linux/drivers/watchdog/tegra_wdt.c
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   1/*
   2 * Copyright (c) 2014, NVIDIA CORPORATION.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or modify it
   5 * under the terms and conditions of the GNU General Public License,
   6 * version 2, as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope it will be useful, but WITHOUT
   9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11 * more details.
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/module.h>
  16#include <linux/interrupt.h>
  17#include <linux/io.h>
  18#include <linux/of.h>
  19#include <linux/platform_device.h>
  20#include <linux/watchdog.h>
  21
  22/* minimum and maximum watchdog trigger timeout, in seconds */
  23#define MIN_WDT_TIMEOUT                 1
  24#define MAX_WDT_TIMEOUT                 255
  25
  26/*
  27 * Base of the WDT registers, from the timer base address.  There are
  28 * actually 5 watchdogs that can be configured (by pairing with an available
  29 * timer), at bases 0x100 + (WDT ID) * 0x20, where WDT ID is 0 through 4.
  30 * This driver only configures the first watchdog (WDT ID 0).
  31 */
  32#define WDT_BASE                        0x100
  33#define WDT_ID                          0
  34
  35/*
  36 * Register base of the timer that's selected for pairing with the watchdog.
  37 * This driver arbitrarily uses timer 5, which is currently unused by
  38 * other drivers (in particular, the Tegra clocksource driver).  If this
  39 * needs to change, take care that the new timer is not used by the
  40 * clocksource driver.
  41 */
  42#define WDT_TIMER_BASE                  0x60
  43#define WDT_TIMER_ID                    5
  44
  45/* WDT registers */
  46#define WDT_CFG                         0x0
  47#define WDT_CFG_PERIOD_SHIFT            4
  48#define WDT_CFG_PERIOD_MASK             0xff
  49#define WDT_CFG_INT_EN                  (1 << 12)
  50#define WDT_CFG_PMC2CAR_RST_EN          (1 << 15)
  51#define WDT_STS                         0x4
  52#define WDT_STS_COUNT_SHIFT             4
  53#define WDT_STS_COUNT_MASK              0xff
  54#define WDT_STS_EXP_SHIFT               12
  55#define WDT_STS_EXP_MASK                0x3
  56#define WDT_CMD                         0x8
  57#define WDT_CMD_START_COUNTER           (1 << 0)
  58#define WDT_CMD_DISABLE_COUNTER         (1 << 1)
  59#define WDT_UNLOCK                      (0xc)
  60#define WDT_UNLOCK_PATTERN              (0xc45a << 0)
  61
  62/* Timer registers */
  63#define TIMER_PTV                       0x0
  64#define TIMER_EN                        (1 << 31)
  65#define TIMER_PERIODIC                  (1 << 30)
  66
  67struct tegra_wdt {
  68        struct watchdog_device  wdd;
  69        void __iomem            *wdt_regs;
  70        void __iomem            *tmr_regs;
  71};
  72
  73#define WDT_HEARTBEAT 120
  74static int heartbeat = WDT_HEARTBEAT;
  75module_param(heartbeat, int, 0);
  76MODULE_PARM_DESC(heartbeat,
  77        "Watchdog heartbeats in seconds. (default = "
  78        __MODULE_STRING(WDT_HEARTBEAT) ")");
  79
  80static bool nowayout = WATCHDOG_NOWAYOUT;
  81module_param(nowayout, bool, 0);
  82MODULE_PARM_DESC(nowayout,
  83        "Watchdog cannot be stopped once started (default="
  84        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  85
  86static int tegra_wdt_start(struct watchdog_device *wdd)
  87{
  88        struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
  89        u32 val;
  90
  91        /*
  92         * This thing has a fixed 1MHz clock.  Normally, we would set the
  93         * period to 1 second by writing 1000000ul, but the watchdog system
  94         * reset actually occurs on the 4th expiration of this counter,
  95         * so we set the period to 1/4 of this amount.
