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_WDD;
 115         wdt->mr |= AT91_WDT_SET_WDV(value);
 116         wdt->mr |= AT91_WDT_SET_WDD(value);
 117
 118         /*
 119          * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
 120          * setting the WDDIS bit, and while it is set, the fields WDV and WDD
 121          * must not be modified.
 122          * If the watchdog is enabled, then the timeout can be updated. Else,
 123          * wait that the user enables it.
 124          */
 125         if (wdt_enabled)
 126                 wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
 127
 128         wdd->timeout = timeout;
 129
 130         return 0;
 131 }
 132
 133 static const struct watchdog_info sama5d4_wdt_info = {
 134         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 135         .identity = "Atmel SAMA5D4 Watchdog",
 136 };
 137
 138 static const struct watchdog_ops sama5d4_wdt_ops = {
 139         .owner = THIS_MODULE,
 140         .start = sama5d4_wdt_start,
 141         .stop = sama5d4_wdt_stop,
 142         .ping = sama5d4_wdt_ping,
 143         .set_timeout = sama5d4_wdt_set_timeout,
 144 };
 145
 146 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 147 {
 148         struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
 149
 150         if (wdt_read(wdt, AT91_WDT_SR)) {
 151                 pr_crit("Atmel Watchdog Software Reset\n");
 152                 emergency_restart();
 153                 pr_crit("Reboot didn't succeed\n");
 154         }
 155
 156         return IRQ_HANDLED;
 157 }
 158
 159 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 160 {
 161         const char *tmp;
 162
 163         wdt->mr = AT91_WDT_WDDIS;
 164
 165         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 166             !strcmp(tmp, "software"))
 167                 wdt->mr |= AT91_WDT_WDFIEN;
 168         else
 169                 wdt->mr |= AT91_WDT_WDRSTEN;
 170
 171         if (of_property_read_bool(np, "atmel,idle-halt"))
 172                 wdt->mr |= AT91_WDT_WDIDLEHLT;
 173
 174         if (of_property_read_bool(np, "atmel,dbg-halt"))
 175                 wdt->mr |= AT91_WDT_WDDBGHLT;
 176
 177         return 0;
 178 }
 179
 180 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 181 {
 182         u32 reg;
 183         /*
 184          * When booting and resuming, the bootloader may have changed the
 185          * watchdog configuration.
 186          * If the watchdog is already running, we can safely update it.
 187          * Else, we have to disable it properly.
 188          */
 189         if (wdt_enabled) {
 190                 wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
 191         } else {
 192                 reg = wdt_read(wdt, AT91_WDT_MR);
 193                 if (!(reg & AT91_WDT_WDDIS))
 194                         wdt_write_nosleep(wdt, AT91_WDT_MR,
 195                                           reg | AT91_WDT_WDDIS);
 196         }
 197         return 0;
 198 }
 199
 200 static int sama5d4_wdt_probe(struct platform_device *pdev)
 201 {
 202         struct watchdog_device *wdd;
 203         struct sama5d4_wdt *wdt;
 204         struct resource *res;
 205         void __iomem *regs;
 206         u32 irq = 0;
 207         u32 timeout;
 208         int ret;
 209
 210         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 211         if (!wdt)
 212                 return -ENOMEM;
 213
 214         wdd = &wdt->wdd;
 215         wdd->timeout = WDT_DEFAULT_TIMEOUT;
 216         wdd->info = &sama5d4_wdt_info;
 217         wdd->ops = &sama5d4_wdt_ops;
 218         wdd->min_timeout = MIN_WDT_TIMEOUT;
 219         wdd->max_timeout = MAX_WDT_TIMEOUT;
 220         wdt->last_ping = jiffies;
 221
 222         watchdog_set_drvdata(wdd, wdt);
 223
 224         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 225         regs = devm_ioremap_resource(&pdev->dev, res);
 226         if (IS_ERR(regs))
 227                 return PTR_ERR(regs);
 228
 229         wdt->reg_base = regs;
 230
 231         irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
 232         if (!irq)
 233                 dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
 234
 235         ret = of_sama5d4_wdt_init(pdev->dev.of_node, wdt);
 236         if (ret)
 237                 return ret;
 238
 239         if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
 240                 ret = devm_request_irq(&pdev->dev, irq, sama5d4_wdt_irq_handler,
 241                                        IRQF_SHARED | IRQF_IRQPOLL |
 242                                        IRQF_NO_SUSPEND, pdev->name, pdev);
 243                 if (ret) {
 244                         dev_err(&pdev->dev,
 245                                 "cannot register interrupt handler\n");
 246                         return ret;
 247                 }
 248         }
 249
 250         watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
 251
 252         timeout = WDT_SEC2TICKS(wdd->timeout);
 253
 254         wdt->mr |= AT91_WDT_SET_WDD(timeout);
 255         wdt->mr |= AT91_WDT_SET_WDV(timeout);
 256
 257         ret = sama5d4_wdt_init(wdt);
 258         if (ret)
 259                 return ret;
 260
 261         watchdog_set_nowayout(wdd, nowayout);
 262
 263         ret = watchdog_register_device(wdd);
 264         if (ret) {
 265                 dev_err(&pdev->dev, "failed to register watchdog device\n");
 266                 return ret;
 267         }
 268
 269         platform_set_drvdata(pdev, wdt);
 270
 271         dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 272                  wdd->timeout, nowayout);
 273
 274         return 0;
 275 }
 276
 277 static int sama5d4_wdt_remove(struct platform_device *pdev)
 278 {
 279         struct sama5d4_wdt *wdt = platform_get_drvdata(pdev);
 280
 281         sama5d4_wdt_stop(&wdt->wdd);
 282
 283         watchdog_unregister_device(&wdt->wdd);
 284
 285         return 0;
 286 }
 287
 288 static const struct of_device_id sama5d4_wdt_of_match[] = {
 289         { .compatible = "atmel,sama5d4-wdt", },
 290         { }
 291 };
 292 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
 293
 294 #ifdef CONFIG_PM_SLEEP
 295 static int sama5d4_wdt_resume(struct device *dev)
 296 {
 297         struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 298
 299         /*
 300          * FIXME: writing MR also pings the watchdog which may not be desired.
 301          * This should only be done when the registers are lost on suspend but
 302          * there is no way to get this information right now.
 303          */
 304         sama5d4_wdt_init(wdt);
 305
 306         return 0;
 307 }
 308 #endif
 309
 310 static SIMPLE_DEV_PM_OPS(sama5d4_wdt_pm_ops, NULL,
 311                          sama5d4_wdt_resume);
 312
 313 static struct platform_driver sama5d4_wdt_driver = {
 314         .probe          = sama5d4_wdt_probe,
 315         .remove         = sama5d4_wdt_remove,
 316         .driver         = {
 317                 .name   = "sama5d4_wdt",
 318                 .pm     = &sama5d4_wdt_pm_ops,
 319                 .of_match_table = sama5d4_wdt_of_match,
 320         }
 321 };
 322 module_platform_driver(sama5d4_wdt_driver);
 323
 324 MODULE_AUTHOR("Atmel Corporation");
 325 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
 326 MODULE_LICENSE("GPL v2");