drivers/watchdog/pnx833x_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  PNX833x Hardware Watchdog Driver
   4  *  Copyright 2008 NXP Semiconductors
   5  *  Daniel Laird <daniel.j.laird@nxp.com>
   6  *  Andre McCurdy <andre.mccurdy@nxp.com>
   7  *
   8  *  Heavily based upon - IndyDog        0.3
   9  *  A Hardware Watchdog Device for SGI IP22
  10  *
  11  * (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>, All Rights Reserved.
  12  *
  13  * based on softdog.c by Alan Cox <alan@redhat.com>
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/types.h>
  21 #include <linux/kernel.h>
  22 #include <linux/fs.h>
  23 #include <linux/mm.h>
  24 #include <linux/miscdevice.h>
  25 #include <linux/watchdog.h>
  26 #include <linux/notifier.h>
  27 #include <linux/reboot.h>
  28 #include <linux/init.h>
  29 #include <asm/mach-pnx833x/pnx833x.h>
  30
  31 #define WATCHDOG_TIMEOUT 30             /* 30 sec Maximum timeout */
  32 #define WATCHDOG_COUNT_FREQUENCY 68000000U /* Watchdog counts at 68MHZ. */
  33 #define PNX_WATCHDOG_TIMEOUT    (WATCHDOG_TIMEOUT * WATCHDOG_COUNT_FREQUENCY)
  34 #define PNX_TIMEOUT_VALUE       2040000000U
  35
  36 /** CONFIG block */
  37 #define PNX833X_CONFIG                      (0x07000U)
  38 #define PNX833X_CONFIG_CPU_WATCHDOG         (0x54)
  39 #define PNX833X_CONFIG_CPU_WATCHDOG_COMPARE (0x58)
  40 #define PNX833X_CONFIG_CPU_COUNTERS_CONTROL (0x1c)
  41
  42 /** RESET block */
  43 #define PNX833X_RESET                       (0x08000U)
  44 #define PNX833X_RESET_CONFIG                (0x08)
  45
  46 static int pnx833x_wdt_alive;
  47
  48 /* Set default timeout in MHZ.*/
  49 static int pnx833x_wdt_timeout = PNX_WATCHDOG_TIMEOUT;
  50 module_param(pnx833x_wdt_timeout, int, 0);
  51 MODULE_PARM_DESC(timeout, "Watchdog timeout in Mhz. (68Mhz clock), default="
  52                         __MODULE_STRING(PNX_TIMEOUT_VALUE) "(30 seconds).");
  53
  54 static bool nowayout = WATCHDOG_NOWAYOUT;
  55 module_param(nowayout, bool, 0);
  56 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  57                                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  58
  59 #define START_DEFAULT   1
  60 static int start_enabled = START_DEFAULT;
  61 module_param(start_enabled, int, 0);
  62 MODULE_PARM_DESC(start_enabled, "Watchdog is started on module insertion "
  63                                 "(default=" __MODULE_STRING(START_DEFAULT) ")");
  64
  65 static void pnx833x_wdt_start(void)
  66 {
  67         /* Enable watchdog causing reset. */
  68         PNX833X_REG(PNX833X_RESET + PNX833X_RESET_CONFIG) |= 0x1;
  69         /* Set timeout.*/
  70         PNX833X_REG(PNX833X_CONFIG +
  71                 PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
  72         /* Enable watchdog. */
  73         PNX833X_REG(PNX833X_CONFIG +
  74                                 PNX833X_CONFIG_CPU_COUNTERS_CONTROL) |= 0x1;
  75
  76         pr_info("Started watchdog timer\n");
  77 }
  78
  79 static void pnx833x_wdt_stop(void)
  80 {
  81         /* Disable watchdog causing reset. */
  82         PNX833X_REG(PNX833X_RESET + PNX833X_CONFIG) &= 0xFFFFFFFE;
  83         /* Disable watchdog.*/
  84         PNX833X_REG(PNX833X_CONFIG +
  85                         PNX833X_CONFIG_CPU_COUNTERS_CONTROL) &= 0xFFFFFFFE;
  86
  87         pr_info("Stopped watchdog timer\n");
  88 }
  89
  90 static void pnx833x_wdt_ping(void)
  91 {
  92         PNX833X_REG(PNX833X_CONFIG +
  93                 PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
  94 }
  95
  96 /*
  97  *      Allow only one person to hold it open
  98  */
  99 static int pnx833x_wdt_open(struct inode *inode, struct file *file)
 100 {
 101         if (test_and_set_bit(0, &pnx833x_wdt_alive))
 102                 return -EBUSY;
 103
 104         if (nowayout)
 105                 __module_get(THIS_MODULE);
 106
 107         /* Activate timer */
 108         if (!start_enabled)
 109                 pnx833x_wdt_start();
 110
 111         pnx833x_wdt_ping();
 112
 113         pr_info("Started watchdog timer\n");
 114
 115         return stream_open(inode, file);
 116 }
 117
 118 static int pnx833x_wdt_release(struct inode *inode, struct file *file)
 119 {
 120         /* Shut off the timer.
