// SPDX-License-Identifier: GPL-2.0-or-later /* * SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x * * Based on acquirewdt.c by Alan Cox <[email protected]> * and some other existing drivers * * The authors do NOT admit liability nor provide warranty for * any of this software. This material is provided "AS-IS" in * the hope that it may be useful for others. * * (C) Copyright 2003-2006 Sven Anders <[email protected]> * * History: * 2003 - Created version 1.0 for Linux 2.4.x. * 2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE * features. Released version 1.1 * * Theory of operation: * * A Watchdog Timer (WDT) is a hardware circuit that can * reset the computer system in case of a software fault. * You probably knew that already. * * Usually a userspace daemon will notify the kernel WDT driver * via the /dev/watchdog special device file that userspace is * still alive, at regular intervals. When such a notification * occurs, the driver will usually tell the hardware watchdog * that everything is in order, and that the watchdog should wait * for yet another little while to reset the system. * If userspace fails (RAM error, kernel bug, whatever), the * notifications cease to occur, and the hardware watchdog will * reset the system (causing a reboot) after the timeout occurs. * * Create device with: * mknod /dev/watchdog c 10 130 * * For an example userspace keep-alive daemon, see: * Documentation/watchdog/wdt.rst */ #define pr_fmt(fmt) … #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/types.h> #include <linux/miscdevice.h> #include <linux/watchdog.h> #include <linux/delay.h> #include <linux/fs.h> #include <linux/ioport.h> #include <linux/notifier.h> #include <linux/reboot.h> #include <linux/init.h> #include <linux/spinlock.h> #include <linux/io.h> #include <linux/uaccess.h> /* enable support for minutes as units? */ /* (does not always work correctly, so disabled by default!) */ #define SMSC_SUPPORT_MINUTES #undef SMSC_SUPPORT_MINUTES #define MAX_TIMEOUT … #define UNIT_SECOND … #define UNIT_MINUTE … #define VERSION … #define IOPORT … #define IOPORT_SIZE … #define IODEV_NO … static int unit = …; /* timer's unit */ static int timeout = …; /* timeout value: default is 60 "units" */ static unsigned long timer_enabled; /* is the timer enabled? */ static char expect_close; /* is the close expected? */ static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */ static bool nowayout = … WATCHDOG_NOWAYOUT; /* -- Low level function ----------------------------------------*/ /* unlock the IO chip */ static inline void open_io_config(void) { … } /* lock the IO chip */ static inline void close_io_config(void) { … } /* select the IO device */ static inline void select_io_device(unsigned char devno) { … } /* write to the control register */ static inline void write_io_cr(unsigned char reg, unsigned char data) { … } /* read from the control register */ static inline char read_io_cr(unsigned char reg) { … } /* -- Medium level functions ------------------------------------*/ static inline void gpio_bit12(unsigned char reg) { … } static inline void gpio_bit13(unsigned char reg) { … } static inline void wdt_timer_units(unsigned char new_units) { … } static inline void wdt_timeout_value(unsigned char new_timeout) { … } static inline void wdt_timer_conf(unsigned char conf) { … } static inline void wdt_timer_ctrl(unsigned char reg) { … } /* -- Higher level functions ------------------------------------*/ /* initialize watchdog */ static void wb_smsc_wdt_initialize(void) { … } /* shutdown the watchdog */ static void wb_smsc_wdt_shutdown(void) { … } /* set timeout => enable watchdog */ static void wb_smsc_wdt_set_timeout(unsigned char new_timeout) { … } /* get timeout */ static unsigned char wb_smsc_wdt_get_timeout(void) { … } /* disable watchdog */ static void wb_smsc_wdt_disable(void) { … } /* enable watchdog by setting the current timeout */ static void wb_smsc_wdt_enable(void) { … } /* reset the timer */ static void wb_smsc_wdt_reset_timer(void) { … } /* return, if the watchdog is enabled (timeout is set...) */ static int wb_smsc_wdt_status(void) { … } /* -- File operations -------------------------------------------*/ /* open => enable watchdog and set initial timeout */ static int wb_smsc_wdt_open(struct inode *inode, struct file *file) { … } /* close => shut off the timer */ static int wb_smsc_wdt_release(struct inode *inode, struct file *file) { … } /* write => update the timer to keep the machine alive */ static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) { … } /* ioctl => control interface */ static long wb_smsc_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { … } /* -- Notifier funtions -----------------------------------------*/ static int wb_smsc_wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused) { … } /* -- Module's structures ---------------------------------------*/ static const struct file_operations wb_smsc_wdt_fops = …; static struct notifier_block wb_smsc_wdt_notifier = …; static struct miscdevice wb_smsc_wdt_miscdev = …; /* -- Module init functions -------------------------------------*/ /* module's "constructor" */ static int __init wb_smsc_wdt_init(void) { … } /* module's "destructor" */ static void __exit wb_smsc_wdt_exit(void) { … } module_init(…) …; module_exit(wb_smsc_wdt_exit); MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; #ifdef SMSC_SUPPORT_MINUTES module_param(unit, int, 0); MODULE_PARM_DESC(unit, "set unit to use, 0=seconds or 1=minutes, default is 0"); #endif module_param(timeout, int, 0); MODULE_PARM_DESC(…) …; module_param(nowayout, bool, 0); MODULE_PARM_DESC(…) …;
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