// 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 * 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 * * 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) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* 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 255 #define UNIT_SECOND 0 #define UNIT_MINUTE 1 #define VERSION "1.1" #define IOPORT 0x3F0 #define IOPORT_SIZE 2 #define IODEV_NO 8 static int unit = UNIT_SECOND; /* timer's unit */ static int timeout = 60; /* 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) { outb(0x55, IOPORT); mdelay(1); outb(0x55, IOPORT); } /* lock the IO chip */ static inline void close_io_config(void) { outb(0xAA, IOPORT); } /* select the IO device */ static inline void select_io_device(unsigned char devno) { outb(0x07, IOPORT); outb(devno, IOPORT+1); } /* write to the control register */ static inline void write_io_cr(unsigned char reg, unsigned char data) { outb(reg, IOPORT); outb(data, IOPORT+1); } /* read from the control register */ static inline char read_io_cr(unsigned char reg) { outb(reg, IOPORT); return inb(IOPORT+1); } /* -- Medium level functions ------------------------------------*/ static inline void gpio_bit12(unsigned char reg) { /* -- General Purpose I/O Bit 1.2 -- * Bit 0, In/Out: 0 = Output, 1 = Input * Bit 1, Polarity: 0 = No Invert, 1 = Invert * Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17, * 11 = Either Edge Triggered Intr. 2 * Bit 5/6 (Reserved) * Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain */ write_io_cr(0xE2, reg); } static inline void gpio_bit13(unsigned char reg) { /* -- General Purpose I/O Bit 1.3 -- * Bit 0, In/Out: 0 = Output, 1 = Input * Bit 1, Polarity: 0 = No Invert, 1 = Invert * Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable * Bit 3, Function select: 0 = GPI/O, 1 = LED * Bit 4-6 (Reserved) * Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain */ write_io_cr(0xE3, reg); } static inline void wdt_timer_units(unsigned char new_units) { /* -- Watchdog timer units -- * Bit 0-6 (Reserved) * Bit 7, WDT Time-out Value Units Select * (0 = Minutes, 1 = Seconds) */ write_io_cr(0xF1, new_units); } static inline void wdt_timeout_value(unsigned char new_timeout) { /* -- Watchdog Timer Time-out Value -- * Bit 0-7 Binary coded units (0=Disabled, 1..255) */ write_io_cr(0xF2, new_timeout); } static inline void wdt_timer_conf(unsigned char conf) { /* -- Watchdog timer configuration -- * Bit 0 Joystick enable: 0* = No Reset, 1 = Reset WDT upon * Gameport I/O * Bit 1 Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr. * Bit 2 Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr * Bit 3 Reset the timer * (Wrong in SMsC documentation? Given as: PowerLED Timout * Enabled) * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled, * 0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15) */ write_io_cr(0xF3, conf); } static inline void wdt_timer_ctrl(unsigned char reg) { /* -- Watchdog timer control -- * Bit 0 Status Bit: 0 = Timer counting, 1 = Timeout occurred * Bit 1 Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz * Bit 2 Force Timeout: 1 = Forces WD timeout event (self-cleaning) * Bit 3 P20 Force Timeout enabled: * 0 = P20 activity does not generate the WD timeout event * 1 = P20 Allows rising edge of P20, from the keyboard * controller, to force the WD timeout event. * Bit 4 (Reserved) * -- Soft power management -- * Bit 5 Stop Counter: 1 = Stop software power down counter * set via register 0xB8, (self-cleaning) * (Upon read: 0 = Counter running, 1 = Counter stopped) * Bit 6 Restart Counter: 1 = Restart software power down counter * set via register 0xB8, (self-cleaning) * Bit 7 SPOFF: 1 = Force software power down (self-cleaning) */ write_io_cr(0xF4, reg); } /* -- Higher level functions ------------------------------------*/ /* initialize watchdog */ static void wb_smsc_wdt_initialize(void) { unsigned