2 * Watchdog driver for IMX2 and later processors
4 * Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
6 * some parts adapted by similar drivers from Darius Augulis and Vladimir
7 * Zapolskiy, additional improvements by Wim Van Sebroeck.
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.
13 * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
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
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>
33 #include <linux/uaccess.h>
34 #include <linux/timer.h>
35 #include <linux/jiffies.h>
36 #include <mach/hardware.h>
38 #define DRIVER_NAME "imx2-wdt"
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 */
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 */
49 #define IMX2_WDT_MAX_TIME 128
50 #define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */
52 #define WDOG_SEC_TO_COUNT(s) ((s * 2 - 1) << 8)
54 #define IMX2_WDT_STATUS_OPEN 0
55 #define IMX2_WDT_STATUS_STARTED 1
56 #define IMX2_WDT_EXPECT_CLOSE 2
63 struct timer_list timer; /* Pings the watchdog when closed */
66 static struct miscdevice imx2_wdt_miscdev;
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) ")");
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) ")");
79 static const struct watchdog_info imx2_wdt_info = {
80 .identity = "imx2+ watchdog",
81 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
84 static inline void imx2_wdt_setup(void)
86 u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
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);
97 __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
99 /* enable the watchdog */
100 val |= IMX2_WDT_WCR_WDE;
101 __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
104 static inline void imx2_wdt_ping(void)
106 __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
107 __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
110 static void imx2_wdt_timer_ping(unsigned long arg)
112 /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
114 mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
117 static void imx2_wdt_start(void)
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);
124 } else /* delete the timer that pings the watchdog after close */
125 del_timer_sync(&imx2_wdt.timer);
127 /* Watchdog is enabled - time to reload the timeout value */
131 static void imx2_wdt_stop(void)
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);
138 static void imx2_wdt_set_timeout(int new_timeout)
140 u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
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);
148 static int imx2_wdt_open(struct inode *inode, struct file *file)
150 if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
154 return nonseekable_open(inode, file);
157 static int imx2_wdt_close(struct inode *inode, struct file *file)
159 if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
162 dev_crit(imx2_wdt_miscdev.parent,
163 "Unexpected close: Expect reboot!\n");
167 clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
168 clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
172 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
175 void __user *argp = (void __user *)arg;
176 int __user *p = argp;
180 case WDIOC_GETSUPPORT:
181 return copy_to_user(argp, &imx2_wdt_info,
182 sizeof(struct watchdog_info)) ? -EFAULT : 0;
184 case WDIOC_GETSTATUS:
185 case WDIOC_GETBOOTSTATUS:
186 return put_user(0, p);
188 case WDIOC_KEEPALIVE:
192 case WDIOC_SETTIMEOUT:
193 if (get_user(new_value, p))
195 if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
197 imx2_wdt_set_timeout(new_value);
198 imx2_wdt.timeout = new_value;
201 /* Fallthrough to return current value */
202 case WDIOC_GETTIMEOUT:
203 return put_user(imx2_wdt.timeout, p);
210 static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
211 size_t len, loff_t *ppos)
216 if (len == 0) /* Can we see this even ? */
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))
225 set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
232 static const struct file_operations imx2_wdt_fops = {
233 .owner = THIS_MODULE,
235 .unlocked_ioctl = imx2_wdt_ioctl,
236 .open = imx2_wdt_open,
237 .release = imx2_wdt_close,
238 .write = imx2_wdt_write,
241 static struct miscdevice imx2_wdt_miscdev = {
242 .minor = WATCHDOG_MINOR,
244 .fops = &imx2_wdt_fops,
247 static int __init imx2_wdt_probe(struct platform_device *pdev)
251 struct resource *res;
253 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
255 dev_err(&pdev->dev, "can't get device resources\n");
259 res_size = resource_size(res);
260 if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
262 dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
263 res_size, res->start);
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");
273 imx2_wdt.clk = clk_get_sys("imx-wdt.0", 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);
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);
284 setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
286 imx2_wdt_miscdev.parent = &pdev->dev;
287 ret = misc_register(&imx2_wdt_miscdev);
292 "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
293 imx2_wdt.timeout, nowayout);
297 imx2_wdt_miscdev.parent = NULL;
298 clk_put(imx2_wdt.clk);
302 static int __exit imx2_wdt_remove(struct platform_device *pdev)
304 misc_deregister(&imx2_wdt_miscdev);
306 if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
307 del_timer_sync(&imx2_wdt.timer);
309 dev_crit(imx2_wdt_miscdev.parent,
310 "Device removed: Expect reboot!\n");
312 clk_put(imx2_wdt.clk);
314 imx2_wdt_miscdev.parent = NULL;
318 static void imx2_wdt_shutdown(struct platform_device *pdev)
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);
327 dev_crit(imx2_wdt_miscdev.parent,
328 "Device shutdown: Expect reboot!\n");
332 static struct platform_driver imx2_wdt_driver = {
333 .remove = __exit_p(imx2_wdt_remove),
334 .shutdown = imx2_wdt_shutdown,
337 .owner = THIS_MODULE,
341 static int __init imx2_wdt_init(void)
343 return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
345 module_init(imx2_wdt_init);
347 static void __exit imx2_wdt_exit(void)
349 platform_driver_unregister(&imx2_wdt_driver);
351 module_exit(imx2_wdt_exit);
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);