1 /* 2 * Watchdog driver for Atmel AT91SAM9x processors. 3 * 4 * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 /* 13 * The Watchdog Timer Mode Register can be only written to once. If the 14 * timeout need to be set from Linux, be sure that the bootstrap or the 15 * bootloader doesn't write to this register. 16 */ 17 18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 19 20 #include <linux/errno.h> 21 #include <linux/init.h> 22 #include <linux/interrupt.h> 23 #include <linux/io.h> 24 #include <linux/kernel.h> 25 #include <linux/module.h> 26 #include <linux/moduleparam.h> 27 #include <linux/platform_device.h> 28 #include <linux/reboot.h> 29 #include <linux/types.h> 30 #include <linux/watchdog.h> 31 #include <linux/jiffies.h> 32 #include <linux/timer.h> 33 #include <linux/bitops.h> 34 #include <linux/uaccess.h> 35 #include <linux/of.h> 36 #include <linux/of_irq.h> 37 38 #include "at91sam9_wdt.h" 39 40 #define DRV_NAME "AT91SAM9 Watchdog" 41 42 #define wdt_read(wdt, field) \ 43 __raw_readl((wdt)->base + (field)) 44 #define wdt_write(wtd, field, val) \ 45 __raw_writel((val), (wdt)->base + (field)) 46 47 /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz, 48 * use this to convert a watchdog 49 * value from/to milliseconds. 50 */ 51 #define ticks_to_hz_rounddown(t) ((((t) + 1) * HZ) >> 8) 52 #define ticks_to_hz_roundup(t) (((((t) + 1) * HZ) + 255) >> 8) 53 #define ticks_to_secs(t) (((t) + 1) >> 8) 54 #define secs_to_ticks(s) ((s) ? (((s) << 8) - 1) : 0) 55 56 #define WDT_MR_RESET 0x3FFF2FFF 57 58 /* Watchdog max counter value in ticks */ 59 #define WDT_COUNTER_MAX_TICKS 0xFFF 60 61 /* Watchdog max delta/value in secs */ 62 #define WDT_COUNTER_MAX_SECS ticks_to_secs(WDT_COUNTER_MAX_TICKS) 63 64 /* Hardware timeout in seconds */ 65 #define WDT_HW_TIMEOUT 2 66 67 /* Timer heartbeat (500ms) */ 68 #define WDT_TIMEOUT (HZ/2) 69 70 /* User land timeout */ 71 #define WDT_HEARTBEAT 15 72 static int heartbeat; 73 module_param(heartbeat, int, 0); 74 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. " 75 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")"); 76 77 static bool nowayout = WATCHDOG_NOWAYOUT; 78 module_param(nowayout, bool, 0); 79 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " 80 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 81 82 #define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd) 83 struct at91wdt { 84 struct watchdog_device wdd; 85 void __iomem *base; 86 unsigned long next_heartbeat; /* the next_heartbeat for the timer */ 87 struct timer_list timer; /* The timer that pings the watchdog */ 88 u32 mr; 89 u32 mr_mask; 90 unsigned long heartbeat; /* WDT heartbeat in jiffies */ 91 bool nowayout; 92 unsigned int irq; 93 }; 94 95 /* ......................................................................... */ 96 97 static irqreturn_t wdt_interrupt(int irq, void *dev_id) 98 { 99 struct at91wdt *wdt = (struct at91wdt *)dev_id; 100 101 if (wdt_read(wdt, AT91_WDT_SR)) { 102 pr_crit("at91sam9 WDT software reset\n"); 103 emergency_restart(); 104 pr_crit("Reboot didn't ?????\n"); 105 } 106 107 return IRQ_HANDLED; 108 } 109 110 /* 111 * Reload the watchdog timer. (ie, pat the watchdog) 112 */ 113 static inline void at91_wdt_reset(struct at91wdt *wdt) 114 { 115 wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT); 116 } 117 118 /* 119 * Timer tick 120 */ 121 static void at91_ping(unsigned long data) 122 { 123 struct at91wdt *wdt = (struct at91wdt *)data; 124 if (time_before(jiffies, wdt->next_heartbeat) || 125 !watchdog_active(&wdt->wdd)) { 126 at91_wdt_reset(wdt); 127 mod_timer(&wdt->timer, jiffies + wdt->heartbeat); 128 } else { 129 pr_crit("I will reset your machine !