 121          * Lock it in if it's a module and we defined ...NOWAYOUT */
 122         if (!nowayout)
 123                 pnx833x_wdt_stop(); /* Turn the WDT off */
 124
 125         clear_bit(0, &pnx833x_wdt_alive);
 126         return 0;
 127 }
 128
 129 static ssize_t pnx833x_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
 130 {
 131         /* Refresh the timer. */
 132         if (len)
 133                 pnx833x_wdt_ping();
 134
 135         return len;
 136 }
 137
 138 static long pnx833x_wdt_ioctl(struct file *file, unsigned int cmd,
 139                                                         unsigned long arg)
 140 {
 141         int options, new_timeout = 0;
 142         uint32_t timeout, timeout_left = 0;
 143
 144         static const struct watchdog_info ident = {
 145                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
 146                 .firmware_version = 0,
 147                 .identity = "Hardware Watchdog for PNX833x",
 148         };
 149
 150         switch (cmd) {
 151         default:
 152                 return -ENOTTY;
 153
 154         case WDIOC_GETSUPPORT:
 155                 if (copy_to_user((struct watchdog_info *)arg,
 156                                  &ident, sizeof(ident)))
 157                         return -EFAULT;
 158                 return 0;
 159
 160         case WDIOC_GETSTATUS:
 161         case WDIOC_GETBOOTSTATUS:
 162                 return put_user(0, (int *)arg);
 163
 164         case WDIOC_SETOPTIONS:
 165                 if (get_user(options, (int *)arg))
 166                         return -EFAULT;
 167
 168                 if (options & WDIOS_DISABLECARD)
 169                         pnx833x_wdt_stop();
 170
 171                 if (options & WDIOS_ENABLECARD)
 172                         pnx833x_wdt_start();
 173
 174                 return 0;
 175
 176         case WDIOC_KEEPALIVE:
 177                 pnx833x_wdt_ping();
 178                 return 0;
 179
 180         case WDIOC_SETTIMEOUT:
 181         {
 182                 if (get_user(new_timeout, (int *)arg))
 183                         return -EFAULT;
 184
 185                 pnx833x_wdt_timeout = new_timeout;
 186                 PNX833X_REG(PNX833X_CONFIG +
 187                         PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = new_timeout;
 188                 return put_user(new_timeout, (int *)arg);
 189         }
 190
 191         case WDIOC_GETTIMEOUT:
 192                 timeout = PNX833X_REG(PNX833X_CONFIG +
 193                                         PNX833X_CONFIG_CPU_WATCHDOG_COMPARE);
 194                 return put_user(timeout, (int *)arg);
 195
 196         case WDIOC_GETTIMELEFT:
 197                 timeout_left = PNX833X_REG(PNX833X_CONFIG +
 198                                                 PNX833X_CONFIG_CPU_WATCHDOG);
 199                 return put_user(timeout_left, (int *)arg);
 200
 201         }
 202 }
 203
 204 static int pnx833x_wdt_notify_sys(struct notifier_block *this,
 205                                         unsigned long code, void *unused)
 206 {
 207         if (code == SYS_DOWN || code == SYS_HALT)
 208                 pnx833x_wdt_stop(); /* Turn the WDT off */
 209
 210         return NOTIFY_DONE;
 211 }
 212
 213 static const struct file_operations pnx833x_wdt_fops = {
 214         .owner          = THIS_MODULE,
 215         .llseek         = no_llseek,
 216         .write          = pnx833x_wdt_write,
 217         .unlocked_ioctl = pnx833x_wdt_ioctl,
 218         .compat_ioctl   = compat_ptr_ioctl,
 219         .open           = pnx833x_wdt_open,
 220         .release        = pnx833x_wdt_release,
 221 };
 222
 223 static struct miscdevice pnx833x_wdt_miscdev = {
 224         .minor          = WATCHDOG_MINOR,
 225         .name           = "watchdog",
 226         .fops           = &pnx833x_wdt_fops,
 227 };
 228
 229 static struct notifier_block pnx833x_wdt_notifier = {
 230         .notifier_call = pnx833x_wdt_notify_sys,
 231 };
 232
 233 static int __init watchdog_init(void)
 234 {
 235         int ret, cause;
 236
 237         /* Lets check the reason for the reset.*/
 238         cause = PNX833X_REG(PNX833X_RESET);
 239         /*If bit 31 is set then watchdog was cause of reset.*/
 240         if (cause & 0x80000000) {
 241                 pr_info("The system was previously reset due to the watchdog firing - please investigate...\n");
 242         }
 243
 244         ret = register_reboot_notifier(&pnx833x_wdt_notifier);
 245         if (ret) {
 246                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 247                 return ret;
 248         }
 249
 250         ret = misc_register(&pnx833x_wdt_miscdev);
 251         if (ret) {
 252                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 253                        WATCHDOG_MINOR, ret);
 254                 unregister_reboot_notifier(&pnx833x_wdt_notifier);
 255                 return ret;
 256         }
 257
 258         pr_info("Hardware Watchdog Timer for PNX833x: Version 0.1\n");
 259
 260         if (start_enabled)
 261                 pnx833x_wdt_start();
 262
 263         return 0;
 264 }
 265
 266 static void __exit watchdog_exit(void)
 267 {
 268         misc_deregister(&pnx833x_wdt_miscdev);
 269         unregister_reboot_notifier(&pnx833x_wdt_notifier);
 270 }
 271
 272 module_init(watchdog_init);
 273 module_exit(watchdog_exit);
 274
 275 MODULE_AUTHOR("Daniel Laird/Andre McCurdy");
 276 MODULE_DESCRIPTION("Hardware Watchdog Device for PNX833x");
 277 MODULE_LICENSE("GPL");