drivers/watchdog/at91rm9200_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Watchdog driver for Atmel AT91RM9200 (Thunder)
   4  *
   5  *  Copyright (C) 2003 SAN People (Pty) Ltd
   6  *
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/bitops.h>
  12 #include <linux/delay.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/init.h>
  16 #include <linux/io.h>
  17 #include <linux/kernel.h>
  18 #include <linux/mfd/syscon.h>
  19 #include <linux/mfd/syscon/atmel-st.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/mod_devicetable.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/reboot.h>
  26 #include <linux/regmap.h>
  27 #include <linux/types.h>
  28 #include <linux/watchdog.h>
  29 #include <linux/uaccess.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 static struct regmap *regmap_st;
  37
  38 module_param(wdt_time, int, 0);
  39 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  40                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  41
  42 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  43 module_param(nowayout, bool, 0);
  44 MODULE_PARM_DESC(nowayout,
  45                 "Watchdog cannot be stopped once started (default="
  46                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  47 #endif
  48
  49
  50 static unsigned long at91wdt_busy;
  51
  52 /* ......................................................................... */
  53
  54 static int at91rm9200_restart(struct notifier_block *this,
  55                                         unsigned long mode, void *cmd)
  56 {
  57         /*
  58          * Perform a hardware reset with the use of the Watchdog timer.
  59          */
  60         regmap_write(regmap_st, AT91_ST_WDMR,
  61                      AT91_ST_RSTEN | AT91_ST_EXTEN | 1);
  62         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
  63
  64         mdelay(2000);
  65
  66         pr_emerg("Unable to restart system\n");
  67         return NOTIFY_DONE;
  68 }
  69
  70 static struct notifier_block at91rm9200_restart_nb = {
  71         .notifier_call = at91rm9200_restart,
  72         .priority = 192,
  73 };
  74
  75 /*
  76  * Disable the watchdog.
  77  */
  78 static inline void at91_wdt_stop(void)
  79 {
  80         regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN);
  81 }
  82
  83 /*
  84  * Enable and reset the watchdog.
  85  */
  86 static inline void at91_wdt_start(void)
  87 {
  88         regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  89                                 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  90         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
  91 }
  92
  93 /*
  94  * Reload the watchdog timer.  (ie, pat the watchdog)
  95  */
  96 static inline void at91_wdt_reload(void)
  97 {
  98         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
  99 }
 100
 101 /* ......................................................................... */
 102
 103 /*
 104  * Watchdog device is opened, and watchdog starts running.
 105  */
 106 static int at91_wdt_open(struct inode *inode, struct file *file)
 107 {
 108         if (test_and_set_bit(0, &at91wdt_busy))
 109                 return -EBUSY;
 110
 111         at91_wdt_start();
 112         return stream_open(inode, file);
 113 }
 114
 115 /*
 116  * Close the watchdog device.
 117  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
 118  *  disabled.
 119  */
 120 static int at91_wdt_close(struct inode *inode, struct file *file)
 121 {
 122         /* Disable the watchdog when file is closed */
 123         if (!nowayout)
 124                 at91_wdt_stop();
 125
 126         clear_bit(0, &at91wdt_busy);
 127         return 0;
 128 }
 129
 130 /*
 131  * Change the watchdog time interval.
 132  */
 133 static int at91_wdt_settimeout(int new_time)
 134 {
 135         /*
 136          * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 137          *
 138          * Since WDV is a 16-bit counter, the maximum period is
 139          * 65536 / 256 = 256 seconds.
 140          */
 141         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 142                 return -EINVAL;
 143
 144         /* Set new watchdog time. It will be used when
 145            at91_wdt_start() is called. */
 146         wdt_time = new_time;
 147         return 0;
 148 }
 149
 150 static const struct watchdog_info at91_wdt_info = {
 151         .identity       = "at91 watchdog",
 152         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 153 };
 154
 155 /*
 156  * Handle commands from user-space.
 157  */
 158 static long at91_wdt_ioctl(struct file *file,
 159                                         unsigned int cmd, unsigned long arg)
 160 {
 161         void __user *argp = (void __user *)arg;
 162         int __user *p = argp;
 163         int new_value;
 164
 165         switch (cmd) {
 166         case WDIOC_GETSUPPORT:
 167                 return copy_to_user(argp, &at91_wdt_info,
 168                                 sizeof(at91_wdt_info)) ? -EFAULT : 0;
 169         case WDIOC_GETSTATUS:
 170         case WDIOC_GETBOOTSTATUS:
 171                 return put_user(0, p);
 172         case WDIOC_SETOPTIONS:
 173                 if (get_user(new_value, p))
 174                         return -EFAULT;
 175                 if (new_value & WDIOS_DISABLECARD)
 176                         at91_wdt_stop();
 177                 if (new_value & WDIOS_ENABLECARD)
 178                         at91_wdt_start();
 179                 return 0;
 180         case WDIOC_KEEPALIVE:
 181                 at91_wdt_reload();      /* pat the watchdog */
 182                 return 0;
 183         case WDIOC_SETTIMEOUT:
 184                 if (get_user(new_value, p))
 185                         return -EFAULT;
 186                 if (at91_wdt_settimeout(new_value))
 187                         return -EINVAL;
 188                 /* Enable new time value */
 189                 at91_wdt_start();
 190                 /* Return current value */
 191                 return put_user(wdt_time, p);
 192         case WDIOC_GETTIMEOUT:
 193                 return put_user(wdt_time, p);
 194         default:
 195                 return -ENOTTY;
 196         }
 197 }
 198
 199 /*
 200  * Pat the watchdog whenever device is written to.