  96         */
  97        val = 1000000ul / 4;
  98        val |= (TIMER_EN | TIMER_PERIODIC);
  99        writel(val, wdt->tmr_regs + TIMER_PTV);
 100
 101        /*
 102         * Set number of periods and start counter.
 103         *
 104         * Interrupt handler is not required for user space
 105         * WDT accesses, since the caller is responsible to ping the
 106         * WDT to reset the counter before expiration, through ioctls.
 107         */
 108        val = WDT_TIMER_ID |
 109              (wdd->timeout << WDT_CFG_PERIOD_SHIFT) |
 110              WDT_CFG_PMC2CAR_RST_EN;
 111        writel(val, wdt->wdt_regs + WDT_CFG);
 112
 113        writel(WDT_CMD_START_COUNTER, wdt->wdt_regs + WDT_CMD);
 114
 115        return 0;
 116}
 117
 118static int tegra_wdt_stop(struct watchdog_device *wdd)
 119{
 120        struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
 121
 122        writel(WDT_UNLOCK_PATTERN, wdt->wdt_regs + WDT_UNLOCK);
 123        writel(WDT_CMD_DISABLE_COUNTER, wdt->wdt_regs + WDT_CMD);
 124        writel(0, wdt->tmr_regs + TIMER_PTV);
 125
 126        return 0;
 127}
 128
 129static int tegra_wdt_ping(struct watchdog_device *wdd)
 130{
 131        struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
 132
 133        writel(WDT_CMD_START_COUNTER, wdt->wdt_regs + WDT_CMD);
 134
 135        return 0;
 136}
 137
 138static int tegra_wdt_set_timeout(struct watchdog_device *wdd,
 139                                 unsigned int timeout)
 140{
 141        wdd->timeout = timeout;
 142
 143        if (watchdog_active(wdd)) {
 144                tegra_wdt_stop(wdd);
 145                return tegra_wdt_start(wdd);
 146        }
 147
 148        return 0;
 149}
 150
 151static unsigned int tegra_wdt_get_timeleft(struct watchdog_device *wdd)
 152{
 153        struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
 154        u32 val;
 155        int count;
 156        int exp;
 157
 158        val = readl(wdt->wdt_regs + WDT_STS);
 159
 160        /* Current countdown (from timeout) */
 161        count = (val >> WDT_STS_COUNT_SHIFT) & WDT_STS_COUNT_MASK;
 162
 163        /* Number of expirations (we are waiting for the 4th expiration) */
 164        exp = (val >> WDT_STS_EXP_SHIFT) & WDT_STS_EXP_MASK;
 165
 166        /*
 167         * The entire thing is divided by 4 because we are ticking down 4 times
 168         * faster due to needing to wait for the 4th expiration.
 169         */
 170        return (((3 - exp) * wdd->timeout) + count) / 4;
 171}
 172
 173static const struct watchdog_info tegra_wdt_info = {
 174        .options        = WDIOF_SETTIMEOUT |
 175                          WDIOF_MAGICCLOSE |
 176                          WDIOF_KEEPALIVEPING,
 177        .firmware_version = 0,
 178        .identity       = "Tegra Watchdog",
 179};
 180
 181static struct watchdog_ops tegra_wdt_ops = {
 182        .owner = THIS_MODULE,
 183        .start = tegra_wdt_start,
 184        .stop = tegra_wdt_stop,
 185        .ping = tegra_wdt_ping,
 186        .set_timeout = tegra_wdt_set_timeout,
 187        .get_timeleft = tegra_wdt_get_timeleft,
 188};
 189
 190static int tegra_wdt_probe(struct platform_device *pdev)
 191{
 192        struct watchdog_device *wdd;
 193        struct tegra_wdt *wdt;
 194        struct resource *res;
 195        void __iomem *regs;
 196        int ret;
 197
 198        /* This is the timer base. */
 199        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 200        regs = devm_ioremap_resource(&pdev->dev, res);
 201        if (IS_ERR(regs))
 202                return PTR_ERR(regs);
 203
 204        /*
 205         * Allocate our watchdog driver data, which has the
 206         * struct watchdog_device nested within it.
