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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 16 17 #include <linux/module.h> 18 #include <linux/fs.h> 19 #include <linux/smp.h> 20 #include <linux/miscdevice.h> 21 #include <linux/notifier.h> 22 #include <linux/watchdog.h> 23 #include <linux/uaccess.h> 24 25 #include <asm/reg_booke.h> 26 #include <asm/time.h> 27 #include <asm/div64.h> 28 29 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot. 30 * Also, the wdt_period sets the watchdog timer period timeout. 31 * For E500 cpus the wdt_period sets which bit changing from 0->1 will 32 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the 33 * first time nothing will happen, the second time a watchdog exception will 34 * occur, and the final time the board will reset. 35 */ 36 37 u32 booke_wdt_enabled; 38 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT; 39 40 #ifdef CONFIG_FSL_BOOKE 41 #define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) 42 #define WDTP_MASK (WDTP(0x3f)) 43 #else 44 #define WDTP(x) (TCR_WP(x)) 45 #define WDTP_MASK (TCR_WP_MASK) 46 #endif 47 48 static DEFINE_SPINLOCK(booke_wdt_lock); 49 50 /* For the specified period, determine the number of seconds 51 * corresponding to the reset time. There will be a watchdog 52 * exception at approximately 3/5 of this time. 53 * 54 * The formula to calculate this is given by: 55 * 2.5 * (2^(63-period+1)) / timebase_freq 56 * 57 * In order to simplify things, we assume that period is 58 * at least 1. This will still result in a very long timeout. 59 */ 60 static unsigned long long period_to_sec(unsigned int period) 61 { 62 unsigned long long tmp = 1ULL << (64 - period); 63 unsigned long tmp2 = ppc_tb_freq; 64 65 /* tmp may be a very large number and we don't want to overflow, 66 * so divide the timebase freq instead of multiplying tmp 67 */ 68 tmp2 = tmp2 / 5 * 2; 69 70 do_div(tmp, tmp2); 71 return tmp; 72 } 73 74 /* 75 * This procedure will find the highest period which will give a timeout 76 * greater than the one required. e.g. for a bus speed of 66666666 and 77 * and a parameter of 2 secs, then this procedure will return a value of 38. 78 */ 79 static unsigned int sec_to_period(unsigned int secs) 80 { 81 unsigned int period; 82 for (period = 63; period > 0; period--) { 83 if (period_to_sec(period) >= secs) 84 return period; 85 } 86 return 0; 87 } 88 89 static void __booke_wdt_set(void *data) 90 { 91 u32 val; 92 93 val = mfspr(SPRN_TCR); 94 val &= ~WDTP_MASK; 95 val |= WDTP(booke_wdt_period); 96 97 mtspr(SPRN_TCR, val); 98 } 99 100 static void booke_wdt_set(void) 101 { 102 on_each_cpu(__booke_wdt_set, NULL, 0); 103 } 104 105 static void __booke_wdt_ping(void *data) 106 { 107 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 108 } 109 110 static void booke_wdt_ping(void) 111 { 112 on_each_cpu(__booke_wdt_ping, NULL, 0); 113 } 114 115 static void __booke_wdt_enable(void *data) 116 { 117 u32 val; 118 119 /* clear status before enabling watchdog */ 120 __booke_wdt_ping(NULL); 121 val = mfspr(SPRN_TCR); 122 val &= ~WDTP_MASK; 123 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period)); 124 125 mtspr(SPRN_TCR, val); 126 } 127 128 /** 129 * booke_wdt_disable - disable the watchdog on the given CPU 130 * 131 * This function is called on each CPU. It disables the watchdog on that CPU. 132 * 133 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can 134 * effectively disable the watchdog by setting its period to the maximum value. 