timbuart.c revision ae8d8a146725a966bd7c59c94f4d0016dcf7a04f 
1/*
2 * timbuart.c timberdale FPGA UART driver
3 * Copyright (c) 2009 Intel Corporation
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19/* Supports:
20 * Timberdale FPGA UART
21 */
22
23#include <linux/pci.h>
24#include <linux/interrupt.h>
25#include <linux/serial_core.h>
26#include <linux/tty.h>
27#include <linux/tty_flip.h>
28#include <linux/kernel.h>
29#include <linux/platform_device.h>
30#include <linux/ioport.h>
31#include <linux/slab.h>
32#include <linux/module.h>
33
34#include "timbuart.h"
35
36struct timbuart_port {
37	struct uart_port	port;
38	struct tasklet_struct	tasklet;
39	int			usedma;
40	u32			last_ier;
41	struct platform_device  *dev;
42};
43
44static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
45	921600, 1843200, 3250000};
46
47static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
48
49static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
50
51static void timbuart_stop_rx(struct uart_port *port)
52{
53	/* spin lock held by upper layer, disable all RX interrupts */
54	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
55	iowrite32(ier, port->membase + TIMBUART_IER);
56}
57
58static void timbuart_stop_tx(struct uart_port *port)
59{
60	/* spinlock held by upper layer, disable TX interrupt */
61	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
62	iowrite32(ier, port->membase + TIMBUART_IER);
63}
64
65static void timbuart_start_tx(struct uart_port *port)
66{
67	struct timbuart_port *uart =
68		container_of(port, struct timbuart_port, port);
69
70	/* do not transfer anything here -> fire off the tasklet */
71	tasklet_schedule(&uart->tasklet);
72}
73
74static unsigned int timbuart_tx_empty(struct uart_port *port)
75{
76	u32 isr = ioread32(port->membase + TIMBUART_ISR);
77
78	return (isr & TXBE) ? TIOCSER_TEMT : 0;
79}
80
81static void timbuart_flush_buffer(struct uart_port *port)
82{
83	if (!timbuart_tx_empty(port)) {
84		u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
85			TIMBUART_CTRL_FLSHTX;
86
87		iowrite8(ctl, port->membase + TIMBUART_CTRL);
88		iowrite32(TXBF, port->membase + TIMBUART_ISR);
89	}
90}
91
92static void timbuart_rx_chars(struct uart_port *port)
93{
94	struct tty_struct *tty = port->state->port.tty;
95
96	while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
97		u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
98		port->icount.rx++;
99		tty_insert_flip_char(tty, ch, TTY_NORMAL);
100	}
101
102	spin_unlock(&port->lock);
103	tty_flip_buffer_push(port->state->port.tty);
104	spin_lock(&port->lock);
105
106	dev_dbg(port->dev, "%s - total read %d bytes\n",
107		__func__, port->icount.rx);
108}
109
110static void timbuart_tx_chars(struct uart_port *port)
111{
112	struct circ_buf *xmit = &port->state->xmit;
113
114	while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
115		!uart_circ_empty(xmit)) {
116		iowrite8(xmit->buf[xmit->tail],
117			port->membase + TIMBUART_TXFIFO);
118		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
119		port->icount.tx++;
120	}
121
122	dev_dbg(port->dev,
123		"%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
124		 __func__,
125		port->icount.tx,
126		ioread8(port->membase + TIMBUART_CTRL),
127		port->mctrl & TIOCM_RTS,
128		ioread8(port->membase + TIMBUART_BAUDRATE));
129}
130
131static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
132{
133	struct timbuart_port *uart =
134		container_of(port, struct timbuart_port, port);
135	struct circ_buf *xmit = &port->state->xmit;
136
137	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
138		return;
139
140	if (port->x_char)
141		return;
142
143	if (isr & TXFLAGS) {
144		timbuart_tx_chars(port);
145		/* clear all TX interrupts */
146		iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
147
148		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
149			uart_write_wakeup(port);
150	} else
151		/* Re-enable any tx interrupt */
152		*ier |= uart->last_ier & TXFLAGS;
153
154	/* enable interrupts if there are chars in the transmit buffer,
155	 * Or if we delivered some bytes and want the almost empty interrupt
156	 * we wake up the upper layer later when we got the interrupt
157	 * to give it some time to go out...