\n"); 130 } 131 } 132 133 static int at91_wdt_start(struct watchdog_device *wdd) 134 { 135 struct at91wdt *wdt = to_wdt(wdd); 136 /* calculate when the next userspace timeout will be */ 137 wdt->next_heartbeat = jiffies + wdd->timeout * HZ; 138 return 0; 139 } 140 141 static int at91_wdt_stop(struct watchdog_device *wdd) 142 { 143 /* The watchdog timer hardware can not be stopped... */ 144 return 0; 145 } 146 147 static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout) 148 { 149 wdd->timeout = new_timeout; 150 return at91_wdt_start(wdd); 151 } 152 153 static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt) 154 { 155 u32 tmp; 156 u32 delta; 157 u32 value; 158 int err; 159 u32 mask = wdt->mr_mask; 160 unsigned long min_heartbeat = 1; 161 struct device *dev = &pdev->dev; 162 163 tmp = wdt_read(wdt, AT91_WDT_MR); 164 if ((tmp & mask) != (wdt->mr & mask)) { 165 if (tmp == WDT_MR_RESET) { 166 wdt_write(wdt, AT91_WDT_MR, wdt->mr); 167 tmp = wdt_read(wdt, AT91_WDT_MR); 168 } 169 } 170 171 if (tmp & AT91_WDT_WDDIS) { 172 if (wdt->mr & AT91_WDT_WDDIS) 173 return 0; 174 dev_err(dev, "watchdog is disabled\n"); 175 return -EINVAL; 176 } 177 178 value = tmp & AT91_WDT_WDV; 179 delta = (tmp & AT91_WDT_WDD) >> 16; 180 181 if (delta < value) 182 min_heartbeat = ticks_to_hz_roundup(value - delta); 183 184 wdt->heartbeat = ticks_to_hz_rounddown(value); 185 if (!wdt->heartbeat) { 186 dev_err(dev, 187 "heartbeat is too small for the system to handle it correctly\n"); 188 return -EINVAL; 189 } 190 191 if (wdt->heartbeat < min_heartbeat + 4) { 192 wdt->heartbeat = min_heartbeat; 193 dev_warn(dev, 194 "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n"); 195 if (wdt->heartbeat < 4) 196 dev_warn(dev, 197 "heartbeat might be too small for the system to handle it correctly\n"); 198 } else { 199 wdt->heartbeat -= 4; 200 } 201 202 if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) { 203 err = request_irq(wdt->irq, wdt_interrupt, 204 IRQF_SHARED | IRQF_IRQPOLL, 205 pdev->name, wdt); 206 if (err) 207 return err; 208 } 209 210 if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask)) 211 dev_warn(dev, 212 "watchdog already configured differently (mr = %x expecting %x)\n", 213 tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask); 214 215 setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt); 216 mod_timer(&wdt->timer, jiffies + wdt->heartbeat); 217 218 /* Try to set timeout from device tree first */ 219 if (watchdog_init_timeout(&wdt->wdd, 0, dev)) 220 watchdog_init_timeout(&wdt->wdd, heartbeat, dev); 221 watchdog_set_nowayout(&wdt->wdd, wdt->nowayout); 222 err = watchdog_register_device(&wdt->wdd); 223 if (err) 224 goto out_stop_timer; 225 226 wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ; 227 228 return 0; 229 230 out_stop_timer: 231 del_timer(&wdt->timer); 232 return err; 233 } 234 235 /* ......................................................................... */ 236 237 static const struct watchdog_info at91_wdt_info = { 238 .identity = DRV_NAME, 239 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 240 WDIOF_MAGICCLOSE, 241 }; 242 243 static const struct watchdog_ops at91_wdt_ops = { 244 .owner = THIS_MODULE, 245 .start = at91_wdt_start, 246 .stop = at91_wdt_stop, 247 .set_timeout = at91_wdt_set_timeout, 248 }; 249 250 #if defined(CONFIG_OF) 251 static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt) 252 { 253 u32 min = 0; 254 u32 max = WDT_COUNTER_MAX_SECS; 255 const char *tmp; 256 257 /* Get the