 207         */
 208        wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 209        if (!wdt)
 210                return -ENOMEM;
 211
 212        /* Initialize struct tegra_wdt. */
 213        wdt->wdt_regs = regs + WDT_BASE;
 214        wdt->tmr_regs = regs + WDT_TIMER_BASE;
 215
 216        /* Initialize struct watchdog_device. */
 217        wdd = &wdt->wdd;
 218        wdd->timeout = heartbeat;
 219        wdd->info = &tegra_wdt_info;
 220        wdd->ops = &tegra_wdt_ops;
 221        wdd->min_timeout = MIN_WDT_TIMEOUT;
 222        wdd->max_timeout = MAX_WDT_TIMEOUT;
 223        wdd->parent = &pdev->dev;
 224
 225        watchdog_set_drvdata(wdd, wdt);
 226
 227        watchdog_set_nowayout(wdd, nowayout);
 228
 229        ret = watchdog_register_device(wdd);
 230        if (ret) {
 231                dev_err(&pdev->dev,
 232                        "failed to register watchdog device\n");
 233                return ret;
 234        }
 235
 236        platform_set_drvdata(pdev, wdt);
 237
 238        dev_info(&pdev->dev,
 239                 "initialized (heartbeat = %d sec, nowayout = %d)\n",
 240                 heartbeat, nowayout);
 241
 242        return 0;
 243}
 244
 245static int tegra_wdt_remove(struct platform_device *pdev)
 246{
 247        struct tegra_wdt *wdt = platform_get_drvdata(pdev);
 248
 249        tegra_wdt_stop(&wdt->wdd);
 250
 251        watchdog_unregister_device(&wdt->wdd);
 252
 253        dev_info(&pdev->dev, "removed wdt\n");
 254
 255        return 0;
 256}
 257
 258#ifdef CONFIG_PM_SLEEP
 259static int tegra_wdt_runtime_suspend(struct device *dev)
 260{
 261        struct tegra_wdt *wdt = dev_get_drvdata(dev);
 262
 263        if (watchdog_active(&wdt->wdd))
 264                tegra_wdt_stop(&wdt->wdd);
 265
 266        return 0;
 267}
 268
 269static int tegra_wdt_runtime_resume(struct device *dev)
 270{
 271        struct tegra_wdt *wdt = dev_get_drvdata(dev);
 272
 273        if (watchdog_active(&wdt->wdd))
 274                tegra_wdt_start(&wdt->wdd);
 275
 276        return 0;
 277}
 278#endif
 279
 280static const struct of_device_id tegra_wdt_of_match[] = {
 281        { .compatible = "nvidia,tegra30-timer", },
 282        { },
 283};
 284MODULE_DEVICE_TABLE(of, tegra_wdt_of_match);
 285
 286static const struct dev_pm_ops tegra_wdt_pm_ops = {
 287        SET_SYSTEM_SLEEP_PM_OPS(tegra_wdt_runtime_suspend,
 288                                tegra_wdt_runtime_resume)
 289};
 290
 291static struct platform_driver tegra_wdt_driver = {
 292        .probe          = tegra_wdt_probe,
 293        .remove         = tegra_wdt_remove,
 294        .driver         = {
 295                .name   = "tegra-wdt",
 296                .pm     = &tegra_wdt_pm_ops,
 297                .of_match_table = tegra_wdt_of_match,
 298        },
 299};
 300module_platform_driver(tegra_wdt_driver);
 301
 302MODULE_AUTHOR("NVIDIA Corporation");
 303MODULE_DESCRIPTION("Tegra Watchdog Driver");
 304MODULE_LICENSE("GPL v2");
 305
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