drivers/watchdog/pnx833x_wdt.c

   1 /*
   2  *  PNX833x Hardware Watchdog Driver
   3  *  Copyright 2008 NXP Semiconductors
   4  *  Daniel Laird <daniel.j.laird@nxp.com>
   5  *  Andre McCurdy <andre.mccurdy@nxp.com>
   6  *
   7  *  Heavily based upon - IndyDog        0.3
   8  *  A Hardware Watchdog Device for SGI IP22
   9  *
  10  * (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>, All Rights Reserved.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version
  15  * 2 of the License, or (at your option) any later version.
  16  *
  17  * based on softdog.c by Alan Cox <alan@redhat.com>
  18  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/types.h>
  25 #include <linux/kernel.h>
  26 #include <linux/fs.h>
  27 #include <linux/mm.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/notifier.h>
  31 #include <linux/reboot.h>
  32 #include <linux/init.h>
  33 #include <asm/mach-pnx833x/pnx833x.h>
  34
  35 #define WATCHDOG_TIMEOUT 30             /* 30 sec Maximum timeout */
  36 #define WATCHDOG_COUNT_FREQUENCY 68000000U /* Watchdog counts at 68MHZ. */
  37 #define PNX_WATCHDOG_TIMEOUT    (WATCHDOG_TIMEOUT * WATCHDOG_COUNT_FREQUENCY)
  38 #define PNX_TIMEOUT_VALUE       2040000000U
  39
  40 /** CONFIG block */
  41 #define PNX833X_CONFIG                      (0x07000U)
  42 #define PNX833X_CONFIG_CPU_WATCHDOG         (0x54)
  43 #define PNX833X_CONFIG_CPU_WATCHDOG_COMPARE (0x58)
  44 #define PNX833X_CONFIG_CPU_COUNTERS_CONTROL (0x1c)
  45
  46 /** RESET block */
  47 #define PNX833X_RESET                       (0x08000U)
  48 #define PNX833X_RESET_CONFIG                (0x08)
  49
  50 static int pnx833x_wdt_alive;
  51
  52 /* Set default timeout in MHZ.*/
  53 static int pnx833x_wdt_timeout = PNX_WATCHDOG_TIMEOUT;
  54 module_param(pnx833x_wdt_timeout, int, 0);
  55 MODULE_PARM_DESC(timeout, "Watchdog timeout in Mhz. (68Mhz clock), default="
  56                         __MODULE_STRING(PNX_TIMEOUT_VALUE) "(30 seconds).");
  57
  58 static bool nowayout = WATCHDOG_NOWAYOUT;
  59 module_param(nowayout, bool, 0);
  60 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  61                                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  62
  63 #define START_DEFAULT   1
  64 static int start_enabled = START_DEFAULT;
  65 module_param(start_enabled, int, 0);
  66 MODULE_PARM_DESC(start_enabled, "Watchdog is started on module insertion "
  67                                 "(default=" __MODULE_STRING(START_DEFAULT) ")");
  68
  69 static void pnx833x_wdt_start(void)
  70 {
  71         /* Enable watchdog causing reset. */
  72         PNX833X_REG(PNX833X_RESET + PNX833X_RESET_CONFIG) |= 0x1;
  73         /* Set timeout.*/
  74         PNX833X_REG(PNX833X_CONFIG +
  75                 PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
  76         /* Enable watchdog. */
  77         PNX833X_REG(PNX833X_CONFIG +
  78                                 PNX833X_CONFIG_CPU_COUNTERS_CONTROL) |= 0x1;
  79
  80         pr_info("Started watchdog timer\n");
  81 }
  82
  83 static void pnx833x_wdt_stop(void)
  84 {
  85         /* Disable watchdog causing reset. */
  86         PNX833X_REG(PNX833X_RESET + PNX833X_CONFIG) &= 0xFFFFFFFE;
  87         /* Disable watchdog.*/
  88         PNX833X_REG(PNX833X_CONFIG +
  89                         PNX833X_CONFIG_CPU_COUNTERS_CONTROL) &= 0xFFFFFFFE;
  90
  91         pr_info("Stopped watchdog timer\n");
  92 }
  93
  94 static void pnx833x_wdt_ping(void)
  95 {
  96         PNX833X_REG(PNX833X_CONFIG +
  97                 PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
  98 }
  99
 100 /*
 101  *      Allow only one person to hold it open
 102  */
 103 static int pnx833x_wdt_open(struct inode *inode, struct file *file)
 104 {
 105         if (test_and_set_bit(0, &pnx833x_wdt_alive))
 106                 return -EBUSY;
 107
 108         if (nowayout)
 109                 __module_get(THIS_MODULE);
 110
 111         /* Activate timer */
 112         if (!start_enabled)
 113                 pnx833x_wdt_start();
 114
 115         pnx833x_wdt_ping();
 116
 117         pr_info("Started watchdog timer\n");
 118
 119         return nonseekable_open(inode, file);
 120 }
 121
 122 static int pnx833x_wdt_release(struct inode *inode, struct file *file)
 123 {
 124         /* Shut off the timer.
