drivers/watchdog/at91sam9_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Watchdog driver for Atmel AT91SAM9x processors.
   4  *
   5  * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
   6  *
   7  */
   8
   9 /*
  10  * The Watchdog Timer Mode Register can be only written to once. If the
  11  * timeout need to be set from Linux, be sure that the bootstrap or the
  12  * bootloader doesn't write to this register.
  13  */
  14
  15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  16
  17 #include <linux/clk.h>
  18 #include <linux/errno.h>
  19 #include <linux/init.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/io.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/reboot.h>
  27 #include <linux/types.h>
  28 #include <linux/watchdog.h>
  29 #include <linux/jiffies.h>
  30 #include <linux/timer.h>
  31 #include <linux/bitops.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/of.h>
  34 #include <linux/of_irq.h>
  35
  36 #include "at91sam9_wdt.h"
  37
  38 #define DRV_NAME "AT91SAM9 Watchdog"
  39
  40 #define wdt_read(wdt, field) \
  41         readl_relaxed((wdt)->base + (field))
  42 #define wdt_write(wtd, field, val) \
  43         writel_relaxed((val), (wdt)->base + (field))
  44
  45 /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
  46  * use this to convert a watchdog
  47  * value from/to milliseconds.
  48  */
  49 #define ticks_to_hz_rounddown(t)        ((((t) + 1) * HZ) >> 8)
  50 #define ticks_to_hz_roundup(t)          (((((t) + 1) * HZ) + 255) >> 8)
  51 #define ticks_to_secs(t)                (((t) + 1) >> 8)
  52 #define secs_to_ticks(s)                ((s) ? (((s) << 8) - 1) : 0)
  53
  54 #define WDT_MR_RESET    0x3FFF2FFF
  55
  56 /* Watchdog max counter value in ticks */
  57 #define WDT_COUNTER_MAX_TICKS   0xFFF
  58
  59 /* Watchdog max delta/value in secs */
  60 #define WDT_COUNTER_MAX_SECS    ticks_to_secs(WDT_COUNTER_MAX_TICKS)
  61
  62 /* Hardware timeout in seconds */
  63 #define WDT_HW_TIMEOUT 2
  64
  65 /* Timer heartbeat (500ms) */
  66 #define WDT_TIMEOUT     (HZ/2)
  67
  68 /* User land timeout */
  69 #define WDT_HEARTBEAT 15
  70 static int heartbeat;
  71 module_param(heartbeat, int, 0);
  72 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
  73         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
  74
  75 static bool nowayout = WATCHDOG_NOWAYOUT;
  76 module_param(nowayout, bool, 0);
  77 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  78         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  79
  80 #define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd)
  81 struct at91wdt {
  82         struct watchdog_device wdd;
  83         void __iomem *base;
  84         unsigned long next_heartbeat;   /* the next_heartbeat for the timer */
  85         struct timer_list timer;        /* The timer that pings the watchdog */
  86         u32 mr;
  87         u32 mr_mask;
  88         unsigned long heartbeat;        /* WDT heartbeat in jiffies */
  89         bool nowayout;
  90         unsigned int irq;
  91         struct clk *sclk;
  92 };
  93
  94 /* ......................................................................... */
  95
  96 static irqreturn_t wdt_interrupt(int irq, void *dev_id)
  97 {
  98         struct at91wdt *wdt = (struct at91wdt *)dev_id;
  99
 100         if (wdt_read(wdt, AT91_WDT_SR)) {
 101                 pr_crit("at91sam9 WDT software reset\n");
 102                 emergency_restart();
 103                 pr_crit("Reboot didn't ?????\n");
 104         }
 105
 106         return IRQ_HANDLED;
 107 }
 108
 109 /*
 110  * Reload the watchdog timer.  (ie, pat the watchdog)
 111  */
 112 static inline void at91_wdt_reset(struct at91wdt *wdt)
 113 {
 114         wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
 115 }
 116
 117 /*
 118  * Timer tick
 119  */
 120 static void at91_ping(struct timer_list *t)
 121 {
 122         struct at91wdt *wdt = from_timer(wdt, t, timer);
 123         if (time_before(jiffies, wdt->next_heartbeat) ||
 124             !watchdog_active(&wdt->wdd)) {
 125                 at91_wdt_reset(wdt);
 126                 mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
 127         } else {
 128                 pr_crit("I will reset your machine !\n");
 129         }
 130 }
 131
 132 static int at91_wdt_start(struct watchdog_device *wdd)
 133 {
 134         struct at91wdt *wdt = to_wdt(wdd);
 135         /* calculate when the next userspace timeout will be */
 136         wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
 137         return 0;
 138 }
 139
 140 static int at91_wdt_stop(struct watchdog_device *wdd)
 141 {
 142         /* The watchdog timer hardware can not be stopped... */
 143         return 0;
 144 }
 145
 146 static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
 147 {
 148         wdd->timeout = new_timeout;
 149         return at91_wdt_start(wdd);
 150 }
 151
 152 static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
 153 {
 154         u32 tmp;
 155         u32 delta;
 156         u32 value;
 157         int err;
 158         u32 mask = wdt->mr_mask;
 159         unsigned long min_heartbeat = 1;
 160         unsigned long max_heartbeat;
 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         max_heartbeat = ticks_to_hz_rounddown(value);
 185         if (!max_heartbeat) {
 186                 dev_err(dev,
 187                         "heartbeat is too small for the system to handle it correctly\n");
 188                 return -EINVAL;
 189         }
 190
 191         /*
 192          * Try to reset the watchdog counter 4 or 2 times more often than
 193          * actually requested, to avoid spurious watchdog reset.
