drivers/watchdog/sama5d4_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for Atmel SAMA5D4 Watchdog Timer
   4  *
   5  * Copyright (C) 2015 Atmel Corporation
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/io.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/of_irq.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/reboot.h>
  17 #include <linux/watchdog.h>
  18
  19 #include "at91sam9_wdt.h"
  20
  21 /* minimum and maximum watchdog timeout, in seconds */
  22 #define MIN_WDT_TIMEOUT         1
  23 #define MAX_WDT_TIMEOUT         16
  24 #define WDT_DEFAULT_TIMEOUT     MAX_WDT_TIMEOUT
  25
  26 #define WDT_SEC2TICKS(s)        ((s) ? (((s) << 8) - 1) : 0)
  27
  28 struct sama5d4_wdt {
  29         struct watchdog_device  wdd;
  30         void __iomem            *reg_base;
  31         u32                     mr;
  32         unsigned long           last_ping;
  33 };
  34
  35 static int wdt_timeout;
  36 static bool nowayout = WATCHDOG_NOWAYOUT;
  37
  38 module_param(wdt_timeout, int, 0);
  39 MODULE_PARM_DESC(wdt_timeout,
  40         "Watchdog timeout in seconds. (default = "
  41         __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
  42
  43 module_param(nowayout, bool, 0);
  44 MODULE_PARM_DESC(nowayout,
  45         "Watchdog cannot be stopped once started (default="
  46         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  47
  48 #define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
  49
  50 #define wdt_read(wdt, field) \
  51         readl_relaxed((wdt)->reg_base + (field))
  52
  53 /* 4 slow clock periods is 4/32768 = 122.07µs*/
  54 #define WDT_DELAY       usecs_to_jiffies(123)
  55
  56 static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
  57 {
  58         /*
  59          * WDT_CR and WDT_MR must not be modified within three slow clock
  60          * periods following a restart of the watchdog performed by a write
  61          * access in WDT_CR.
  62          */
  63         while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
  64                 usleep_range(30, 125);
  65         writel_relaxed(val, wdt->reg_base + field);
  66         wdt->last_ping = jiffies;
  67 }
  68
  69 static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
  70 {
  71         if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
  72                 udelay(123);
  73         writel_relaxed(val, wdt->reg_base + field);
  74         wdt->last_ping = jiffies;
  75 }
  76
  77 static int sama5d4_wdt_start(struct watchdog_device *wdd)
  78 {
  79         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  80
  81         wdt->mr &= ~AT91_WDT_WDDIS;
  82         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
  83
  84         return 0;
  85 }
  86
  87 static int sama5d4_wdt_stop(struct watchdog_device *wdd)
  88 {
  89         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  90
  91         wdt->mr |= AT91_WDT_WDDIS;
  92         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
  93
  94         return 0;
  95 }
  96
  97 static int sama5d4_wdt_ping(struct watchdog_device *wdd)
  98 {
  99         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 100
 101         wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
 102
 103         return 0;
 104 }
 105
 106 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
 107                                  unsigned int timeout)
 108 {
 109         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 110         u32 value = WDT_SEC2TICKS(timeout);
 111
 112         wdt->mr &= ~AT91_WDT_WDV;
 113         wdt->mr &= ~AT91_WDT_WDD;
 114         wdt->mr |= AT91_WDT_SET_WDV(value);
 115         wdt->mr |= AT91_WDT_SET_WDD(value);
 116
 117         /*
 118          * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
 119          * setting the WDDIS bit, and while it is set, the fields WDV and WDD
 120          * must not be modified.
 121          * If the watchdog is enabled, then the timeout can be updated. Else,
 122          * wait that the user enables it.
 123          */
 124         if (wdt_enabled)
 125                 wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
 126
 127         wdd->timeout = timeout;
 128
 129         return 0;
 130 }
 131
 132 static const struct watchdog_info sama5d4_wdt_info = {
 133         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 134         .identity = "Atmel SAMA5D4 Watchdog",
 135 };
 136
 137 static const struct watchdog_ops sama5d4_wdt_ops = {
 138         .owner = THIS_MODULE,
 139         .start = sama5d4_wdt_start,
 140         .stop = sama5d4_wdt_stop,
 141         .ping = sama5d4_wdt_ping,
 142         .set_timeout = sama5d4_wdt_set_timeout,
 143 };
 144
 145 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 146 {
 147         struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
 148
 149         if (wdt_read(wdt, AT91_WDT_SR)) {
 150                 pr_crit("Atmel Watchdog Software Reset\n");
 151                 emergency_restart();
 152                 pr_crit("Reboot didn't succeed\n");
 153         }
 154
 155         return IRQ_HANDLED;
 156 }
 157
 158 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 159 {
 160         const char *tmp;
 161
 162         wdt->mr = AT91_WDT_WDDIS;
 163
 164         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 165             !strcmp(tmp, "software"))
 166                 wdt->mr |= AT91_WDT_WDFIEN;
 167         else
 168                 wdt->mr |= AT91_WDT_WDRSTEN;
 169
 170         if (of_property_read_bool(np, "atmel,idle-halt"))
 171                 wdt->mr |= AT91_WDT_WDIDLEHLT;
 172
 173         if (of_property_read_bool(np, "atmel,dbg-halt"))
 174                 wdt->mr |= AT91_WDT_WDDBGHLT;
 175
 176         return 0;
 177 }
 178
 179 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 180 {
 181         u32 reg;
 182         /*
 183          * When booting and resuming, the bootloader may have changed the
 184          * watchdog configuration.
