xref: /openbmc/linux/drivers/watchdog/imx2_wdt.c (revision 37be287c) 
1 /*
2  * Watchdog driver for IMX2 and later processors
3  *
4  *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
5  *  Copyright (C) 2014 Freescale Semiconductor, Inc.
6  *
7  * some parts adapted by similar drivers from Darius Augulis and Vladimir
8  * Zapolskiy, additional improvements by Wim Van Sebroeck.
9  *
10  * This program is free software; you can redistribute it and/or modify it
11  * under the terms of the GNU General Public License version 2 as published by
12  * the Free Software Foundation.
13  *
14  * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
15  *
16  *			MX1:		MX2+:
17  *			----		-----
18  * Registers:		32-bit		16-bit
19  * Stopable timer:	Yes		No
20  * Need to enable clk:	No		Yes
21  * Halt on suspend:	Manual		Can be automatic
22  */
23 
24 #include <linux/init.h>
25 #include <linux/kernel.h>
26 #include <linux/miscdevice.h>
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/platform_device.h>
30 #include <linux/watchdog.h>
31 #include <linux/clk.h>
32 #include <linux/fs.h>
33 #include <linux/io.h>
34 #include <linux/uaccess.h>
35 #include <linux/timer.h>
36 #include <linux/jiffies.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 #define IMX2_WDT_WCR_WDZST	(1 << 0)	/* -> Watchdog timer Suspend */
45 
46 #define IMX2_WDT_WSR		0x02		/* Service Register */
47 #define IMX2_WDT_SEQ1		0x5555		/* -> service sequence 1 */
48 #define IMX2_WDT_SEQ2		0xAAAA		/* -> service sequence 2 */
49 
50 #define IMX2_WDT_WRSR		0x04		/* Reset Status Register */
51 #define IMX2_WDT_WRSR_TOUT	(1 << 1)	/* -> Reset due to Timeout */
52 
53 #define IMX2_WDT_MAX_TIME	128
54 #define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */
55 
56 #define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)
57 
58 #define IMX2_WDT_STATUS_OPEN	0
59 #define IMX2_WDT_STATUS_STARTED	1
60 #define IMX2_WDT_EXPECT_CLOSE	2
61 
62 static struct {
63 	struct clk *clk;
64 	void __iomem *base;
65 	unsigned timeout;
66 	unsigned long status;
67 	struct timer_list timer;	/* Pings the watchdog when closed */
68 } imx2_wdt;
69 
70 static struct miscdevice imx2_wdt_miscdev;
71 
72 static bool nowayout = WATCHDOG_NOWAYOUT;
73 module_param(nowayout, bool, 0);
74 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
75 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
76 
77 
78 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
79 module_param(timeout, uint, 0);
80 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
81 				__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
82 
83 static const struct watchdog_info imx2_wdt_info = {
84 	.identity = "imx2+ watchdog",
85 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
86 };
87 
88 static inline void imx2_wdt_setup(void)
89 {
90 	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
91 
92 	/* Suspend timer in low power mode, write once-only */
93 	val |= IMX2_WDT_WCR_WDZST;
94 	/* Strip the old watchdog Time-Out value */
95 	val &= ~IMX2_WDT_WCR_WT;
96 	/* Generate reset if WDOG times out */
97 	val &= ~IMX2_WDT_WCR_WRE;
98 	/* Keep Watchdog Disabled */
99 	val &= ~IMX2_WDT_WCR_WDE;
100 	/* Set the watchdog's Time-Out value */
101 	val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
102 
103 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
104 
105 	/* enable the watchdog */
106 	val |= IMX2_WDT_WCR_WDE;
107 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
108 }
109 
110 static inline void imx2_wdt_ping(void)
111 {
112 	__raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
113 	__raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
114 }
115 
116 static void imx2_wdt_timer_ping(unsigned long arg)
117 {
118 	/* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
119 	imx2_wdt_ping();
120 	mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
121 }
122 
123 static void imx2_wdt_start(void)
124 {
125 	if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
126 		/* at our first start we enable clock and do initialisations */
127 		clk_prepare_enable(imx2_wdt.clk);
128 
129 		imx2_wdt_setup();
130 	} else	/* delete the timer that pings the watchdog after close */
131 		del_timer_sync(&imx2_wdt.timer);
132 
133 	/* Watchdog is enabled - time to reload the timeout value */
134 	imx2_wdt_ping();
135 }
136 
137 static void imx2_wdt_stop(void)
138 {
139 	/* we don't need a clk_disable, it cannot be disabled once started.
