/* * Watchdog timer for PowerPC Book-E systems * * Author: Matthew McClintock * Maintainer: Kumar Gala <galak@kernel.crashing.org> * * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc. * * 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. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/smp.h> #include <linux/watchdog.h> #include <asm/reg_booke.h> #include <asm/time.h> #include <asm/div64.h> /* If the kernel parameter wdt=1, the watchdog will be enabled at boot. * Also, the wdt_period sets the watchdog timer period timeout. * For E500 cpus the wdt_period sets which bit changing from 0->1 will * trigger a watchog timeout. This watchdog timeout will occur 3 times, the * first time nothing will happen, the second time a watchdog exception will * occur, and the final time the board will reset. */ #ifdef CONFIG_PPC_FSL_BOOK3E #define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) #define WDTP_MASK (WDTP(0x3f)) #else #define WDTP(x) (TCR_WP(x)) #define WDTP_MASK (TCR_WP_MASK) #endif static bool booke_wdt_enabled; module_param(booke_wdt_enabled, bool, 0); static int booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT; module_param(booke_wdt_period, int, 0); #ifdef CONFIG_PPC_FSL_BOOK3E /* For the specified period, determine the number of seconds * corresponding to the reset time. There will be a watchdog * exception at approximately 3/5 of this time. * * The formula to calculate this is given by: * 2.5 * (2^(63-period+1)) / timebase_freq * * In order to simplify things, we assume that period is * at least 1. This will still result in a very long timeout. */ static unsigned long long period_to_sec(unsigned int period) { unsigned long long tmp = 1ULL << (64 - period); unsigned long tmp2 = ppc_tb_freq; /* tmp may be a very large number and we don't want to overflow, * so divide the timebase freq instead of multiplying tmp */ tmp2 = tmp2 / 5 * 2; do_div(tmp, tmp2); return tmp; } /* * This procedure will find the highest period which will give a timeout * greater than the one required. e.g. for a bus speed of 66666666 and * and a parameter of 2 secs, then this procedure will return a value of 38. */ static unsigned int sec_to_period(unsigned int secs) { unsigned int period; for (period = 63; period > 0; period--) { if (period_to_sec(period) >= secs) return period; } return 0; } #define MAX_WDT_TIMEOUT period_to_sec(1) #else /* CONFIG_PPC_FSL_BOOK3E */ static unsigned long long period_to_sec(unsigned int period) { return period; } static unsigned int sec_to_period(unsigned int secs) { return secs; } #define MAX_WDT_TIMEOUT 3 /* from Kconfig */ #endif /* !CONFIG_PPC_FSL_BOOK3E */ static void __booke_wdt_set(void *data) { u32 val; struct watchdog_device *wdog = data; val = mfspr(SPRN_TCR); val &= ~WDTP_MASK; val |= WDTP(sec_to_period(wdog->timeout)); mtspr(SPRN_TCR, val); } static void booke_wdt_set(void *data) { on_each_cpu(__booke_wdt_set, data, 0); } static void __booke_wdt_ping(void *data) { mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); } static int booke_wdt_ping(struct watchdog_device *wdog) { on_each_cpu(__booke_wdt_ping, NULL, 0); return 0; } static void __booke_wdt_enable(void *data) { u32 val; struct watchdog_device *wdog = data; /* clear status before enabling watchdog */ __booke_wdt_ping(NULL); val = mfspr(SPRN_TCR); val &= ~WDTP_MASK; val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(sec_to_period(wdog->timeout))); mtspr(SPRN_TCR, val); } /** * booke_wdt_disable - disable the watchdog on the given CPU * * This function is called on each CPU. It disables the watchdog on that CPU. * * TCR[WRC] cannot be changed once it has been set to non-zero, but we can * effectively disable the watchdog by setting its period to the maximum value. */ static void __booke_wdt_disable(void *data) { u32 val; val = mfspr(SPRN_TCR); val &= ~(TCR_WIE | WDTP_MASK); mtspr(SPRN_TCR, val); /* clear status to make sure nothing is pending */ __booke_wdt_ping(NULL); } static int booke_wdt_start(struct watchdog_device *wdog) { on_each_cpu(__booke_wdt_enable, wdog, 0); pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout); return 0; } static int booke_wdt_stop(struct watchdog_device *wdog) { on_each_cpu(__booke_wdt_disable, NULL, 0); pr_debug("watchdog disabled\n"); return 0; } static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev, unsigned int timeout) { wdt_dev->timeout = timeout; booke_wdt_set(wdt_dev); return 0; } static struct watchdog_info booke_wdt_info = { .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, .identity = "PowerPC Book-E Watchdog", }; static struct watchdog_ops booke_wdt_ops = { .owner = THIS_MODULE, .start = booke_wdt_start, .stop = booke_wdt_stop, .ping = booke_wdt_ping, .set_timeout = booke_wdt_set_timeout, }; static struct watchdog_device booke_wdt_dev = { .info = &booke_wdt_info, .ops = &booke_wdt_ops, .min_timeout = 1, }; static void __exit booke_wdt_exit(void) { watchdog_unregister_device(&booke_wdt_dev); } static int __init booke_wdt_init(void) { int ret = 0; bool nowayout = WATCHDOG_NOWAYOUT; pr_info("powerpc book-e watchdog driver loaded\n"); booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value; booke_wdt_set_timeout(&booke_wdt_dev, period_to_sec(booke_wdt_period)); watchdog_set_nowayout(&booke_wdt_dev, nowayout); booke_wdt_dev.max_timeout = MAX_WDT_TIMEOUT; if (booke_wdt_enabled) booke_wdt_start(&booke_wdt_dev); ret = watchdog_register_device(&booke_wdt_dev); return ret; } module_init(booke_wdt_init); module_exit(booke_wdt_exit); MODULE_ALIAS("booke_wdt"); MODULE_DESCRIPTION("PowerPC Book-E watchdog driver"); MODULE_LICENSE("GPL");