xmit))
160 		apbuart_stop_tx(port);
161 }
162 
163 static irqreturn_t apbuart_int(int irq, void *dev_id)
164 {
165 	struct uart_port *port = dev_id;
166 	unsigned int status;
167 
168 	spin_lock(&port->lock);
169 
170 	status = UART_GET_STATUS(port);
171 	if (status & UART_STATUS_DR)
172 		apbuart_rx_chars(port);
173 	if (status & UART_STATUS_THE)
174 		apbuart_tx_chars(port);
175 
176 	spin_unlock(&port->lock);
177 
178 	return IRQ_HANDLED;
179 }
180 
181 static unsigned int apbuart_tx_empty(struct uart_port *port)
182 {
183 	unsigned int status = UART_GET_STATUS(port);
184 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
185 }
186 
187 static unsigned int apbuart_get_mctrl(struct uart_port *port)
188 {
189 	/* The GRLIB APBUART handles flow control in hardware */
190 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
191 }
192 
193 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
194 {
195 	/* The GRLIB APBUART handles flow control in hardware */
196 }
197 
198 static void apbuart_break_ctl(struct uart_port *port, int break_state)
199 {
200 	/* We don't support sending break */
201 }
202 
203 static int apbuart_startup(struct uart_port *port)
204 {
205 	int retval;
206 	unsigned int cr;
207 
208 	/* Allocate the IRQ */
209 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
210 	if (retval)
211 		return retval;
212 
213 	/* Finally, enable interrupts */
214 	cr = UART_GET_CTRL(port);
215 	UART_PUT_CTRL(port,
216 		      cr | UART_CTRL_RE | UART_CTRL_TE |
217 		      UART_CTRL_RI | UART_CTRL_TI);
218 
219 	return 0;
220 }
221 
222 static void apbuart_shutdown(struct uart_port *port)
223 {
224 	unsigned int cr;
225 
226 	/* disable all interrupts, disable the port */
227 	cr = UART_GET_CTRL(port);
228 	UART_PUT_CTRL(port,
229 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
230 			     UART_CTRL_RI | UART_CTRL_TI));
231 
232 	/* Free the interrupt */
233 	free_irq(port->irq, port);
234 }
235 
236 static void apbuart_set_termios(struct uart_port *port,
237 				struct ktermios *termios, struct ktermios *old)
238 {
239 	unsigned int cr;
240 	unsigned long flags;
241 	unsigned int baud, quot;
242 
243 	/* Ask the core to calculate the divisor for us. */
244 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
245 	if (baud == 0)
246 		panic("invalid baudrate %i\n", port->uartclk / 16);
247 
248 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
249 	quot = (uart_get_divisor(port, baud)) * 2;
250 	cr = UART_GET_CTRL(port);
251 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
252 
253 	if (termios->c_cflag & PARENB) {
254 		cr |= UART_CTRL_PE;
255 		if ((termios->c_cflag & PARODD))
256 			cr |= UART_CTRL_PS;
257 	}
258 
259 	/* Enable flow control. */
260 	if (termios->c_cflag & CRTSCTS)
261 		cr |= UART_CTRL_FL;
262 
263 	spin_lock_irqsave(&port->lock, flags);
264 
265 	/* Update the per-port timeout. */
266 	uart_update_timeout(port, termios->c_cflag, baud);
267 
268 	port->read_status_mask = UART_STATUS_OE;
269 	if (termios->c_iflag & INPCK)
270 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
271 
272 	/* Characters to ignore */
273 	port->ignore_status_mask = 0;
274 	if (termios->c_iflag & IGNPAR)
275 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
