/drivers/tty/serial/vt8500_serial.c

  1/*
  2 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
  3 *
  4 * Based on msm_serial.c, which is:
  5 * Copyright (C) 2007 Google, Inc.
  6 * Author: Robert Love <rlove@google.com>
  7 *
  8 * This software is licensed under the terms of the GNU General Public
  9 * License version 2, as published by the Free Software Foundation, and
 10 * may be copied, distributed, and modified under those terms.
 11 *
 12 * This program is distributed in the hope that it will be useful,
 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15 * GNU General Public License for more details.
 16 */
 17
 18#if defined(CONFIG_SERIAL_VT8500_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
 19# define SUPPORT_SYSRQ
 20#endif
 21
 22#include <linux/hrtimer.h>
 23#include <linux/delay.h>
 24#include <linux/module.h>
 25#include <linux/io.h>
 26#include <linux/ioport.h>
 27#include <linux/irq.h>
 28#include <linux/init.h>
 29#include <linux/console.h>
 30#include <linux/tty.h>
 31#include <linux/tty_flip.h>
 32#include <linux/serial_core.h>
 33#include <linux/serial.h>
 34#include <linux/slab.h>
 35#include <linux/clk.h>
 36#include <linux/platform_device.h>
 37
 38/*
 39 * UART Register offsets
 40 */
 41
 42#define VT8500_URTDR		0x0000	/* Transmit data */
 43#define VT8500_URRDR		0x0004	/* Receive data */
 44#define VT8500_URDIV		0x0008	/* Clock/Baud rate divisor */
 45#define VT8500_URLCR		0x000C	/* Line control */
 46#define VT8500_URICR		0x0010	/* IrDA control */
 47#define VT8500_URIER		0x0014	/* Interrupt enable */
 48#define VT8500_URISR		0x0018	/* Interrupt status */
 49#define VT8500_URUSR		0x001c	/* UART status */
 50#define VT8500_URFCR		0x0020	/* FIFO control */
 51#define VT8500_URFIDX		0x0024	/* FIFO index */
 52#define VT8500_URBKR		0x0028	/* Break signal count */
 53#define VT8500_URTOD		0x002c	/* Time out divisor */
 54#define VT8500_TXFIFO		0x1000	/* Transmit FIFO (16x8) */
 55#define VT8500_RXFIFO		0x1020	/* Receive FIFO (16x10) */
 56
 57/*
 58 * Interrupt enable and status bits
 59 */
 60
 61#define TXDE	(1 << 0)	/* Tx Data empty */
 62#define RXDF	(1 << 1)	/* Rx Data full */
 63#define TXFAE	(1 << 2)	/* Tx FIFO almost empty */
 64#define TXFE	(1 << 3)	/* Tx FIFO empty */
 65#define RXFAF	(1 << 4)	/* Rx FIFO almost full */
 66#define RXFF	(1 << 5)	/* Rx FIFO full */
 67#define TXUDR	(1 << 6)	/* Tx underrun */
 68#define RXOVER	(1 << 7)	/* Rx overrun */
 69#define PER	(1 << 8)	/* Parity error */
 70#define FER	(1 << 9)	/* Frame error */
 71#define TCTS	(1 << 10)	/* Toggle of CTS */
 72#define RXTOUT	(1 << 11)	/* Rx timeout */
 73#define BKDONE	(1 << 12)	/* Break signal done */
 74#define ERR	(1 << 13)	/* AHB error response */
 75
 76#define RX_FIFO_INTS	(RXFAF | RXFF | RXOVER | PER | FER | RXTOUT)
 77#define TX_FIFO_INTS	(TXFAE | TXFE | TXUDR)
 78
 79struct vt8500_port {
 80	struct uart_port	uart;
 81	char			name[16];
 82	struct clk		*clk;
 83	unsigned int		ier;
 84};
 85
 86static inline void vt8500_write(struct uart_port *port, unsigned int val,
 87			     unsigned int off)
 88{
 89	writel(val, port->membase + off);
 90}
 91
 92static inline unsigned int vt8500_read(struct uart_port *port, unsigned int off)
 93{
 94	return readl(port->membase + off);
 95}
 96
 97static void vt8500_stop_tx(struct uart_port *port)
 98{
 99	struct vt8500_port *vt8500_port = container_of(port,
100						       struct vt8500_port,
101						       uart);
102
103	vt8500_port->ier &= ~TX_FIFO_INTS;
104	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
105}
106
107static void vt8500_stop_rx(struct uart_port *port)
108{
