xref: /openbmc/linux/drivers/watchdog/imx2_wdt.c (revision b6bec26c) 
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 
37 #define DRIVER_NAME "imx2-wdt"
38 
39 #define IMX2_WDT_WCR		0x00		/* Control Register */
40 #define IMX2_WDT_WCR_WT		(0xFF << 8)	/* -> Watchdog Timeout Field */
41 #define IMX2_WDT_WCR_WRE	(1 << 3)	/* -> WDOG Reset Enable */
42 #define IMX2_WDT_WCR_WDE	(1 << 2)	/* -> Watchdog Enable */
43 
44 #define IMX2_WDT_WSR		0x02		/* Service Register */
45 #define IMX2_WDT_SEQ1		0x5555		/* -> service sequence 1 */
46 #define IMX2_WDT_SEQ2		0xAAAA		/* -> service sequence 2 */
47 
48 #define IMX2_WDT_WRSR		0x04		/* Reset Status Register */
49 #define IMX2_WDT_WRSR_TOUT	(1 << 1)	/* -> Reset due to Timeout */
50 
51 #define IMX2_WDT_MAX_TIME	128
52 #define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */
53 
54 #define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)
55 
56 #define IMX2_WDT_STATUS_OPEN	0
57 #define IMX2_WDT_STATUS_STARTED	1
58 #define IMX2_WDT_EXPECT_CLOSE	2
59 
60 static struct {
61 	struct clk *clk;
62 	void __iomem *base;
63 	unsigned timeout;
64 	unsigned long status;
65 	struct timer_list timer;	/* Pings the watchdog when closed */
66 } imx2_wdt;
67 
68 static struct miscdevice imx2_wdt_miscdev;
69 
70 static bool nowayout = WATCHDOG_NOWAYOUT;
71 module_param(nowayout, bool, 0);
72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
73 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
74 
75 
76 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
77 module_param(timeout, uint, 0);
78 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
79 				__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
80 
81 static const struct watchdog_info imx2_wdt_info = {
82 	.identity = "imx2+ watchdog",
83 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
84 };
85 
86 static inline void imx2_wdt_setup(void)
87 {
88 	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
89 
90 	/* Strip the old watchdog Time-Out value */
91 	val &= ~IMX2_WDT_WCR_WT;
92 	/* Generate reset if WDOG times out */
93 	val &= ~IMX2_WDT_WCR_WRE;
94 	/* Keep Watchdog Disabled */
95 	val &= ~IMX2_WDT_WCR_WDE;
96 	/* Set the watchdog's Time-Out value */
97 	val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
98 
99 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
100 
101 	/* enable the watchdog */
102 	val |= IMX2_WDT_WCR_WDE;
103 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
104 }
105 
106 static inline void imx2_wdt_ping(void)
107 {
108 	__raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
109 	__raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
110 }
111 
112 static void imx2_wdt_timer_ping(unsigned long arg)
113 {
114 	/* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
115 	imx2_wdt_ping();
116 	mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
117 }
118 
119 static void imx2_wdt_start(void)
120 {
121 	if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
122 		/* at our first start we enable clock and do initialisations */
123 		clk_prepare_enable(imx2_wdt.clk);
124 
125 		imx2_wdt_setup();
126 	} else	/* delete the timer that pings the watchdog after close */
127 		del_timer_sync(&imx2_wdt.timer);
128 
129 	/* Watchdog is enabled - time to reload the timeout value */
130 	imx2_wdt_ping();
131 }
132 
133 static void imx2_wdt_stop(void)
134 {
135 	/* we don't need a clk_disable, it cannot be disabled once started.
136 	 * We use a timer to ping the watchdog while /dev/watchdog is closed */
137 	imx2_wdt_timer_ping(0);
138 }
139 
140 static void imx2_wdt_set_timeout(int new_timeout)
141 {
142 	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
143 
144 	/* set the new timeout value in the WSR */
145 	val &= ~IMX2_WDT_WCR_WT;
146 	val |= WDOG_SEC_TO_COUNT(new_timeout);
147 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
148 }
149 
150 static int imx2_wdt_open(struct inode *inode, struct file *file)
151 {
152 	if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
153 		return -EBUSY;
154 
155 	imx2_wdt_start();
156 	return nonseekable_open(inode, file);
157 }
158 
159 static int imx2_wdt_close(struct inode *inode, struct file *file)
160 {
161 	if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
162 		imx2_wdt_stop();
163 	else {
164 		dev_crit(imx2_wdt_miscdev.parent,
165 			"Unexpected close: Expect reboot!\n");
166 		imx2_wdt_ping();
167 	}
168 
169 	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
170 	clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
171 	return 0;
172 }
173 
174 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
175 							unsigned long arg)
176 {
177 	void __user *argp = (void __user *)arg;
178 	int __user *p = argp;
179 	int new_value;
180 	u16 val;
181 
182 	switch (cmd) {
183 	case WDIOC_GETSUPPORT:
184 		return copy_to_user(argp, &imx2_wdt_info,
185 			sizeof(struct watchdog_info)) ? -EFAULT : 0;
