1/*
2 * Watchdog driver for IMX2 and later processors
3 *
4 *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
5 *
6 * some parts adapted by similar drivers from Darius Augulis and Vladimir
7 * Zapolskiy, additional improvements by Wim Van Sebroeck.
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License version 2 as published by
11 * the Free Software Foundation.
12 *
13 * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
14 *
15 *			MX1:		MX2+:
16 *			----		-----
17 * Registers:		32-bit		16-bit
18 * Stopable timer:	Yes		No
19 * Need to enable clk:	No		Yes
20 * Halt on suspend:	Manual		Can be automatic
21 */
22
23#include <linux/init.h>
24#include <linux/kernel.h>
25#include <linux/miscdevice.h>
26#include <linux/module.h>
27#include <linux/moduleparam.h>
28#include <linux/platform_device.h>
29#include <linux/watchdog.h>
30#include <linux/clk.h>
31#include <linux/fs.h>
32#include <linux/io.h>
33#include <linux/uaccess.h>
34#include <linux/timer.h>
35#include <linux/jiffies.h>
36#include <mach/hardware.h>
37
38#define DRIVER_NAME "imx2-wdt"
39
40#define IMX2_WDT_WCR		0x00		/* Control Register */
41#define IMX2_WDT_WCR_WT		(0xFF << 8)	/* -> Watchdog Timeout Field */
42#define IMX2_WDT_WCR_WRE	(1 << 3)	/* -> WDOG Reset Enable */
43#define IMX2_WDT_WCR_WDE	(1 << 2)	/* -> Watchdog Enable */
44
45#define IMX2_WDT_WSR		0x02		/* Service Register */
46#define IMX2_WDT_SEQ1		0x5555		/* -> service sequence 1 */
47#define IMX2_WDT_SEQ2		0xAAAA		/* -> service sequence 2 */
48
49#define IMX2_WDT_WRSR		0x04		/* Reset Status Register */
50#define IMX2_WDT_WRSR_TOUT	(1 << 1)	/* -> Reset due to Timeout */
51
52#define IMX2_WDT_MAX_TIME	128
53#define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */
54
55#define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)
56
57#define IMX2_WDT_STATUS_OPEN	0
58#define IMX2_WDT_STATUS_STARTED	1
59#define IMX2_WDT_EXPECT_CLOSE	2
60
61static struct {
62	struct clk *clk;
63	void __iomem *base;
64	unsigned timeout;
65	unsigned long status;
66	struct timer_list timer;	/* Pings the watchdog when closed */
67} imx2_wdt;
68
69static struct miscdevice imx2_wdt_miscdev;
70
71static bool nowayout = WATCHDOG_NOWAYOUT;
72module_param(nowayout, bool, 0);
73MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
74				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
75
76
77static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
78module_param(timeout, uint, 0);
79MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
80				__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
81
82static const struct watchdog_info imx2_wdt_info = {
83	.identity = "imx2+ watchdog",
84	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
85};
86
87static inline void imx2_wdt_setup(void)
88{
89	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
90
91	/* Strip the old watchdog Time-Out value */
92	val &= ~IMX2_WDT_WCR_WT;
93	/* Generate reset if WDOG times out */
94	val &= ~IMX2_WDT_WCR_WRE;
95	/* Keep Watchdog Disabled */
96	val &= ~IMX2_WDT_WCR_WDE;
97	/* Set the watchdog's Time-Out value */
98	val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
99
100	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
101
102	/* enable the watchdog */
103	val |= IMX2_WDT_WCR_WDE;
104	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
105}
106
107static inline void imx2_wdt_ping(void)
108{
109	__raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
110	__raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
111}
112
113static void imx2_wdt_timer_ping(unsigned long arg)
114{
115	/* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
116	imx2_wdt_ping();
117	mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
118}
119
120static void imx2_wdt_start(void)
121{
122	if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
123		/* at our first start we enable clock and do initialisations */
124		clk_enable(imx2_wdt.clk);
125
126		imx2_wdt_setup();
127	} else	/* delete the timer that pings the watchdog after close */
128		del_timer_sync(&imx2_wdt.timer);
129
130	/* Watchdog is enabled - time to reload the timeout value */
131	imx2_wdt_ping();
132}
133
134static void imx2_wdt_stop(void)
135{
136	/* we don't need a clk_disable, it cannot be disabled once started.
