xref: /openbmc/linux/drivers/watchdog/imx2_wdt.c (revision 63dc02bd) 
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 
61 static 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 
69 static struct miscdevice imx2_wdt_miscdev;
70 
71 static bool nowayout = WATCHDOG_NOWAYOUT;
72 module_param(nowayout, bool, 0);
73 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
74 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
75 
76 
77 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
78 module_param(timeout, uint, 0);
79 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
80 				__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
81 
82 static const struct watchdog_info imx2_wdt_info = {
83 	.identity = "imx2+ watchdog",
84 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
85 };
86 
87 static 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 
107 static 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 
113 static 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 
120 static 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 
134 static 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 
141 static 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 
151 static 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 
160 static 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 
175 static 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 
218 static 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 
240 static 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 
249 static struct miscdevice imx2_wdt_miscdev = {
250 	.minor = WATCHDOG_MINOR,
251 	.name = "watchdog",
252 	.fops = &imx2_wdt_fops,
253 };
254 
255 static 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 
295 fail:
296 	imx2_wdt_miscdev.parent = NULL;
297 	clk_put(imx2_wdt.clk);
298 	return ret;
299 }
300 
301 static 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 
317 static 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 
331 static const struct of_device_id imx2_wdt_dt_ids[] = {
332 	{ .compatible = "fsl,imx21-wdt", },
333 	{ /* sentinel */ }
334 };
335 
336 static 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 
346 static int __init imx2_wdt_init(void)
347 {
348 	return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
349 }
350 module_init(imx2_wdt_init);
351 
352 static void __exit imx2_wdt_exit(void)
353 {
354 	platform_driver_unregister(&imx2_wdt_driver);
355 }
356 module_exit(imx2_wdt_exit);
357 
358 MODULE_AUTHOR("Wolfram Sang");
359 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
360 MODULE_LICENSE("GPL v2");
361 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
362 MODULE_ALIAS("platform:" DRIVER_NAME);
363