drivers/watchdog/sama5d4_wdt.c

   1 /*
   2  * Driver for Atmel SAMA5D4 Watchdog Timer
   3  *
   4  * Copyright (C) 2015 Atmel Corporation
   5  *
   6  * Licensed under GPLv2.
   7  */
   8
   9 #include <linux/delay.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/io.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/reboot.h>
  18 #include <linux/watchdog.h>
  19
  20 #include "at91sam9_wdt.h"
  21
  22 /* minimum and maximum watchdog timeout, in seconds */
  23 #define MIN_WDT_TIMEOUT         1
  24 #define MAX_WDT_TIMEOUT         16
  25 #define WDT_DEFAULT_TIMEOUT     MAX_WDT_TIMEOUT
  26
  27 #define WDT_SEC2TICKS(s)        ((s) ? (((s) << 8) - 1) : 0)
  28
  29 struct sama5d4_wdt {
  30         struct watchdog_device  wdd;
  31         void __iomem            *reg_base;
  32         u32                     mr;
  33         unsigned long           last_ping;
  34 };
  35
  36 static int wdt_timeout;
  37 static bool nowayout = WATCHDOG_NOWAYOUT;
  38
  39 module_param(wdt_timeout, int, 0);
  40 MODULE_PARM_DESC(wdt_timeout,
  41         "Watchdog timeout in seconds. (default = "
  42         __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
  43
  44 module_param(nowayout, bool, 0);
  45 MODULE_PARM_DESC(nowayout,
  46         "Watchdog cannot be stopped once started (default="
  47         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  48
  49 #define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
  50
  51 #define wdt_read(wdt, field) \
  52         readl_relaxed((wdt)->reg_base + (field))
  53
  54 /* 4 slow clock periods is 4/32768 = 122.07µs*/
  55 #define WDT_DELAY       usecs_to_jiffies(123)
  56
  57 static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
  58 {
  59         /*
  60          * WDT_CR and WDT_MR must not be modified within three slow clock
  61          * periods following a restart of the watchdog performed by a write
  62          * access in WDT_CR.
  63          */
  64         while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
  65                 usleep_range(30, 125);
  66         writel_relaxed(val, wdt->reg_base + field);
  67         wdt->last_ping = jiffies;
  68 }
  69
  70 static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
  71 {
  72         if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
  73                 udelay(123);
  74         writel_relaxed(val, wdt->reg_base + field);
  75         wdt->last_ping = jiffies;
  76 }
  77
  78 static int sama5d4_wdt_start(struct watchdog_device *wdd)
  79 {
  80         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  81
  82         wdt->mr &= ~AT91_WDT_WDDIS;
  83         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
  84
  85         return 0;
  86 }
  87
  88 static int sama5d4_wdt_stop(struct watchdog_device *wdd)
  89 {
  90         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  91
  92         wdt->mr |= AT91_WDT_WDDIS;
  93         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
  94
  95         return 0;
  96 }
  97
  98 static int sama5d4_wdt_ping(struct watchdog_device *wdd)
  99 {
 100         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 101
 102         wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
 103
 104         return 0;
 105 }
 106
 107 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
 108                                  unsigned int timeout)
 109 {
 110         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 111         u32 value = WDT_SEC2TICKS(timeout);
 112
 113         wdt->mr &= ~AT91_WDT_WDV;
 114         wdt->mr |= AT91_WDT_SET_WDV(value);
 115
 116         /*
 117          * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
 118          * setting the WDDIS bit, and while it is set, the fields WDV and WDD
 119          * must not be modified.
 120          * If the watchdog is enabled, then the timeout can be updated. Else,
 121          * wait that the user enables it.
 122          */
 123         if (wdt_enabled)
 124                 wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
 125
 126         wdd->timeout = timeout;
 127
 128         return 0;
 129 }
 130
 131 static const struct watchdog_info sama5d4_wdt_info = {
 132         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 133         .identity = "Atmel SAMA5D4 Watchdog",
 134 };
 135
 136 static const struct watchdog_ops sama5d4_wdt_ops = {
 137         .owner = THIS_MODULE,
 138         .start = sama5d4_wdt_start,
 139         .stop = sama5d4_wdt_stop,
 140         .ping = sama5d4_wdt_ping,
 141         .set_timeout = sama5d4_wdt_set_timeout,
 142 };
 143
 144 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 145 {
 146         struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
 147
 148         if (wdt_read(wdt, AT91_WDT_SR)) {
 149                 pr_crit("Atmel Watchdog Software Reset\n");
 150                 emergency_restart();
 151                 pr_crit("Reboot didn't succeed\n");
 152         }
 153
 154         return IRQ_HANDLED;
 155 }
 156
 157 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 158 {
 159         const char *tmp;
 160
 161         wdt->mr = AT91_WDT_WDDIS;
 162
 163         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 164             !strcmp(tmp, "software"))
 165                 wdt->mr |= AT91_WDT_WDFIEN;
 166         else
 167                 wdt->mr |= AT91_WDT_WDRSTEN;
 168
 169         if (of_property_read_bool(np, "atmel,idle-halt"))
 170                 wdt->mr |= AT91_WDT_WDIDLEHLT;
 171
 172         if (of_property_read_bool(np, "atmel,dbg-halt"))
 173                 wdt->mr |= AT91_WDT_WDDBGHLT;
 174
 175         return 0;
 176 }
 177
 178 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 179 {
 180         u32 reg;
 181         /*
 182          * When booting and resuming, the bootloader may have changed the
 183          * watchdog configuration.
