xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision f4fc91af) 
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 #include <linux/module.h>
15 #include <linux/tty.h>
16 #include <linux/tty_flip.h>
17 #include <linux/ioport.h>
18 #include <linux/init.h>
19 #include <linux/serial.h>
20 #include <linux/console.h>
21 #include <linux/sysrq.h>
22 #include <linux/kthread.h>
23 #include <linux/device.h>
24 #include <linux/of.h>
25 #include <linux/of_device.h>
26 #include <linux/of_platform.h>
27 #include <linux/of_irq.h>
28 #include <linux/platform_device.h>
29 #include <linux/io.h>
30 #include <linux/serial_core.h>
31 #include <asm/irq.h>
32 
33 #include "apbuart.h"
34 
35 #define SERIAL_APBUART_MAJOR	TTY_MAJOR
36 #define SERIAL_APBUART_MINOR	64
37 #define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
38 
39 static void apbuart_tx_chars(struct uart_port *port);
40 
41 static void apbuart_stop_tx(struct uart_port *port)
42 {
43 	unsigned int cr;
44 
45 	cr = UART_GET_CTRL(port);
46 	cr &= ~UART_CTRL_TI;
47 	UART_PUT_CTRL(port, cr);
48 }
49 
50 static void apbuart_start_tx(struct uart_port *port)
51 {
52 	unsigned int cr;
53 
54 	cr = UART_GET_CTRL(port);
55 	cr |= UART_CTRL_TI;
56 	UART_PUT_CTRL(port, cr);
57 
58 	if (UART_GET_STATUS(port) & UART_STATUS_THE)
59 		apbuart_tx_chars(port);
60 }
61 
62 static void apbuart_stop_rx(struct uart_port *port)
63 {
64 	unsigned int cr;
65 
66 	cr = UART_GET_CTRL(port);
67 	cr &= ~(UART_CTRL_RI);
68 	UART_PUT_CTRL(port, cr);
69 }
70 
71 static void apbuart_rx_chars(struct uart_port *port)
72 {
73 	unsigned int status, ch, rsr, flag;
74 	unsigned int max_chars = port->fifosize;
75 
76 	status = UART_GET_STATUS(port);
77 
78 	while (UART_RX_DATA(status) && (max_chars--)) {
79 
80 		ch = UART_GET_CHAR(port);
81 		flag = TTY_NORMAL;
82 
83 		port->icount.rx++;
84 
85 		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
86 		UART_PUT_STATUS(port, 0);
87 		if (rsr & UART_STATUS_ERR) {
88 
89 			if (rsr & UART_STATUS_BR) {
90 				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
91 				port->icount.brk++;
92 				if (uart_handle_break(port))
93 					goto ignore_char;
94 			} else if (rsr & UART_STATUS_PE) {
95 				port->icount.parity++;
96 			} else if (rsr & UART_STATUS_FE) {
97 				port->icount.frame++;
98 			}
99 			if (rsr & UART_STATUS_OE)
100 				port->icount.overrun++;
101 
102 			rsr &= port->read_status_mask;
103 
104 			if (rsr & UART_STATUS_PE)
105 				flag = TTY_PARITY;
106 			else if (rsr & UART_STATUS_FE)
107 				flag = TTY_FRAME;
108 		}
109 
110 		if (uart_handle_sysrq_char(port, ch))
111 			goto ignore_char;
112 
113 		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
114 
115 
116 	      ignore_char:
117 		status = UART_GET_STATUS(port);
118 	}
119 
120 	spin_unlock(&port->lock);
121 	tty_flip_buffer_push(&port->state->port);
122 	spin_lock(&port->lock);
123 }
124 
125 static void apbuart_tx_chars(struct uart_port *port)
126 {
127 	struct circ_buf *xmit = &port->state->xmit;
128 	int count;
129 
130 	if (port->x_char) {
131 		UART_PUT_CHAR(port, port->x_char);
132 		port->icount.tx++;
133 		port->x_char = 0;
134 		return;
135 	}
136 
137 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
138 		apbuart_stop_tx(port);
139 		return;
140 	}
141 
142 	/* amba: fill FIFO */
143 	count = port->fifosize >> 1;
144 	do {
145 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