 185          * If the watchdog is already running, we can safely update it.
 186          * Else, we have to disable it properly.
 187          */
 188         if (wdt_enabled) {
 189                 wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
 190         } else {
 191                 reg = wdt_read(wdt, AT91_WDT_MR);
 192                 if (!(reg & AT91_WDT_WDDIS))
 193                         wdt_write_nosleep(wdt, AT91_WDT_MR,
 194                                           reg | AT91_WDT_WDDIS);
 195         }
 196         return 0;
 197 }
 198
 199 static int sama5d4_wdt_probe(struct platform_device *pdev)
 200 {
 201         struct device *dev = &pdev->dev;
 202         struct watchdog_device *wdd;
 203         struct sama5d4_wdt *wdt;
 204         void __iomem *regs;
 205         u32 irq = 0;
 206         u32 timeout;
 207         int ret;
 208
 209         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 210         if (!wdt)
 211                 return -ENOMEM;
 212
 213         wdd = &wdt->wdd;
 214         wdd->timeout = WDT_DEFAULT_TIMEOUT;
 215         wdd->info = &sama5d4_wdt_info;
 216         wdd->ops = &sama5d4_wdt_ops;
 217         wdd->min_timeout = MIN_WDT_TIMEOUT;
 218         wdd->max_timeout = MAX_WDT_TIMEOUT;
 219         wdt->last_ping = jiffies;
 220
 221         watchdog_set_drvdata(wdd, wdt);
 222
 223         regs = devm_platform_ioremap_resource(pdev, 0);
 224         if (IS_ERR(regs))
 225                 return PTR_ERR(regs);
 226
 227         wdt->reg_base = regs;
 228
 229         irq = irq_of_parse_and_map(dev->of_node, 0);
 230         if (!irq)
 231                 dev_warn(dev, "failed to get IRQ from DT\n");
 232
 233         ret = of_sama5d4_wdt_init(dev->of_node, wdt);
 234         if (ret)
 235                 return ret;
 236
 237         if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
 238                 ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
 239                                        IRQF_SHARED | IRQF_IRQPOLL |
 240                                        IRQF_NO_SUSPEND, pdev->name, pdev);
 241                 if (ret) {
 242                         dev_err(dev, "cannot register interrupt handler\n");
 243                         return ret;
 244                 }
 245         }
 246
 247         watchdog_init_timeout(wdd, wdt_timeout, dev);
 248
 249         timeout = WDT_SEC2TICKS(wdd->timeout);
 250
 251         wdt->mr |= AT91_WDT_SET_WDD(timeout);
 252         wdt->mr |= AT91_WDT_SET_WDV(timeout);
 253
 254         ret = sama5d4_wdt_init(wdt);
 255         if (ret)
 256                 return ret;
 257
 258         watchdog_set_nowayout(wdd, nowayout);
 259
 260         watchdog_stop_on_unregister(wdd);
 261         ret = devm_watchdog_register_device(dev, wdd);
 262         if (ret) {
 263                 dev_err(dev, "failed to register watchdog device\n");
 264                 return ret;
 265         }
 266
 267         platform_set_drvdata(pdev, wdt);
 268
 269         dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 270                  wdd->timeout, nowayout);
 271
 272         return 0;
 273 }
 274
 275 static const struct of_device_id sama5d4_wdt_of_match[] = {
 276         { .compatible = "atmel,sama5d4-wdt", },
 277         { }
 278 };
 279 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
 280
 281 #ifdef CONFIG_PM_SLEEP
 282 static int sama5d4_wdt_resume(struct device *dev)
 283 {
 284         struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 285
 286         /*
 287          * FIXME: writing MR also pings the watchdog which may not be desired.
 288          * This should only be done when the registers are lost on suspend but
 289          * there is no way to get this information right now.
 290          */
 291         sama5d4_wdt_init(wdt);
 292
 293         return 0;
 294 }
 295 #endif
 296
 297 static SIMPLE_DEV_PM_OPS(sama5d4_wdt_pm_ops, NULL,
 298                          sama5d4_wdt_resume);
 299
 300 static struct platform_driver sama5d4_wdt_driver = {
 301         .probe          = sama5d4_wdt_probe,
 302         .driver         = {
 303                 .name   = "sama5d4_wdt",
 304                 .pm     = &sama5d4_wdt_pm_ops,
 305                 .of_match_table = sama5d4_wdt_of_match,
 306         }
 307 };
 308 module_platform_driver(sama5d4_wdt_driver);
 309
 310 MODULE_AUTHOR("Atmel Corporation");
 311 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
 312 MODULE_LICENSE("GPL v2");