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/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     config;
  32 };
  33
  34 static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
  35 static bool nowayout = WATCHDOG_NOWAYOUT;
  36
  37 module_param(wdt_timeout, int, 0);
  38 MODULE_PARM_DESC(wdt_timeout,
  39         "Watchdog timeout in seconds. (default = "
  40         __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
  41
  42 module_param(nowayout, bool, 0);
  43 MODULE_PARM_DESC(nowayout,
  44         "Watchdog cannot be stopped once started (default="
  45         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  46
  47 #define wdt_read(wdt, field) \
  48         readl_relaxed((wdt)->reg_base + (field))
  49
  50 #define wdt_write(wtd, field, val) \
  51         writel_relaxed((val), (wdt)->reg_base + (field))
  52
  53 static int sama5d4_wdt_start(struct watchdog_device *wdd)
  54 {
  55         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  56         u32 reg;
  57
  58         reg = wdt_read(wdt, AT91_WDT_MR);
  59         reg &= ~AT91_WDT_WDDIS;
  60         wdt_write(wdt, AT91_WDT_MR, reg);
  61
  62         return 0;
  63 }
  64
  65 static int sama5d4_wdt_stop(struct watchdog_device *wdd)
  66 {
  67         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  68         u32 reg;
  69
  70         reg = wdt_read(wdt, AT91_WDT_MR);
  71         reg |= AT91_WDT_WDDIS;
  72         wdt_write(wdt, AT91_WDT_MR, reg);
  73
  74         return 0;
  75 }
  76
  77 static int sama5d4_wdt_ping(struct watchdog_device *wdd)
  78 {
  79         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  80
  81         wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
  82
  83         return 0;
  84 }
  85
  86 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
  87                                  unsigned int timeout)
  88 {
  89         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  90         u32 value = WDT_SEC2TICKS(timeout);
  91         u32 reg;
  92
  93         reg = wdt_read(wdt, AT91_WDT_MR);
  94         reg &= ~AT91_WDT_WDV;
  95         reg &= ~AT91_WDT_WDD;
  96         reg |= AT91_WDT_SET_WDV(value);
  97         reg |= AT91_WDT_SET_WDD(value);
  98         wdt_write(wdt, AT91_WDT_MR, reg);
  99
 100         wdd->timeout = timeout;
 101
 102         return 0;
 103 }
 104
 105 static const struct watchdog_info sama5d4_wdt_info = {
 106         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 107         .identity = "Atmel SAMA5D4 Watchdog",
 108 };
 109
 110 static struct watchdog_ops sama5d4_wdt_ops = {
 111         .owner = THIS_MODULE,
 112         .start = sama5d4_wdt_start,
 113         .stop = sama5d4_wdt_stop,
 114         .ping = sama5d4_wdt_ping,
 115         .set_timeout = sama5d4_wdt_set_timeout,
 116 };
 117
 118 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 119 {
 120         struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
 121
 122         if (wdt_read(wdt, AT91_WDT_SR)) {
 123                 pr_crit("Atmel Watchdog Software Reset\n");
 124                 emergency_restart();
 125                 pr_crit("Reboot didn't succeed\n");
 126         }
 127
 128         return IRQ_HANDLED;
 129 }
 130
 131 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 132 {
 133         const char *tmp;
 134
 135         wdt->config = AT91_WDT_WDDIS;
 136
 137         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 138             !strcmp(tmp, "software"))
 139                 wdt->config |= AT91_WDT_WDFIEN;
 140         else
 141                 wdt->config |= AT91_WDT_WDRSTEN;
 142
 143         if (of_property_read_bool(np, "atmel,idle-halt"))
 144                 wdt->config |= AT91_WDT_WDIDLEHLT;
 145
 146         if (of_property_read_bool(np, "atmel,dbg-halt"))
 147                 wdt->config |= AT91_WDT_WDDBGHLT;
 148
 149         return 0;
 150 }
 151
 152 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 153 {
 154         struct watchdog_device *wdd = &wdt->wdd;
 155         u32 value = WDT_SEC2TICKS(wdd->timeout);
 156         u32 reg;
 157
 158         /*
 159          * Because the fields WDV and WDD must not be modified when the WDDIS
 160          * bit is set, so clear the WDDIS bit before writing the WDT_MR.