 201  */
 202 static ssize_t at91_wdt_write(struct file *file, const char *data,
 203                                                 size_t len, loff_t *ppos)
 204 {
 205         at91_wdt_reload();              /* pat the watchdog */
 206         return len;
 207 }
 208
 209 /* ......................................................................... */
 210
 211 static const struct file_operations at91wdt_fops = {
 212         .owner          = THIS_MODULE,
 213         .unlocked_ioctl = at91_wdt_ioctl,
 214         .compat_ioctl   = compat_ptr_ioctl,
 215         .open           = at91_wdt_open,
 216         .release        = at91_wdt_close,
 217         .write          = at91_wdt_write,
 218 };
 219
 220 static struct miscdevice at91wdt_miscdev = {
 221         .minor          = WATCHDOG_MINOR,
 222         .name           = "watchdog",
 223         .fops           = &at91wdt_fops,
 224 };
 225
 226 static int at91wdt_probe(struct platform_device *pdev)
 227 {
 228         struct device *dev = &pdev->dev;
 229         struct device *parent;
 230         int res;
 231
 232         if (at91wdt_miscdev.parent)
 233                 return -EBUSY;
 234         at91wdt_miscdev.parent = &pdev->dev;
 235
 236         parent = dev->parent;
 237         if (!parent) {
 238                 dev_err(dev, "no parent\n");
 239                 return -ENODEV;
 240         }
 241
 242         regmap_st = syscon_node_to_regmap(parent->of_node);
 243         if (IS_ERR(regmap_st))
 244                 return -ENODEV;
 245
 246         res = misc_register(&at91wdt_miscdev);
 247         if (res)
 248                 return res;
 249
 250         res = register_restart_handler(&at91rm9200_restart_nb);
 251         if (res)
 252                 dev_warn(dev, "failed to register restart handler\n");
 253
 254         pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
 255                 wdt_time, nowayout ? ", nowayout" : "");
 256         return 0;
 257 }
 258
 259 static void at91wdt_remove(struct platform_device *pdev)
 260 {
 261         struct device *dev = &pdev->dev;
 262         int res;
 263
 264         res = unregister_restart_handler(&at91rm9200_restart_nb);
 265         if (res)
 266                 dev_warn(dev, "failed to unregister restart handler\n");
 267
 268         misc_deregister(&at91wdt_miscdev);
 269         at91wdt_miscdev.parent = NULL;
 270 }
 271
 272 static void at91wdt_shutdown(struct platform_device *pdev)
 273 {
 274         at91_wdt_stop();
 275 }
 276
 277 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 278 {
 279         at91_wdt_stop();
 280         return 0;
 281 }
 282
 283 static int at91wdt_resume(struct platform_device *pdev)
 284 {
 285         if (at91wdt_busy)
 286                 at91_wdt_start();
 287         return 0;
 288 }
 289
 290 static const struct of_device_id at91_wdt_dt_ids[] = {
 291         { .compatible = "atmel,at91rm9200-wdt" },
 292         { /* sentinel */ }
 293 };
 294 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
 295
 296 static struct platform_driver at91wdt_driver = {
 297         .probe          = at91wdt_probe,
 298         .remove         = at91wdt_remove,
 299         .shutdown       = at91wdt_shutdown,
 300         .suspend        = pm_ptr(at91wdt_suspend),
 301         .resume         = pm_ptr(at91wdt_resume),
 302         .driver         = {
 303                 .name   = "atmel_st_watchdog",
 304                 .of_match_table = at91_wdt_dt_ids,
 305         },
 306 };
 307
 308 static int __init at91_wdt_init(void)
 309 {
 310         /* Check that the heartbeat value is within range;
 311            if not reset to the default */
 312         if (at91_wdt_settimeout(wdt_time)) {
 313                 at91_wdt_settimeout(WDT_DEFAULT_TIME);
 314                 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
 315                         wdt_time);
 316         }
 317
 318         return platform_driver_register(&at91wdt_driver);
 319 }
 320
 321 static void __exit at91_wdt_exit(void)
 322 {
 323         platform_driver_unregister(&at91wdt_driver);
 324 }
 325
 326 module_init(at91_wdt_init);
 327 module_exit(at91_wdt_exit);
 328
 329 MODULE_AUTHOR("Andrew Victor");
 330 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 331 MODULE_LICENSE("GPL");
 332 MODULE_ALIAS("platform:atmel_st_watchdog");