// SPDX-License-Identifier: GPL-2.0+ /* * Driver for the MTX-1 Watchdog. * * (C) Copyright 2005 4G Systems <info@4g-systems.biz>, * All Rights Reserved. * http://www.4g-systems.biz * * (C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org> * (c) Copyright 2005 4G Systems <info@4g-systems.biz> * * Release 0.01. * Author: Michael Stickel michael.stickel@4g-systems.biz * * Release 0.02. * Author: Florian Fainelli florian@openwrt.org * use the Linux watchdog/timer APIs * * The Watchdog is configured to reset the MTX-1 * if it is not triggered for 100 seconds. * It should not be triggered more often than 1.6 seconds. * * A timer triggers the watchdog every 5 seconds, until * it is opened for the first time. After the first open * it MUST be triggered every 2..95 seconds. */ #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/types.h> #include <linux/errno.h> #include <linux/miscdevice.h> #include <linux/fs.h> #include <linux/ioport.h> #include <linux/timer.h> #include <linux/completion.h> #include <linux/jiffies.h> #include <linux/watchdog.h> #include <linux/platform_device.h> #include <linux/io.h> #include <linux/uaccess.h> #include <linux/gpio/consumer.h> #define MTX1_WDT_INTERVAL (5 * HZ) static int ticks = 100 * HZ; static struct { struct completion stop; spinlock_t lock; int running; struct timer_list timer; int queue; int default_ticks; unsigned long inuse; struct gpio_desc *gpiod; unsigned int gstate; } mtx1_wdt_device; static void mtx1_wdt_trigger(struct timer_list *unused) { spin_lock(&mtx1_wdt_device.lock); if (mtx1_wdt_device.running) ticks--; /* toggle wdt gpio */ mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate; gpiod_set_value(mtx1_wdt_device.gpiod, mtx1_wdt_device.gstate); if (mtx1_wdt_device.queue && ticks) mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL); else complete(&mtx1_wdt_device.stop); spin_unlock(&mtx1_wdt_device.lock); } static void mtx1_wdt_reset(void) { ticks = mtx1_wdt_device.default_ticks; } static void mtx1_wdt_start(void) { unsigned long flags; spin_lock_irqsave(&mtx1_wdt_device.lock, flags); if (!mtx1_wdt_device.queue) { mtx1_wdt_device.queue = 1; mtx1_wdt_device.gstate = 1; gpiod_set_value(mtx1_wdt_device.gpiod, 1); mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL); } mtx1_wdt_device.running++; spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags); } static int mtx1_wdt_stop(void) { unsigned long flags; spin_lock_irqsave(&mtx1_wdt_device.lock, flags); if (mtx1_wdt_device.queue) { mtx1_wdt_device.queue = 0; mtx1_wdt_device.gstate = 0; gpiod_set_value(mtx1_wdt_device.gpiod, 0); } ticks = mtx1_wdt_device.default_ticks; spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags); return 0; } /* Filesystem functions */ static int mtx1_wdt_open(struct inode *inode, struct file *file) { if (test_and_set_bit(0, &mtx1_wdt_device.inuse)) return -EBUSY; return stream_open(inode, file); } static int mtx1_wdt_release(struct inode *inode, struct file *file) { clear_bit(0, &mtx1_wdt_device.inuse); return 0; } static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { void __user *argp = (void __user *)arg; int __user *p = (int __user *)argp; unsigned int value; static const struct watchdog_info ident = { .options = WDIOF_CARDRESET, .identity = "MTX-1 WDT", }; switch (cmd) { case WDIOC_GETSUPPORT: if (copy_to_user(argp, &ident, sizeof(ident))) return -EFAULT; break; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: put_user(0, p); break; case WDIOC_SETOPTIONS: if (get_user(value, p)) return -EFAULT; if (value & WDIOS_ENABLECARD) mtx1_wdt_start(); else if (value & WDIOS_DISABLECARD) mtx1_wdt_stop(); else return -EINVAL; return 0; case WDIOC_KEEPALIVE: mtx1_wdt_reset(); break; default: return -ENOTTY; } return 0; } static ssize_t mtx1_wdt_write(struct file *file, const char *buf, size_t count, loff_t *ppos) { if (!count) return -EIO; mtx1_wdt_reset(); return count; } static const struct file_operations mtx1_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .unlocked_ioctl = mtx1_wdt_ioctl, .compat_ioctl = compat_ptr_ioctl, .open = mtx1_wdt_open, .write = mtx1_wdt_write, .release = mtx1_wdt_release, }; static struct miscdevice mtx1_wdt_misc = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &mtx1_wdt_fops, }; static int mtx1_wdt_probe(struct platform_device *pdev) { int ret; mtx1_wdt_device.gpiod = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_HIGH); if (IS_ERR(mtx1_wdt_device.gpiod)) { dev_err(&pdev->dev, "failed to request gpio"); return PTR_ERR(mtx1_wdt_device.gpiod); } spin_lock_init(&mtx1_wdt_device.lock); init_completion(&mtx1_wdt_device.stop); mtx1_wdt_device.queue = 0; clear_bit(0, &mtx1_wdt_device.inuse); timer_setup(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0); mtx1_wdt_device.default_ticks = ticks; ret = misc_register(&mtx1_wdt_misc); if (ret < 0) { dev_err(&pdev->dev, "failed to register\n"); return ret; } mtx1_wdt_start(); dev_info(&pdev->dev, "MTX-1 Watchdog driver\n"); return 0; } static void mtx1_wdt_remove(struct platform_device *pdev) { /* FIXME: do we need to lock this test ? */ if (mtx1_wdt_device.queue) { mtx1_wdt_device.queue = 0; wait_for_completion(&mtx1_wdt_device.stop); } misc_deregister(&mtx1_wdt_misc); } static struct platform_driver mtx1_wdt_driver = { .probe = mtx1_wdt_probe, .remove_new = mtx1_wdt_remove, .driver.name = "mtx1-wdt", }; module_platform_driver(mtx1_wdt_driver); MODULE_AUTHOR("Michael Stickel, Florian Fainelli"); MODULE_DESCRIPTION("Driver for the MTX-1 watchdog"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:mtx1-wdt");