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/smp.h> 19 #include <linux/watchdog.h> 20 21 #include <asm/reg_booke.h> 22 #include <asm/time.h> 23 #include <asm/div64.h> 24 25 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot. 26 * Also, the wdt_period sets the watchdog timer period timeout. 27 * For E500 cpus the wdt_period sets which bit changing from 0->1 will 28 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the 29 * first time nothing will happen, the second time a watchdog exception will 30 * occur, and the final time the board will reset. 31 */ 32 33 u32 booke_wdt_enabled; 34 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT; 35 36 #ifdef CONFIG_PPC_FSL_BOOK3E 37 #define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) 38 #define WDTP_MASK (WDTP(0x3f)) 39 #else 40 #define WDTP(x) (TCR_WP(x)) 41 #define WDTP_MASK (TCR_WP_MASK) 42 #endif 43 44 /* Checks wdt=x and wdt_period=xx command-line option */ 45 notrace int __init early_parse_wdt(char *p) 46 { 47 if (p && strncmp(p, "0", 1) != 0) 48 booke_wdt_enabled = 1; 49 50 return 0; 51 } 52 early_param("wdt", early_parse_wdt); 53 54 int __init early_parse_wdt_period(char *p) 55 { 56 unsigned long ret; 57 if (p) { 58 if (!kstrtol(p, 0, &ret)) 59 booke_wdt_period = ret; 60 } 61 62 return 0; 63 } 64 early_param("wdt_period", early_parse_wdt_period); 65 66 #ifdef CONFIG_PPC_FSL_BOOK3E 67 68 /* For the specified period, determine the number of seconds 69 * corresponding to the reset time. There will be a watchdog 70 * exception at approximately 3/5 of this time. 71 * 72 * The formula to calculate this is given by: 73 * 2.5 * (2^(63-period+1)) / timebase_freq 74 * 75 * In order to simplify things, we assume that period is 76 * at least 1. This will still result in a very long timeout. 77 */ 78 static unsigned long long period_to_sec(unsigned int period) 79 { 80 unsigned long long tmp = 1ULL << (64 - period); 81 unsigned long tmp2 = ppc_tb_freq; 82 83 /* tmp may be a very large number and we don't want to overflow, 84 * so divide the timebase freq instead of multiplying tmp 85 */ 86 tmp2 = tmp2 / 5 * 2; 87 88 do_div(tmp, tmp2); 89 return tmp; 90 } 91 92 /* 93 * This procedure will find the highest period which will give a timeout 94 * greater than the one required. e.g. for a bus speed of 66666666 and 95 * and a parameter of 2 secs, then this procedure will return a value of 38. 96 */ 97 static unsigned int sec_to_period(unsigned int secs) 98 { 99 unsigned int period; 100 for (period = 63; period > 0; period--) { 101 if (period_to_sec(period) >= secs) 102 return period; 103 } 104 return 0; 105 } 106 107 #define MAX_WDT_TIMEOUT period_to_sec(1) 108 109 #else /* CONFIG_PPC_FSL_BOOK3E */ 110 111 static unsigned long long period_to_sec(unsigned int period) 112 { 113 return period; 114 } 115 116 static unsigned int sec_to_period(unsigned int secs) 117 { 118 return secs; 119 } 120 121 #define MAX_WDT_TIMEOUT 3 /* from Kconfig */ 122 123 #endif /* !CONFIG_PPC_FSL_BOOK3E */ 124 125 static void __booke_wdt_set(void *data) 126 { 127 u32 val; 128 struct watchdog_device *wdog = data; 129 130 val = mfspr(SPRN_TCR); 131 val &= ~WDTP_MASK; 132 val |= WDTP(sec_to_period(wdog->timeout)); 133 134 mtspr(SPRN_TCR, val); 135 } 136 137 static void booke_wdt_set(void *data) 138 { 139 on_each_cpu(__booke_wdt_set, data, 0); 140 } 141 142 static void __booke_wdt_ping(void *data) 143 { 144 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); 145 } 146 147 static int booke_wdt_ping(struct watchdog_device *wdog) 148 { 149 on_each_cpu(__booke_wdt_ping, NULL, 0); 150 151 return 0; 152 } 153 154 static void __booke_wdt_enable(void *data) 155 { 156 u32 val; 157 struct watchdog_device *wdog = data; 158 159 /* clear status before enabling watchdog */ 160 __booke_wdt_ping(NULL); 161 val = mfspr(SPRN_TCR); 162 val &= ~WDTP_MASK; 163 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(sec_to_period(wdog->timeout))); 164 165 mtspr(SPRN_TCR, val); 166 } 167 168 /** 169 * booke_wdt_disable - disable the watchdog on the given CPU 170 * 171 * This function is called on each CPU. It disables the watchdog on that CPU. 172 * 173 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can 174 * effectively disable the watchdog by setting its period to the maximum value. 175 */ 176 static void __booke_wdt_disable(void *data) 177 { 178 u32 val; 179 180 val = mfspr(SPRN_TCR); 181 val &= ~(TCR_WIE | WDTP_MASK); 182 mtspr(SPRN_TCR, val); 183 184 /* clear status to make sure nothing is pending */ 185 __booke_wdt_ping(NULL); 186 187 } 188 189 static int booke_wdt_start(struct watchdog_device *wdog) 190 { 191 on_each_cpu(__booke_wdt_enable, wdog, 0); 192 pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout); 193 194 return 0; 195 } 196 197 static int booke_wdt_stop(struct watchdog_device *wdog) 198 { 199 on_each_cpu(__booke_wdt_disable, NULL, 0); 200 pr_debug("watchdog disabled\n"); 201 202 return 0; 203 } 204 205 static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev, 206 unsigned int timeout) 207 { 208 if (timeout > MAX_WDT_TIMEOUT) 209 return -EINVAL; 210 wdt_dev->timeout = timeout; 211 booke_wdt_set(wdt_dev); 212 213 return 0; 214 } 215 216 static struct watchdog_info booke_wdt_info = { 217 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 218 .identity = "PowerPC Book-E Watchdog", 219 }; 220 221 static struct watchdog_ops booke_wdt_ops = { 222 .owner = THIS_MODULE, 223 .start = booke_wdt_start, 224 .stop = booke_wdt_stop, 225 .ping = booke_wdt_ping, 226 .set_timeout = booke_wdt_set_timeout, 227 }; 228 229 static struct watchdog_device booke_wdt_dev = { 230 .info = &booke_wdt_info, 231 .ops = &booke_wdt_ops, 232 .min_timeout = 1, 233 .max_timeout = 0xFFFF 234 }; 235 236 static void __exit booke_wdt_exit(void) 237 { 238 watchdog_unregister_device(&booke_wdt_dev); 239 } 240 241 static int __init booke_wdt_init(void) 242 { 243 int ret = 0; 244 bool nowayout = WATCHDOG_NOWAYOUT; 245 246 pr_info("powerpc book-e watchdog driver loaded\n"); 247 booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value; 248 booke_wdt_set_timeout(&booke_wdt_dev, 249 period_to_sec(booke_wdt_period)); 250 watchdog_set_nowayout(&booke_wdt_dev, nowayout); 251 if (booke_wdt_enabled) 252 booke_wdt_start(&booke_wdt_dev); 253 254 ret = watchdog_register_device(&booke_wdt_dev); 255 256 return ret; 257 } 258 259 module_init(booke_wdt_init); 260 module_exit(booke_wdt_exit); 261 262 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver"); 263 MODULE_LICENSE("GPL"); 264