xref: /openbmc/linux/drivers/watchdog/imx2_wdt.c (revision 22fd411a) 
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_MAX_TIME	128
50 #define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */
51 
52 #define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)
53 
54 #define IMX2_WDT_STATUS_OPEN	0
55 #define IMX2_WDT_STATUS_STARTED	1
56 #define IMX2_WDT_EXPECT_CLOSE	2
57 
58 static struct {
59 	struct clk *clk;
60 	void __iomem *base;
61 	unsigned timeout;
62 	unsigned long status;
63 	struct timer_list timer;	/* Pings the watchdog when closed */
64 } imx2_wdt;
65 
66 static struct miscdevice imx2_wdt_miscdev;
67 
68 static int nowayout = WATCHDOG_NOWAYOUT;
69 module_param(nowayout, int, 0);
70 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
71 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
72 
73 
74 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
75 module_param(timeout, uint, 0);
76 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
77 				__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
78 
79 static const struct watchdog_info imx2_wdt_info = {
80 	.identity = "imx2+ watchdog",
81 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
82 };
83 
84 static inline void imx2_wdt_setup(void)
85 {
86 	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
87 
88 	/* Strip the old watchdog Time-Out value */
89 	val &= ~IMX2_WDT_WCR_WT;
90 	/* Generate reset if WDOG times out */
91 	val &= ~IMX2_WDT_WCR_WRE;
92 	/* Keep Watchdog Disabled */
93 	val &= ~IMX2_WDT_WCR_WDE;
94 	/* Set the watchdog's Time-Out value */
95 	val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
96 
97 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
98 
99 	/* enable the watchdog */
100 	val |= IMX2_WDT_WCR_WDE;
101 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
102 }
103 
104 static inline void imx2_wdt_ping(void)
105 {
106 	__raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
107 	__raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
108 }
109 
110 static void imx2_wdt_timer_ping(unsigned long arg)
111 {
112 	/* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
113 	imx2_wdt_ping();
114 	mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
115 }
116 
117 static void imx2_wdt_start(void)
118 {
119 	if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
120 		/* at our first start we enable clock and do initialisations */
121 		clk_enable(imx2_wdt.clk);
122 
123 		imx2_wdt_setup();
124 	} else	/* delete the timer that pings the watchdog after close */
125 		del_timer_sync(&imx2_wdt.timer);
126 
127 	/* Watchdog is enabled - time to reload the timeout value */
128 	imx2_wdt_ping();
129 }
130 
131 static void imx2_wdt_stop(void)
132 {
133 	/* we don't need a clk_disable, it cannot be disabled once started.
134 	 * We use a timer to ping the watchdog while /dev/watchdog is closed */
135 	imx2_wdt_timer_ping(0);
136 }
137 
138 static void imx2_wdt_set_timeout(int new_timeout)
139 {
140 	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
141 
142 	/* set the new timeout value in the WSR */
143 	val &= ~IMX2_WDT_WCR_WT;
144 	val |= WDOG_SEC_TO_COUNT(new_timeout);
145 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
146 }
147 
148 static int imx2_wdt_open(struct inode *inode, struct file *file)
149 {
150 	if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
151 		return -EBUSY;
152 
153 	imx2_wdt_start();
154 	return nonseekable_open(inode, file);
155 }
156 
157 static int imx2_wdt_close(struct inode *inode, struct file *file)
158 {
159 	if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
160 		imx2_wdt_stop();
161 	else {
162 		dev_crit(imx2_wdt_miscdev.parent,
163 			"Unexpected close: Expect reboot!\n");
164 		imx2_wdt_ping();
165 	}
166 
167 	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
168 	clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
169 	return 0;
170 }
171 
172 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
173 							unsigned long arg)
174 {
175 	void __user *argp = (void __user *)arg;
176 	int __user *p = argp;
177 	int new_value;
178 
179 	switch (cmd) {
180 	case WDIOC_GETSUPPORT:
181 		return copy_to_user(argp, &imx2_wdt_info,
182 			sizeof(struct watchdog_info)) ? -EFAULT : 0;
183 
184 	case WDIOC_GETSTATUS:
185 	case WDIOC_GETBOOTSTATUS:
186 		return put_user(0, p);
187 
188 	case WDIOC_KEEPALIVE:
189 		imx2_wdt_ping();
190 		return 0;
191 
192 	case WDIOC_SETTIMEOUT:
193 		if (get_user(new_value, p))
194 			return -EFAULT;
195 		if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
