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 #define WDTP_MASK (WDTP(0)) 46 #else 47 #define WDTP(x) (TCR_WP(x)) 48 #define WDTP_MASK (TCR_WP_MASK) 49 #endif 50 51 static DEFINE_SPINLOCK(booke_wdt_lock); 52 53 static void __booke_wdt_ping(void *data) 54 { 55 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 56 } 57 58 static void booke_wdt_ping(void) 59 { 60 on_each_cpu(__booke_wdt_ping, NULL, 0); 61 } 62 63 static void __booke_wdt_enable(void *data) 64 { 65 u32 val; 66 67 /* clear status before enabling watchdog */ 68 __booke_wdt_ping(NULL); 69 val = mfspr(SPRN_TCR); 70 val &= ~WDTP_MASK; 71 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period)); 72 73 mtspr(SPRN_TCR, val); 74 } 75 76 static ssize_t booke_wdt_write(struct file *file, const char __user *buf, 77 size_t count, loff_t *ppos) 78 { 79 booke_wdt_ping(); 80 return count; 81 } 82 83 static struct watchdog_info ident = { 84 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 85 .identity = "PowerPC Book-E Watchdog", 86 }; 87 88 static long booke_wdt_ioctl(struct file *file, 89 unsigned int cmd, unsigned long arg) 90 { 91 u32 tmp = 0; 92 u32 __user *p = (u32 __user *)arg; 93 94 switch (cmd) { 95 case WDIOC_GETSUPPORT: 96 if (copy_to_user(arg, &ident, sizeof(struct watchdog_info))) 97 return -EFAULT; 98 case WDIOC_GETSTATUS: 99 return put_user(ident.options, p); 100 case WDIOC_GETBOOTSTATUS: 101 /* XXX: something is clearing TSR */ 102 tmp = mfspr(SPRN_TSR) & TSR_WRS(3); 103 /* returns 1 if last reset was caused by the WDT */ 104 return (tmp ? 1 : 0); 105 case WDIOC_SETOPTIONS: 106 if (get_user(tmp, p)) 107 return -EINVAL; 108 if (tmp == WDIOS_ENABLECARD) { 109 booke_wdt_ping(); 110 break; 111 } else 112 return -EINVAL; 113 return 0; 114 case WDIOC_KEEPALIVE: 115 booke_wdt_ping(); 116 return 0; 117 case WDIOC_SETTIMEOUT: 118 if (get_user(booke_wdt_period, p)) 119 return -EFAULT; 120 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP_MASK) | 121 WDTP(booke_wdt_period)); 122 return 0; 123 case WDIOC_GETTIMEOUT: 124 return put_user(booke_wdt_period, p); 125 default: 126 return -ENOTTY; 127 } 128 129 return 0; 130 } 131 132 static int booke_wdt_open(struct inode *inode, struct file *file) 133 { 134 spin_lock(&booke_wdt_lock); 135 if (booke_wdt_enabled == 0) { 136 booke_wdt_enabled = 1; 137 on_each_cpu(__booke_wdt_enable, NULL, 0); 138 printk(KERN_INFO 139 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 140 booke_wdt_period); 141 } 142 spin_unlock(&booke_wdt_lock); 143 144 return nonseekable_open(inode, file); 145 } 146 147 static const struct file_operations booke_wdt_fops = { 148 .owner = THIS_MODULE, 149 .llseek = no_llseek, 150 .write = booke_wdt_write, 151 .unlocked_ioctl = booke_wdt_ioctl, 152 .open = booke_wdt_open, 153 }; 154 155 static struct miscdevice booke_wdt_miscdev = { 156 .minor = WATCHDOG_MINOR, 157 .name = "watchdog", 158 .fops = &booke_wdt_fops, 159 }; 160 161 static void __exit booke_wdt_exit(void) 162 { 163 misc_deregister(&booke_wdt_miscdev); 164 } 165 166 static int __init booke_wdt_init(void) 167 { 168 int ret = 0; 169 170 printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n"); 171 ident.firmware_version = cur_cpu_spec->pvr_value; 172 173 ret = misc_register(&booke_wdt_miscdev); 174 if (ret) { 175 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n", 176 WATCHDOG_MINOR, ret); 177 return ret; 178 } 179 180 spin_lock(&booke_wdt_lock); 181 if (booke_wdt_enabled == 1) { 182 printk(KERN_INFO 183 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", 184 booke_wdt_period); 185 on_each_cpu(__booke_wdt_enable, NULL, 0); 186 } 187 spin_unlock(&booke_wdt_lock); 188 189 return ret; 190 } 191 device_initcall(booke_wdt_init); 192