1/* 2 * Watchdog timer for PowerPC Book-E systems 3 * 4 * Author: Matthew McClintock 5 * Maintainer: Kumar Gala <galak@kernel.crashing.org> 6 * 7 * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc. 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License as published by the 11 * Free Software Foundation; either version 2 of the License, or (at your 12 * option) any later version. 13 */ 14 15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 16 17#include <linux/module.h> 18#include <linux/smp.h> 19#include <linux/watchdog.h> 20 21#include <asm/reg_booke.h> 22#include <asm/time.h> 23#include <asm/div64.h> 24 25/* If the kernel parameter wdt=1, the watchdog will be enabled at boot. 26 * Also, the wdt_period sets the watchdog timer period timeout. 27 * For E500 cpus the wdt_period sets which bit changing from 0->1 will 28 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the 29 * first time nothing will happen, the second time a watchdog exception will 30 * occur, and the final time the board will reset. 31 */ 32 33 34#ifdef CONFIG_PPC_FSL_BOOK3E 35#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) 36#define WDTP_MASK (WDTP(0x3f)) 37#else 38#define WDTP(x) (TCR_WP(x)) 39#define WDTP_MASK (TCR_WP_MASK) 40#endif 41 42static bool booke_wdt_enabled; 43module_param(booke_wdt_enabled, bool, 0); 44static int booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT; 45module_param(booke_wdt_period, int, 0); 46 47#ifdef CONFIG_PPC_FSL_BOOK3E 48 49/* For the specified period, determine the number of seconds 50 * corresponding to the reset time. There will be a watchdog 51 * exception at approximately 3/5 of this time. 52 * 53 * The formula to calculate this is given by: 54 * 2.5 * (2^(63-period+1)) / timebase_freq 55 * 56 * In order to simplify things, we assume that period is 57 * at least 1. This will still result in a very long timeout. 58 */ 59static unsigned long long period_to_sec(unsigned int period) 60{ 61 unsigned long long tmp = 1ULL << (64 - period); 62 unsigned long tmp2 = ppc_tb_freq; 63 64 /* tmp may be a very large number and we don't want to overflow, 65 * so divide the timebase freq instead of multiplying tmp 66 */ 67 tmp2 = tmp2 / 5 * 2; 68 69 do_div(tmp, tmp2); 70 return tmp; 71} 72 73/* 74 * This procedure will find the highest period which will give a timeout 75 * greater than the one required. e.g. for a bus speed of 66666666 and 76 * and a parameter of 2 secs, then this procedure will return a value of 38. 77 */ 78static unsigned int sec_to_period(unsigned int secs) 79{ 80 unsigned int period; 81 for (period = 63; period > 0; period--) { 82 if (period_to_sec(period) >= secs) 83 return period; 84 } 85 return 0; 86} 87 88#define MAX_WDT_TIMEOUT period_to_sec(1) 89 90#else /* CONFIG_PPC_FSL_BOOK3E */ 91 92static unsigned long long period_to_sec(unsigned int period) 93{ 94 return period; 95} 96 97static unsigned int sec_to_period(unsigned int secs) 98{ 99 return secs; 100} 101 102#define MAX_WDT_TIMEOUT 3 /* from Kconfig */ 103 104#endif /* !CONFIG_PPC_FSL_BOOK3E */ 105 106static void __booke_wdt_set(void *data) 107{ 108 u32 val; 109 struct watchdog_device *wdog = data; 110 111 val = mfspr(SPRN_TCR); 112 val &= ~WDTP_MASK; 113 val |= WDTP(sec_to_period(wdog->timeout)); 114 115 mtspr(SPRN_TCR, val); 116} 117 118static void booke_wdt_set(void *data) 119{ 120 on_each_cpu(__booke_wdt_set, data, 0); 121} 122 123static void __booke_wdt_ping(void *data) 124{ 125 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 126} 127 128static int booke_wdt_ping(struct watchdog_device *wdog) 129{ 130 on_each_cpu(__booke_wdt_ping, NULL, 0); 131 132 return 0; 133} 134 135static void __booke_wdt_enable(void *data) 136{ 137 u32 val; 138 struct watchdog_device *wdog = data; 139 140 /* clear status before enabling watchdog */ 141 __booke_wdt_ping(NULL); 142 val = mfspr(SPRN_TCR); 143 val &= ~WDTP_MASK; 144 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(sec_to_period(wdog->timeout))); 145 146 mtspr(SPRN_TCR, val); 147} 148 149/** 150 * booke_wdt_disable - disable the watchdog on the given CPU 151 * 152 * This function is called on each CPU. It disables the watchdog on that CPU. 153 * 154 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can 155 * effectively disable the watchdog by setting its period to the maximum value. 156 */ 157static void __booke_wdt_disable(void *data) 158{ 159 u32 val; 160 161 val = mfspr(SPRN_TCR); 162 val &= ~(TCR_WIE | WDTP_MASK); 163 mtspr(SPRN_TCR, val); 164 165 /* clear status to make sure nothing is pending */ 166 __booke_wdt_ping(NULL); 167 168} 169 170static int booke_wdt_start(struct watchdog_device *wdog) 171{ 172 on_each_cpu(__booke_wdt_enable, wdog, 0); 173 pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout); 174 175 return 0; 176} 177 178static int booke_wdt_stop(struct watchdog_device *wdog) 179{ 180 on_each_cpu(__booke_wdt_disable, NULL, 0); 181 pr_debug("watchdog disabled\n"); 182 183 return 0; 184} 185 186static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev, 187 unsigned int timeout) 188{ 189 if (timeout > MAX_WDT_TIMEOUT) 190 return -EINVAL; 191 wdt_dev->timeout = timeout; 192 booke_wdt_set(wdt_dev); 193 194 return 0; 195} 196 197static struct watchdog_info booke_wdt_info = { 198 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 199 .identity = "PowerPC Book-E Watchdog", 200}; 201 202static struct watchdog_ops booke_wdt_ops = { 203 .owner = THIS_MODULE, 204 .start = booke_wdt_start, 205 .stop = booke_wdt_stop, 206 .ping = booke_wdt_ping, 207 .set_timeout = booke_wdt_set_timeout, 208}; 209 210static struct watchdog_device booke_wdt_dev = { 211 .info = &booke_wdt_info, 212 .ops = &booke_wdt_ops, 213 .min_timeout = 1, 214 .max_timeout = 0xFFFF 215}; 216 217static void __exit booke_wdt_exit(void) 218{ 219 watchdog_unregister_device(&booke_wdt_dev); 220} 221 222static int __init booke_wdt_init(void) 223{ 224 int ret = 0; 225 bool nowayout = WATCHDOG_NOWAYOUT; 226 227 pr_info("powerpc book-e watchdog driver loaded\n"); 228 booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value; 229 booke_wdt_set_timeout(&booke_wdt_dev, 230 period_to_sec(booke_wdt_period)); 231 watchdog_set_nowayout(&booke_wdt_dev, nowayout); 232 if (booke_wdt_enabled) 233 booke_wdt_start(&booke_wdt_dev); 234 235 ret = watchdog_register_device(&booke_wdt_dev); 236 237 return ret; 238} 239 240module_init(booke_wdt_init); 241module_exit(booke_wdt_exit); 242 243MODULE_ALIAS("booke_wdt"); 244MODULE_DESCRIPTION("PowerPC Book-E watchdog driver"); 245MODULE_LICENSE("GPL"); 246