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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/errno.h>
 16 #include <linux/fs.h>
 17 #include <linux/init.h>
 18 #include <linux/io.h>
 19 #include <linux/kernel.h>
 20 #include <linux/miscdevice.h>
 21 #include <linux/module.h>
 22 #include <linux/moduleparam.h>
 23 #include <linux/platform_device.h>
 24 #include <linux/types.h>
 25 #include <linux/watchdog.h>
 26 #include <linux/uaccess.h>
 27 #include <linux/of.h>
 28 #include <linux/of_device.h>
 29 #include <mach/at91_st.h>
 30 
 31 #define WDT_DEFAULT_TIME        5       /* seconds */
 32 #define WDT_MAX_TIME            256     /* seconds */
 33 
 34 static int wdt_time = WDT_DEFAULT_TIME;
 35 static bool nowayout = WATCHDOG_NOWAYOUT;
 36 
 37 module_param(wdt_time, int, 0);
 38 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
 39                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
 40 
 41 #ifdef CONFIG_WATCHDOG_NOWAYOUT
 42 module_param(nowayout, bool, 0);
 43 MODULE_PARM_DESC(nowayout,
 44                 "Watchdog cannot be stopped once started (default="
 45                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 46 #endif
 47 
 48 
 49 static unsigned long at91wdt_busy;
 50 
 51 /* ......................................................................... */
 52 
 53 /*
 54  * Disable the watchdog.
 55  */
 56 static inline void at91_wdt_stop(void)
 57 {
 58         at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN);
 59 }
 60 
 61 /*
 62  * Enable and reset the watchdog.
 63  */
 64 static inline void at91_wdt_start(void)
 65 {
 66         at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
 67                                 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
 68         at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
 69 }
 70 
 71 /*
 72  * Reload the watchdog timer.  (ie, pat the watchdog)
 73  */
 74 static inline void at91_wdt_reload(void)
 75 {
 76         at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
 77 }
 78 
 79 /* ......................................................................... */
 80 
 81 /*
 82  * Watchdog device is opened, and watchdog starts running.
 83  */
 84 static int at91_wdt_open(struct inode *inode, struct file *file)
 85 {
 86         if (test_and_set_bit(0, &at91wdt_busy))
 87                 return -EBUSY;
 88 
 89         at91_wdt_start();
 90         return nonseekable_open(inode, file);
 91 }
 92 
 93 /*
 94  * Close the watchdog device.
 95  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
 96  *  disabled.
 97  */
 98 static int at91_wdt_close(struct inode *inode, struct file *file)
 99 {
100         /* Disable the watchdog when file is closed */
101         if (!nowayout)
102                 at91_wdt_stop();
103 
104         clear_bit(0, &at91wdt_busy);
105         return 0;
106 }
107 
108 /*
109  * Change the watchdog time interval.
110  */
111 static int at91_wdt_settimeout(int new_time)
112 {
113         /*
114          * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
115          *
116          * Since WDV is a 16-bit counter, the maximum period is
117          * 65536 / 256 = 256 seconds.
118          */
119         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
120                 return -EINVAL;
121 
122         /* Set new watchdog time. It will be used when
123            at91_wdt_start() is called. */
124         wdt_time = new_time;
125         return 0;
126 }
127 
128 static const struct watchdog_info at91_wdt_info = {
129         .identity       = "at91 watchdog",
130         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
131 };
132 
133 /*
134  * Handle commands from user-space.
135  */
136 static long at91_wdt_ioctl(struct file *file,
137                                         unsigned int cmd, unsigned long arg)
138 {
139         void __user *argp = (void __user *)arg;
140         int __user *p = argp;
141         int new_value;
142 
143         switch (cmd) {
144         case WDIOC_GETSUPPORT:
145                 return copy_to_user(argp, &at91_wdt_info,
146                                 sizeof(at91_wdt_info)) ? -EFAULT : 0;
147         case WDIOC_GETSTATUS:
148         case WDIOC_GETBOOTSTATUS:
149                 return put_user(0, p);
150         case WDIOC_SETOPTIONS:
151                 if (get_user(new_value, p))
152                         return -EFAULT;
153                 if (new_value & WDIOS_DISABLECARD)
154                         at91_wdt_stop();
155                 if (new_value & WDIOS_ENABLECARD)
156                         at91_wdt_start();
157                 return 0;
158         case WDIOC_KEEPALIVE:
159                 at91_wdt_reload();      /* pat the watchdog */
160                 return 0;
161         case WDIOC_SETTIMEOUT:
162                 if (get_user(new_value, p))
163                         return -EFAULT;
164                 if (at91_wdt_settimeout(new_value))
165                         return -EINVAL;
166                 /* Enable new time value */
167                 at91_wdt_start();
168                 /* Return current value */
169                 return put_user(wdt_time, p);
170         case WDIOC_GETTIMEOUT:
171                 return put_user(wdt_time, p);
172         default:
173                 return -ENOTTY;
174         }
175 }
176 
177 /*
178  * Pat the watchdog whenever device is written to.