158	 */
159	if (!uart_circ_empty(xmit))
160		*ier |= TXBAE;
161
162	dev_dbg(port->dev, "%s - leaving\n", __func__);
163}
164
165void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
166{
167	if (isr & RXFLAGS) {
168		/* Some RX status is set */
169		if (isr & RXBF) {
170			u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
171				TIMBUART_CTRL_FLSHRX;
172			iowrite8(ctl, port->membase + TIMBUART_CTRL);
173			port->icount.overrun++;
174		} else if (isr & (RXDP))
175			timbuart_rx_chars(port);
176
177		/* ack all RX interrupts */
178		iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
179	}
180
181	/* always have the RX interrupts enabled */
182	*ier |= RXBAF | RXBF | RXTT;
183
184	dev_dbg(port->dev, "%s - leaving\n", __func__);
185}
186
187void timbuart_tasklet(unsigned long arg)
188{
189	struct timbuart_port *uart = (struct timbuart_port *)arg;
190	u32 isr, ier = 0;
191
192	spin_lock(&uart->port.lock);
193
194	isr = ioread32(uart->port.membase + TIMBUART_ISR);
195	dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
196
197	if (!uart->usedma)
198		timbuart_handle_tx_port(&uart->port, isr, &ier);
199
200	timbuart_mctrl_check(&uart->port, isr, &ier);
201
202	if (!uart->usedma)
203		timbuart_handle_rx_port(&uart->port, isr, &ier);
204
205	iowrite32(ier, uart->port.membase + TIMBUART_IER);
206
207	spin_unlock(&uart->port.lock);
208	dev_dbg(uart->port.dev, "%s leaving\n", __func__);
209}
210
211static unsigned int timbuart_get_mctrl(struct uart_port *port)
212{
213	u8 cts = ioread8(port->membase + TIMBUART_CTRL);
214	dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
215
216	if (cts & TIMBUART_CTRL_CTS)
217		return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
218	else
219		return TIOCM_DSR | TIOCM_CAR;
220}
221
222static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
223{
224	dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
225
226	if (mctrl & TIOCM_RTS)
227		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
228	else
229		iowrite8(0, port->membase + TIMBUART_CTRL);
230}
231
232static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
233{
234	unsigned int cts;
235
236	if (isr & CTS_DELTA) {
237		/* ack */
238		iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
239		cts = timbuart_get_mctrl(port);
240		uart_handle_cts_change(port, cts & TIOCM_CTS);
241		wake_up_interruptible(&port->state->port.delta_msr_wait);
242	}
243
244	*ier |= CTS_DELTA;
245}
246
247static void timbuart_enable_ms(struct uart_port *port)
248{
249	/* N/A */
250}
251
252static void timbuart_break_ctl(struct uart_port *port, int ctl)
253{
254	/* N/A */
255}
256
257static int timbuart_startup(struct uart_port *port)
258{
259	struct timbuart_port *uart =
260		container_of(port, struct timbuart_port, port);
261
262	dev_dbg(port->dev, "%s\n", __func__);
263
264	iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
265	iowrite32(0x1ff, port->membase + TIMBUART_ISR);
266	/* Enable all but TX interrupts */
267	iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
268		port->membase + TIMBUART_IER);
269
270	return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
271		"timb-uart", uart);
272}
273
274static void timbuart_shutdown(struct uart_port *port)
275{
276	struct timbuart_port *uart =
277		container_of(port, struct timbuart_port, port);
278	dev_dbg(port->dev, "%s\n", __func__);
279	free_irq(port->irq, uart);
280	iowrite32(0, port->membase + TIMBUART_IER);
281}
282
283static int get_bindex(int baud)
284{
285	int i;
286
287	for (i = 0; i < ARRAY_SIZE(baudrates); i++)
288		if (baud <= baudrates[i])
289			return i;
290
291	return -1;
292}
293
294static void timbuart_set_termios(struct uart_port *port,
295	struct ktermios *termios,
296	struct ktermios *old)
297{
298	unsigned int baud;
299	short bindex;
300	unsigned long flags;
301
302	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
303	bindex = get_bindex(baud);
304	dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
305
306	if (bindex < 0)
307		bindex = 0;
308	baud = baudrates[bindex];
309
310	/* The serial layer calls into this once with old = NULL when setting
311	   up initially */
312	if (old)
313		tty_termios_copy_hw(termios, old);
314	tty_termios_encode_baud_rate(termios, baud, baud);
315
316	spin_lock_irqsave(&port->lock, flags);
317	iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
318	uart_update_timeout(port, termios->c_cflag, baud);
319	spin_unlock_irqrestore(&port->lock, flags);
320}
321
322static const char *timbuart_type(struct uart_port *port)
323{
324	return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
325}
326
327/* We do not request/release mappings of the registers here,
328 * currently it's done in the proble function.
329 */
330static void timbuart_release_port(struct uart_port *port)
331{
332	struct platform_device *pdev = to_platform_device(port->dev);
333	int size =
334		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
335
336	if (port->flags & UPF_IOREMAP) {
337		iounmap(port->membase);
338		port->membase = NULL;
339	}
340
341	release_mem_region(port->mapbase, size);
342}
343
344static int timbuart_request_port(struct uart_port *port)
345{
346	struct platform_device *pdev = to_platform_device(port->dev);
347	int size =
348		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
349
350	if (!request_mem_region(port->mapbase, size, "timb-uart"))
351		return -EBUSY;
352
353	if (port->flags & UPF_IOREMAP) {
354		port->membase = ioremap(port->mapbase, size);
355		if (port->membase == NULL) {
356			release_mem_region(port->mapbase, size);
357			return -ENOMEM;
358		}
359	}
360
361	return 0;
362}
363
364static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
365{
366	struct timbuart_port *uart = (struct timbuart_port *)devid;
367
368	if (ioread8(uart->port.membase + TIMBUART_IPR)) {
369		uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
370
371		/* disable interrupts, the tasklet enables them again */
372		iowrite32(0, uart->port.membase + TIMBUART_IER);
373
374		/* fire off bottom half */
375		tasklet_schedule(&uart->tasklet);
376
377		return IRQ_HANDLED;
378	} else
379		return IRQ_NONE;
380}
381
382/*
383 * Configure/autoconfigure the port.