char old; spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* enable the watchdog */ gpio_bit13(0x08); /* Select pin 80 = LED not GPIO */ gpio_bit12(0x0A); /* Set pin 79 = WDT not GPIO/Output/Polarity=Invert */ /* disable the timeout */ wdt_timeout_value(0); /* reset control register */ wdt_timer_ctrl(0x00); /* reset configuration register */ wdt_timer_conf(0x00); /* read old (timer units) register */ old = read_io_cr(0xF1) & 0x7F; if (unit == UNIT_SECOND) old |= 0x80; /* set to seconds */ /* set the watchdog timer units */ wdt_timer_units(old); close_io_config(); spin_unlock(&io_lock); } /* shutdown the watchdog */ static void wb_smsc_wdt_shutdown(void) { spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* disable the watchdog */ gpio_bit13(0x09); gpio_bit12(0x09); /* reset watchdog config register */ wdt_timer_conf(0x00); /* reset watchdog control register */ wdt_timer_ctrl(0x00); /* disable timeout */ wdt_timeout_value(0x00); close_io_config(); spin_unlock(&io_lock); } /* set timeout => enable watchdog */ static void wb_smsc_wdt_set_timeout(unsigned char new_timeout) { spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* set Power LED to blink, if we enable the timeout */ wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02); /* set timeout value */ wdt_timeout_value(new_timeout); close_io_config(); spin_unlock(&io_lock); } /* get timeout */ static unsigned char wb_smsc_wdt_get_timeout(void) { unsigned char set_timeout; spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); set_timeout = read_io_cr(0xF2); close_io_config(); spin_unlock(&io_lock); return set_timeout; } /* disable watchdog */ static void wb_smsc_wdt_disable(void) { /* set the timeout to 0 to disable the watchdog */ wb_smsc_wdt_set_timeout(0); } /* enable watchdog by setting the current timeout */ static void wb_smsc_wdt_enable(void) { /* set the current timeout... */ wb_smsc_wdt_set_timeout(timeout); } /* reset the timer */ static void wb_smsc_wdt_reset_timer(void) { spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* reset the timer */ wdt_timeout_value(timeout); wdt_timer_conf(0x08); close_io_config(); spin_unlock(&io_lock); } /* return, if the watchdog is enabled (timeout is set...) */ static int wb_smsc_wdt_status(void) { return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING; } /* -- File operations -------------------------------------------*/ /* open => enable watchdog and set initial timeout */ static int wb_smsc_wdt_open(struct inode *inode, struct file *file) { /* /dev/watchdog can only be opened once */ if (test_and_set_bit(0, &timer_enabled)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); /* Reload and activate timer */ wb_smsc_wdt_enable(); pr_info("Watchdog enabled. Timeout set to %d %s\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); return stream_open(inode, file); } /* close => shut off the timer */ static int wb_smsc_wdt_release(struct inode *inode, struct file *file) { /* Shut off the timer. */ if (expect_close == 42) { wb_smsc_wdt_disable(); pr_info("Watchdog disabled, sleeping again...\n"); } else { pr_crit("Unexpected close, not stopping watchdog!\n"); wb_smsc_wdt_reset_timer(); } clear_bit(0, &timer_enabled); expect_close = 0; return 0; } /* 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) { /* See if we got the magic character 'V' and reload the timer */ if (len) { if (!nowayout) { size_t i; /* reset expect flag */ expect_close = 0; /* scan to see whether or not we got the magic character */ for (i = 0; i != len; i++) { char c; if (get_user(c, data + i)) return -EFAULT; if (c == 'V') expect_close = 42; } } /* someone wrote to us, we should reload the timer */ wb_smsc_wdt_reset_timer(); } return len; } /* ioctl => control interface */ static long wb_smsc_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { int new_timeout; union { struct watchdog_info __user *ident; int __user *i; } uarg; static const struct watchdog_info ident = { .