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 #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 u32 booke_wdt_enabled; 37 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT; 38 39 #ifdef CONFIG_FSL_BOOKE 40 #define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) 41 #define WDTP_MASK (WDTP(0x3f)) 42 #else 43 #define WDTP(x) (TCR_WP(x)) 44 #define WDTP_MASK (TCR_WP_MASK) 45 #endif 46 47 static DEFINE_SPINLOCK(booke_wdt_lock); 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 */ 59 static 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 */ 78 static 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 static void __booke_wdt_set(void *data) 89 { 90 u32 val; 91 92 val = mfspr(SPRN_TCR); 93 val &= ~WDTP_MASK; 94 val |= WDTP(booke_wdt_period); 95 96 mtspr(SPRN_TCR, val); 97 } 98 99 static void booke_wdt_set(void) 100 { 101 on_each_cpu(__booke_wdt_set, NULL, 0); 102 } 103 104 static void __booke_wdt_ping(void *data) 105 { 106 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 107 } 108 109 static void booke_wdt_ping(void) 110 { 111 on_each_cpu(__booke_wdt_ping, NULL, 0); 112 } 113 114 static void __booke_wdt_enable(void *data) 115 { 116 u32 val; 117 118 /* clear status before enabling watchdog */ 119 __booke_wdt_ping(NULL); 120 val = mfspr(SPRN_TCR); 121 val &= ~WDTP_MASK; 122 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period)); 123 124 mtspr(SPRN_TCR, val); 125 } 126 127 /** 128 * booke_wdt_disable - disable the watchdog on the given CPU 129 * 130 * This function is called on each CPU. It disables the watchdog on that CPU. 131 * 132 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can 133 * effectively disable the watchdog by setting its period to the maximum value. 134 */ 135 static void __booke_wdt_disable(void *data) 136 { 137 u32 val; 138 139 val = mfspr(SPRN_TCR); 140 val &= ~(TCR_WIE | WDTP_MASK); 141 mtspr(SPRN_TCR, val); 142 143 /* clear status to make sure nothing is pending */ 144 __booke_wdt_ping(NULL); 145 146 } 147 148 static ssize_t booke_wdt_write(struct file *file, const char __user *buf, 149 size_t count, loff_t *ppos) 150 { 151 booke_wdt_ping(); 152 return count; 153 } 154 155 static struct watchdog_info ident = { 156 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 157 .identity = "PowerPC Book-E Watchdog", 158 }; 159 160 static long booke_wdt_ioctl(struct file *file, 161 unsigned int cmd, unsigned long arg) 162 { 163 u32 tmp = 0; 164 u32 __user *p = (u32 __user *)arg; 165 166 switch (cmd) { 167 case WDIOC_GETSUPPORT: 168 if (copy_to_user((void *)arg, &ident, sizeof(ident))) 169 return -EFAULT; 170 case WDIOC_GETSTATUS: 171 return put_user(0, p); 172 case WDIOC_GETBOOTSTATUS: 173 /* XXX: something is clearing TSR */ 174 tmp = mfspr(SPRN_TSR) & TSR_WRS(3); 175 /* returns CARDRESET if last reset was caused by the WDT */ 176 return (tmp ? WDIOF_CARDRESET : 0); 177 case WDIOC_SETOPTIONS: 178 if (get_user(tmp, p)) 179 return -EINVAL; 180 if (tmp == WDIOS_ENABLECARD) { 181 booke_wdt_ping(); 182 break; 183 } else 184 return -EINVAL; 185 return 0; 186 case WDIOC_KEEPALIVE: 187 booke_wdt_ping(); 188 return 0; 189 case WDIOC_SETTIMEOUT: 190 if (get_user(tmp, p)) 191 return -EFAULT; 192 #ifdef CONFIG_FSL_BOOKE 193 /* period of 1 gives the largest possible timeout */ 194 if (tmp > period_to_sec(1)) 195 return -EINVAL; 196 booke_wdt_period = sec_to_period(tmp); 197 #else 198 booke_wdt_period = tmp; 199 #endif 200 booke_wdt_set(); 201 return 0; 202 case WDIOC_GETTIMEOUT: 203 return put_user(booke_wdt_period, p); 204 default: 205 return -ENOTTY; 206 } 207 208 return 0; 209 } 210 211 /* wdt_is_active stores wether or not the /dev/watchdog device is opened */ 212 static unsigned long wdt_is_active; 213 214 static int booke_wdt_open(struct inode *inode, struct file *file) 215 { 216 /* /dev/watchdog can only be opened once */ 217 if (test_and_set_bit(0, &wdt_is_active)) 218 return -EBUSY; 219 220 spin_lock(&booke_wdt_lock); 221 if (booke_wdt_enabled == 0) { 222 booke_wdt_enabled = 1; 223 on_each_cpu(__booke_wdt_enable, NULL, 0); 224 pr_debug("booke_wdt: watchdog enabled (timeout = %llu sec)\n", 225 period_to_sec(booke_wdt_period)); 226 } 227 spin_unlock(&booke_wdt_lock); 228 229 return nonseekable_open(inode, file); 230 } 231 232 static int booke_wdt_release(struct inode *inode, struct file *file) 233 { 234 #ifndef CONFIG_WATCHDOG_NOWAYOUT 235 /* Normally, the watchdog is disabled when /dev/watchdog is closed, but 236 * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the 237 * watchdog should remain enabled. So we disable it only if 238 * CONFIG_WATCHDOG_NOWAYOUT is not defined. 239 */ 240 on_each_cpu(__booke_wdt_disable, NULL, 0); 241 booke_wdt_enabled = 0; 242 pr_debug("booke_wdt: watchdog disabled\n"); 243 #endif 244 245 clear_bit(0, &wdt_is_active); 246 247 return 0; 248 } 249 250 static const struct file_operations booke_wdt_fops = { 251 .owner = THIS_MODULE, 252 .llseek = no_llseek, 253 .write = booke_wdt_write, 254 .unlocked_ioctl = booke_wdt_ioctl, 255 .open = booke_wdt_open, 256 .release = booke_wdt_release, 257 }; 258 259 static struct miscdevice booke_wdt_miscdev = { 260 .minor = WATCHDOG_MINOR, 261 .name = "watchdog", 262 .fops = &booke_wdt_fops, 263 }; 264 265 static void __exit booke_wdt_exit(void) 266 { 267 misc_deregister(&booke_wdt_miscdev); 268 } 269 270 static int __init booke_wdt_init(void) 271 { 272 int ret = 0; 273 274 pr_info("booke_wdt: powerpc book-e watchdog driver loaded\n"); 275 ident.firmware_version = cur_cpu_spec->pvr_value; 276 277 ret = misc_register(&booke_wdt_miscdev); 278 if (ret) { 279 pr_err("booke_wdt: cannot register device (minor=%u, ret=%i)\n", 280 WATCHDOG_MINOR, ret); 281 return ret; 282 } 283 284 spin_lock(&booke_wdt_lock); 285 if (booke_wdt_enabled == 1) { 286 pr_info("booke_wdt: watchdog enabled (timeout = %llu sec)\n", 287 period_to_sec(booke_wdt_period)); 288 on_each_cpu(__booke_wdt_enable, NULL, 0); 289 } 290 spin_unlock(&booke_wdt_lock); 291 292 return ret; 293 } 294 295 module_init(booke_wdt_init); 296 module_exit(booke_wdt_exit); 297 298 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver"); 299 MODULE_LICENSE("GPL"); 300