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imx2_wdt.c
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1 /*
2  * Watchdog driver for IMX2 and later processors
3  *
4  * Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <[email protected]>
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="
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="
81 
82 static const struct watchdog_info imx2_wdt_info = {
83  .identity = "imx2+ watchdog",
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_prepare_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");
362 MODULE_ALIAS("platform:" DRIVER_NAME);