146 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
147 		port->icount.tx++;
148 		if (uart_circ_empty(xmit))
149 			break;
150 	} while (--count > 0);
151 
152 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
153 		uart_write_wakeup(port);
154 
155 	if (uart_circ_empty(xmit))
156 		apbuart_stop_tx(port);
157 }
158 
159 static irqreturn_t apbuart_int(int irq, void *dev_id)
160 {
161 	struct uart_port *port = dev_id;
162 	unsigned int status;
163 
164 	spin_lock(&port->lock);
165 
166 	status = UART_GET_STATUS(port);
167 	if (status & UART_STATUS_DR)
168 		apbuart_rx_chars(port);
169 	if (status & UART_STATUS_THE)
170 		apbuart_tx_chars(port);
171 
172 	spin_unlock(&port->lock);
173 
174 	return IRQ_HANDLED;
175 }
176 
177 static unsigned int apbuart_tx_empty(struct uart_port *port)
178 {
179 	unsigned int status = UART_GET_STATUS(port);
180 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
181 }
182 
183 static unsigned int apbuart_get_mctrl(struct uart_port *port)
184 {
185 	/* The GRLIB APBUART handles flow control in hardware */
186 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
187 }
188 
189 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
190 {
191 	/* The GRLIB APBUART handles flow control in hardware */
192 }
193 
194 static void apbuart_break_ctl(struct uart_port *port, int break_state)
195 {
196 	/* We don't support sending break */
197 }
198 
199 static int apbuart_startup(struct uart_port *port)
200 {
201 	int retval;
202 	unsigned int cr;
203 
204 	/* Allocate the IRQ */
205 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
206 	if (retval)
207 		return retval;
208 
209 	/* Finally, enable interrupts */
210 	cr = UART_GET_CTRL(port);
211 	UART_PUT_CTRL(port,
212 		      cr | UART_CTRL_RE | UART_CTRL_TE |
213 		      UART_CTRL_RI | UART_CTRL_TI);
214 
215 	return 0;
216 }
217 
218 static void apbuart_shutdown(struct uart_port *port)
219 {
220 	unsigned int cr;
221 
222 	/* disable all interrupts, disable the port */
223 	cr = UART_GET_CTRL(port);
224 	UART_PUT_CTRL(port,
225 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
226 			     UART_CTRL_RI | UART_CTRL_TI));
227 
228 	/* Free the interrupt */
229 	free_irq(port->irq, port);
230 }
231 
232 static void apbuart_set_termios(struct uart_port *port,
233 				struct ktermios *termios, struct ktermios *old)
234 {
235 	unsigned int cr;
236 	unsigned long flags;
237 	unsigned int baud, quot;
238 
239 	/* Ask the core to calculate the divisor for us. */
240 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
241 	if (baud == 0)
242 		panic("invalid baudrate %i\n", port->uartclk / 16);
243 
244 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
245 	quot = (uart_get_divisor(port, baud)) * 2;
246 	cr = UART_GET_CTRL(port);
247 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
248 
249 	if (termios->c_cflag & PARENB) {
250 		cr |= UART_CTRL_PE;
251 		if ((termios->c_cflag & PARODD))
252 			cr |= UART_CTRL_PS;
253 	}
254 
255 	/* Enable flow control. */
256 	if (termios->c_cflag & CRTSCTS)
257 		cr |= UART_CTRL_FL;
258 
259 	spin_lock_irqsave(&port->lock, flags);
260 
261 	/* Update the per-port timeout. */
262 	uart_update_timeout(port, termios->c_cflag, baud);
263 
264 	port->read_status_mask = UART_STATUS_OE;
265 	if (termios->c_iflag & INPCK)
266 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
267 