276 
277 	/* Ignore all characters if CREAD is not set. */
278 	if ((termios->c_cflag & CREAD) == 0)
279 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
280 
281 	/* Set baud rate */
282 	quot -= 1;
283 	UART_PUT_SCAL(port, quot);
284 	UART_PUT_CTRL(port, cr);
285 
286 	spin_unlock_irqrestore(&port->lock, flags);
287 }
288 
289 static const char *apbuart_type(struct uart_port *port)
290 {
291 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
292 }
293 
294 static void apbuart_release_port(struct uart_port *port)
295 {
296 	release_mem_region(port->mapbase, 0x100);
297 }
298 
299 static int apbuart_request_port(struct uart_port *port)
300 {
301 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
302 	    != NULL ? 0 : -EBUSY;
303 	return 0;
304 }
305 
306 /* Configure/autoconfigure the port */
307 static void apbuart_config_port(struct uart_port *port, int flags)
308 {
309 	if (flags & UART_CONFIG_TYPE) {
310 		port->type = PORT_APBUART;
311 		apbuart_request_port(port);
312 	}
313 }
314 
315 /* Verify the new serial_struct (for TIOCSSERIAL) */
316 static int apbuart_verify_port(struct uart_port *port,
317 			       struct serial_struct *ser)
318 {
319 	int ret = 0;
320 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
321 		ret = -EINVAL;
322 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
323 		ret = -EINVAL;
324 	if (ser->baud_base < 9600)
325 		ret = -EINVAL;
326 	return ret;
327 }
328 
329 static const struct uart_ops grlib_apbuart_ops = {
330 	.tx_empty = apbuart_tx_empty,
331 	.set_mctrl = apbuart_set_mctrl,
332 	.get_mctrl = apbuart_get_mctrl,
333 	.stop_tx = apbuart_stop_tx,
334 	.start_tx = apbuart_start_tx,
335 	.stop_rx = apbuart_stop_rx,
336 	.break_ctl = apbuart_break_ctl,
337 	.startup = apbuart_startup,
338 	.shutdown = apbuart_shutdown,
339 	.set_termios = apbuart_set_termios,
340 	.type = apbuart_type,
341 	.release_port = apbuart_release_port,
342 	.request_port = apbuart_request_port,
343 	.config_port = apbuart_config_port,
344 	.verify_port = apbuart_verify_port,
345 };
346 
347 static struct uart_port grlib_apbuart_ports[UART_NR];
348 static struct device_node *grlib_apbuart_nodes[UART_NR];
349 
350 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
351 {
352 	int ctrl, loop = 0;
353 	int status;
354 	int fifosize;
355 	unsigned long flags;
356 
357 	ctrl = UART_GET_CTRL(port);
358 
359 	/*
360 	 * Enable the transceiver and wait for it to be ready to send data.
361 	 * Clear interrupts so that this process will not be externally
362 	 * interrupted in the middle (which can cause the transceiver to
363 	 * drain prematurely).
364 	 */
365 
366 	local_irq_save(flags);
367 
368 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
369 
370 	while (!UART_TX_READY(UART_GET_STATUS(port)))
371 		loop++;
372 
373 	/*
374 	 * Disable the transceiver so data isn't actually sent during the
375 	 * actual test.
376 	 */
377 
378 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
379 
380 	fifosize = 1;
381 	UART_PUT_CHAR(port, 0);
382 
383 	/*
384 	 * So long as transmitting a character increments the tranceivier FIFO
385 	 * length the FIFO must be at least that big. These bytes will
386 	 * automatically drain off of the FIFO.