 194          * If this is not possible because of the min_heartbeat value, reset
 195          * it at the min_heartbeat period.
 196          */
 197         if ((max_heartbeat / 4) >= min_heartbeat)
 198                 wdt->heartbeat = max_heartbeat / 4;
 199         else if ((max_heartbeat / 2) >= min_heartbeat)
 200                 wdt->heartbeat = max_heartbeat / 2;
 201         else
 202                 wdt->heartbeat = min_heartbeat;
 203
 204         if (max_heartbeat < min_heartbeat + 4)
 205                 dev_warn(dev,
 206                          "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");
 207
 208         if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
 209                 err = request_irq(wdt->irq, wdt_interrupt,
 210                                   IRQF_SHARED | IRQF_IRQPOLL |
 211                                   IRQF_NO_SUSPEND,
 212                                   pdev->name, wdt);
 213                 if (err)
 214                         return err;
 215         }
 216
 217         if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
 218                 dev_warn(dev,
 219                          "watchdog already configured differently (mr = %x expecting %x)\n",
 220                          tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
 221
 222         timer_setup(&wdt->timer, at91_ping, 0);
 223
 224         /*
 225          * Use min_heartbeat the first time to avoid spurious watchdog reset:
 226          * we don't know for how long the watchdog counter is running, and
 227          *  - resetting it right now might trigger a watchdog fault reset
 228          *  - waiting for heartbeat time might lead to a watchdog timeout
 229          *    reset
 230          */
 231         mod_timer(&wdt->timer, jiffies + min_heartbeat);
 232
 233         /* Try to set timeout from device tree first */
 234         if (watchdog_init_timeout(&wdt->wdd, 0, dev))
 235                 watchdog_init_timeout(&wdt->wdd, heartbeat, dev);
 236         watchdog_set_nowayout(&wdt->wdd, wdt->nowayout);
 237         err = watchdog_register_device(&wdt->wdd);
 238         if (err)
 239                 goto out_stop_timer;
 240
 241         wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;
 242
 243         return 0;
 244
 245 out_stop_timer:
 246         del_timer(&wdt->timer);
 247         return err;
 248 }
 249
 250 /* ......................................................................... */
 251
 252 static const struct watchdog_info at91_wdt_info = {
 253         .identity       = DRV_NAME,
 254         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 255                                                 WDIOF_MAGICCLOSE,
 256 };
 257
 258 static const struct watchdog_ops at91_wdt_ops = {
 259         .owner =        THIS_MODULE,
 260         .start =        at91_wdt_start,
 261         .stop =         at91_wdt_stop,
 262         .set_timeout =  at91_wdt_set_timeout,
 263 };
 264
 265 #if defined(CONFIG_OF)
 266 static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
 267 {
 268         u32 min = 0;
 269         u32 max = WDT_COUNTER_MAX_SECS;
 270         const char *tmp;
 271
 272         /* Get the interrupts property */
 273         wdt->irq = irq_of_parse_and_map(np, 0);
 274         if (!wdt->irq)
 275                 dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n");
 276
 277         if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0,
 278                                         &max)) {
 279                 if (!max || max > WDT_COUNTER_MAX_SECS)
 280                         max = WDT_COUNTER_MAX_SECS;
 281
 282                 if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec",
 283                                                 0, &min)) {
 284                         if (min >= max)
 285                                 min = max - 1;
 286                 }
 287         }
 288
 289         min = secs_to_ticks(min);
 290         max = secs_to_ticks(max);
 291
 292         wdt->mr_mask = 0x3FFFFFFF;
 293         wdt->mr = 0;
