drivers/watchdog/at91sam9_wdt.c

   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         readl_relaxed((wdt)->base + (field))
  44 #define wdt_write(wtd, field, val) \
  45         writel_relaxed((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         unsigned long max_heartbeat;
 162         struct device *dev = &pdev->dev;
 163
 164         tmp = wdt_read(wdt, AT91_WDT_MR);
 165         if ((tmp & mask) != (wdt->mr & mask)) {
 166                 if (tmp == WDT_MR_RESET) {
 167                         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
 168                         tmp = wdt_read(wdt, AT91_WDT_MR);
 169                 }
 170         }
 171
 172         if (tmp & AT91_WDT_WDDIS) {
 173                 if (wdt->mr & AT91_WDT_WDDIS)
 174                         return 0;
 175                 dev_err(dev, "watchdog is disabled\n");
 176                 return -EINVAL;
 177         }
 178
 179         value = tmp & AT91_WDT_WDV;
 180         delta = (tmp & AT91_WDT_WDD) >> 16;
 181
 182         if (delta < value)
 183                 min_heartbeat = ticks_to_hz_roundup(value - delta);
 184
 185         max_heartbeat = ticks_to_hz_rounddown(value);
 186         if (!max_heartbeat) {
 187                 dev_err(dev,
 188                         "heartbeat is too small for the system to handle it correctly\n");
 189                 return -EINVAL;
 190         }
 191
 192         /*
 193          * Try to reset the watchdog counter 4 or 2 times more often than
 194          * actually requested, to avoid spurious watchdog reset.
 195          * If this is not possible because of the min_heartbeat value, reset
 196          * it at the min_heartbeat period.
 197          */
 198         if ((max_heartbeat / 4) >= min_heartbeat)
 199                 wdt->heartbeat = max_heartbeat / 4;
 200         else if ((max_heartbeat / 2) >= min_heartbeat)
 201                 wdt->heartbeat = max_heartbeat / 2;
 202         else
 203                 wdt->heartbeat = min_heartbeat;
 204
 205         if (max_heartbeat < min_heartbeat + 4)
 206                 dev_warn(dev,
 207                          "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");
 208
 209         if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
 210                 err = request_irq(wdt->irq, wdt_interrupt,
 211                                   IRQF_SHARED | IRQF_IRQPOLL |
 212                                   IRQF_NO_SUSPEND,
 213                                   pdev->name, wdt);
 214                 if (err)
 215                         return err;
 216         }
 217
 218         if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
 219                 dev_warn(dev,
 220                          "watchdog already configured differently (mr = %x expecting %x)\n",
 221                          tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
 222
 223         setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
 224
 225         /*
 226          * Use min_heartbeat the first time to avoid spurious watchdog reset:
 227          * we don't know for how long the watchdog counter is running, and
 228          *  - resetting it right now might trigger a watchdog fault reset
 229          *  - waiting for heartbeat time might lead to a watchdog timeout
 230          *    reset
 231          */
 232         mod_timer(&wdt->timer, jiffies + min_heartbeat);
 233
 234         /* Try to set timeout from device tree first */
 235         if (watchdog_init_timeout(&wdt->wdd, 0, dev))
 236                 watchdog_init_timeout(&wdt->wdd, heartbeat, dev);
 237         watchdog_set_nowayout(&wdt->wdd, wdt->nowayout);
 238         err = watchdog_register_device(&wdt->wdd);
 239         if (err)
 240                 goto out_stop_timer;
 241
 242         wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;
 243
 244         return 0;
 245
 246 out_stop_timer:
 247         del_timer(&wdt->timer);
 248         return err;
 249 }
 250
 251 /* ......................................................................... */
 252
 253 static const struct watchdog_info at91_wdt_info = {
 254         .identity       = DRV_NAME,
 255         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 256                                                 WDIOF_MAGICCLOSE,
 257 };
 258
 259 static const struct watchdog_ops at91_wdt_ops = {
 260         .owner =        THIS_MODULE,
 261         .start =        at91_wdt_start,
 262         .stop =         at91_wdt_stop,
 263         .set_timeout =  at91_wdt_set_timeout,
 264 };
 265
 266 #if defined(CONFIG_OF)
 267 static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
 268 {
 269         u32 min = 0;