109	struct vt8500_port *vt8500_port = container_of(port,
110						       struct vt8500_port,
111						       uart);
112
113	vt8500_port->ier &= ~RX_FIFO_INTS;
114	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
115}
116
117static void vt8500_enable_ms(struct uart_port *port)
118{
119	struct vt8500_port *vt8500_port = container_of(port,
120						       struct vt8500_port,
121						       uart);
122
123	vt8500_port->ier |= TCTS;
124	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
125}
126
127static void handle_rx(struct uart_port *port)
128{
129	struct tty_struct *tty = tty_port_tty_get(&port->state->port);
130	if (!tty) {
131		/* Discard data: no tty available */
132		int count = (vt8500_read(port, VT8500_URFIDX) & 0x1f00) >> 8;
133		u16 ch;
134		while (count--)
135			ch = readw(port->membase + VT8500_RXFIFO);
136		return;
137	}
138
139	/*
140	 * Handle overrun
141	 */
142	if ((vt8500_read(port, VT8500_URISR) & RXOVER)) {
143		port->icount.overrun++;
144		tty_insert_flip_char(tty, 0, TTY_OVERRUN);
145	}
146
147	/* and now the main RX loop */
148	while (vt8500_read(port, VT8500_URFIDX) & 0x1f00) {
149		unsigned int c;
150		char flag = TTY_NORMAL;
151
152		c = readw(port->membase + VT8500_RXFIFO) & 0x3ff;
153
154		/* Mask conditions we're ignorning. */
155		c &= ~port->read_status_mask;
156
157		if (c & FER) {
158			port->icount.frame++;
159			flag = TTY_FRAME;
160		} else if (c & PER) {
161			port->icount.parity++;
162			flag = TTY_PARITY;
163		}
164		port->icount.rx++;
165
166		if (!uart_handle_sysrq_char(port, c))
167			tty_insert_flip_char(tty, c, flag);
168	}
169
170	tty_flip_buffer_push(tty);
171	tty_kref_put(tty);
172}
173
174static void handle_tx(struct uart_port *port)
175{
176	struct circ_buf *xmit = &port->state->xmit;
177
178	if (port->x_char) {
179		writeb(port->x_char, port->membase + VT8500_TXFIFO);
180		port->icount.tx++;
181		port->x_char = 0;
182	}
183	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
184		vt8500_stop_tx(port);
185		return;
186	}
187
188	while ((vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16) {
189		if (uart_circ_empty(xmit))
190			break;
191
192		writeb(xmit->buf[xmit->tail], port->membase + VT8500_TXFIFO);
193
194		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
195		port->icount.tx++;
196	}
197
198	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
199		uart_write_wakeup(port);
200
201	if (uart_circ_empty(xmit))
202		vt8500_stop_tx(port);
203}
204
205static void vt8500_start_tx(struct uart_port *port)
206{
207	struct vt8500_port *vt8500_port = container_of(port,
208						       struct vt8500_port,
209						       uart);
210
211	vt8500_port->ier &= ~TX_FIFO_INTS;
212	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
213	handle_tx(port);
214	vt8500_port->ier |= TX_FIFO_INTS;
215	vt8500_write(port, vt8500_port->ier, VT8500_URIER);
216}
217
218static void handle_delta_cts(struct uart_port *port)
219{
220	port->icount.cts++;
221	wake_up_interruptible(&port->state->port.delta_msr_wait);
222}
223
224static irqreturn_t vt8500_irq(int irq, void *dev_id)
225{
226	struct uart_port *port = dev_id;
227	unsigned long isr;
228
229	spin_lock(&port->lock);
230	isr = vt8500_read(port, VT8500_URISR);
231
232	/* Acknowledge active status bits */
233	vt8500_write(port, isr, VT8500_URISR);
234
235	if (isr & RX_FIFO_INTS)
236		handle_rx(port);
237	if (isr & TX_FIFO_INTS)
238		handle_tx(port);
239	if (isr & TCTS)
240		handle_delta_cts(port);
241
242	spin_unlock(&port->lock);
243
244	return IRQ_HANDLED;
245}
246
247static unsigned int vt8500_tx_empty(struct uart_port *port)
248{
249	return (vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16 ?
