/* * drivers/watchdog/shwdt.c * * Watchdog driver for integrated watchdog in the SuperH processors. * * Copyright (C) 2001 - 2012 Paul Mundt <lethal@linux-sh.org> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. * * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT * * 19-Apr-2002 Rob Radez <rob@osinvestor.com> * Added expect close support, made emulated timeout runtime changeable * general cleanups, add some ioctls */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/platform_device.h> #include <linux/init.h> #include <linux/types.h> #include <linux/spinlock.h> #include <linux/watchdog.h> #include <linux/pm_runtime.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/slab.h> #include <linux/io.h> #include <linux/clk.h> #include <linux/err.h> #include <asm/watchdog.h> #define DRV_NAME "sh-wdt" /* * Default clock division ratio is 5.25 msecs. For an additional table of * values, consult the asm-sh/watchdog.h. Overload this at module load * time. * * In order for this to work reliably we need to have HZ set to 1000 or * something quite higher than 100 (or we need a proper high-res timer * implementation that will deal with this properly), otherwise the 10ms * resolution of a jiffy is enough to trigger the overflow. For things like * the SH-4 and SH-5, this isn't necessarily that big of a problem, though * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely * necssary. * * As a result of this timing problem, the only modes that are particularly * feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms * overflow periods respectively. * * Also, since we can't really expect userspace to be responsive enough * before the overflow happens, we maintain two separate timers .. One in * the kernel for clearing out WOVF every 2ms or so (again, this depends on * HZ == 1000), and another for monitoring userspace writes to the WDT device. * * As such, we currently use a configurable heartbeat interval which defaults * to 30s. In this case, the userspace daemon is only responsible for periodic * writes to the device before the next heartbeat is scheduled. If the daemon * misses its deadline, the kernel timer will allow the WDT to overflow. */ static int clock_division_ratio = WTCSR_CKS_4096; #define next_ping_period(cks) (jiffies + msecs_to_jiffies(cks - 4)) #define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */ static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */ static bool nowayout = WATCHDOG_NOWAYOUT; static unsigned long next_heartbeat; struct sh_wdt { void __iomem *base; struct device *dev; struct clk *clk; spinlock_t lock; struct timer_list timer; }; static int sh_wdt_start(struct watchdog_device *wdt_dev) { struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); unsigned long flags; u8 csr; pm_runtime_get_sync(wdt->dev); clk_enable(wdt->clk); spin_lock_irqsave(&wdt->lock, flags); next_heartbeat = jiffies + (heartbeat * HZ); mod_timer(&wdt->timer, next_ping_period(clock_division_ratio)); csr = sh_wdt_read_csr(); csr |= WTCSR_WT | clock_division_ratio; sh_wdt_write_csr(csr); sh_wdt_write_cnt(0); /* * These processors have a bit of an inconsistent initialization * process.. starting with SH-3, RSTS was moved to WTCSR, and the * RSTCSR register was removed. * * On the SH-2 however, in addition with bits being in different * locations, we must deal with RSTCSR outright.. */ csr = sh_wdt_read_csr(); csr |= WTCSR_TME; csr &= ~WTCSR_RSTS; sh_wdt_write_csr(csr); #ifdef CONFIG_CPU_SH2 csr = sh_wdt_read_rstcsr(); csr &= ~RSTCSR_RSTS; sh_wdt_write_rstcsr(csr); #endif spin_unlock_irqrestore(&wdt->lock, flags); return 0; } static int sh_wdt_stop(struct watchdog_device *wdt_dev) { struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); unsigned long flags; u8 csr; spin_lock_irqsave(&wdt->lock, flags); del_timer(&wdt->timer); csr = sh_wdt_read_csr(); csr &= ~WTCSR_TME; sh_wdt_write_csr(csr); spin_unlock_irqrestore(&wdt->lock, flags); clk_disable(wdt->clk); pm_runtime_put_sync(wdt->dev); return 0; } static int sh_wdt_keepalive(struct watchdog_device *wdt_dev) { struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); unsigned long flags; spin_lock_irqsave(&wdt->lock, flags); next_heartbeat = jiffies + (heartbeat * HZ); spin_unlock_irqrestore(&wdt->lock, flags); return 0; } static int sh_wdt_set_heartbeat(struct watchdog_device *wdt_dev, unsigned t) { struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); unsigned long flags; if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */ return -EINVAL; spin_lock_irqsave(&wdt->lock, flags); heartbeat = t; wdt_dev->timeout = t; spin_unlock_irqrestore(&wdt->lock, flags); return 0; } static void sh_wdt_ping(unsigned long data) { struct sh_wdt *wdt = (struct sh_wdt *)data; unsigned long flags; spin_lock_irqsave(&wdt->lock, flags); if (time_before(jiffies, next_heartbeat)) { u8 csr; csr = sh_wdt_read_csr(); csr &= ~WTCSR_IOVF; sh_wdt_write_csr(csr); sh_wdt_write_cnt(0); mod_timer(&wdt->timer, next_ping_period(clock_division_ratio)); } else dev_warn(wdt->dev, "Heartbeat lost! Will not ping " "the watchdog\n"); spin_unlock_irqrestore(&wdt->lock, flags); } static const struct watchdog_info sh_wdt_info = { .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, .firmware_version = 1, .identity = "SH WDT", }; static const struct watchdog_ops sh_wdt_ops = { .owner = THIS_MODULE, .start = sh_wdt_start, .stop = sh_wdt_stop, .ping = sh_wdt_keepalive, .set_timeout = sh_wdt_set_heartbeat, }; static struct watchdog_device sh_wdt_dev = { .info = &sh_wdt_info, .ops = &sh_wdt_ops, }; static int sh_wdt_probe(struct platform_device *pdev) { struct sh_wdt *wdt; struct resource *res; int rc; /* * As this driver only covers the global watchdog case, reject * any attempts to register per-CPU watchdogs. */ if (pdev->id != -1) return -EINVAL; wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL); if (unlikely(!wdt)) return -ENOMEM; wdt->dev = &pdev->dev; wdt->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(wdt->clk)) { /* * Clock framework support is optional, continue on * anyways if we don't find a matching clock. */ wdt->clk = NULL; } res = platform_get_resource(pdev, IORESOURCE_MEM, 0); wdt->base = devm_ioremap_resource(wdt->dev, res); if (IS_ERR(wdt->base)) return PTR_ERR(wdt->base); watchdog_set_nowayout(&sh_wdt_dev, nowayout); watchdog_set_drvdata(&sh_wdt_dev, wdt); sh_wdt_dev.parent = &pdev->dev; spin_lock_init(&wdt->lock); rc = sh_wdt_set_heartbeat(&sh_wdt_dev, heartbeat); if (unlikely(rc)) { /* Default timeout if invalid */ sh_wdt_set_heartbeat(&sh_wdt_dev, WATCHDOG_HEARTBEAT); dev_warn(&pdev->dev, "heartbeat value must be 1<=x<=3600, using %d\n", sh_wdt_dev.timeout); } dev_info(&pdev->dev, "configured with heartbeat=%d sec (nowayout=%d)\n", sh_wdt_dev.timeout, nowayout); rc = watchdog_register_device(&sh_wdt_dev); if (unlikely(rc)) { dev_err(&pdev->dev, "Can't register watchdog (err=%d)\n", rc); return rc; } init_timer(&wdt->timer); wdt->timer.function = sh_wdt_ping; wdt->timer.data = (unsigned long)wdt; wdt->timer.expires = next_ping_period(clock_division_ratio); dev_info(&pdev->dev, "initialized.\n"); pm_runtime_enable(&pdev->dev); return 0; } static int sh_wdt_remove(struct platform_device *pdev) { watchdog_unregister_device(&sh_wdt_dev); pm_runtime_disable(&pdev->dev); return 0; } static void sh_wdt_shutdown(struct platform_device *pdev) { sh_wdt_stop(&sh_wdt_dev); } static struct platform_driver sh_wdt_driver = { .driver = { .name = DRV_NAME, }, .probe = sh_wdt_probe, .remove = sh_wdt_remove, .shutdown = sh_wdt_shutdown, }; static int __init sh_wdt_init(void) { if (unlikely(clock_division_ratio < 0x5 || clock_division_ratio > 0x7)) { clock_division_ratio = WTCSR_CKS_4096; pr_info("divisor must be 0x5<=x<=0x7, using %d\n", clock_division_ratio); } return platform_driver_register(&sh_wdt_driver); } static void __exit sh_wdt_exit(void) { platform_driver_unregister(&sh_wdt_driver); } module_init(sh_wdt_init); module_exit(sh_wdt_exit); MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); MODULE_DESCRIPTION("SuperH watchdog driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:" DRV_NAME); module_param(clock_division_ratio, int, 0); MODULE_PARM_DESC(clock_division_ratio, "Clock division ratio. Valid ranges are from 0x5 (1.31ms) " "to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")"); module_param(heartbeat, int, 0); MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")"); module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");