196 			return -EINVAL;
197 		imx2_wdt_set_timeout(new_value);
198 		imx2_wdt.timeout = new_value;
199 		imx2_wdt_ping();
200 
201 		/* Fallthrough to return current value */
202 	case WDIOC_GETTIMEOUT:
203 		return put_user(imx2_wdt.timeout, p);
204 
205 	default:
206 		return -ENOTTY;
207 	}
208 }
209 
210 static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
211 						size_t len, loff_t *ppos)
212 {
213 	size_t i;
214 	char c;
215 
216 	if (len == 0)	/* Can we see this even ? */
217 		return 0;
218 
219 	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
220 	/* scan to see whether or not we got the magic character */
221 	for (i = 0; i != len; i++) {
222 		if (get_user(c, data + i))
223 			return -EFAULT;
224 		if (c == 'V')
225 			set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
226 	}
227 
228 	imx2_wdt_ping();
229 	return len;
230 }
231 
232 static const struct file_operations imx2_wdt_fops = {
233 	.owner = THIS_MODULE,
234 	.llseek = no_llseek,
235 	.unlocked_ioctl = imx2_wdt_ioctl,
236 	.open = imx2_wdt_open,
237 	.release = imx2_wdt_close,
238 	.write = imx2_wdt_write,
239 };
240 
241 static struct miscdevice imx2_wdt_miscdev = {
242 	.minor = WATCHDOG_MINOR,
243 	.name = "watchdog",
244 	.fops = &imx2_wdt_fops,
245 };
246 
247 static int __init imx2_wdt_probe(struct platform_device *pdev)
248 {
249 	int ret;
250 	int res_size;
251 	struct resource *res;
252 
253 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
254 	if (!res) {
255 		dev_err(&pdev->dev, "can't get device resources\n");
256 		return -ENODEV;
257 	}
258 
259 	res_size = resource_size(res);
260 	if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
261 		res->name)) {
262 		dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
263 			res_size, res->start);
264 		return -ENOMEM;
265 	}
266 
267 	imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size);
268 	if (!imx2_wdt.base) {
269 		dev_err(&pdev->dev, "ioremap failed\n");
270 		return -ENOMEM;
271 	}
272 
273 	imx2_wdt.clk = clk_get(&pdev->dev, NULL);
274 	if (IS_ERR(imx2_wdt.clk)) {
275 		dev_err(&pdev->dev, "can't get Watchdog clock\n");
276 		return PTR_ERR(imx2_wdt.clk);
277 	}
278 
279 	imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
280 	if (imx2_wdt.timeout != timeout)
281 		dev_warn(&pdev->dev, "Initial timeout out of range! "
282 			"Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
283 
284 	setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
285 
286 	imx2_wdt_miscdev.parent = &pdev->dev;
287 	ret = misc_register(&imx2_wdt_miscdev);
288 	if (ret)
289 		goto fail;
290 
291 	dev_info(&pdev->dev,
292 		"IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
293 						imx2_wdt.timeout, nowayout);
294 	return 0;
295 
296 fail:
297 	imx2_wdt_miscdev.parent = NULL;
298 	clk_put(imx2_wdt.clk);
299 	return ret;
300 }
301 
302 static int __exit imx2_wdt_remove(struct platform_device *pdev)
303 {
304 	misc_deregister(&imx2_wdt_miscdev);
305 
306 	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
307 		del_timer_sync(&imx2_wdt.timer);
308 
309 		dev_crit(imx2_wdt_miscdev.parent,
310 			"Device removed: Expect reboot!\n");
311 	} else
312 		clk_put(imx2_wdt.clk);
313 
314 	imx2_wdt_miscdev.parent = NULL;
315 	return 0;
316 }
317 
318 static void imx2_wdt_shutdown(struct platform_device *pdev)
319 {
320 	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
321 		/* we are running, we need to delete the timer but will give
322 		 * max timeout before reboot will take place */
323 		del_timer_sync(&imx2_wdt.timer);
324 		imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
325 		imx2_wdt_ping();
326 
327 		dev_crit(imx2_wdt_miscdev.parent,
328 			"Device shutdown: Expect reboot!\n");
329 	}
330 }
331 
332 static struct platform_driver imx2_wdt_driver = {
333 	.remove		= __exit_p(imx2_wdt_remove),
334 	.shutdown	= imx2_wdt_shutdown,
335 	.driver		= {
336 		.name	= DRIVER_NAME,
337 		.owner	= THIS_MODULE,
338 	},
339 };
340 
341 static int __init imx2_wdt_init(void)
342 {
343 	return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
344 }
345 module_init(imx2_wdt_init);
346 
347 static void __exit imx2_wdt_exit(void)
348 {
349 	platform_driver_unregister(&imx2_wdt_driver);
350 }
351 module_exit(imx2_wdt_exit);
352 
353 MODULE_AUTHOR("Wolfram Sang");
354 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
355 MODULE_LICENSE("GPL v2");
356 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
357 MODULE_ALIAS("platform:" DRIVER_NAME);
358