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 26 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot. 27 * Also, the wdt_period sets the watchdog timer period timeout. 28 * For E500 cpus the wdt_period sets which bit changing from 0->1 will 29 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the 30 * first time nothing will happen, the second time a watchdog exception will 31 * occur, and the final time the board will reset. 32 */ 33 34 #ifdef CONFIG_FSL_BOOKE 35 #define WDT_PERIOD_DEFAULT 63 /* Ex. wdt_period=28 bus=333Mhz,reset=~40sec */ 36 #else 37 #define WDT_PERIOD_DEFAULT 3 /* Refer to the PPC40x and PPC4xx manuals */ 38 #endif /* for timing information */ 39 40 u32 booke_wdt_enabled; 41 u32 booke_wdt_period = WDT_PERIOD_DEFAULT; 42 43 #ifdef CONFIG_FSL_BOOKE 44 #define WDTP(x) ((((63-x)&0x3)<<30)|(((63-x)&0x3c)<<15)) 45 #else 46 #define WDTP(x) (TCR_WP(x)) 47 #endif 48 49 static DEFINE_SPINLOCK(booke_wdt_lock); 50 51 static void __booke_wdt_ping(void *data) 52 { 53 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 54 } 55 56 static void booke_wdt_ping(void) 57 { 58 on_each_cpu(__booke_wdt_ping, NULL, 0); 59 } 60 61 static void __booke_wdt_enable(void *data) 62 { 63 u32 val; 64 65 /* clear status before enabling watchdog */ 66 __booke_wdt_ping(NULL); 67 val = mfspr(SPRN_TCR); 68 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period)); 69 70 mtspr(SPRN_TCR, val); 71 } 72 73 static ssize_t booke_wdt_write(struct file *file, const char __user *buf, 74 size_t count, loff_t *ppos) 75 { 76 booke_wdt_ping(); 77 return count; 78 } 79 80 static struct watchdog_info ident = { 81 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 82 .identity = "PowerPC Book-E Watchdog", 83 }; 84 85 static long booke_wdt_ioctl(struct file *file, 86 unsigned int cmd, unsigned long arg) 87 { 88 u32 tmp = 0; 89 u32 __user *p = (u32 __user *)arg; 90 91 switch (cmd) { 92 case WDIOC_GETSUPPORT: 93 if (copy_to_user(arg, &ident, sizeof(struct watchdog_info))) 94 return -EFAULT; 95 case WDIOC_GETSTATUS: 96 return put_user(ident.options, p); 97 case WDIOC_GETBOOTSTATUS: 98 /* XXX: something is clearing TSR */ 99 tmp = mfspr(SPRN_TSR) & TSR_WRS(3); 100 /* returns 1 if last reset was caused by the WDT */ 101 return (tmp ? 1 : 0); 102 case WDIOC_SETOPTIONS: 103 if (get_user(tmp, p)) 104 return -EINVAL; 105 if (tmp == WDIOS_ENABLECARD) { 106 booke_wdt_ping(); 107 break; 108 } else 109 return -EINVAL; 110 return 0; 111 case WDIOC_KEEPALIVE: 112 booke_wdt_ping(); 113 return 0; 114 case WDIOC_SETTIMEOUT: 115 if (get_user(booke_wdt_period, p)) 116 return -EFAULT; 117 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP(0)) | 118 WDTP(booke_wdt_period)); 119 return 0; 120 case WDIOC_GETTIMEOUT: 121 return put_user(booke_wdt_period, p); 122 default: 123 return -ENOTTY; 124 } 125 126 return 0; 127 } 128 129 static int booke_wdt_open(struct inode *inode, struct file *file) 130 { 131 spin_lock(&booke_wdt_lock); 132 if (booke_wdt_enabled == 0) { 133 booke_wdt_enabled = 1; 134 on_each_cpu(__booke_wdt_enable, NULL, 0); 135 printk(KERN_INFO 136 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 137 booke_wdt_period); 138 } 139 spin_unlock(&booke_wdt_lock); 140 141 return nonseekable_open(inode, file); 142 } 143 144 static const struct file_operations booke_wdt_fops = { 145 .owner = THIS_MODULE, 146 .llseek = no_llseek, 147 .write = booke_wdt_write, 148 .unlocked_ioctl = booke_wdt_ioctl, 149 .open = booke_wdt_open, 150 }; 151 152 static struct miscdevice booke_wdt_miscdev = { 153 .minor = WATCHDOG_MINOR, 154 .name = "watchdog", 155 .fops = &booke_wdt_fops, 156 }; 157 158 static void __exit booke_wdt_exit(void) 159 { 160 misc_deregister(&booke_wdt_miscdev); 161 } 162 163 static int __init booke_wdt_init(void) 164 { 165 int ret = 0; 166 167 printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n"); 168 ident.firmware_version = cur_cpu_spec->pvr_value; 169 170 ret = misc_register(&booke_wdt_miscdev); 171 if (ret) { 172 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n", 173 WATCHDOG_MINOR, ret); 174 return ret; 175 } 176 177 spin_lock(&booke_wdt_lock); 178 if (booke_wdt_enabled == 1) { 179 printk(KERN_INFO 180 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 181 booke_wdt_period); 182 on_each_cpu(__booke_wdt_enable, NULL, 0); 183 } 184 spin_unlock(&booke_wdt_lock); 185 186 return ret; 187 } 188 device_initcall(booke_wdt_init); 189