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 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#include <linux/module.h> 16#include <linux/fs.h> 17#include <linux/smp.h> 18#include <linux/miscdevice.h> 19#include <linux/notifier.h> 20#include <linux/watchdog.h> 21#include <linux/uaccess.h> 22 23#include <asm/reg_booke.h> 24#include <asm/system.h> 25#include <asm/time.h> 26#include <asm/div64.h> 27 28/* If the kernel parameter wdt=1, the watchdog will be enabled at boot. 29 * Also, the wdt_period sets the watchdog timer period timeout. 30 * For E500 cpus the wdt_period sets which bit changing from 0->1 will 31 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the 32 * first time nothing will happen, the second time a watchdog exception will 33 * occur, and the final time the board will reset. 34 */ 35 36#ifdef CONFIG_FSL_BOOKE 37#define WDT_PERIOD_DEFAULT 38 /* Ex. wdt_period=28 bus=333Mhz,reset=~40sec */ 38#else 39#define WDT_PERIOD_DEFAULT 3 /* Refer to the PPC40x and PPC4xx manuals */ 40#endif /* for timing information */ 41 42u32 booke_wdt_enabled; 43u32 booke_wdt_period = WDT_PERIOD_DEFAULT; 44 45#ifdef CONFIG_FSL_BOOKE 46#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) 47#define WDTP_MASK (WDTP(0x3f)) 48#else 49#define WDTP(x) (TCR_WP(x)) 50#define WDTP_MASK (TCR_WP_MASK) 51#endif 52 53static DEFINE_SPINLOCK(booke_wdt_lock); 54 55/* For the specified period, determine the number of seconds 56 * corresponding to the reset time. There will be a watchdog 57 * exception at approximately 3/5 of this time. 58 * 59 * The formula to calculate this is given by: 60 * 2.5 * (2^(63-period+1)) / timebase_freq 61 * 62 * In order to simplify things, we assume that period is 63 * at least 1. This will still result in a very long timeout. 64 */ 65static unsigned long long period_to_sec(unsigned int period) 66{ 67 unsigned long long tmp = 1ULL << (64 - period); 68 unsigned long tmp2 = ppc_tb_freq; 69 70 /* tmp may be a very large number and we don't want to overflow, 71 * so divide the timebase freq instead of multiplying tmp 72 */ 73 tmp2 = tmp2 / 5 * 2; 74 75 do_div(tmp, tmp2); 76 return tmp; 77} 78 79/* 80 * This procedure will find the highest period which will give a timeout 81 * greater than the one required. e.g. for a bus speed of 66666666 and 82 * and a parameter of 2 secs, then this procedure will return a value of 38. 83 */ 84static unsigned int sec_to_period(unsigned int secs) 85{ 86 unsigned int period; 87 for (period = 63; period > 0; period--) { 88 if (period_to_sec(period) >= secs) 89 return period; 90 } 91 return 0; 92} 93 94static void __booke_wdt_ping(void *data) 95{ 96 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 97} 98 99static void booke_wdt_ping(void) 100{ 101 on_each_cpu(__booke_wdt_ping, NULL, 0); 102} 103 104static void __booke_wdt_enable(void *data) 105{ 106 u32 val; 107 108 /* clear status before enabling watchdog */ 109 __booke_wdt_ping(NULL); 110 val = mfspr(SPRN_TCR); 111 val &= ~WDTP_MASK; 112 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period)); 113 114 mtspr(SPRN_TCR, val); 115} 116 117static ssize_t booke_wdt_write(struct file *file, const char __user *buf, 118 size_t count, loff_t *ppos) 119{ 120 booke_wdt_ping(); 121 return count; 122} 123 124static struct watchdog_info ident = { 125 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 126 .identity = "PowerPC Book-E Watchdog", 127}; 128 129static long booke_wdt_ioctl(struct file *file, 130 unsigned int cmd, unsigned long arg) 131{ 132 u32 tmp = 0; 133 u32 __user *p = (u32 __user *)arg; 134 135 switch (cmd) { 136 case WDIOC_GETSUPPORT: 137 if (copy_to_user((void *)arg, &ident, sizeof(ident))) 138 return -EFAULT; 139 case WDIOC_GETSTATUS: 140 return put_user(0, p); 141 case WDIOC_GETBOOTSTATUS: 142 tmp = mfspr(SPRN_TSR) & TSR_WRS(3); 143 /* returns CARDRESET if last reset was caused by the WDT */ 144 return (tmp ? WDIOF_CARDRESET : 0); 145 case WDIOC_SETOPTIONS: 146 if (get_user(tmp, p)) 147 return -EINVAL; 148 if (tmp == WDIOS_ENABLECARD) { 149 booke_wdt_ping(); 150 break; 151 } else 152 return -EINVAL; 153 return 0; 154 case WDIOC_KEEPALIVE: 155 booke_wdt_ping(); 156 return 0; 157 case WDIOC_SETTIMEOUT: 158 if (get_user(tmp, p)) 159 return -EFAULT; 160#ifdef CONFIG_FSL_BOOKE 161 /* period of 1 gives the largest possible timeout */ 162 if (tmp > period_to_sec(1)) 163 return -EINVAL; 164 booke_wdt_period = sec_to_period(tmp); 165#else 166 booke_wdt_period = tmp; 167#endif 168 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP_MASK) | 169 WDTP(booke_wdt_period)); 170 return 0; 171 case WDIOC_GETTIMEOUT: 172 return put_user(booke_wdt_period, p); 173 default: 174 return -ENOTTY; 175 } 176 177 return 0; 178} 179 180static int booke_wdt_open(struct inode *inode, struct file *file) 181{ 182 spin_lock(&booke_wdt_lock); 183 if (booke_wdt_enabled == 0) { 184 booke_wdt_enabled = 1; 185 on_each_cpu(__booke_wdt_enable, NULL, 0); 186 printk(KERN_INFO 187 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 188 booke_wdt_period); 189 } 190 spin_unlock(&booke_wdt_lock); 191 192 return nonseekable_open(inode, file); 193} 194 195static const struct file_operations booke_wdt_fops = { 196 .owner = THIS_MODULE, 197 .llseek = no_llseek, 198 .write = booke_wdt_write, 199 .unlocked_ioctl = booke_wdt_ioctl, 200 .open = booke_wdt_open, 201}; 202 203static struct miscdevice booke_wdt_miscdev = { 204 .minor = WATCHDOG_MINOR, 205 .name = "watchdog", 206 .fops = &booke_wdt_fops, 207}; 208 209static void __exit booke_wdt_exit(void) 210{ 211 misc_deregister(&booke_wdt_miscdev); 212} 213 214static int __init booke_wdt_init(void) 215{ 216 int ret = 0; 217 218 printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n"); 219 ident.firmware_version = cur_cpu_spec->pvr_value; 220 221 ret = misc_register(&booke_wdt_miscdev); 222 if (ret) { 223 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n", 224 WATCHDOG_MINOR, ret); 225 return ret; 226 } 227 228 spin_lock(&booke_wdt_lock); 229 if (booke_wdt_enabled == 1) { 230 printk(KERN_INFO 231 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 232 booke_wdt_period); 233 on_each_cpu(__booke_wdt_enable, NULL, 0); 234 } 235 spin_unlock(&booke_wdt_lock); 236 237 return ret; 238} 239device_initcall(booke_wdt_init); 240