 184          * If the watchdog is already running, we can safely update it.
 185          * Else, we have to disable it properly.
 186          */
 187         if (wdt_enabled) {
 188                 wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
 189         } else {
 190                 reg = wdt_read(wdt, AT91_WDT_MR);
 191                 if (!(reg & AT91_WDT_WDDIS))
 192                         wdt_write_nosleep(wdt, AT91_WDT_MR,
 193                                           reg | AT91_WDT_WDDIS);
 194         }
 195         return 0;
 196 }
 197
 198 static int sama5d4_wdt_probe(struct platform_device *pdev)
 199 {
 200         struct watchdog_device *wdd;
 201         struct sama5d4_wdt *wdt;
 202         struct resource *res;
 203         void __iomem *regs;
 204         u32 irq = 0;
 205         u32 timeout;
 206         int ret;
 207
 208         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 209         if (!wdt)
 210                 return -ENOMEM;
 211
 212         wdd = &wdt->wdd;
 213         wdd->timeout = WDT_DEFAULT_TIMEOUT;
 214         wdd->info = &sama5d4_wdt_info;
 215         wdd->ops = &sama5d4_wdt_ops;
 216         wdd->min_timeout = MIN_WDT_TIMEOUT;
 217         wdd->max_timeout = MAX_WDT_TIMEOUT;
 218         wdt->last_ping = jiffies;
 219
 220         watchdog_set_drvdata(wdd, wdt);
 221
 222         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 223         regs = devm_ioremap_resource(&pdev->dev, res);
 224         if (IS_ERR(regs))
 225                 return PTR_ERR(regs);
 226
 227         wdt->reg_base = regs;
 228
 229         irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
 230         if (!irq)
 231                 dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
 232
 233         ret = of_sama5d4_wdt_init(pdev->dev.of_node, wdt);
 234         if (ret)
 235                 return ret;
 236
 237         if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
 238                 ret = devm_request_irq(&pdev->dev, irq, sama5d4_wdt_irq_handler,
 239                                        IRQF_SHARED | IRQF_IRQPOLL |
 240                                        IRQF_NO_SUSPEND, pdev->name, pdev);
 241                 if (ret) {
 242                         dev_err(&pdev->dev,
 243                                 "cannot register interrupt handler\n");
 244                         return ret;
 245                 }
 246         }
 247
 248         watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
 249
 250         timeout = WDT_SEC2TICKS(wdd->timeout);
 251
 252         wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
 253         wdt->mr |= AT91_WDT_SET_WDV(timeout);
 254
 255         ret = sama5d4_wdt_init(wdt);
 256         if (ret)
 257                 return ret;
 258
 259         watchdog_set_nowayout(wdd, nowayout);
 260
 261         ret = watchdog_register_device(wdd);
 262         if (ret) {
 263                 dev_err(&pdev->dev, "failed to register watchdog device\n");
 264                 return ret;
 265         }
 266
 267         platform_set_drvdata(pdev, wdt);
 268
 269         dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 270                  wdd->timeout, nowayout);
 271
 272         return 0;
 273 }
 274
 275 static int sama5d4_wdt_remove(struct platform_device *pdev)
 276 {
 277         struct sama5d4_wdt *wdt = platform_get_drvdata(pdev);
 278
 279         sama5d4_wdt_stop(&wdt->wdd);
 280
 281         watchdog_unregister_device(&wdt->wdd);
 282
 283         return 0;
 284 }
 285
 286 static const struct of_device_id sama5d4_wdt_of_match[] = {
 287         { .compatible = "atmel,sama5d4-wdt", },
 288         { }
 289 };
 290 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
 291
 292 #ifdef CONFIG_PM_SLEEP
 293 static int sama5d4_wdt_resume(struct device *dev)
 294 {
 295         struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 296
 297         /*
 298          * FIXME: writing MR also pings the watchdog which may not be desired.
 299          * This should only be done when the registers are lost on suspend but
 300          * there is no way to get this information right now.
 301          */
 302         sama5d4_wdt_init(wdt);
 303
 304         return 0;
 305 }
 306 #endif
 307
 308 static SIMPLE_DEV_PM_OPS(sama5d4_wdt_pm_ops, NULL,
 309                          sama5d4_wdt_resume);
 310
 311 static struct platform_driver sama5d4_wdt_driver = {
 312         .probe          = sama5d4_wdt_probe,
 313         .remove         = sama5d4_wdt_remove,
 314         .driver         = {
 315                 .name   = "sama5d4_wdt",
 316                 .pm     = &sama5d4_wdt_pm_ops,
 317                 .of_match_table = sama5d4_wdt_of_match,
 318         }
 319 };
 320 module_platform_driver(sama5d4_wdt_driver);
 321
 322 MODULE_AUTHOR("Atmel Corporation");
 323 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
 324 MODULE_LICENSE("GPL v2");