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Linux/drivers/watchdog/at91rm9200_wdt.c

  1 /*
  2  * Watchdog driver for Atmel AT91RM9200 (Thunder)
  3  *
  4  *  Copyright (C) 2003 SAN People (Pty) Ltd
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the License, or (at your option) any later version.
 10  */
 11 
 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 13 
 14 #include <linux/bitops.h>
 15 #include <linux/delay.h>
 16 #include <linux/errno.h>
 17 #include <linux/fs.h>
 18 #include <linux/init.h>
 19 #include <linux/io.h>
 20 #include <linux/kernel.h>
 21 #include <linux/mfd/syscon.h>
 22 #include <linux/mfd/syscon/atmel-st.h>
 23 #include <linux/miscdevice.h>
 24 #include <linux/module.h>
 25 #include <linux/moduleparam.h>
 26 #include <linux/platform_device.h>
 27 #include <linux/reboot.h>
 28 #include <linux/regmap.h>
 29 #include <linux/types.h>
 30 #include <linux/watchdog.h>
 31 #include <linux/uaccess.h>
 32 #include <linux/of.h>
 33 #include <linux/of_device.h>
 34 
 35 #define WDT_DEFAULT_TIME        5       /* seconds */
 36 #define WDT_MAX_TIME            256     /* seconds */
 37 
 38 static int wdt_time = WDT_DEFAULT_TIME;
 39 static bool nowayout = WATCHDOG_NOWAYOUT;
 40 static struct regmap *regmap_st;
 41 
 42 module_param(wdt_time, int, 0);
 43 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
 44                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
 45 
 46 #ifdef CONFIG_WATCHDOG_NOWAYOUT
 47 module_param(nowayout, bool, 0);
 48 MODULE_PARM_DESC(nowayout,
 49                 "Watchdog cannot be stopped once started (default="
 50                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 51 #endif
 52 
 53 
 54 static unsigned long at91wdt_busy;
 55 
 56 /* ......................................................................... */
 57 
 58 static int at91rm9200_restart(struct notifier_block *this,
 59                                         unsigned long mode, void *cmd)
 60 {
 61         /*
 62          * Perform a hardware reset with the use of the Watchdog timer.
 63          */
 64         regmap_write(regmap_st, AT91_ST_WDMR,
 65                      AT91_ST_RSTEN | AT91_ST_EXTEN | 1);
 66         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
 67 
 68         mdelay(2000);
 69 
 70         pr_emerg("Unable to restart system\n");
 71         return NOTIFY_DONE;
 72 }
 73 
 74 static struct notifier_block at91rm9200_restart_nb = {
 75         .notifier_call = at91rm9200_restart,
 76         .priority = 192,
 77 };
 78 
 79 /*
 80  * Disable the watchdog.
 81  */
 82 static inline void at91_wdt_stop(void)
 83 {
 84         regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN);
 85 }
 86 
 87 /*
 88  * Enable and reset the watchdog.
 89  */
 90 static inline void at91_wdt_start(void)
 91 {
 92         regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
 93                                 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
 94         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
 95 }
 96 
 97 /*
 98  * Reload the watchdog timer.  (ie, pat the watchdog)
 99  */
100 static inline void at91_wdt_reload(void)
101 {
102         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
103 }
104 
105 /* ......................................................................... */
106 
107 /*
108  * Watchdog device is opened, and watchdog starts running.
109  */
110 static int at91_wdt_open(struct inode *inode, struct file *file)
111 {
112         if (test_and_set_bit(0, &at91wdt_busy))
113                 return -EBUSY;
114 
115         at91_wdt_start();
116         return nonseekable_open(inode, file);
117 }
118 
119 /*
120  * Close the watchdog device.
121  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
122  *  disabled.
123  */
124 static int at91_wdt_close(struct inode *inode, struct file *file)
125 {
126         /* Disable the watchdog when file is closed */
127         if (!nowayout)
128                 at91_wdt_stop();
129 
130         clear_bit(0, &at91wdt_busy);
131         return 0;
132 }
133 
134 /*
135  * Change the watchdog time interval.
136  */
137 static int at91_wdt_settimeout(int new_time)
138 {
139         /*
140          * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
141          *
142          * Since WDV is a 16-bit counter, the maximum period is
143          * 65536 / 256 = 256 seconds.
144          */
145         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
146                 return -EINVAL;
147 
148         /* Set new watchdog time. It will be used when
149            at91_wdt_start() is called. */
150         wdt_time = new_time;
151         return 0;
152 }
153 
154 static const struct watchdog_info at91_wdt_info = {
155         .identity       = "at91 watchdog",
156         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
157 };
158 
159 /*
160  * Handle commands from user-space.