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, .firmware_version = 0, .identity = "SMsC 37B787 Watchdog", }; uarg.i = (int __user *)arg; switch (cmd) { case WDIOC_GETSUPPORT: return copy_to_user(uarg.ident, &ident, sizeof(ident)) ? -EFAULT : 0; case WDIOC_GETSTATUS: return put_user(wb_smsc_wdt_status(), uarg.i); case WDIOC_GETBOOTSTATUS: return put_user(0, uarg.i); case WDIOC_SETOPTIONS: { int options, retval = -EINVAL; if (get_user(options, uarg.i)) return -EFAULT; if (options & WDIOS_DISABLECARD) { wb_smsc_wdt_disable(); retval = 0; } if (options & WDIOS_ENABLECARD) { wb_smsc_wdt_enable(); retval = 0; } return retval; } case WDIOC_KEEPALIVE: wb_smsc_wdt_reset_timer(); return 0; case WDIOC_SETTIMEOUT: if (get_user(new_timeout, uarg.i)) return -EFAULT; /* the API states this is given in secs */ if (unit == UNIT_MINUTE) new_timeout /= 60; if (new_timeout < 0 || new_timeout > MAX_TIMEOUT) return -EINVAL; timeout = new_timeout; wb_smsc_wdt_set_timeout(timeout); fallthrough; /* and return the new timeout */ case WDIOC_GETTIMEOUT: new_timeout = timeout; if (unit == UNIT_MINUTE) new_timeout *= 60; return put_user(new_timeout, uarg.i); default: return -ENOTTY; } } /* -- Notifier funtions -----------------------------------------*/ static int wb_smsc_wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused) { if (code == SYS_DOWN || code == SYS_HALT) { /* set timeout to 0, to avoid possible race-condition */ timeout = 0; wb_smsc_wdt_disable(); } return NOTIFY_DONE; } /* -- Module's structures ---------------------------------------*/ static const struct file_operations wb_smsc_wdt_fops = { .owner = THIS_MODULE, .write = wb_smsc_wdt_write, .unlocked_ioctl = wb_smsc_wdt_ioctl, .compat_ioctl = compat_ptr_ioctl, .open = wb_smsc_wdt_open, .release = wb_smsc_wdt_release, }; static struct notifier_block wb_smsc_wdt_notifier = { .notifier_call = wb_smsc_wdt_notify_sys, }; static struct miscdevice wb_smsc_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &wb_smsc_wdt_fops, }; /* -- Module init functions -------------------------------------*/ /* module's "constructor" */ static int __init wb_smsc_wdt_init(void) { int ret; pr_info("SMsC 37B787 watchdog component driver " VERSION " initialising...\n"); if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) { pr_err("Unable to register IO port %#x\n", IOPORT); ret = -EBUSY; goto out_pnp; } /* set new maximum, if it's too big */ if (timeout > MAX_TIMEOUT) timeout = MAX_TIMEOUT; /* init the watchdog timer */ wb_smsc_wdt_initialize(); ret = register_reboot_notifier(&wb_smsc_wdt_notifier); if (ret) { pr_err("Unable to register reboot notifier err = %d\n", ret); goto out_io; } ret = misc_register(&wb_smsc_wdt_miscdev); if (ret) { pr_err("Unable to register miscdev on minor %d\n", WATCHDOG_MINOR); goto out_rbt; } /* output info */ pr_info("Timeout set to %d %s\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n", nowayout); out_clean: return ret; out_rbt: unregister_reboot_notifier(&wb_smsc_wdt_notifier); out_io: release_region(IOPORT, IOPORT_SIZE); out_pnp: goto out_clean; } /* module's "destructor" */ static void __exit wb_smsc_wdt_exit(void) { /* Stop the timer before we leave */ if (!nowayout) { wb_smsc_wdt_shutdown(); pr_info("Watchdog disabled\n"); } misc_deregister(&wb_smsc_wdt_miscdev); unregister_reboot_notifier(&wb_smsc_wdt_notifier); release_region(IOPORT, IOPORT_SIZE); pr_info("SMsC 37B787 watchdog component driver removed\n"); } module_init(wb_smsc_wdt_init); module_exit(wb_smsc_wdt_exit); MODULE_AUTHOR("Sven Anders "); MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version " VERSION ")"); MODULE_LICENSE("GPL"); #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(timeout, "range is 1-255 units, default is 60"); module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");