 270         u32 max = WDT_COUNTER_MAX_SECS;
 271         const char *tmp;
 272
 273         /* Get the interrupts property */
 274         wdt->irq = irq_of_parse_and_map(np, 0);
 275         if (!wdt->irq)
 276                 dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n");
 277
 278         if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0,
 279                                         &max)) {
 280                 if (!max || max > WDT_COUNTER_MAX_SECS)
 281                         max = WDT_COUNTER_MAX_SECS;
 282
 283                 if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec",
 284                                                 0, &min)) {
 285                         if (min >= max)
 286                                 min = max - 1;
 287                 }
 288         }
 289
 290         min = secs_to_ticks(min);
 291         max = secs_to_ticks(max);
 292
 293         wdt->mr_mask = 0x3FFFFFFF;
 294         wdt->mr = 0;
 295         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 296             !strcmp(tmp, "software")) {
 297                 wdt->mr |= AT91_WDT_WDFIEN;
 298                 wdt->mr_mask &= ~AT91_WDT_WDRPROC;
 299         } else {
 300                 wdt->mr |= AT91_WDT_WDRSTEN;
 301         }
 302
 303         if (!of_property_read_string(np, "atmel,reset-type", &tmp) &&
 304             !strcmp(tmp, "proc"))
 305                 wdt->mr |= AT91_WDT_WDRPROC;
 306
 307         if (of_property_read_bool(np, "atmel,disable")) {
 308                 wdt->mr |= AT91_WDT_WDDIS;
 309                 wdt->mr_mask &= AT91_WDT_WDDIS;
 310         }
 311
 312         if (of_property_read_bool(np, "atmel,idle-halt"))
 313                 wdt->mr |= AT91_WDT_WDIDLEHLT;
 314
 315         if (of_property_read_bool(np, "atmel,dbg-halt"))
 316                 wdt->mr |= AT91_WDT_WDDBGHLT;
 317
 318         wdt->mr |= max | ((max - min) << 16);
 319
 320         return 0;
 321 }
 322 #else
 323 static inline int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
 324 {
 325         return 0;
 326 }
 327 #endif
 328
 329 static int __init at91wdt_probe(struct platform_device *pdev)
 330 {
 331         struct resource *r;
 332         int err;
 333         struct at91wdt *wdt;
 334
 335         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 336         if (!wdt)
 337                 return -ENOMEM;
 338
 339         wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN | AT91_WDT_WDD |
 340                   AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT;
 341         wdt->mr_mask = 0x3FFFFFFF;
 342         wdt->nowayout = nowayout;
 343         wdt->wdd.parent = &pdev->dev;
 344         wdt->wdd.info = &at91_wdt_info;
 345         wdt->wdd.ops = &at91_wdt_ops;
 346         wdt->wdd.timeout = WDT_HEARTBEAT;
 347         wdt->wdd.min_timeout = 1;
 348         wdt->wdd.max_timeout = 0xFFFF;
 349
 350         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 351         wdt->base = devm_ioremap_resource(&pdev->dev, r);
 352         if (IS_ERR(wdt->base))
 353                 return PTR_ERR(wdt->base);
 354
 355         if (pdev->dev.of_node) {
 356                 err = of_at91wdt_init(pdev->dev.of_node, wdt);
 357                 if (err)
 358                         return err;
 359         }
 360
 361         err = at91_wdt_init(pdev, wdt);
 362         if (err)
 363                 return err;
 364
 365         platform_set_drvdata(pdev, wdt);
 366
 367         pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
 368                 wdt->wdd.timeout, wdt->nowayout);
 369
 370         return 0;
 371 }
 372
 373 static int __exit at91wdt_remove(struct platform_device *pdev)
 374 {
 375         struct at91wdt *wdt = platform_get_drvdata(pdev);
 376         watchdog_unregister_device(&wdt->wdd);
 377
 378         pr_warn("I quit now, hardware will probably reboot!\n");
 379         del_timer(&wdt->timer);
 380
 381         return 0;
 382 }
 383
 384 #if defined(CONFIG_OF)
 385 static const struct of_device_id at91_wdt_dt_ids[] = {
 386         { .compatible = "atmel,at91sam9260-wdt" },
 387         { /* sentinel */ }
 388 };
 389
 390 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
 391 #endif
 392
 393 static struct platform_driver at91wdt_driver = {
 394         .remove         = __exit_p(at91wdt_remove),
 395         .driver         = {
 396                 .name   = "at91_wdt",
 397                 .of_match_table = of_match_ptr(at91_wdt_dt_ids),
 398         },
 399 };
 400
 401 module_platform_driver_probe(at91wdt_driver, at91wdt_probe);
 402
 403 MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
 404 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
 405 MODULE_LICENSE("GPL");