186 
187 	case WDIOC_GETSTATUS:
188 		return put_user(0, p);
189 
190 	case WDIOC_GETBOOTSTATUS:
191 		val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
192 		new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
193 		return put_user(new_value, p);
194 
195 	case WDIOC_KEEPALIVE:
196 		imx2_wdt_ping();
197 		return 0;
198 
199 	case WDIOC_SETTIMEOUT:
200 		if (get_user(new_value, p))
201 			return -EFAULT;
202 		if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
203 			return -EINVAL;
204 		imx2_wdt_set_timeout(new_value);
205 		imx2_wdt.timeout = new_value;
206 		imx2_wdt_ping();
207 
208 		/* Fallthrough to return current value */
209 	case WDIOC_GETTIMEOUT:
210 		return put_user(imx2_wdt.timeout, p);
211 
212 	default:
213 		return -ENOTTY;
214 	}
215 }
216 
217 static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
218 						size_t len, loff_t *ppos)
219 {
220 	size_t i;
221 	char c;
222 
223 	if (len == 0)	/* Can we see this even ? */
224 		return 0;
225 
226 	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
227 	/* scan to see whether or not we got the magic character */
228 	for (i = 0; i != len; i++) {
229 		if (get_user(c, data + i))
230 			return -EFAULT;
231 		if (c == 'V')
232 			set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
233 	}
234 
235 	imx2_wdt_ping();
236 	return len;
237 }
238 
239 static const struct file_operations imx2_wdt_fops = {
240 	.owner = THIS_MODULE,
241 	.llseek = no_llseek,
242 	.unlocked_ioctl = imx2_wdt_ioctl,
243 	.open = imx2_wdt_open,
244 	.release = imx2_wdt_close,
245 	.write = imx2_wdt_write,
246 };
247 
248 static struct miscdevice imx2_wdt_miscdev = {
249 	.minor = WATCHDOG_MINOR,
250 	.name = "watchdog",
251 	.fops = &imx2_wdt_fops,
252 };
253 
254 static int __init imx2_wdt_probe(struct platform_device *pdev)
255 {
256 	int ret;
257 	struct resource *res;
258 
259 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
260 	if (!res) {
261 		dev_err(&pdev->dev, "can't get device resources\n");
262 		return -ENODEV;
263 	}
264 
265 	imx2_wdt.base = devm_request_and_ioremap(&pdev->dev, res);
266 	if (!imx2_wdt.base) {
267 		dev_err(&pdev->dev, "ioremap failed\n");
268 		return -ENOMEM;
269 	}
270 
271 	imx2_wdt.clk = clk_get(&pdev->dev, NULL);
272 	if (IS_ERR(imx2_wdt.clk)) {
273 		dev_err(&pdev->dev, "can't get Watchdog clock\n");
274 		return PTR_ERR(imx2_wdt.clk);
275 	}
276 
277 	imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
278 	if (imx2_wdt.timeout != timeout)
279 		dev_warn(&pdev->dev, "Initial timeout out of range! "
280 			"Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
281 
282 	setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
283 
284 	imx2_wdt_miscdev.parent = &pdev->dev;
285 	ret = misc_register(&imx2_wdt_miscdev);
286 	if (ret)
287 		goto fail;
288 
289 	dev_info(&pdev->dev,
290 		"IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
291 						imx2_wdt.timeout, nowayout);
292 	return 0;
293 
294 fail:
295 	imx2_wdt_miscdev.parent = NULL;
296 	clk_put(imx2_wdt.clk);
297 	return ret;
298 }
299 
300 static int __exit imx2_wdt_remove(struct platform_device *pdev)
301 {
302 	misc_deregister(&imx2_wdt_miscdev);
303 
304 	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
305 		del_timer_sync(&imx2_wdt.timer);
306 
307 		dev_crit(imx2_wdt_miscdev.parent,
308 			"Device removed: Expect reboot!\n");
309 	} else
310 		clk_put(imx2_wdt.clk);
311 
312 	imx2_wdt_miscdev.parent = NULL;
313 	return 0;
314 }
315 
316 static void imx2_wdt_shutdown(struct platform_device *pdev)
317 {
318 	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
319 		/* we are running, we need to delete the timer but will give
320 		 * max timeout before reboot will take place */
321 		del_timer_sync(&imx2_wdt.timer);
322 		imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
323 		imx2_wdt_ping();
324 
325 		dev_crit(imx2_wdt_miscdev.parent,
326 			"Device shutdown: Expect reboot!\n");
327 	}
328 }
329 
330 static const struct of_device_id imx2_wdt_dt_ids[] = {
331 	{ .compatible = "fsl,imx21-wdt", },
332 	{ /* sentinel */ }
333 };
334 
335 static struct platform_driver imx2_wdt_driver = {
336 	.remove		= __exit_p(imx2_wdt_remove),
337 	.shutdown	= imx2_wdt_shutdown,
338 	.driver		= {
339 		.name	= DRIVER_NAME,
340 		.owner	= THIS_MODULE,
341 		.of_match_table = imx2_wdt_dt_ids,
342 	},
343 };
344 
345 static int __init imx2_wdt_init(void)
346 {
347 	return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
348 }
349 module_init(imx2_wdt_init);
350 
351 static void __exit imx2_wdt_exit(void)
352 {
353 	platform_driver_unregister(&imx2_wdt_driver);
354 }
355 module_exit(imx2_wdt_exit);
356 
357 MODULE_AUTHOR("Wolfram Sang");
358 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
359 MODULE_LICENSE("GPL v2");
360 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
361 MODULE_ALIAS("platform:" DRIVER_NAME);
362