387 	 */
388 
389 	status = UART_GET_STATUS(port);
390 	while (((status >> 20) & 0x3F) == fifosize) {
391 		fifosize++;
392 		UART_PUT_CHAR(port, 0);
393 		status = UART_GET_STATUS(port);
394 	}
395 
396 	fifosize--;
397 
398 	UART_PUT_CTRL(port, ctrl);
399 	local_irq_restore(flags);
400 
401 	if (fifosize == 0)
402 		fifosize = 1;
403 
404 	return fifosize;
405 }
406 
407 static void apbuart_flush_fifo(struct uart_port *port)
408 {
409 	int i;
410 
411 	for (i = 0; i < port->fifosize; i++)
412 		UART_GET_CHAR(port);
413 }
414 
415 
416 /* ======================================================================== */
417 /* Console driver, if enabled                                               */
418 /* ======================================================================== */
419 
420 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
421 
422 static void apbuart_console_putchar(struct uart_port *port, int ch)
423 {
424 	unsigned int status;
425 	do {
426 		status = UART_GET_STATUS(port);
427 	} while (!UART_TX_READY(status));
428 	UART_PUT_CHAR(port, ch);
429 }
430 
431 static void
432 apbuart_console_write(struct console *co, const char *s, unsigned int count)
433 {
434 	struct uart_port *port = &grlib_apbuart_ports[co->index];
435 	unsigned int status, old_cr, new_cr;
436 
437 	/* First save the CR then disable the interrupts */
438 	old_cr = UART_GET_CTRL(port);
439 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
440 	UART_PUT_CTRL(port, new_cr);
441 
442 	uart_console_write(port, s, count, apbuart_console_putchar);
443 
444 	/*
445 	 *      Finally, wait for transmitter to become empty
446 	 *      and restore the TCR
447 	 */
448 	do {
449 		status = UART_GET_STATUS(port);
450 	} while (!UART_TX_READY(status));
451 	UART_PUT_CTRL(port, old_cr);
452 }
453 
454 static void __init
455 apbuart_console_get_options(struct uart_port *port, int *baud,
456 			    int *parity, int *bits)
457 {
458 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
459 
460 		unsigned int quot, status;
461 		status = UART_GET_STATUS(port);
462 
463 		*parity = 'n';
464 		if (status & UART_CTRL_PE) {
465 			if ((status & UART_CTRL_PS) == 0)
466 				*parity = 'e';
467 			else
468 				*parity = 'o';
469 		}
470 
471 		*bits = 8;
472 		quot = UART_GET_SCAL(port) / 8;
473 		*baud = port->uartclk / (16 * (quot + 1));
474 	}
475 }
476 
477 static int __init apbuart_console_setup(struct console *co, char *options)
478 {
479 	struct uart_port *port;
480 	int baud = 38400;
481 	int bits = 8;
482 	int parity = 'n';
483 	int flow = 'n';
484 
485 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
486 		 co, co->index, options);
487 
488 	/*
489 	 * Check whether an invalid uart number has been specified, and
490 	 * if so, search for the first available port that does have
491 	 * console support.
492 	 */
493 	if (co->index >= grlib_apbuart_port_nr)
494 		co->index = 0;
495 
496 	port = &grlib_apbuart_ports[co->index];
497 
498 	spin_lock_init(&port->lock);
499 
500 	if (options)
501 		uart_parse_options(options, &baud, &parity, &bits, &flow);
502 	else
503 		apbuart_console_get_options(port, &baud, &parity, &bits);
504 
505 	return uart_set_options(port, co, baud, parity, bits, flow);
506 }
507 
508 static struct uart_driver grlib_apbuart_driver;
509 
510 static struct console grlib_apbuart_console = {
511 	.name = "ttyS",
512 	.write = apbuart_console_write,
513 	.device = uart_console_device,
514 	.setup = apbuart_console_setup,
515 	.flags = CON_PRINTBUFFER,
516 	.index = -1,
517 	.data = &grlib_apbuart_driver,
518 };
519 
520 
521 static int grlib_apbuart_configure(void);
522 
523 static int __init apbuart_console_init(void)
524 {
525 	if (grlib_apbuart_configure())
526 		return -ENODEV;
527 	register_console(&grlib_apbuart_console);
528 	return 0;
529 }
530 
531 console_initcall(apbuart_console_init);
532 
533 #define APBUART_CONSOLE	(&grlib_apbuart_console)
534 #else
535 #define APBUART_CONSOLE	NULL
536 #endif
537 
538 static struct uart_driver grlib_apbuart_driver = {
539 	.owner = THIS_MODULE,
540 	.driver_name = "serial",
541 	.dev_name = "ttyS",
542 	.major = SERIAL_APBUART_MAJOR,