268 	/* Characters to ignore */
269 	port->ignore_status_mask = 0;
270 	if (termios->c_iflag & IGNPAR)
271 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
272 
273 	/* Ignore all characters if CREAD is not set. */
274 	if ((termios->c_cflag & CREAD) == 0)
275 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
276 
277 	/* Set baud rate */
278 	quot -= 1;
279 	UART_PUT_SCAL(port, quot);
280 	UART_PUT_CTRL(port, cr);
281 
282 	spin_unlock_irqrestore(&port->lock, flags);
283 }
284 
285 static const char *apbuart_type(struct uart_port *port)
286 {
287 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
288 }
289 
290 static void apbuart_release_port(struct uart_port *port)
291 {
292 	release_mem_region(port->mapbase, 0x100);
293 }
294 
295 static int apbuart_request_port(struct uart_port *port)
296 {
297 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
298 	    != NULL ? 0 : -EBUSY;
299 	return 0;
300 }
301 
302 /* Configure/autoconfigure the port */
303 static void apbuart_config_port(struct uart_port *port, int flags)
304 {
305 	if (flags & UART_CONFIG_TYPE) {
306 		port->type = PORT_APBUART;
307 		apbuart_request_port(port);
308 	}
309 }
310 
311 /* Verify the new serial_struct (for TIOCSSERIAL) */
312 static int apbuart_verify_port(struct uart_port *port,
313 			       struct serial_struct *ser)
314 {
315 	int ret = 0;
316 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
317 		ret = -EINVAL;
318 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
319 		ret = -EINVAL;
320 	if (ser->baud_base < 9600)
321 		ret = -EINVAL;
322 	return ret;
323 }
324 
325 static const struct uart_ops grlib_apbuart_ops = {
326 	.tx_empty = apbuart_tx_empty,
327 	.set_mctrl = apbuart_set_mctrl,
328 	.get_mctrl = apbuart_get_mctrl,
329 	.stop_tx = apbuart_stop_tx,
330 	.start_tx = apbuart_start_tx,
331 	.stop_rx = apbuart_stop_rx,
332 	.break_ctl = apbuart_break_ctl,
333 	.startup = apbuart_startup,
334 	.shutdown = apbuart_shutdown,
335 	.set_termios = apbuart_set_termios,
336 	.type = apbuart_type,
337 	.release_port = apbuart_release_port,
338 	.request_port = apbuart_request_port,
339 	.config_port = apbuart_config_port,
340 	.verify_port = apbuart_verify_port,
341 };
342 
343 static struct uart_port grlib_apbuart_ports[UART_NR];
344 static struct device_node *grlib_apbuart_nodes[UART_NR];
345 
346 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
347 {
348 	int ctrl, loop = 0;
349 	int status;
350 	int fifosize;
351 	unsigned long flags;
352 
353 	ctrl = UART_GET_CTRL(port);
354 
355 	/*
356 	 * Enable the transceiver and wait for it to be ready to send data.
357 	 * Clear interrupts so that this process will not be externally
358 	 * interrupted in the middle (which can cause the transceiver to
359 	 * drain prematurely).
360 	 */
361 
362 	local_irq_save(flags);
363 
364 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
365 
366 	while (!UART_TX_READY(UART_GET_STATUS(port)))
367 		loop++;
368 
369 	/*
370 	 * Disable the transceiver so data isn't actually sent during the
371 	 * actual test.
372 	 */
373 
374 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
375 
376 	fifosize = 1;
377 	UART_PUT_CHAR(port, 0);
378 
379 	/*
380 	 * So long as transmitting a character increments the tranceivier FIFO
381 	 * length the FIFO must be at least that big. These bytes will
382 	 * automatically drain off of the FIFO.
