// SPDX-License-Identifier: GPL-2.0+ /* * IB700 Single Board Computer WDT driver * * (c) Copyright 2001 Charles Howes * * Based on advantechwdt.c which is based on acquirewdt.c which * is based on wdt.c. * * (c) Copyright 2000-2001 Marek Michalkiewicz * * Based on acquirewdt.c which is based on wdt.c. * Original copyright messages: * * (c) Copyright 1996 Alan Cox , * All Rights Reserved. * * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide * warranty for any of this software. This material is provided * "AS-IS" and at no charge. * * (c) Copyright 1995 Alan Cox * * 14-Dec-2001 Matt Domsch * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT * Added timeout module option to override default * */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include static struct platform_device *ibwdt_platform_device; static unsigned long ibwdt_is_open; static DEFINE_SPINLOCK(ibwdt_lock); static char expect_close; /* Module information */ #define DRV_NAME "ib700wdt" /* * * Watchdog Timer Configuration * * The function of the watchdog timer is to reset the system * automatically and is defined at I/O port 0443H. To enable the * watchdog timer and allow the system to reset, write I/O port 0443H. * To disable the timer, write I/O port 0441H for the system to stop the * watchdog function. The timer has a tolerance of 20% for its * intervals. * * The following describes how the timer should be programmed. * * Enabling Watchdog: * MOV AX,000FH (Choose the values from 0 to F) * MOV DX,0443H * OUT DX,AX * * Disabling Watchdog: * MOV AX,000FH (Any value is fine.) * MOV DX,0441H * OUT DX,AX * * Watchdog timer control table: * Level Value Time/sec | Level Value Time/sec * 1 F 0 | 9 7 16 * 2 E 2 | 10 6 18 * 3 D 4 | 11 5 20 * 4 C 6 | 12 4 22 * 5 B 8 | 13 3 24 * 6 A 10 | 14 2 26 * 7 9 12 | 15 1 28 * 8 8 14 | 16 0 30 * */ #define WDT_STOP 0x441 #define WDT_START 0x443 /* Default timeout */ #define WATCHDOG_TIMEOUT 30 /* 30 seconds +/- 20% */ static int timeout = WATCHDOG_TIMEOUT; /* in seconds */ module_param(timeout, int, 0); MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. 0<= timeout <=30, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) "."); static bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); /* * Watchdog Operations */ static void ibwdt_ping(void) { int wd_margin = 15 - ((timeout + 1) / 2); spin_lock(&ibwdt_lock); /* Write a watchdog value */ outb_p(wd_margin, WDT_START); spin_unlock(&ibwdt_lock); } static void ibwdt_disable(void) { spin_lock(&ibwdt_lock); outb_p(0, WDT_STOP); spin_unlock(&ibwdt_lock); } static int ibwdt_set_heartbeat(int t) { if (t < 0 || t > 30) return -EINVAL; timeout = t; return 0; } /* * /dev/watchdog handling */ static ssize_t ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { if (count) { if (!nowayout) { size_t i; /* In case it was set long ago */ expect_close = 0; for (i = 0; i != count; i++) { char c; if (get_user(c, buf + i)) return -EFAULT; if (c == 'V') expect_close = 42; } } ibwdt_ping(); } return count; } static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { int new_margin; void __user *argp = (void __user *)arg; int __user *p = argp; static const struct watchdog_info ident = { .