 125          * Lock it in if it's a module and we defined ...NOWAYOUT */
 126         if (!nowayout)
 127                 pnx833x_wdt_stop(); /* Turn the WDT off */
 128
 129         clear_bit(0, &pnx833x_wdt_alive);
 130         return 0;
 131 }
 132
 133 static ssize_t pnx833x_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
 134 {
 135         /* Refresh the timer. */
 136         if (len)
 137                 pnx833x_wdt_ping();
 138
 139         return len;
 140 }
 141
 142 static long pnx833x_wdt_ioctl(struct file *file, unsigned int cmd,
 143                                                         unsigned long arg)
 144 {
 145         int options, new_timeout = 0;
 146         uint32_t timeout, timeout_left = 0;
 147
 148         static const struct watchdog_info ident = {
 149                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
 150                 .firmware_version = 0,
 151                 .identity = "Hardware Watchdog for PNX833x",
 152         };
 153
 154         switch (cmd) {
 155         default:
 156                 return -ENOTTY;
 157
 158         case WDIOC_GETSUPPORT:
 159                 if (copy_to_user((struct watchdog_info *)arg,
 160                                  &ident, sizeof(ident)))
 161                         return -EFAULT;
 162                 return 0;
 163
 164         case WDIOC_GETSTATUS:
 165         case WDIOC_GETBOOTSTATUS:
 166                 return put_user(0, (int *)arg);
 167
 168         case WDIOC_SETOPTIONS:
 169                 if (get_user(options, (int *)arg))
 170                         return -EFAULT;
 171
 172                 if (options & WDIOS_DISABLECARD)
 173                         pnx833x_wdt_stop();
 174
 175                 if (options & WDIOS_ENABLECARD)
 176                         pnx833x_wdt_start();
 177
 178                 return 0;
 179
 180         case WDIOC_KEEPALIVE:
 181                 pnx833x_wdt_ping();
 182                 return 0;
 183
 184         case WDIOC_SETTIMEOUT:
 185         {
 186                 if (get_user(new_timeout, (int *)arg))
 187                         return -EFAULT;
 188
 189                 pnx833x_wdt_timeout = new_timeout;
 190                 PNX833X_REG(PNX833X_CONFIG +
 191                         PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = new_timeout;
 192                 return put_user(new_timeout, (int *)arg);
 193         }
 194
 195         case WDIOC_GETTIMEOUT:
 196                 timeout = PNX833X_REG(PNX833X_CONFIG +
 197                                         PNX833X_CONFIG_CPU_WATCHDOG_COMPARE);
 198                 return put_user(timeout, (int *)arg);
 199
 200         case WDIOC_GETTIMELEFT:
 201                 timeout_left = PNX833X_REG(PNX833X_CONFIG +
 202                                                 PNX833X_CONFIG_CPU_WATCHDOG);
 203                 return put_user(timeout_left, (int *)arg);
 204
 205         }
 206 }
 207
 208 static int pnx833x_wdt_notify_sys(struct notifier_block *this,
 209                                         unsigned long code, void *unused)
 210 {
 211         if (code == SYS_DOWN || code == SYS_HALT)
 212                 pnx833x_wdt_stop(); /* Turn the WDT off */
 213
 214         return NOTIFY_DONE;
 215 }
 216
 217 static const struct file_operations pnx833x_wdt_fops = {
 218         .owner          = THIS_MODULE,
 219         .llseek         = no_llseek,
 220         .write          = pnx833x_wdt_write,
 221         .unlocked_ioctl = pnx833x_wdt_ioctl,
 222         .open           = pnx833x_wdt_open,
 223         .release        = pnx833x_wdt_release,
 224 };
 225
 226 static struct miscdevice pnx833x_wdt_miscdev = {
 227         .minor          = WATCHDOG_MINOR,
 228         .name           = "watchdog",
 229         .fops           = &pnx833x_wdt_fops,
 230 };
 231
 232 static struct notifier_block pnx833x_wdt_notifier = {
 233         .notifier_call = pnx833x_wdt_notify_sys,
 234 };
 235
 236 static int __init watchdog_init(void)
 237 {
 238         int ret, cause;
 239
 240         /* Lets check the reason for the reset.*/
 241         cause = PNX833X_REG(PNX833X_RESET);
 242         /*If bit 31 is set then watchdog was cause of reset.*/
 243         if (cause & 0x80000000) {
 244                 pr_info("The system was previously reset due to the watchdog firing - please investigate...\n");
 245         }
 246
 247         ret = register_reboot_notifier(&pnx833x_wdt_notifier);
 248         if (ret) {
 249                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 250                 return ret;
 251         }
 252
 253         ret = misc_register(&pnx833x_wdt_miscdev);
 254         if (ret) {
 255                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 256                        WATCHDOG_MINOR, ret);
 257                 unregister_reboot_notifier(&pnx833x_wdt_notifier);
 258                 return ret;
 259         }
 260
 261         pr_info("Hardware Watchdog Timer for PNX833x: Version 0.1\n");
 262
 263         if (start_enabled)
 264                 pnx833x_wdt_start();
 265
 266         return 0;
 267 }
 268
 269 static void __exit watchdog_exit(void)
 270 {
 271         misc_deregister(&pnx833x_wdt_miscdev);
 272         unregister_reboot_notifier(&pnx833x_wdt_notifier);
 273 }
 274
 275 module_init(watchdog_init);
 276 module_exit(watchdog_exit);
 277
 278 MODULE_AUTHOR("Daniel Laird/Andre McCurdy");
 279 MODULE_DESCRIPTION("Hardware Watchdog Device for PNX833x");
 280 MODULE_LICENSE("GPL");