383 	 */
384 
385 	status = UART_GET_STATUS(port);
386 	while (((status >> 20) & 0x3F) == fifosize) {
387 		fifosize++;
388 		UART_PUT_CHAR(port, 0);
389 		status = UART_GET_STATUS(port);
390 	}
391 
392 	fifosize--;
393 
394 	UART_PUT_CTRL(port, ctrl);
395 	local_irq_restore(flags);
396 
397 	if (fifosize == 0)
398 		fifosize = 1;
399 
400 	return fifosize;
401 }
402 
403 static void apbuart_flush_fifo(struct uart_port *port)
404 {
405 	int i;
406 
407 	for (i = 0; i < port->fifosize; i++)
408 		UART_GET_CHAR(port);
409 }
410 
411 
412 /* ======================================================================== */
413 /* Console driver, if enabled                                               */
414 /* ======================================================================== */
415 
416 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
417 
418 static void apbuart_console_putchar(struct uart_port *port, int ch)
419 {
420 	unsigned int status;
421 	do {
422 		status = UART_GET_STATUS(port);
423 	} while (!UART_TX_READY(status));
424 	UART_PUT_CHAR(port, ch);
425 }
426 
427 static void
428 apbuart_console_write(struct console *co, const char *s, unsigned int count)
429 {
430 	struct uart_port *port = &grlib_apbuart_ports[co->index];
431 	unsigned int status, old_cr, new_cr;
432 
433 	/* First save the CR then disable the interrupts */
434 	old_cr = UART_GET_CTRL(port);
435 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
436 	UART_PUT_CTRL(port, new_cr);
437 
438 	uart_console_write(port, s, count, apbuart_console_putchar);
439 
440 	/*
441 	 *      Finally, wait for transmitter to become empty
442 	 *      and restore the TCR
443 	 */
444 	do {
445 		status = UART_GET_STATUS(port);
446 	} while (!UART_TX_READY(status));
447 	UART_PUT_CTRL(port, old_cr);
448 }
449 
450 static void __init
451 apbuart_console_get_options(struct uart_port *port, int *baud,
452 			    int *parity, int *bits)
453 {
454 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
455 
456 		unsigned int quot, status;
457 		status = UART_GET_STATUS(port);
458 
459 		*parity = 'n';
460 		if (status & UART_CTRL_PE) {
461 			if ((status & UART_CTRL_PS) == 0)
462 				*parity = 'e';
463 			else
464 				*parity = 'o';
465 		}
466 
467 		*bits = 8;
468 		quot = UART_GET_SCAL(port) / 8;
469 		*baud = port->uartclk / (16 * (quot + 1));
470 	}
471 }
472 
473 static int __init apbuart_console_setup(struct console *co, char *options)
474 {
475 	struct uart_port *port;
476 	int baud = 38400;
477 	int bits = 8;
478 	int parity = 'n';
479 	int flow = 'n';
480 
481 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
482 		 co, co->index, options);
483 
484 	/*
485 	 * Check whether an invalid uart number has been specified, and
486 	 * if so, search for the first available port that does have
487 	 * console support.
488 	 */
489 	if (co->index >= grlib_apbuart_port_nr)
490 		co->index = 0;
491 
492 	port = &grlib_apbuart_ports[co->index];
493 
494 	spin_lock_init(&port->lock);
495 
496 	if (options)
497 		uart_parse_options(options, &baud, &parity, &bits, &flow);
498 	else
499 		apbuart_console_get_options(port, &baud, &parity, &bits);
500 
501 	return uart_set_options(port, co, baud, parity, bits, flow);
502 }
503 
504 static struct uart_driver grlib_apbuart_driver;
505 
506 static struct console grlib_apbuart_console = {
507 	.name = "ttyS",
508 	.write = apbuart_console_write,
509 	.device = uart_console_device,
510 	.setup = apbuart_console_setup,
511 	.flags = CON_PRINTBUFFER,
512 	.index = -1,
513 	.data = &grlib_apbuart_driver,
514 };
515 
516 
517 static int grlib_apbuart_configure(void);
518 
519 static int __init apbuart_console_init(void)
520 {
521 	if (grlib_apbuart_configure())
522 		return -ENODEV;
523 	register_console(&grlib_apbuart_console);
524 	return 0;
525 }
526 
527 console_initcall(apbuart_console_init);
528 
529 #define APBUART_CONSOLE	(&grlib_apbuart_console)
530 #else
531 #define APBUART_CONSOLE	NULL
532 #endif
533 
534 static struct uart_driver grlib_apbuart_driver = {
535 	.owner = THIS_MODULE,
536 	.driver_name = "serial",
537 	.dev_name = "ttyS",
538 	.major = SERIAL_APBUART_MAJOR,