137	 * We use a timer to ping the watchdog while /dev/watchdog is closed */
138	imx2_wdt_timer_ping(0);
139}
140
141static void imx2_wdt_set_timeout(int new_timeout)
142{
143	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
144
145	/* set the new timeout value in the WSR */
146	val &= ~IMX2_WDT_WCR_WT;
147	val |= WDOG_SEC_TO_COUNT(new_timeout);
148	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
149}
150
151static int imx2_wdt_open(struct inode *inode, struct file *file)
152{
153	if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
154		return -EBUSY;
155
156	imx2_wdt_start();
157	return nonseekable_open(inode, file);
158}
159
160static int imx2_wdt_close(struct inode *inode, struct file *file)
161{
162	if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
163		imx2_wdt_stop();
164	else {
165		dev_crit(imx2_wdt_miscdev.parent,
166			"Unexpected close: Expect reboot!\n");
167		imx2_wdt_ping();
168	}
169
170	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
171	clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
172	return 0;
173}
174
175static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
176							unsigned long arg)
177{
178	void __user *argp = (void __user *)arg;
179	int __user *p = argp;
180	int new_value;
181	u16 val;
182
183	switch (cmd) {
184	case WDIOC_GETSUPPORT:
185		return copy_to_user(argp, &imx2_wdt_info,
186			sizeof(struct watchdog_info)) ? -EFAULT : 0;
187
188	case WDIOC_GETSTATUS:
189		return put_user(0, p);
190
191	case WDIOC_GETBOOTSTATUS:
192		val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
193		new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
194		return put_user(new_value, p);
195
196	case WDIOC_KEEPALIVE:
197		imx2_wdt_ping();
198		return 0;
199
200	case WDIOC_SETTIMEOUT:
201		if (get_user(new_value, p))
202			return -EFAULT;
203		if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
204			return -EINVAL;
205		imx2_wdt_set_timeout(new_value);
206		imx2_wdt.timeout = new_value;
207		imx2_wdt_ping();
208
209		/* Fallthrough to return current value */
210	case WDIOC_GETTIMEOUT:
211		return put_user(imx2_wdt.timeout, p);
212
213	default:
214		return -ENOTTY;
215	}
216}
217
218static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
219						size_t len, loff_t *ppos)
220{
221	size_t i;
222	char c;
223
224	if (len == 0)	/* Can we see this even ? */
225		return 0;
226
227	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
228	/* scan to see whether or not we got the magic character */
229	for (i = 0; i != len; i++) {
230		if (get_user(c, data + i))
231			return -EFAULT;
232		if (c == 'V')
233			set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
234	}
235
236	imx2_wdt_ping();
237	return len;
238}
239
240static const struct file_operations imx2_wdt_fops = {
241	.owner = THIS_MODULE,
242	.llseek = no_llseek,
243	.unlocked_ioctl = imx2_wdt_ioctl,
244	.open = imx2_wdt_open,
245	.release = imx2_wdt_close,
246	.write = imx2_wdt_write,
247};
248
249static struct miscdevice imx2_wdt_miscdev = {
250	.minor = WATCHDOG_MINOR,
251	.name = "watchdog",
252	.fops = &imx2_wdt_fops,
253};
254
255static int __init imx2_wdt_probe(struct platform_device *pdev)
256{
257	int ret;
258	struct resource *res;
259
260	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
261	if (!res) {
262		dev_err(&pdev->dev, "can't get device resources\n");
263		return -ENODEV;
264	}
265
266	imx2_wdt.base = devm_request_and_ioremap(&pdev->dev, res);
267	if (!imx2_wdt.base) {
268		dev_err(&pdev->dev, "ioremap failed\n");
269		return -ENOMEM;
270	}
271
272	imx2_wdt.clk = clk_get(&pdev->dev, NULL);
273	if (IS_ERR(imx2_wdt.clk)) {
274		dev_err(&pdev->dev, "can't get Watchdog clock\n");
275		return PTR_ERR(imx2_wdt.clk);
276	}
277
278	imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
279	if (imx2_wdt.timeout != timeout)
280		dev_warn(&pdev->dev, "Initial timeout out of range! "
281			"Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
282
283	setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
284
285	imx2_wdt_miscdev.parent = &pdev->dev;
286	ret = misc_register(&imx2_wdt_miscdev);
287	if (ret)
288		goto fail;
289
290	dev_info(&pdev->dev,
291		"IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
292						imx2_wdt.timeout, nowayout);
293	return 0;
294
295fail:
296	imx2_wdt_miscdev.parent = NULL;
297	clk_put(imx2_wdt.clk);
298	return ret;
299}
300
301static int __exit imx2_wdt_remove(struct platform_device *pdev)
302{
303	misc_deregister(&imx2_wdt_miscdev);
304
305	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
306		del_timer_sync(&imx2_wdt.timer);
307
308		dev_crit(imx2_wdt_miscdev.parent,
309			"Device removed: Expect reboot!\n");
310	} else
311		clk_put(imx2_wdt.clk);
312
313	imx2_wdt_miscdev.parent = NULL;
314	return 0;
315}
316
317static void imx2_wdt_shutdown(struct platform_device *pdev)
318{
319	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
320		/* we are running, we need to delete the timer but will give
321		 * max timeout before reboot will take place */
322		del_timer_sync(&imx2_wdt.timer);
323		imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
324		imx2_wdt_ping();
325
326		dev_crit(imx2_wdt_miscdev.parent,
327			"Device shutdown: Expect reboot!\n");
328	}
329}
330
331static const struct of_device_id imx2_wdt_dt_ids[] = {
332	{ .compatible = "fsl,imx21-wdt", },
333	{ /* sentinel */ }
334};
335
336static struct platform_driver imx2_wdt_driver = {
337	.remove		= __exit_p(imx2_wdt_remove),
338	.shutdown	= imx2_wdt_shutdown,
339	.driver		= {
340		.name	= DRIVER_NAME,
341		.owner	= THIS_MODULE,
342		.of_match_table = imx2_wdt_dt_ids,
343	},
344};
345
346static int __init imx2_wdt_init(void)
347{
348	return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
349}
350module_init(imx2_wdt_init);
351
352static void __exit imx2_wdt_exit(void)
353{
354	platform_driver_unregister(&imx2_wdt_driver);
355}
356module_exit(imx2_wdt_exit);
357
358MODULE_AUTHOR("Wolfram Sang");
359MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
360MODULE_LICENSE("GPL v2");
361MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
362MODULE_ALIAS("platform:" DRIVER_NAME);
363