 161          */
 162         reg = wdt_read(wdt, AT91_WDT_MR);
 163         reg &= ~AT91_WDT_WDDIS;
 164         wdt_write(wdt, AT91_WDT_MR, reg);
 165
 166         reg = wdt->config;
 167         reg |= AT91_WDT_SET_WDD(value);
 168         reg |= AT91_WDT_SET_WDV(value);
 169
 170         wdt_write(wdt, AT91_WDT_MR, reg);
 171
 172         return 0;
 173 }
 174
 175 static int sama5d4_wdt_probe(struct platform_device *pdev)
 176 {
 177         struct watchdog_device *wdd;
 178         struct sama5d4_wdt *wdt;
 179         struct resource *res;
 180         void __iomem *regs;
 181         u32 irq = 0;
 182         int ret;
 183
 184         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 185         if (!wdt)
 186                 return -ENOMEM;
 187
 188         wdd = &wdt->wdd;
 189         wdd->timeout = wdt_timeout;
 190         wdd->info = &sama5d4_wdt_info;
 191         wdd->ops = &sama5d4_wdt_ops;
 192         wdd->min_timeout = MIN_WDT_TIMEOUT;
 193         wdd->max_timeout = MAX_WDT_TIMEOUT;
 194
 195         watchdog_set_drvdata(wdd, wdt);
 196
 197         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 198         regs = devm_ioremap_resource(&pdev->dev, res);
 199         if (IS_ERR(regs))
 200                 return PTR_ERR(regs);
 201
 202         wdt->reg_base = regs;
 203
 204         if (pdev->dev.of_node) {
 205                 irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
 206                 if (!irq)
 207                         dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
 208
 209                 ret = of_sama5d4_wdt_init(pdev->dev.of_node, wdt);
 210                 if (ret)
 211                         return ret;
 212         }
 213
 214         if ((wdt->config & AT91_WDT_WDFIEN) && irq) {
 215                 ret = devm_request_irq(&pdev->dev, irq, sama5d4_wdt_irq_handler,
 216                                        IRQF_SHARED | IRQF_IRQPOLL |
 217                                        IRQF_NO_SUSPEND, pdev->name, pdev);
 218                 if (ret) {
 219                         dev_err(&pdev->dev,
 220                                 "cannot register interrupt handler\n");
 221                         return ret;
 222                 }
 223         }
 224
 225         ret = watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
 226         if (ret) {
 227                 dev_err(&pdev->dev, "unable to set timeout value\n");
 228                 return ret;
 229         }
 230
 231         ret = sama5d4_wdt_init(wdt);
 232         if (ret)
 233                 return ret;
 234
 235         watchdog_set_nowayout(wdd, nowayout);
 236
 237         ret = watchdog_register_device(wdd);
 238         if (ret) {
 239                 dev_err(&pdev->dev, "failed to register watchdog device\n");
 240                 return ret;
 241         }
 242
 243         platform_set_drvdata(pdev, wdt);
 244
 245         dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 246                  wdt_timeout, nowayout);
 247
 248         return 0;
 249 }
 250
 251 static int sama5d4_wdt_remove(struct platform_device *pdev)
 252 {
 253         struct sama5d4_wdt *wdt = platform_get_drvdata(pdev);
 254
 255         sama5d4_wdt_stop(&wdt->wdd);
 256
 257         watchdog_unregister_device(&wdt->wdd);
 258
 259         return 0;
 260 }
 261
 262 static const struct of_device_id sama5d4_wdt_of_match[] = {
 263         { .compatible = "atmel,sama5d4-wdt", },
 264         { }
 265 };
 266 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
 267
 268 static struct platform_driver sama5d4_wdt_driver = {
 269         .probe          = sama5d4_wdt_probe,
 270         .remove         = sama5d4_wdt_remove,
 271         .driver         = {
 272                 .name   = "sama5d4_wdt",
 273                 .of_match_table = sama5d4_wdt_of_match,
 274         }
 275 };
 276 module_platform_driver(sama5d4_wdt_driver);
 277
 278 MODULE_AUTHOR("Atmel Corporation");
 279 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
 280 MODULE_LICENSE("GPL v2");