539 	.minor = SERIAL_APBUART_MINOR,
540 	.nr = UART_NR,
541 	.cons = APBUART_CONSOLE,
542 };
543 
544 
545 /* ======================================================================== */
546 /* OF Platform Driver                                                       */
547 /* ======================================================================== */
548 
549 static int apbuart_probe(struct platform_device *op)
550 {
551 	int i;
552 	struct uart_port *port = NULL;
553 
554 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
555 		if (op->dev.of_node == grlib_apbuart_nodes[i])
556 			break;
557 	}
558 
559 	port = &grlib_apbuart_ports[i];
560 	port->dev = &op->dev;
561 	port->irq = op->archdata.irqs[0];
562 
563 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
564 
565 	apbuart_flush_fifo((struct uart_port *) port);
566 
567 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
568 	       (unsigned long long) port->mapbase, port->irq);
569 	return 0;
570 }
571 
572 static const struct of_device_id apbuart_match[] = {
573 	{
574 	 .name = "GAISLER_APBUART",
575 	 },
576 	{
577 	 .name = "01_00c",
578 	 },
579 	{},
580 };
581 MODULE_DEVICE_TABLE(of, apbuart_match);
582 
583 static struct platform_driver grlib_apbuart_of_driver = {
584 	.probe = apbuart_probe,
585 	.driver = {
586 		.name = "grlib-apbuart",
587 		.of_match_table = apbuart_match,
588 	},
589 };
590 
591 
592 static int __init grlib_apbuart_configure(void)
593 {
594 	struct device_node *np;
595 	int line = 0;
596 
597 	for_each_matching_node(np, apbuart_match) {
598 		const int *ampopts;
599 		const u32 *freq_hz;
600 		const struct amba_prom_registers *regs;
601 		struct uart_port *port;
602 		unsigned long addr;
603 
604 		ampopts = of_get_property(np, "ampopts", NULL);
605 		if (ampopts && (*ampopts == 0))
606 			continue; /* Ignore if used by another OS instance */
607 		regs = of_get_property(np, "reg", NULL);
608 		/* Frequency of APB Bus is frequency of UART */
609 		freq_hz = of_get_property(np, "freq", NULL);
610 
611 		if (!regs || !freq_hz || (*freq_hz == 0))
612 			continue;
613 
614 		grlib_apbuart_nodes[line] = np;
615 
616 		addr = regs->phys_addr;
617 
618 		port = &grlib_apbuart_ports[line];
619 
620 		port->mapbase = addr;
621 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
622 		port->irq = 0;
623 		port->iotype = UPIO_MEM;
624 		port->ops = &grlib_apbuart_ops;
625 		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE);
626 		port->flags = UPF_BOOT_AUTOCONF;
627 		port->line = line;
628 		port->uartclk = *freq_hz;
629 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
630 		line++;
631 
632 		/* We support maximum UART_NR uarts ... */
633 		if (line == UART_NR)
634 			break;
635 	}
636 
637 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
638 	return line ? 0 : -ENODEV;
639 }
640 
641 static int __init grlib_apbuart_init(void)
642 {
643 	int ret;
644 
645 	/* Find all APBUARTS in device the tree and initialize their ports */
646 	ret = grlib_apbuart_configure();
647 	if (ret)
648 		return ret;
649 
650 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
651 
652 	ret = uart_register_driver(&grlib_apbuart_driver);
653 
654 	if (ret) {
655 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
656 		       __FILE__, ret);
657 		return ret;
658 	}
659 
660 	ret = platform_driver_register(&grlib_apbuart_of_driver);
661 	if (ret) {
662 		printk(KERN_ERR
663 		       "%s: platform_driver_register failed (%i)\n",
664 		       __FILE__, ret);
665 		uart_unregister_driver(&grlib_apbuart_driver);
666 		return ret;
667 	}
668 
669 	return ret;
670 }
671 
672 static void __exit grlib_apbuart_exit(void)
673 {
674 	int i;
675 
676 	for (i = 0; i < grlib_apbuart_port_nr; i++)
677 		uart_remove_one_port(&grlib_apbuart_driver,
678 				     &grlib_apbuart_ports[i]);
679 
680 	uart_unregister_driver(&grlib_apbuart_driver);
681 	platform_driver_unregister(&grlib_apbuart_of_driver);
682 }
683 
684 module_init(grlib_apbuart_init);
685 module_exit(grlib_apbuart_exit);
686 
687 MODULE_AUTHOR("Aeroflex Gaisler AB");
688 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
689 MODULE_VERSION("2.1");
690 MODULE_LICENSE("GPL");
691