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
imx2_wdt_setup(void)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
imx2_wdt_ping(void)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
imx2_wdt_timer_ping(unsigned long arg)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
imx2_wdt_start(void)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
imx2_wdt_stop(void)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
imx2_wdt_set_timeout(int new_timeout)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
imx2_wdt_open(struct inode * inode,struct file * file)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
imx2_wdt_close(struct inode * inode,struct file * file)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
imx2_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
imx2_wdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)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
imx2_wdt_probe(struct platform_device * pdev)247 static int __init imx2_wdt_probe(struct platform_device *pdev)
248 {
249 int ret;
250 struct resource *res;
251
252 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
253 if (!res) {
254 dev_err(&pdev->dev, "can't get device resources\n");
255 return -ENODEV;
256 }
257
258 imx2_wdt.base = devm_request_and_ioremap(&pdev->dev, res);
259 if (!imx2_wdt.base) {
260 dev_err(&pdev->dev, "ioremap failed\n");
261 return -ENOMEM;
262 }
263
264 imx2_wdt.clk = clk_get(&pdev->dev, NULL);
265 if (IS_ERR(imx2_wdt.clk)) {
266 dev_err(&pdev->dev, "can't get Watchdog clock\n");
267 return PTR_ERR(imx2_wdt.clk);
268 }
269
270 imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
271 if (imx2_wdt.timeout != timeout)
272 dev_warn(&pdev->dev, "Initial timeout out of range! "
273 "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
274
275 setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
276
277 imx2_wdt_miscdev.parent = &pdev->dev;
278 ret = misc_register(&imx2_wdt_miscdev);
279 if (ret)
280 goto fail;
281
282 dev_info(&pdev->dev,
283 "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
284 imx2_wdt.timeout, nowayout);
285 return 0;
286
287 fail:
288 imx2_wdt_miscdev.parent = NULL;
289 clk_put(imx2_wdt.clk);
290 return ret;
291 }
292
imx2_wdt_remove(struct platform_device * pdev)293 static int __exit imx2_wdt_remove(struct platform_device *pdev)
294 {
295 misc_deregister(&imx2_wdt_miscdev);
296
297 if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
298 del_timer_sync(&imx2_wdt.timer);
299
300 dev_crit(imx2_wdt_miscdev.parent,
301 "Device removed: Expect reboot!\n");
302 } else
303 clk_put(imx2_wdt.clk);
304
305 imx2_wdt_miscdev.parent = NULL;
306 return 0;
307 }
308
imx2_wdt_shutdown(struct platform_device * pdev)309 static void imx2_wdt_shutdown(struct platform_device *pdev)
310 {
311 if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
312 /* we are running, we need to delete the timer but will give
313 * max timeout before reboot will take place */
314 del_timer_sync(&imx2_wdt.timer);
315 imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
316 imx2_wdt_ping();
317
318 dev_crit(imx2_wdt_miscdev.parent,
319 "Device shutdown: Expect reboot!\n");
320 }
321 }
322
323 static const struct of_device_id imx2_wdt_dt_ids[] = {
324 { .compatible = "fsl,imx21-wdt", },
325 { /* sentinel */ }
326 };
327
328 static struct platform_driver imx2_wdt_driver = {
329 .remove = __exit_p(imx2_wdt_remove),
330 .shutdown = imx2_wdt_shutdown,
331 .driver = {
332 .name = DRIVER_NAME,
333 .owner = THIS_MODULE,
334 .of_match_table = imx2_wdt_dt_ids,
335 },
336 };
337
imx2_wdt_init(void)338 static int __init imx2_wdt_init(void)
339 {
340 return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
341 }
342 module_init(imx2_wdt_init);
343
imx2_wdt_exit(void)344 static void __exit imx2_wdt_exit(void)
345 {
346 platform_driver_unregister(&imx2_wdt_driver);
347 }
348 module_exit(imx2_wdt_exit);
349
350 MODULE_AUTHOR("Wolfram Sang");
351 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
352 MODULE_LICENSE("GPL v2");
353 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
354 MODULE_ALIAS("platform:" DRIVER_NAME);
355