135 */ 136 static void __booke_wdt_disable(void *data) 137 { 138 u32 val; 139 140 val = mfspr(SPRN_TCR); 141 val &= ~(TCR_WIE | WDTP_MASK); 142 mtspr(SPRN_TCR, val); 143 144 /* clear status to make sure nothing is pending */ 145 __booke_wdt_ping(NULL); 146 147 } 148 149 static ssize_t booke_wdt_write(struct file *file, const char __user *buf, 150 size_t count, loff_t *ppos) 151 { 152 booke_wdt_ping(); 153 return count; 154 } 155 156 static struct watchdog_info ident = { 157 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 158 .identity = "PowerPC Book-E Watchdog", 159 }; 160 161 static long booke_wdt_ioctl(struct file *file, 162 unsigned int cmd, unsigned long arg) 163 { 164 u32 tmp = 0; 165 u32 __user *p = (u32 __user *)arg; 166 167 switch (cmd) { 168 case WDIOC_GETSUPPORT: 169 if (copy_to_user((void *)arg, &ident, sizeof(ident))) 170 return -EFAULT; 171 case WDIOC_GETSTATUS: 172 return put_user(0, p); 173 case WDIOC_GETBOOTSTATUS: 174 /* XXX: something is clearing TSR */ 175 tmp = mfspr(SPRN_TSR) & TSR_WRS(3); 176 /* returns CARDRESET if last reset was caused by the WDT */ 177 return (tmp ? WDIOF_CARDRESET : 0); 178 case WDIOC_SETOPTIONS: 179 if (get_user(tmp, p)) 180 return -EINVAL; 181 if (tmp == WDIOS_ENABLECARD) { 182 booke_wdt_ping(); 183 break; 184 } else 185 return -EINVAL; 186 return 0; 187 case WDIOC_KEEPALIVE: 188 booke_wdt_ping(); 189 return 0; 190 case WDIOC_SETTIMEOUT: 191 if (get_user(tmp, p)) 192 return -EFAULT; 193 #ifdef CONFIG_FSL_BOOKE 194 /* period of 1 gives the largest possible timeout */ 195 if (tmp > period_to_sec(1)) 196 return -EINVAL; 197 booke_wdt_period = sec_to_period(tmp); 198 #else 199 booke_wdt_period = tmp; 200 #endif 201 booke_wdt_set(); 202 /* Fall */ 203 case WDIOC_GETTIMEOUT: 204 #ifdef CONFIG_FSL_BOOKE 205 return put_user(period_to_sec(booke_wdt_period), p); 206 #else 207 return put_user(booke_wdt_period, p); 208 #endif 209 default: 210 return -ENOTTY; 211 } 212 213 return 0; 214 } 215 216 /* wdt_is_active stores wether or not the /dev/watchdog device is opened */ 217 static unsigned long wdt_is_active; 218 219 static int booke_wdt_open(struct inode *inode, struct file *file) 220 { 221 /* /dev/watchdog can only be opened once */ 222 if (test_and_set_bit(0, &wdt_is_active)) 223 return -EBUSY; 224 225 spin_lock(&booke_wdt_lock); 226 if (booke_wdt_enabled == 0) { 227 booke_wdt_enabled = 1; 228 on_each_cpu(__booke_wdt_enable, NULL, 0); 229 pr_debug("watchdog enabled (timeout = %llu sec)\n", 230 period_to_sec(booke_wdt_period)); 231 } 232 spin_unlock(&booke_wdt_lock); 233 234 return nonseekable_open(inode, file); 235 } 236 237 static int booke_wdt_release(struct inode *inode, struct file *file) 238 { 239 #ifndef CONFIG_WATCHDOG_NOWAYOUT 240 /* Normally, the watchdog is disabled when /dev/watchdog is closed, but 241 * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the 242 * watchdog should remain enabled. So we disable it only if 243 * CONFIG_WATCHDOG_NOWAYOUT is not defined. 244 */ 245 on_each_cpu(__booke_wdt_disable, NULL, 0); 246 booke_wdt_enabled = 0; 247 pr_debug("watchdog disabled\n"); 248 #endif 249 250 clear_bit(0, &wdt_is_active); 251 252 return 0; 253 } 254 255 static const struct file_operations booke_wdt_fops = { 256 .owner = THIS_MODULE, 257 .llseek = no_llseek, 258 .write = booke_wdt_write, 259 .unlocked_ioctl = booke_wdt_ioctl, 260 .open = booke_wdt_open, 261 .release = booke_wdt_release, 262 }; 263 264 static struct miscdevice booke_wdt_miscdev = { 265 .minor = WATCHDOG_MINOR, 266 .name = "watchdog", 267 .fops = &booke_wdt_fops, 268 }; 269 270 static void __exit booke_wdt_exit(void) 271 { 272 misc_deregister(&booke_wdt_miscdev); 273 } 274 275 static int __init booke_wdt_init(void) 276 { 277 int ret = 0; 278 279 pr_info("powerpc book-e watchdog driver loaded\n"); 280 ident.firmware_version = cur_cpu_spec->pvr_value; 281 282 ret = misc_register(&booke_wdt_miscdev); 283 if (ret) { 284 pr_err("cannot register device (minor=%u, ret=%i)\n", 285 WATCHDOG_MINOR, ret); 286 return ret; 287 } 288 289 spin_lock(&booke_wdt_lock); 290 if (booke_wdt_enabled == 1) { 291 pr_info("watchdog enabled (timeout = %llu sec)\n", 292 period_to_sec(booke_wdt_period)); 293 on_each_cpu(__booke_wdt_enable, NULL, 0); 294 } 295 spin_unlock(&booke_wdt_lock); 296 297 return ret; 298 } 299 300 module_init(booke_wdt_init); 301 module_exit(booke_wdt_exit); 302 303 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver"); 304 MODULE_LICENSE("GPL"); 305