250						TIOCSER_TEMT : 0;
251}
252
253static unsigned int vt8500_get_mctrl(struct uart_port *port)
254{
255	unsigned int usr;
256
257	usr = vt8500_read(port, VT8500_URUSR);
258	if (usr & (1 << 4))
259		return TIOCM_CTS;
260	else
261		return 0;
262}
263
264static void vt8500_set_mctrl(struct uart_port *port, unsigned int mctrl)
265{
266}
267
268static void vt8500_break_ctl(struct uart_port *port, int break_ctl)
269{
270	if (break_ctl)
271		vt8500_write(port, vt8500_read(port, VT8500_URLCR) | (1 << 9),
272			     VT8500_URLCR);
273}
274
275static int vt8500_set_baud_rate(struct uart_port *port, unsigned int baud)
276{
277	unsigned long div;
278	unsigned int loops = 1000;
279
280	div = vt8500_read(port, VT8500_URDIV) & ~(0x3ff);
281
282	if (unlikely((baud < 900) || (baud > 921600)))
283		div |= 7;
284	else
285		div |= (921600 / baud) - 1;
286
287	while ((vt8500_read(port, VT8500_URUSR) & (1 << 5)) && --loops)
288		cpu_relax();
289	vt8500_write(port, div, VT8500_URDIV);
290
291	return baud;
292}
293
294static int vt8500_startup(struct uart_port *port)
295{
296	struct vt8500_port *vt8500_port =
297			container_of(port, struct vt8500_port, uart);
298	int ret;
299
300	snprintf(vt8500_port->name, sizeof(vt8500_port->name),
301		 "vt8500_serial%d", port->line);
302
303	ret = request_irq(port->irq, vt8500_irq, IRQF_TRIGGER_HIGH,
304			  vt8500_port->name, port);
305	if (unlikely(ret))
306		return ret;
307
308	vt8500_write(port, 0x03, VT8500_URLCR);	/* enable TX & RX */
309
310	return 0;
311}
312
313static void vt8500_shutdown(struct uart_port *port)
314{
315	struct vt8500_port *vt8500_port =
316			container_of(port, struct vt8500_port, uart);
317
318	vt8500_port->ier = 0;
319
320	/* disable interrupts and FIFOs */
321	vt8500_write(&vt8500_port->uart, 0, VT8500_URIER);
322	vt8500_write(&vt8500_port->uart, 0x880, VT8500_URFCR);
323	free_irq(port->irq, port);
324}
325
326static void vt8500_set_termios(struct uart_port *port,
327			       struct ktermios *termios,
328			       struct ktermios *old)
329{
330	struct vt8500_port *vt8500_port =
331			container_of(port, struct vt8500_port, uart);
332	unsigned long flags;
333	unsigned int baud, lcr;
334	unsigned int loops = 1000;
335
336	spin_lock_irqsave(&port->lock, flags);
337
338	/* calculate and set baud rate */
339	baud = uart_get_baud_rate(port, termios, old, 900, 921600);
340	baud = vt8500_set_baud_rate(port, baud);
341	if (tty_termios_baud_rate(termios))
342		tty_termios_encode_baud_rate(termios, baud, baud);
343
344	/* calculate parity */
345	lcr = vt8500_read(&vt8500_port->uart, VT8500_URLCR);
346	lcr &= ~((1 << 5) | (1 << 4));
347	if (termios->c_cflag & PARENB) {
348		lcr |= (1 << 4);
349		termios->c_cflag &= ~CMSPAR;
350		if (termios->c_cflag & PARODD)
351			lcr |= (1 << 5);
352	}
353
354	/* calculate bits per char */
355	lcr &= ~(1 << 2);
356	switch (termios->c_cflag & CSIZE) {
357	case CS7:
358		break;
359	case CS8:
360	default:
361		lcr |= (1 << 2);
362		termios->c_cflag &= ~CSIZE;
363		termios->c_cflag |= CS8;
364		break;
365	}
366
367	/* calculate stop bits */
368	lcr &= ~(1 << 3);
369	if (termios->c_cflag & CSTOPB)
370		lcr |= (1 << 3);
371
372	/* set parity, bits per char, and stop bit */
373	vt8500_write(&vt8500_port->uart, lcr, VT8500_URLCR);
374
375	/* Configure status bits to ignore based on termio flags. */
376	port->read_status_mask = 0;
377	if (termios->c_iflag & IGNPAR)
378		port->read_status_mask = FER | PER;
379
380	uart_update_timeout(port, termios->c_cflag, baud);
381
382	/* Reset FIFOs */
383	vt8500_write(&vt8500_port->uart, 0x88c, VT8500_URFCR);
