diff options
Diffstat (limited to 'drivers/watchdog/scx200_wdt.c')
| -rw-r--r-- | drivers/watchdog/scx200_wdt.c | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/drivers/watchdog/scx200_wdt.c b/drivers/watchdog/scx200_wdt.c new file mode 100644 index 000000000..7b5e18323 --- /dev/null +++ b/drivers/watchdog/scx200_wdt.c @@ -0,0 +1,263 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* drivers/char/watchdog/scx200_wdt.c + + National Semiconductor SCx200 Watchdog support + + Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> + + Some code taken from: + National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver + (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com> + + + The author(s) of this software shall not be held liable for damages + of any nature resulting due to the use of this software. This + software is provided AS-IS with no warranties. */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/init.h> +#include <linux/miscdevice.h> +#include <linux/watchdog.h> +#include <linux/notifier.h> +#include <linux/reboot.h> +#include <linux/fs.h> +#include <linux/ioport.h> +#include <linux/scx200.h> +#include <linux/uaccess.h> +#include <linux/io.h> + +#define DEBUG + +MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>"); +MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver"); +MODULE_LICENSE("GPL"); + +static int margin = 60; /* in seconds */ +module_param(margin, int, 0); +MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); + +static bool nowayout = WATCHDOG_NOWAYOUT; +module_param(nowayout, bool, 0); +MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); + +static u16 wdto_restart; +static char expect_close; +static unsigned long open_lock; +static DEFINE_SPINLOCK(scx_lock); + +/* Bits of the WDCNFG register */ +#define W_ENABLE 0x00fa /* Enable watchdog */ +#define W_DISABLE 0x0000 /* Disable watchdog */ + +/* The scaling factor for the timer, this depends on the value of W_ENABLE */ +#define W_SCALE (32768/1024) + +static void scx200_wdt_ping(void) +{ + spin_lock(&scx_lock); + outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO); + spin_unlock(&scx_lock); +} + +static void scx200_wdt_update_margin(void) +{ + pr_info("timer margin %d seconds\n", margin); + wdto_restart = margin * W_SCALE; +} + +static void scx200_wdt_enable(void) +{ + pr_debug("enabling watchdog timer, wdto_restart = %d\n", wdto_restart); + + spin_lock(&scx_lock); + outw(0, scx200_cb_base + SCx200_WDT_WDTO); + outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); + outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG); + spin_unlock(&scx_lock); + + scx200_wdt_ping(); +} + +static void scx200_wdt_disable(void) +{ + pr_debug("disabling watchdog timer\n"); + + spin_lock(&scx_lock); + outw(0, scx200_cb_base + SCx200_WDT_WDTO); + outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); + outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG); + spin_unlock(&scx_lock); +} + +static int scx200_wdt_open(struct inode *inode, struct file *file) +{ + /* only allow one at a time */ + if (test_and_set_bit(0, &open_lock)) + return -EBUSY; + scx200_wdt_enable(); + + return stream_open(inode, file); +} + +static int scx200_wdt_release(struct inode *inode, struct file *file) +{ + if (expect_close != 42) + pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n"); + else if (!nowayout) + scx200_wdt_disable(); + expect_close = 0; + clear_bit(0, &open_lock); + + return 0; +} + +static int scx200_wdt_notify_sys(struct notifier_block *this, + unsigned long code, void *unused) +{ + if (code == SYS_HALT || code == SYS_POWER_OFF) + if (!nowayout) + scx200_wdt_disable(); + + return NOTIFY_DONE; +} + +static struct notifier_block scx200_wdt_notifier = { + .notifier_call = scx200_wdt_notify_sys, +}; + +static ssize_t scx200_wdt_write(struct file *file, const char __user *data, + size_t len, loff_t *ppos) +{ + /* check for a magic close character */ + if (len) { + size_t i; + + scx200_wdt_ping(); + + expect_close = 0; + for (i = 0; i < len; ++i) { + char c; + if (get_user(c, data + i)) + return -EFAULT; + if (c == 'V') + expect_close = 42; + } + + return len; + } + + return 0; +} + +static long scx200_wdt_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + void __user *argp = (void __user *)arg; + int __user *p = argp; + static const struct watchdog_info ident = { + .identity = "NatSemi SCx200 Watchdog", + .firmware_version = 1, + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | + WDIOF_MAGICCLOSE, + }; + int new_margin; + + switch (cmd) { + case WDIOC_GETSUPPORT: + if (copy_to_user(argp, &ident, sizeof(ident))) + return -EFAULT; + return 0; + case WDIOC_GETSTATUS: + case WDIOC_GETBOOTSTATUS: + if (put_user(0, p)) + return -EFAULT; + return 0; + case WDIOC_KEEPALIVE: + scx200_wdt_ping(); + return 0; + case WDIOC_SETTIMEOUT: + if (get_user(new_margin, p)) + return -EFAULT; + if (new_margin < 1) + return -EINVAL; + margin = new_margin; + scx200_wdt_update_margin(); + scx200_wdt_ping(); + fallthrough; + case WDIOC_GETTIMEOUT: + if (put_user(margin, p)) + return -EFAULT; + return 0; + default: + return -ENOTTY; + } +} + +static const struct file_operations scx200_wdt_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .write = scx200_wdt_write, + .unlocked_ioctl = scx200_wdt_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .open = scx200_wdt_open, + .release = scx200_wdt_release, +}; + +static struct miscdevice scx200_wdt_miscdev = { + .minor = WATCHDOG_MINOR, + .name = "watchdog", + .fops = &scx200_wdt_fops, +}; + +static int __init scx200_wdt_init(void) +{ + int r; + + pr_debug("NatSemi SCx200 Watchdog Driver\n"); + + /* check that we have found the configuration block */ + if (!scx200_cb_present()) + return -ENODEV; + + if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET, + SCx200_WDT_SIZE, + "NatSemi SCx200 Watchdog")) { + pr_warn("watchdog I/O region busy\n"); + return -EBUSY; + } + + scx200_wdt_update_margin(); + scx200_wdt_disable(); + + r = register_reboot_notifier(&scx200_wdt_notifier); + if (r) { + pr_err("unable to register reboot notifier\n"); + release_region(scx200_cb_base + SCx200_WDT_OFFSET, + SCx200_WDT_SIZE); + return r; + } + + r = misc_register(&scx200_wdt_miscdev); + if (r) { + unregister_reboot_notifier(&scx200_wdt_notifier); + release_region(scx200_cb_base + SCx200_WDT_OFFSET, + SCx200_WDT_SIZE); + return r; + } + + return 0; +} + +static void __exit scx200_wdt_cleanup(void) +{ + misc_deregister(&scx200_wdt_miscdev); + unregister_reboot_notifier(&scx200_wdt_notifier); + release_region(scx200_cb_base + SCx200_WDT_OFFSET, + SCx200_WDT_SIZE); +} + +module_init(scx200_wdt_init); +module_exit(scx200_wdt_cleanup); |