140 	 * We use a timer to ping the watchdog while /dev/watchdog is closed */
141 	imx2_wdt_timer_ping(0);
142 }
143 
144 static void imx2_wdt_set_timeout(int new_timeout)
145 {
146 	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
147 
148 	/* set the new timeout value in the WSR */
149 	val &= ~IMX2_WDT_WCR_WT;
150 	val |= WDOG_SEC_TO_COUNT(new_timeout);
151 	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
152 }
153 
154 static int imx2_wdt_open(struct inode *inode, struct file *file)
155 {
156 	if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
157 		return -EBUSY;
158 
159 	imx2_wdt_start();
160 	return nonseekable_open(inode, file);
161 }
162 
163 static int imx2_wdt_close(struct inode *inode, struct file *file)
164 {
165 	if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
166 		imx2_wdt_stop();
167 	else {
168 		dev_crit(imx2_wdt_miscdev.parent,
169 			"Unexpected close: Expect reboot!\n");
170 		imx2_wdt_ping();
171 	}
172 
173 	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
174 	clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
175 	return 0;
176 }
177 
178 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
179 							unsigned long arg)
180 {
181 	void __user *argp = (void __user *)arg;
182 	int __user *p = argp;
183 	int new_value;
184 	u16 val;
185 
186 	switch (cmd) {
187 	case WDIOC_GETSUPPORT:
188 		return copy_to_user(argp, &imx2_wdt_info,
189 			sizeof(struct watchdog_info)) ? -EFAULT : 0;
190 
191 	case WDIOC_GETSTATUS:
192 		return put_user(0, p);
193 
194 	case WDIOC_GETBOOTSTATUS:
195 		val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
196 		new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
197 		return put_user(new_value, p);
198 
199 	case WDIOC_KEEPALIVE:
200 		imx2_wdt_ping();
201 		return 0;
202 
203 	case WDIOC_SETTIMEOUT:
204 		if (get_user(new_value, p))
205 			return -EFAULT;
206 		if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
207 			return -EINVAL;
208 		imx2_wdt_set_timeout(new_value);
209 		imx2_wdt.timeout = new_value;
210 		imx2_wdt_ping();
211 
212 		/* Fallthrough to return current value */
213 	case WDIOC_GETTIMEOUT:
214 		return put_user(imx2_wdt.timeout, p);
215 
216 	default:
217 		return -ENOTTY;
218 	}
219 }
220 
221 static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
222 						size_t len, loff_t *ppos)
223 {
224 	size_t i;
225 	char c;
226 
227 	if (len == 0)	/* Can we see this even ? */
228 		return 0;
229 
230 	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
231 	/* scan to see whether or not we got the magic character */
232 	for (i = 0; i != len; i++) {
233 		if (get_user(c, data + i))
234 			return -EFAULT;
235 		if (c == 'V')
236 			set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
237 	}
238 
239 	imx2_wdt_ping();
240 	return len;
241 }
242 
243 static const struct file_operations imx2_wdt_fops = {
244 	.owner = THIS_MODULE,
245 	.llseek = no_llseek,
246 	.unlocked_ioctl = imx2_wdt_ioctl,
247 	.open = imx2_wdt_open,
248 	.release = imx2_wdt_close,
249 	.write = imx2_wdt_write,
250 };
251 
252 static struct miscdevice imx2_wdt_miscdev = {
253 	.minor = WATCHDOG_MINOR,
254 	.name = "watchdog",
255 	.fops = &imx2_wdt_fops,
256 };
257 
258 static int __init imx2_wdt_probe(struct platform_device *pdev)
259 {
260 	int ret;
261 	struct resource *res;
262 
263 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
264 	imx2_wdt.base = devm_ioremap_resource(&pdev->dev, res);
265 	if (IS_ERR(imx2_wdt.base))
266 		return PTR_ERR(imx2_wdt.base);
267 
268 	imx2_wdt.clk = devm_clk_get(&pdev->dev, NULL);
269 	if (IS_ERR(imx2_wdt.clk)) {
270 		dev_err(&pdev->dev, "can't get Watchdog clock\n");
271 		return PTR_ERR(imx2_wdt.clk);
272 	}
273 
274 	imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
275 	if (imx2_wdt.timeout != timeout)
276 		dev_warn(&pdev->dev, "Initial timeout out of range! "
277 			"Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
278 
279 	setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
280 
281 	imx2_wdt_miscdev.parent = &pdev->dev;
282 	ret = misc_register(&imx2_wdt_miscdev);
283 	if (ret)
284 		goto fail;
285 
286 	dev_info(&pdev->dev,
287 		"IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
288 						imx2_wdt.timeout, nowayout);
289 	return 0;
290 
291 fail:
292 	imx2_wdt_miscdev.parent = NULL;
293 	return ret;
294 }
295 
296 static int __exit imx2_wdt_remove(struct platform_device *pdev)
297 {
298 	misc_deregister(&imx2_wdt_miscdev);
299 
300 	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
301 		del_timer_sync(&imx2_wdt.timer);
302 
303 		dev_crit(imx2_wdt_miscdev.parent,
304 			"Device removed: Expect reboot!\n");
305 	}
306 
307 	imx2_wdt_miscdev.parent = NULL;
308 	return 0;
309 }
310 
311 static void imx2_wdt_shutdown(struct platform_device *pdev)
312 {
313 	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
314 		/* we are running, we need to delete the timer but will give
315 		 * max timeout before reboot will take place */
316 		del_timer_sync(&imx2_wdt.timer);
317 		imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
318 		imx2_wdt_ping();
319 
320 		dev_crit(imx2_wdt_miscdev.parent,
321 			"Device shutdown: Expect reboot!\n");
322 	}
323 }
324 
325 static const struct of_device_id imx2_wdt_dt_ids[] = {
326 	{ .compatible = "fsl,imx21-wdt", },
327 	{ /* sentinel */ }
328 };
329 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
330 
331 static struct platform_driver imx2_wdt_driver = {
332 	.remove		= __exit_p(imx2_wdt_remove),
333 	.shutdown	= imx2_wdt_shutdown,
334 	.driver		= {
335 		.name	= DRIVER_NAME,
336 		.owner	= THIS_MODULE,
337 		.of_match_table = imx2_wdt_dt_ids,
338 	},
339 };
340 
341 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
342 
343 MODULE_AUTHOR("Wolfram Sang");
344 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
345 MODULE_LICENSE("GPL v2");
346 MODULE_ALIAS("platform:" DRIVER_NAME);
347