384	while ((vt8500_read(&vt8500_port->uart, VT8500_URFCR) & 0xc)
385							&& --loops)
386		cpu_relax();
387
388	/* Every possible FIFO-related interrupt */
389	vt8500_port->ier = RX_FIFO_INTS | TX_FIFO_INTS;
390
391	/*
392	 * CTS flow control
393	 */
394	if (UART_ENABLE_MS(&vt8500_port->uart, termios->c_cflag))
395		vt8500_port->ier |= TCTS;
396
397	vt8500_write(&vt8500_port->uart, 0x881, VT8500_URFCR);
398	vt8500_write(&vt8500_port->uart, vt8500_port->ier, VT8500_URIER);
399
400	spin_unlock_irqrestore(&port->lock, flags);
401}
402
403static const char *vt8500_type(struct uart_port *port)
404{
405	struct vt8500_port *vt8500_port =
406			container_of(port, struct vt8500_port, uart);
407	return vt8500_port->name;
408}
409
410static void vt8500_release_port(struct uart_port *port)
411{
412}
413
414static int vt8500_request_port(struct uart_port *port)
415{
416	return 0;
417}
418
419static void vt8500_config_port(struct uart_port *port, int flags)
420{
421	port->type = PORT_VT8500;
422}
423
424static int vt8500_verify_port(struct uart_port *port,
425			      struct serial_struct *ser)
426{
427	if (unlikely(ser->type != PORT_UNKNOWN && ser->type != PORT_VT8500))
428		return -EINVAL;
429	if (unlikely(port->irq != ser->irq))
430		return -EINVAL;
431	return 0;
432}
433
434static struct vt8500_port *vt8500_uart_ports[4];
435static struct uart_driver vt8500_uart_driver;
436
437#ifdef CONFIG_SERIAL_VT8500_CONSOLE
438
439static inline void wait_for_xmitr(struct uart_port *port)
440{
441	unsigned int status, tmout = 10000;
442
443	/* Wait up to 10ms for the character(s) to be sent. */
444	do {
445		status = vt8500_read(port, VT8500_URFIDX);
446
447		if (--tmout == 0)
448			break;
449		udelay(1);
450	} while (status & 0x10);
451}
452
453static void vt8500_console_putchar(struct uart_port *port, int c)
454{
455	wait_for_xmitr(port);
456	writeb(c, port->membase + VT8500_TXFIFO);
457}
458
459static void vt8500_console_write(struct console *co, const char *s,
460			      unsigned int count)
461{
462	struct vt8500_port *vt8500_port = vt8500_uart_ports[co->index];
463	unsigned long ier;
464
465	BUG_ON(co->index < 0 || co->index >= vt8500_uart_driver.nr);
466
467	ier = vt8500_read(&vt8500_port->uart, VT8500_URIER);
468	vt8500_write(&vt8500_port->uart, VT8500_URIER, 0);
469
470	uart_console_write(&vt8500_port->uart, s, count,
471			   vt8500_console_putchar);
472
473	/*
474	 *	Finally, wait for transmitter to become empty
475	 *	and switch back to FIFO
476	 */
477	wait_for_xmitr(&vt8500_port->uart);
478	vt8500_write(&vt8500_port->uart, VT8500_URIER, ier);
479}
480
481static int __init vt8500_console_setup(struct console *co, char *options)
482{
483	struct vt8500_port *vt8500_port;
484	int baud = 9600;
485	int bits = 8;
486	int parity = 'n';
487	int flow = 'n';
488
489	if (unlikely(co->index >= vt8500_uart_driver.nr || co->index < 0))
490		return -ENXIO;
491
492	vt8500_port = vt8500_uart_ports[co->index];
493
494	if (!vt8500_port)
495		return -ENODEV;
496
497	if (options)
498		uart_parse_options(options, &baud, &parity, &bits, &flow);
499
500	return uart_set_options(&vt8500_port->uart,
501				 co, baud, parity, bits, flow);
502}
503
504static struct console vt8500_console = {
505	.name = "ttyWMT",
506	.write = vt8500_console_write,
507	.device = uart_console_device,
508	.setup = vt8500_console_setup,
509	.flags = CON_PRINTBUFFER,
510	.index = -1,
511	.data = &vt8500_uart_driver,
512};
513
514#define VT8500_CONSOLE	(&vt8500_console)
515
516#else
517#define VT8500_CONSOLE	NULL
518#endif
519
