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