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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * IndyDog 0.3 A Hardware Watchdog Device for SGI IP224 *5 * (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>,6 * All Rights Reserved.7 *8 * based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>9 */10 11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt12 13#include <linux/module.h>14#include <linux/moduleparam.h>15#include <linux/types.h>16#include <linux/kernel.h>17#include <linux/fs.h>18#include <linux/mm.h>19#include <linux/miscdevice.h>20#include <linux/watchdog.h>21#include <linux/notifier.h>22#include <linux/reboot.h>23#include <linux/init.h>24#include <linux/uaccess.h>25#include <asm/sgi/mc.h>26 27static unsigned long indydog_alive;28static DEFINE_SPINLOCK(indydog_lock);29 30#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */31 32static bool nowayout = WATCHDOG_NOWAYOUT;33module_param(nowayout, bool, 0);34MODULE_PARM_DESC(nowayout,35 "Watchdog cannot be stopped once started (default="36 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");37 38static void indydog_start(void)39{40 spin_lock(&indydog_lock);41 sgimc->cpuctrl0 |= SGIMC_CCTRL0_WDOG;42 spin_unlock(&indydog_lock);43}44 45static void indydog_stop(void)46{47 spin_lock(&indydog_lock);48 sgimc->cpuctrl0 &= ~SGIMC_CCTRL0_WDOG;49 spin_unlock(&indydog_lock);50 51 pr_info("Stopped watchdog timer\n");52}53 54static void indydog_ping(void)55{56 sgimc->watchdogt = 0;57}58 59/*60 * Allow only one person to hold it open61 */62static int indydog_open(struct inode *inode, struct file *file)63{64 if (test_and_set_bit(0, &indydog_alive))65 return -EBUSY;66 67 if (nowayout)68 __module_get(THIS_MODULE);69 70 /* Activate timer */71 indydog_start();72 indydog_ping();73 74 pr_info("Started watchdog timer\n");75 76 return stream_open(inode, file);77}78 79static int indydog_release(struct inode *inode, struct file *file)80{81 /* Shut off the timer.82 * Lock it in if it's a module and we defined ...NOWAYOUT */83 if (!nowayout)84 indydog_stop(); /* Turn the WDT off */85 clear_bit(0, &indydog_alive);86 return 0;87}88 89static ssize_t indydog_write(struct file *file, const char *data,90 size_t len, loff_t *ppos)91{92 /* Refresh the timer. */93 if (len)94 indydog_ping();95 return len;96}97 98static long indydog_ioctl(struct file *file, unsigned int cmd,99 unsigned long arg)100{101 int options, retval = -EINVAL;102 static const struct watchdog_info ident = {103 .options = WDIOF_KEEPALIVEPING,104 .firmware_version = 0,105 .identity = "Hardware Watchdog for SGI IP22",106 };107 108 switch (cmd) {109 case WDIOC_GETSUPPORT:110 if (copy_to_user((struct watchdog_info *)arg,111 &ident, sizeof(ident)))112 return -EFAULT;113 return 0;114 case WDIOC_GETSTATUS:115 case WDIOC_GETBOOTSTATUS:116 return put_user(0, (int *)arg);117 case WDIOC_SETOPTIONS:118 {119 if (get_user(options, (int *)arg))120 return -EFAULT;121 if (options & WDIOS_DISABLECARD) {122 indydog_stop();123 retval = 0;124 }125 if (options & WDIOS_ENABLECARD) {126 indydog_start();127 retval = 0;128 }129 return retval;130 }131 case WDIOC_KEEPALIVE:132 indydog_ping();133 return 0;134 case WDIOC_GETTIMEOUT:135 return put_user(WATCHDOG_TIMEOUT, (int *)arg);136 default:137 return -ENOTTY;138 }139}140 141static int indydog_notify_sys(struct notifier_block *this,142 unsigned long code, void *unused)143{144 if (code == SYS_DOWN || code == SYS_HALT)145 indydog_stop(); /* Turn the WDT off */146 147 return NOTIFY_DONE;148}149 150static const struct file_operations indydog_fops = {151 .owner = THIS_MODULE,152 .write = indydog_write,153 .unlocked_ioctl = indydog_ioctl,154 .compat_ioctl = compat_ptr_ioctl,155 .open = indydog_open,156 .release = indydog_release,157};158 159static struct miscdevice indydog_miscdev = {160 .minor = WATCHDOG_MINOR,161 .name = "watchdog",162 .fops = &indydog_fops,163};164 165static struct notifier_block indydog_notifier = {166 .notifier_call = indydog_notify_sys,167};168 169static int __init watchdog_init(void)170{171 int ret;172 173 ret = register_reboot_notifier(&indydog_notifier);174 if (ret) {175 pr_err("cannot register reboot notifier (err=%d)\n", ret);176 return ret;177 }178 179 ret = misc_register(&indydog_miscdev);180 if (ret) {181 pr_err("cannot register miscdev on minor=%d (err=%d)\n",182 WATCHDOG_MINOR, ret);183 unregister_reboot_notifier(&indydog_notifier);184 return ret;185 }186 187 pr_info("Hardware Watchdog Timer for SGI IP22: 0.3\n");188 189 return 0;190}191 192static void __exit watchdog_exit(void)193{194 misc_deregister(&indydog_miscdev);195 unregister_reboot_notifier(&indydog_notifier);196}197 198module_init(watchdog_init);199module_exit(watchdog_exit);200 201MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");202MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");203MODULE_LICENSE("GPL");204