520static struct uart_ops vt8500_uart_pops = {
521	.tx_empty	= vt8500_tx_empty,
522	.set_mctrl	= vt8500_set_mctrl,
523	.get_mctrl	= vt8500_get_mctrl,
524	.stop_tx	= vt8500_stop_tx,
525	.start_tx	= vt8500_start_tx,
526	.stop_rx	= vt8500_stop_rx,
527	.enable_ms	= vt8500_enable_ms,
528	.break_ctl	= vt8500_break_ctl,
529	.startup	= vt8500_startup,
530	.shutdown	= vt8500_shutdown,
531	.set_termios	= vt8500_set_termios,
532	.type		= vt8500_type,
533	.release_port	= vt8500_release_port,
534	.request_port	= vt8500_request_port,
535	.config_port	= vt8500_config_port,
536	.verify_port	= vt8500_verify_port,
537};
538
539static struct uart_driver vt8500_uart_driver = {
540	.owner		= THIS_MODULE,
541	.driver_name	= "vt8500_serial",
542	.dev_name	= "ttyWMT",
543	.nr		= 6,
544	.cons		= VT8500_CONSOLE,
545};
546
547static int __init vt8500_serial_probe(struct platform_device *pdev)
548{
549	struct vt8500_port *vt8500_port;
550	struct resource *mmres, *irqres;
551	int ret;
552
553	mmres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
554	irqres = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
555	if (!mmres || !irqres)
556		return -ENODEV;
557
558	vt8500_port = kzalloc(sizeof(struct vt8500_port), GFP_KERNEL);
559	if (!vt8500_port)
560		return -ENOMEM;
561
562	vt8500_port->uart.type = PORT_VT8500;
563	vt8500_port->uart.iotype = UPIO_MEM;
564	vt8500_port->uart.mapbase = mmres->start;
565	vt8500_port->uart.irq = irqres->start;
566	vt8500_port->uart.fifosize = 16;
567	vt8500_port->uart.ops = &vt8500_uart_pops;
568	vt8500_port->uart.line = pdev->id;
569	vt8500_port->uart.dev = &pdev->dev;
570	vt8500_port->uart.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF;
571	vt8500_port->uart.uartclk = 24000000;
572
573	snprintf(vt8500_port->name, sizeof(vt8500_port->name),
574		 "VT8500 UART%d", pdev->id);
575
576	vt8500_port->uart.membase = ioremap(mmres->start, resource_size(mmres));
577	if (!vt8500_port->uart.membase) {
578		ret = -ENOMEM;
579		goto err;
580	}
581
582	vt8500_uart_ports[pdev->id] = vt8500_port;
583
584	uart_add_one_port(&vt8500_uart_driver, &vt8500_port->uart);
585
586	platform_set_drvdata(pdev, vt8500_port);
587
588	return 0;
589
590err:
591	kfree(vt8500_port);
592	return ret;
593}
594
595static int __devexit vt8500_serial_remove(struct platform_device *pdev)
596{
597	struct vt8500_port *vt8500_port = platform_get_drvdata(pdev);
598
599	platform_set_drvdata(pdev, NULL);
600	uart_remove_one_port(&vt8500_uart_driver, &vt8500_port->uart);
601	kfree(vt8500_port);
602
603	return 0;
604}
605
606static struct platform_driver vt8500_platform_driver = {
607	.probe  = vt8500_serial_probe,
608	.remove = vt8500_serial_remove,
609	.driver = {
610		.name = "vt8500_serial",
611		.owner = THIS_MODULE,
612	},
613};
614
615static int __init vt8500_serial_init(void)
616{
617	int ret;
618
619	ret = uart_register_driver(&vt8500_uart_driver);
620	if (unlikely(ret))
621		return ret;
622
623	ret = platform_driver_register(&vt8500_platform_driver);
624
625	if (unlikely(ret))
626		uart_unregister_driver(&vt8500_uart_driver);
627
628	return ret;
629}
630
631static void __exit vt8500_serial_exit(void)
632{
633#ifdef CONFIG_SERIAL_VT8500_CONSOLE
634	unregister_console(&vt8500_console);
635#endif
636	platform_driver_unregister(&vt8500_platform_driver);
637	uart_unregister_driver(&vt8500_uart_driver);
638}
639
640module_init(vt8500_serial_init);
641module_exit(vt8500_serial_exit);
642
643MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
644MODULE_DESCRIPTION("Driver for vt8500 serial device");
645MODULE_LICENSE("GPL");