linux/drivers/watchdog/moxart_wdt.c
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   1/*
   2 * MOXA ART SoCs watchdog driver.
   3 *
   4 * Copyright (C) 2013 Jonas Jensen
   5 *
   6 * Jonas Jensen <jonas.jensen@gmail.com>
   7 *
   8 * This file is licensed under the terms of the GNU General Public
   9 * License version 2.  This program is licensed "as is" without any
  10 * warranty of any kind, whether express or implied.
  11 */
  12
  13#include <linux/clk.h>
  14#include <linux/io.h>
  15#include <linux/module.h>
  16#include <linux/err.h>
  17#include <linux/kernel.h>
  18#include <linux/platform_device.h>
  19#include <linux/watchdog.h>
  20#include <linux/moduleparam.h>
  21
  22#include <asm/system_misc.h>
  23
  24#define REG_COUNT                       0x4
  25#define REG_MODE                        0x8
  26#define REG_ENABLE                      0xC
  27
  28struct moxart_wdt_dev {
  29        struct watchdog_device dev;
  30        void __iomem *base;
  31        unsigned int clock_frequency;
  32};
  33
  34static struct moxart_wdt_dev *moxart_restart_ctx;
  35
  36static int heartbeat;
  37
  38static void moxart_wdt_restart(enum reboot_mode reboot_mode, const char *cmd)
  39{
  40        writel(1, moxart_restart_ctx->base + REG_COUNT);
  41        writel(0x5ab9, moxart_restart_ctx->base + REG_MODE);
  42        writel(0x03, moxart_restart_ctx->base + REG_ENABLE);
  43}
  44
  45static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  46{
  47        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  48
  49        writel(0, moxart_wdt->base + REG_ENABLE);
  50
  51        return 0;
  52}
  53
  54static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  55{
  56        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  57
  58        writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  59               moxart_wdt->base + REG_COUNT);
  60        writel(0x5ab9, moxart_wdt->base + REG_MODE);
  61        writel(0x03, moxart_wdt->base + REG_ENABLE);
  62
  63        return 0;
  64}
  65
  66static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  67                                  unsigned int timeout)
  68{
  69        wdt_dev->timeout = timeout;
  70
  71        return 0;
  72}
  73
  74static const struct watchdog_info moxart_wdt_info = {
  75        .identity       = "moxart-wdt",
  76        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  77                          WDIOF_MAGICCLOSE,
  78};
  79
  80static const struct watchdog_ops moxart_wdt_ops = {
  81        .owner          = THIS_MODULE,
  82        .start          = moxart_wdt_start,
  83        .stop           = moxart_wdt_stop,
  84        .set_timeout    = moxart_wdt_set_timeout,
  85};
  86
  87static int moxart_wdt_probe(struct platform_device *pdev)
  88{
  89        struct moxart_wdt_dev *moxart_wdt;
  90        struct device *dev = &pdev->dev;
  91        struct device_node *node = dev->of_node;
  92        struct resource *res;
  93        struct clk *clk;
  94        int err;
  95        unsigned int max_timeout;
  96        bool nowayout = WATCHDOG_NOWAYOUT;
  97
  98        moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
  99        if (!moxart_wdt)
 100                return -ENOMEM;
 101
 102        platform_set_drvdata(pdev, moxart_wdt);
 103
 104        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 105        moxart_wdt->base = devm_ioremap_resource(dev, res);
 106        if (IS_ERR(moxart_wdt->base))
 107                return PTR_ERR(moxart_wdt->base);
 108
 109        clk = of_clk_get(node, 0);
 110        if (IS_ERR(clk)) {
 111                pr_err("%s: of_clk_get failed\n", __func__);
 112                return PTR_ERR(clk);
 113        }
 114
 115        moxart_wdt->clock_frequency = clk_get_rate(clk);
 116        if (moxart_wdt->clock_frequency == 0) {
 117                pr_err("%s: incorrect clock frequency\n", __func__);
 118                return -EINVAL;
 119        }
 120
 121        max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 122
 123        moxart_wdt->dev.info = &moxart_wdt_info;
 124        moxart_wdt->dev.ops = &moxart_wdt_ops;
 125        moxart_wdt->dev.timeout = max_timeout;
 126        moxart_wdt->dev.min_timeout = 1;
 127        moxart_wdt->dev.max_timeout = max_timeout;
 128        moxart_wdt->dev.parent = dev;
 129
 130        watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 131        watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 132
 133        watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 134
 135        err = watchdog_register_device(&moxart_wdt->dev);
 136        if (err)
 137                return err;
 138
 139        moxart_restart_ctx = moxart_wdt;
 140        arm_pm_restart = moxart_wdt_restart;
 141
 142        dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 143                moxart_wdt->dev.timeout, nowayout);
 144
 145        return 0;
 146}
 147
 148static int moxart_wdt_remove(struct platform_device *pdev)
 149{
 150        struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
 151
 152        arm_pm_restart = NULL;
 153        moxart_wdt_stop(&moxart_wdt->dev);
 154        watchdog_unregister_device(&moxart_wdt->dev);
 155
 156        return 0;
 157}
 158
 159static const struct of_device_id moxart_watchdog_match[] = {
 160        { .compatible = "moxa,moxart-watchdog" },
 161        { },
 162};
 163
 164static struct platform_driver moxart_wdt_driver = {
 165        .probe      = moxart_wdt_probe,
 166        .remove     = moxart_wdt_remove,
 167        .driver     = {
 168                .name           = "moxart-watchdog",
 169                .owner          = THIS_MODULE,
 170                .of_match_table = moxart_watchdog_match,
 171        },
 172};
 173module_platform_driver(moxart_wdt_driver);
 174
 175module_param(heartbeat, int, 0);
 176MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 177
 178MODULE_DESCRIPTION("MOXART watchdog driver");
 179MODULE_LICENSE("GPL");
 180MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
 181
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