384 */
385static void timbuart_config_port(struct uart_port *port, int flags)
386{
387	if (flags & UART_CONFIG_TYPE) {
388		port->type = PORT_TIMBUART;
389		timbuart_request_port(port);
390	}
391}
392
393static int timbuart_verify_port(struct uart_port *port,
394	struct serial_struct *ser)
395{
396	/* we don't want the core code to modify any port params */
397	return -EINVAL;
398}
399
400static struct uart_ops timbuart_ops = {
401	.tx_empty = timbuart_tx_empty,
402	.set_mctrl = timbuart_set_mctrl,
403	.get_mctrl = timbuart_get_mctrl,
404	.stop_tx = timbuart_stop_tx,
405	.start_tx = timbuart_start_tx,
406	.flush_buffer = timbuart_flush_buffer,
407	.stop_rx = timbuart_stop_rx,
408	.enable_ms = timbuart_enable_ms,
409	.break_ctl = timbuart_break_ctl,
410	.startup = timbuart_startup,
411	.shutdown = timbuart_shutdown,
412	.set_termios = timbuart_set_termios,
413	.type = timbuart_type,
414	.release_port = timbuart_release_port,
415	.request_port = timbuart_request_port,
416	.config_port = timbuart_config_port,
417	.verify_port = timbuart_verify_port
418};
419
420static struct uart_driver timbuart_driver = {
421	.owner = THIS_MODULE,
422	.driver_name = "timberdale_uart",
423	.dev_name = "ttyTU",
424	.major = TIMBUART_MAJOR,
425	.minor = TIMBUART_MINOR,
426	.nr = 1
427};
428
429static int timbuart_probe(struct platform_device *dev)
430{
431	int err, irq;
432	struct timbuart_port *uart;
433	struct resource *iomem;
434
435	dev_dbg(&dev->dev, "%s\n", __func__);
436
437	uart = kzalloc(sizeof(*uart), GFP_KERNEL);
438	if (!uart) {
439		err = -EINVAL;
440		goto err_mem;
441	}
442
443	uart->usedma = 0;
444
445	uart->port.uartclk = 3250000 * 16;
446	uart->port.fifosize  = TIMBUART_FIFO_SIZE;
447	uart->port.regshift  = 2;
448	uart->port.iotype  = UPIO_MEM;
449	uart->port.ops = &timbuart_ops;
450	uart->port.irq = 0;
451	uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
452	uart->port.line  = 0;
453	uart->port.dev	= &dev->dev;
454
455	iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
456	if (!iomem) {
457		err = -ENOMEM;
458		goto err_register;
459	}
460	uart->port.mapbase = iomem->start;
461	uart->port.membase = NULL;
462
463	irq = platform_get_irq(dev, 0);
464	if (irq < 0) {
465		err = -EINVAL;
466		goto err_register;
467	}
468	uart->port.irq = irq;
469
470	tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
471
472	err = uart_register_driver(&timbuart_driver);
473	if (err)
474		goto err_register;
475
476	err = uart_add_one_port(&timbuart_driver, &uart->port);
477	if (err)
478		goto err_add_port;
479
480	platform_set_drvdata(dev, uart);
481
482	return 0;
483
484err_add_port:
485	uart_unregister_driver(&timbuart_driver);
486err_register:
487	kfree(uart);
488err_mem:
489	printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
490		err);
491
492	return err;
493}
494
495static int timbuart_remove(struct platform_device *dev)
496{
497	struct timbuart_port *uart = platform_get_drvdata(dev);
498
499	tasklet_kill(&uart->tasklet);
500	uart_remove_one_port(&timbuart_driver, &uart->port);
501	uart_unregister_driver(&timbuart_driver);
502	kfree(uart);
503
504	return 0;
505}
506
507static struct platform_driver timbuart_platform_driver = {
508	.driver = {
509		.name	= "timb-uart",
510		.owner	= THIS_MODULE,
511	},
512	.probe		= timbuart_probe,
513	.remove		= timbuart_remove,
514};
515
516module_platform_driver(timbuart_platform_driver);
517
518MODULE_DESCRIPTION("Timberdale UART driver");
519MODULE_LICENSE("GPL v2");
520MODULE_ALIAS("platform:timb-uart");
521
522