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, .firmware_version = 1, .identity = "IB700 WDT", }; switch (cmd) { case WDIOC_GETSUPPORT: if (copy_to_user(argp, &ident, sizeof(ident))) return -EFAULT; break; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: return put_user(0, p); case WDIOC_SETOPTIONS: { int options, retval = -EINVAL; if (get_user(options, p)) return -EFAULT; if (options & WDIOS_DISABLECARD) { ibwdt_disable(); retval = 0; } if (options & WDIOS_ENABLECARD) { ibwdt_ping(); retval = 0; } return retval; } case WDIOC_KEEPALIVE: ibwdt_ping(); break; case WDIOC_SETTIMEOUT: if (get_user(new_margin, p)) return -EFAULT; if (ibwdt_set_heartbeat(new_margin)) return -EINVAL; ibwdt_ping(); fallthrough; case WDIOC_GETTIMEOUT: return put_user(timeout, p); default: return -ENOTTY; } return 0; } static int ibwdt_open(struct inode *inode, struct file *file) { if (test_and_set_bit(0, &ibwdt_is_open)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); /* Activate */ ibwdt_ping(); return stream_open(inode, file); } static int ibwdt_close(struct inode *inode, struct file *file) { if (expect_close == 42) { ibwdt_disable(); } else { pr_crit("WDT device closed unexpectedly. WDT will not stop!\n"); ibwdt_ping(); } clear_bit(0, &ibwdt_is_open); expect_close = 0; return 0; } /* * Kernel Interfaces */ static const struct file_operations ibwdt_fops = { .owner = THIS_MODULE, .write = ibwdt_write, .unlocked_ioctl = ibwdt_ioctl, .compat_ioctl = compat_ptr_ioctl, .open = ibwdt_open, .release = ibwdt_close, }; static struct miscdevice ibwdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &ibwdt_fops, }; /* * Init & exit routines */ static int __init ibwdt_probe(struct platform_device *dev) { int res; #if WDT_START != WDT_STOP if (!request_region(WDT_STOP, 1, "IB700 WDT")) { pr_err("STOP method I/O %X is not available\n", WDT_STOP); res = -EIO; goto out_nostopreg; } #endif if (!request_region(WDT_START, 1, "IB700 WDT")) { pr_err("START method I/O %X is not available\n", WDT_START); res = -EIO; goto out_nostartreg; } /* Check that the heartbeat value is within it's range ; * if not reset to the default */ if (ibwdt_set_heartbeat(timeout)) { ibwdt_set_heartbeat(WATCHDOG_TIMEOUT); pr_info("timeout value must be 0<=x<=30, using %d\n", timeout); } res = misc_register(&ibwdt_miscdev); if (res) { pr_err("failed to register misc device\n"); goto out_nomisc; } return 0; out_nomisc: release_region(WDT_START, 1); out_nostartreg: #if WDT_START != WDT_STOP release_region(WDT_STOP, 1); #endif out_nostopreg: return res; } static void ibwdt_remove(struct platform_device *dev) { misc_deregister(&ibwdt_miscdev); release_region(WDT_START, 1); #if WDT_START != WDT_STOP release_region(WDT_STOP, 1); #endif } static void ibwdt_shutdown(struct platform_device *dev) { /* Turn the WDT off if we have a soft shutdown */ ibwdt_disable(); } static struct platform_driver ibwdt_driver = { .remove_new = ibwdt_remove, .shutdown = ibwdt_shutdown, .driver = { .name = DRV_NAME, }, }; static int __init ibwdt_init(void) { int err; pr_info("WDT driver for IB700 single board computer initialising\n"); ibwdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0); if (IS_ERR(ibwdt_platform_device)) return PTR_ERR(ibwdt_platform_device); err = platform_driver_probe(&ibwdt_driver, ibwdt_probe); if (err) goto unreg_platform_device; return 0; unreg_platform_device: platform_device_unregister(ibwdt_platform_device); return err; } static void __exit ibwdt_exit(void) { platform_device_unregister(ibwdt_platform_device); platform_driver_unregister(&ibwdt_driver); pr_info("Watchdog Module Unloaded\n"); } module_init(ibwdt_init); module_exit(ibwdt_exit); MODULE_AUTHOR("Charles Howes "); MODULE_DESCRIPTION("IB700 SBC watchdog driver"); MODULE_LICENSE("GPL"); /* end of ib700wdt.c */