 294         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 295             !strcmp(tmp, "software")) {
 296                 wdt->mr |= AT91_WDT_WDFIEN;
 297                 wdt->mr_mask &= ~AT91_WDT_WDRPROC;
 298         } else {
 299                 wdt->mr |= AT91_WDT_WDRSTEN;
 300         }
 301
 302         if (!of_property_read_string(np, "atmel,reset-type", &tmp) &&
 303             !strcmp(tmp, "proc"))
 304                 wdt->mr |= AT91_WDT_WDRPROC;
 305
 306         if (of_property_read_bool(np, "atmel,disable")) {
 307                 wdt->mr |= AT91_WDT_WDDIS;
 308                 wdt->mr_mask &= AT91_WDT_WDDIS;
 309         }
 310
 311         if (of_property_read_bool(np, "atmel,idle-halt"))
 312                 wdt->mr |= AT91_WDT_WDIDLEHLT;
 313
 314         if (of_property_read_bool(np, "atmel,dbg-halt"))
 315                 wdt->mr |= AT91_WDT_WDDBGHLT;
 316
 317         wdt->mr |= max | ((max - min) << 16);
 318
 319         return 0;
 320 }
 321 #else
 322 static inline int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
 323 {
 324         return 0;
 325 }
 326 #endif
 327
 328 static int __init at91wdt_probe(struct platform_device *pdev)
 329 {
 330         int err;
 331         struct at91wdt *wdt;
 332
 333         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 334         if (!wdt)
 335                 return -ENOMEM;
 336
 337         wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN | AT91_WDT_WDD |
 338                   AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT;
 339         wdt->mr_mask = 0x3FFFFFFF;
 340         wdt->nowayout = nowayout;
 341         wdt->wdd.parent = &pdev->dev;
 342         wdt->wdd.info = &at91_wdt_info;
 343         wdt->wdd.ops = &at91_wdt_ops;
 344         wdt->wdd.timeout = WDT_HEARTBEAT;
 345         wdt->wdd.min_timeout = 1;
 346         wdt->wdd.max_timeout = 0xFFFF;
 347
 348         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 349         if (IS_ERR(wdt->base))
 350                 return PTR_ERR(wdt->base);
 351
 352         wdt->sclk = devm_clk_get(&pdev->dev, NULL);
 353         if (IS_ERR(wdt->sclk))
 354                 return PTR_ERR(wdt->sclk);
 355
 356         err = clk_prepare_enable(wdt->sclk);
 357         if (err) {
 358                 dev_err(&pdev->dev, "Could not enable slow clock\n");
 359                 return err;
 360         }
 361
 362         if (pdev->dev.of_node) {
 363                 err = of_at91wdt_init(pdev->dev.of_node, wdt);
 364                 if (err)
 365                         goto err_clk;
 366         }
 367
 368         err = at91_wdt_init(pdev, wdt);
 369         if (err)
 370                 goto err_clk;
 371
 372         platform_set_drvdata(pdev, wdt);
 373
 374         pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
 375                 wdt->wdd.timeout, wdt->nowayout);
 376
 377         return 0;
 378
 379 err_clk:
 380         clk_disable_unprepare(wdt->sclk);
 381
 382         return err;
 383 }
 384
 385 static int __exit at91wdt_remove(struct platform_device *pdev)
 386 {
 387         struct at91wdt *wdt = platform_get_drvdata(pdev);
 388         watchdog_unregister_device(&wdt->wdd);
 389
 390         pr_warn("I quit now, hardware will probably reboot!\n");
 391         del_timer(&wdt->timer);
 392         clk_disable_unprepare(wdt->sclk);
 393
 394         return 0;
 395 }
 396
 397 #if defined(CONFIG_OF)
 398 static const struct of_device_id at91_wdt_dt_ids[] = {
 399         { .compatible = "atmel,at91sam9260-wdt" },
 400         { /* sentinel */ }
 401 };
 402
 403 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
 404 #endif
 405
 406 static struct platform_driver at91wdt_driver = {
 407         .remove         = __exit_p(at91wdt_remove),
 408         .driver         = {
 409                 .name   = "at91_wdt",
 410                 .of_match_table = of_match_ptr(at91_wdt_dt_ids),
 411         },
 412 };
 413
 414 module_platform_driver_probe(at91wdt_driver, at91wdt_probe);
 415
 416 MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
 417 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
 418 MODULE_LICENSE("GPL");