interrupts property */ 258 wdt->irq = irq_of_parse_and_map(np, 0); 259 if (!wdt->irq) 260 dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n"); 261 262 if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0, 263 &max)) { 264 if (!max || max > WDT_COUNTER_MAX_SECS) 265 max = WDT_COUNTER_MAX_SECS; 266 267 if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec", 268 0, &min)) { 269 if (min >= max) 270 min = max - 1; 271 } 272 } 273 274 min = secs_to_ticks(min); 275 max = secs_to_ticks(max); 276 277 wdt->mr_mask = 0x3FFFFFFF; 278 wdt->mr = 0; 279 if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) && 280 !strcmp(tmp, "software")) { 281 wdt->mr |= AT91_WDT_WDFIEN; 282 wdt->mr_mask &= ~AT91_WDT_WDRPROC; 283 } else { 284 wdt->mr |= AT91_WDT_WDRSTEN; 285 } 286 287 if (!of_property_read_string(np, "atmel,reset-type", &tmp) && 288 !strcmp(tmp, "proc")) 289 wdt->mr |= AT91_WDT_WDRPROC; 290 291 if (of_property_read_bool(np, "atmel,disable")) { 292 wdt->mr |= AT91_WDT_WDDIS; 293 wdt->mr_mask &= AT91_WDT_WDDIS; 294 } 295 296 if (of_property_read_bool(np, "atmel,idle-halt")) 297 wdt->mr |= AT91_WDT_WDIDLEHLT; 298 299 if (of_property_read_bool(np, "atmel,dbg-halt")) 300 wdt->mr |= AT91_WDT_WDDBGHLT; 301 302 wdt->mr |= max | ((max - min) << 16); 303 304 return 0; 305 } 306 #else 307 static inline int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt) 308 { 309 return 0; 310 } 311 #endif 312 313 static int __init at91wdt_probe(struct platform_device *pdev) 314 { 315 struct resource *r; 316 int err; 317 struct at91wdt *wdt; 318 319 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); 320 if (!wdt) 321 return -ENOMEM; 322 323 wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN | AT91_WDT_WDD | 324 AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT; 325 wdt->mr_mask = 0x3FFFFFFF; 326 wdt->nowayout = nowayout; 327 wdt->wdd.parent = &pdev->dev; 328 wdt->wdd.info = &at91_wdt_info; 329 wdt->wdd.ops = &at91_wdt_ops; 330 wdt->wdd.timeout = WDT_HEARTBEAT; 331 wdt->wdd.min_timeout = 1; 332 wdt->wdd.max_timeout = 0xFFFF; 333 334 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 335 wdt->base = devm_ioremap_resource(&pdev->dev, r); 336 if (IS_ERR(wdt->base)) 337 return PTR_ERR(wdt->base); 338 339 if (pdev->dev.of_node) { 340 err = of_at91wdt_init(pdev->dev.of_node, wdt); 341 if (err) 342 return err; 343 } 344 345 err = at91_wdt_init(pdev, wdt); 346 if (err) 347 return err; 348 349 platform_set_drvdata(pdev, wdt); 350 351 pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n", 352 wdt->wdd.timeout, wdt->nowayout); 353 354 return 0; 355 } 356 357 static int __exit at91wdt_remove(struct platform_device *pdev) 358 { 359 struct at91wdt *wdt = platform_get_drvdata(pdev); 360 watchdog_unregister_device(&wdt->wdd); 361 362 pr_warn("I quit now, hardware will probably reboot!\n"); 363 del_timer(&wdt->timer); 364 365 return 0; 366 } 367 368 #if defined(CONFIG_OF) 369 static const struct of_device_id at91_wdt_dt_ids[] = { 370 { .compatible = "atmel,at91sam9260-wdt" }, 371 { /* sentinel */ } 372 }; 373 374 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids); 375 #endif 376 377 static struct platform_driver at91wdt_driver = { 378 .remove = __exit_p(at91wdt_remove), 379 .driver = { 380 .name = "at91_wdt", 381 .owner = THIS_MODULE, 382 .of_match_table = of_match_ptr(at91_wdt_dt_ids), 383 }, 384 }; 385 386 module_platform_driver_probe(at91wdt_driver, at91wdt_probe); 387 388 MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>"); 389 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors"); 390 MODULE_LICENSE("GPL"); 391