543 	.minor = SERIAL_APBUART_MINOR,
544 	.nr = UART_NR,
545 	.cons = APBUART_CONSOLE,
546 };
547 
548 
549 /* ======================================================================== */
550 /* OF Platform Driver                                                       */
551 /* ======================================================================== */
552 
553 static int apbuart_probe(struct platform_device *op)
554 {
555 	int i;
556 	struct uart_port *port = NULL;
557 
558 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
559 		if (op->dev.of_node == grlib_apbuart_nodes[i])
560 			break;
561 	}
562 
563 	port = &grlib_apbuart_ports[i];
564 	port->dev = &op->dev;
565 	port->irq = op->archdata.irqs[0];
566 
567 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
568 
569 	apbuart_flush_fifo((struct uart_port *) port);
570 
571 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
572 	       (unsigned long long) port->mapbase, port->irq);
573 	return 0;
574 }
575 
576 static const struct of_device_id apbuart_match[] = {
577 	{
578 	 .name = "GAISLER_APBUART",
579 	 },
580 	{
581 	 .name = "01_00c",
582 	 },
583 	{},
584 };
585 MODULE_DEVICE_TABLE(of, apbuart_match);
586 
587 static struct platform_driver grlib_apbuart_of_driver = {
588 	.probe = apbuart_probe,
589 	.driver = {
590 		.name = "grlib-apbuart",
591 		.of_match_table = apbuart_match,
592 	},
593 };
594 
595 
596 static int __init grlib_apbuart_configure(void)
597 {
598 	struct device_node *np;
599 	int line = 0;
600 
601 	for_each_matching_node(np, apbuart_match) {
602 		const int *ampopts;
603 		const u32 *freq_hz;
604 		const struct amba_prom_registers *regs;
605 		struct uart_port *port;
606 		unsigned long addr;
607 
608 		ampopts = of_get_property(np, "ampopts", NULL);
609 		if (ampopts && (*ampopts == 0))
610 			continue; /* Ignore if used by another OS instance */
611 		regs = of_get_property(np, "reg", NULL);
612 		/* Frequency of APB Bus is frequency of UART */
613 		freq_hz = of_get_property(np, "freq", NULL);
614 
615 		if (!regs || !freq_hz || (*freq_hz == 0))
616 			continue;
617 
618 		grlib_apbuart_nodes[line] = np;
619 
620 		addr = regs->phys_addr;
621 
622 		port = &grlib_apbuart_ports[line];
623 
624 		port->mapbase = addr;
625 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
626 		port->irq = 0;
627 		port->iotype = UPIO_MEM;
628 		port->ops = &grlib_apbuart_ops;
629 		port->flags = UPF_BOOT_AUTOCONF;
630 		port->line = line;
631 		port->uartclk = *freq_hz;
632 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
633 		line++;
634 
635 		/* We support maximum UART_NR uarts ... */
636 		if (line == UART_NR)
637 			break;
638 	}
639 
640 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
641 	return line ? 0 : -ENODEV;
642 }
643 
644 static int __init grlib_apbuart_init(void)
645 {
646 	int ret;
647 
648 	/* Find all APBUARTS in device the tree and initialize their ports */
649 	ret = grlib_apbuart_configure();
650 	if (ret)
651 		return ret;
652 
653 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
654 
655 	ret = uart_register_driver(&grlib_apbuart_driver);
656 
657 	if (ret) {
658 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
659 		       __FILE__, ret);
660 		return ret;
661 	}
662 
663 	ret = platform_driver_register(&grlib_apbuart_of_driver);
664 	if (ret) {
665 		printk(KERN_ERR
666 		       "%s: platform_driver_register failed (%i)\n",
667 		       __FILE__, ret);
668 		uart_unregister_driver(&grlib_apbuart_driver);
669 		return ret;
670 	}
671 
672 	return ret;
673 }
674 
675 static void __exit grlib_apbuart_exit(void)
676 {
677 	int i;
678 
679 	for (i = 0; i < grlib_apbuart_port_nr; i++)
680 		uart_remove_one_port(&grlib_apbuart_driver,
681 				     &grlib_apbuart_ports[i]);
682 
683 	uart_unregister_driver(&grlib_apbuart_driver);
684 	platform_driver_unregister(&grlib_apbuart_of_driver);
685 }
686 
687 module_init(grlib_apbuart_init);
688 module_exit(grlib_apbuart_exit);
689 
690 MODULE_AUTHOR("Aeroflex Gaisler AB");
691 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
692 MODULE_VERSION("2.1");
693 MODULE_LICENSE("GPL");
694