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 42 u32 booke_wdt_enabled; 43 u32 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(0)) 48 #else 49 #define WDTP(x) (TCR_WP(x)) 50 #define WDTP_MASK (TCR_WP_MASK) 51 #endif 52 53 static 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 */ 65 static 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 */ 84 static 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 94 static void __booke_wdt_ping(void *data) 95 { 96 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 97 } 98 99 static void booke_wdt_ping(void) 100 { 101 on_each_cpu(__booke_wdt_ping, NULL, 0); 102 } 103 104 static 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 } 116 117 static 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 } 123 124 static struct watchdog_info ident = { 125 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 126 .identity = "PowerPC Book-E Watchdog", 127 }; 128 129 static 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(ident.options, p); 141 case WDIOC_GETBOOTSTATUS: 142 /* XXX: something is clearing TSR */ 143 tmp = mfspr(SPRN_TSR) & TSR_WRS(3); 144 /* returns 1 if last reset was caused by the WDT */ 145 return (tmp ? 1 : 0); 146 case WDIOC_SETOPTIONS: 147 if (get_user(tmp, p)) 148 return -EINVAL; 149 if (tmp == WDIOS_ENABLECARD) { 150 booke_wdt_ping(); 151 break; 152 } else 153 return -EINVAL; 154 return 0; 155 case WDIOC_KEEPALIVE: 156 booke_wdt_ping(); 157 return 0; 158 case WDIOC_SETTIMEOUT: 159 if (get_user(tmp, p)) 160 return -EFAULT; 161 #ifdef CONFIG_FSL_BOOKE 162 /* period of 1 gives the largest possible timeout */ 163 if (tmp > period_to_sec(1)) 164 return -EINVAL; 165 booke_wdt_period = sec_to_period(tmp); 166 #else 167 booke_wdt_period = tmp; 168 #endif 169 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP_MASK) | 170 WDTP(booke_wdt_period)); 171 return 0; 172 case WDIOC_GETTIMEOUT: 173 return put_user(booke_wdt_period, p); 174 default: 175 return -ENOTTY; 176 } 177 178 return 0; 179 } 180 181 static int booke_wdt_open(struct inode *inode, struct file *file) 182 { 183 spin_lock(&booke_wdt_lock); 184 if (booke_wdt_enabled == 0) { 185 booke_wdt_enabled = 1; 186 on_each_cpu(__booke_wdt_enable, NULL, 0); 187 printk(KERN_INFO 188 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 189 booke_wdt_period); 190 } 191 spin_unlock(&booke_wdt_lock); 192 193 return nonseekable_open(inode, file); 194 } 195 196 static const struct file_operations booke_wdt_fops = { 197 .owner = THIS_MODULE, 198 .llseek = no_llseek, 199 .write = booke_wdt_write, 200 .unlocked_ioctl = booke_wdt_ioctl, 201 .open = booke_wdt_open, 202 }; 203 204 static struct miscdevice booke_wdt_miscdev = { 205 .minor = WATCHDOG_MINOR, 206 .name = "watchdog", 207 .fops = &booke_wdt_fops, 208 }; 209 210 static void __exit booke_wdt_exit(void) 211 { 212 misc_deregister(&booke_wdt_miscdev); 213 } 214 215 static int __init booke_wdt_init(void) 216 { 217 int ret = 0; 218 219 printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n"); 220 ident.firmware_version = cur_cpu_spec->pvr_value; 221 222 ret = misc_register(&booke_wdt_miscdev); 223 if (ret) { 224 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n", 225 WATCHDOG_MINOR, ret); 226 return ret; 227 } 228 229 spin_lock(&booke_wdt_lock); 230 if (booke_wdt_enabled == 1) { 231 printk(KERN_INFO 232 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 233 booke_wdt_period); 234 on_each_cpu(__booke_wdt_enable, NULL, 0); 235 } 236 spin_unlock(&booke_wdt_lock); 237 238 return ret; 239 } 240 device_initcall(booke_wdt_init); 241