161  */
162 static long at91_wdt_ioctl(struct file *file,
163                                         unsigned int cmd, unsigned long arg)
164 {
165         void __user *argp = (void __user *)arg;
166         int __user *p = argp;
167         int new_value;
168 
169         switch (cmd) {
170         case WDIOC_GETSUPPORT:
171                 return copy_to_user(argp, &at91_wdt_info,
172                                 sizeof(at91_wdt_info)) ? -EFAULT : 0;
173         case WDIOC_GETSTATUS:
174         case WDIOC_GETBOOTSTATUS:
175                 return put_user(0, p);
176         case WDIOC_SETOPTIONS:
177                 if (get_user(new_value, p))
178                         return -EFAULT;
179                 if (new_value & WDIOS_DISABLECARD)
180                         at91_wdt_stop();
181                 if (new_value & WDIOS_ENABLECARD)
182                         at91_wdt_start();
183                 return 0;
184         case WDIOC_KEEPALIVE:
185                 at91_wdt_reload();      /* pat the watchdog */
186                 return 0;
187         case WDIOC_SETTIMEOUT:
188                 if (get_user(new_value, p))
189                         return -EFAULT;
190                 if (at91_wdt_settimeout(new_value))
191                         return -EINVAL;
192                 /* Enable new time value */
193                 at91_wdt_start();
194                 /* Return current value */
195                 return put_user(wdt_time, p);
196         case WDIOC_GETTIMEOUT:
197                 return put_user(wdt_time, p);
198         default:
199                 return -ENOTTY;
200         }
201 }
202 
203 /*
204  * Pat the watchdog whenever device is written to.
205  */
206 static ssize_t at91_wdt_write(struct file *file, const char *data,
207                                                 size_t len, loff_t *ppos)
208 {
209         at91_wdt_reload();              /* pat the watchdog */
210         return len;
211 }
212 
213 /* ......................................................................... */
214 
215 static const struct file_operations at91wdt_fops = {
216         .owner          = THIS_MODULE,
217         .llseek         = no_llseek,
218         .unlocked_ioctl = at91_wdt_ioctl,
219         .open           = at91_wdt_open,
220         .release        = at91_wdt_close,
221         .write          = at91_wdt_write,
222 };
223 
224 static struct miscdevice at91wdt_miscdev = {
225         .minor          = WATCHDOG_MINOR,
226         .name           = "watchdog",
227         .fops           = &at91wdt_fops,
228 };
229 
230 static int at91wdt_probe(struct platform_device *pdev)
231 {
232         struct device *dev = &pdev->dev;
233         struct device *parent;
234         int res;
235 
236         if (at91wdt_miscdev.parent)
237                 return -EBUSY;
238         at91wdt_miscdev.parent = &pdev->dev;
239 
240         parent = dev->parent;
241         if (!parent) {
242                 dev_err(dev, "no parent\n");
243                 return -ENODEV;
244         }
245 
246         regmap_st = syscon_node_to_regmap(parent->of_node);
247         if (!regmap_st)
248                 return -ENODEV;
249 
250         res = misc_register(&at91wdt_miscdev);
251         if (res)
252                 return res;
253 
254         res = register_restart_handler(&at91rm9200_restart_nb);
255         if (res)
256                 dev_warn(dev, "failed to register restart handler\n");
257 
258         pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
259                 wdt_time, nowayout ? ", nowayout" : "");
260         return 0;
261 }
262 
263 static int at91wdt_remove(struct platform_device *pdev)
264 {
265         struct device *dev = &pdev->dev;
266         int res;
267 
268         res = unregister_restart_handler(&at91rm9200_restart_nb);
269         if (res)
270                 dev_warn(dev, "failed to unregister restart handler\n");
271 
272         res = misc_deregister(&at91wdt_miscdev);
273         if (!res)
274                 at91wdt_miscdev.parent = NULL;
275 
276         return res;
277 }
278 
279 static void at91wdt_shutdown(struct platform_device *pdev)
280 {
281         at91_wdt_stop();
282 }
283 
284 #ifdef CONFIG_PM
285 
286 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
287 {
288         at91_wdt_stop();
289         return 0;
290 }
291 
292 static int at91wdt_resume(struct platform_device *pdev)
293 {
294         if (at91wdt_busy)
295                 at91_wdt_start();
296         return 0;
297 }
298 
299 #else
300 #define at91wdt_suspend NULL
301 #define at91wdt_resume  NULL
302 #endif
303 
304 static const struct of_device_id at91_wdt_dt_ids[] = {
305         { .compatible = "atmel,at91rm9200-wdt" },
306         { /* sentinel */ }
307 };
308 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
309 
310 static struct platform_driver at91wdt_driver = {
311         .probe          = at91wdt_probe,
312         .remove         = at91wdt_remove,
313         .shutdown       = at91wdt_shutdown,
314         .suspend        = at91wdt_suspend,
315         .resume         = at91wdt_resume,
316         .driver         = {
317                 .name   = "atmel_st_watchdog",
318                 .of_match_table = at91_wdt_dt_ids,
319         },
320 };
321 
322 static int __init at91_wdt_init(void)
323 {
324         /* Check that the heartbeat value is within range;
325            if not reset to the default */
326         if (at91_wdt_settimeout(wdt_time)) {
327                 at91_wdt_settimeout(WDT_DEFAULT_TIME);
328                 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
329                         wdt_time);
330         }
331 
332         return platform_driver_register(&at91wdt_driver);
333 }
334 
335 static void __exit at91_wdt_exit(void)
336 {
337         platform_driver_unregister(&at91wdt_driver);
338 }
339 
340 module_init(at91_wdt_init);
341 module_exit(at91_wdt_exit);
342 
343 MODULE_AUTHOR("Andrew Victor");
344 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
345 MODULE_LICENSE("GPL");
346 MODULE_ALIAS("platform:atmel_st_watchdog");
347 

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