179  */
180 static ssize_t at91_wdt_write(struct file *file, const char *data,
181                                                 size_t len, loff_t *ppos)
182 {
183         at91_wdt_reload();              /* pat the watchdog */
184         return len;
185 }
186 
187 /* ......................................................................... */
188 
189 static const struct file_operations at91wdt_fops = {
190         .owner          = THIS_MODULE,
191         .llseek         = no_llseek,
192         .unlocked_ioctl = at91_wdt_ioctl,
193         .open           = at91_wdt_open,
194         .release        = at91_wdt_close,
195         .write          = at91_wdt_write,
196 };
197 
198 static struct miscdevice at91wdt_miscdev = {
199         .minor          = WATCHDOG_MINOR,
200         .name           = "watchdog",
201         .fops           = &at91wdt_fops,
202 };
203 
204 static int at91wdt_probe(struct platform_device *pdev)
205 {
206         int res;
207 
208         if (at91wdt_miscdev.parent)
209                 return -EBUSY;
210         at91wdt_miscdev.parent = &pdev->dev;
211 
212         res = misc_register(&at91wdt_miscdev);
213         if (res)
214                 return res;
215 
216         pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
217                 wdt_time, nowayout ? ", nowayout" : "");
218         return 0;
219 }
220 
221 static int at91wdt_remove(struct platform_device *pdev)
222 {
223         int res;
224 
225         res = misc_deregister(&at91wdt_miscdev);
226         if (!res)
227                 at91wdt_miscdev.parent = NULL;
228 
229         return res;
230 }
231 
232 static void at91wdt_shutdown(struct platform_device *pdev)
233 {
234         at91_wdt_stop();
235 }
236 
237 #ifdef CONFIG_PM
238 
239 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
240 {
241         at91_wdt_stop();
242         return 0;
243 }
244 
245 static int at91wdt_resume(struct platform_device *pdev)
246 {
247         if (at91wdt_busy)
248                 at91_wdt_start();
249         return 0;
250 }
251 
252 #else
253 #define at91wdt_suspend NULL
254 #define at91wdt_resume  NULL
255 #endif
256 
257 static const struct of_device_id at91_wdt_dt_ids[] = {
258         { .compatible = "atmel,at91rm9200-wdt" },
259         { /* sentinel */ }
260 };
261 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
262 
263 static struct platform_driver at91wdt_driver = {
264         .probe          = at91wdt_probe,
265         .remove         = at91wdt_remove,
266         .shutdown       = at91wdt_shutdown,
267         .suspend        = at91wdt_suspend,
268         .resume         = at91wdt_resume,
269         .driver         = {
270                 .name   = "at91_wdt",
271                 .owner  = THIS_MODULE,
272                 .of_match_table = at91_wdt_dt_ids,
273         },
274 };
275 
276 static int __init at91_wdt_init(void)
277 {
278         /* Check that the heartbeat value is within range;
279            if not reset to the default */
280         if (at91_wdt_settimeout(wdt_time)) {
281                 at91_wdt_settimeout(WDT_DEFAULT_TIME);
282                 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
283                         wdt_time);
284         }
285 
286         return platform_driver_register(&at91wdt_driver);
287 }
288 
289 static void __exit at91_wdt_exit(void)
290 {
291         platform_driver_unregister(&at91wdt_driver);
292 }
293 
294 module_init(at91_wdt_init);
295 module_exit(at91_wdt_exit);
296 
297 MODULE_AUTHOR("Andrew Victor");
298 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
299 MODULE_LICENSE("GPL");
300 MODULE_ALIAS("platform:at91_wdt");
301 

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