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/notifier.h>
  19#include <linux/platform_device.h>
  20#include <linux/reboot.h>
  21#include <linux/watchdog.h>
  22#include <linux/moduleparam.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        struct notifier_block restart_handler;
  33};
  34
  35static int heartbeat;
  36
  37static int moxart_restart_handle(struct notifier_block *this,
  38                                 unsigned long mode, void *cmd)
  39{
  40        struct moxart_wdt_dev *moxart_wdt = container_of(this,
  41                                                         struct moxart_wdt_dev,
  42                                                         restart_handler);
  43        writel(1, moxart_wdt->base + REG_COUNT);
  44        writel(0x5ab9, moxart_wdt->base + REG_MODE);
  45        writel(0x03, moxart_wdt->base + REG_ENABLE);
  46
  47        return NOTIFY_DONE;
  48}
  49
  50static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  51{
  52        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  53
  54        writel(0, moxart_wdt->base + REG_ENABLE);
  55
  56        return 0;
  57}
  58
  59static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  60{
  61        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  62
  63        writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  64               moxart_wdt->base + REG_COUNT);
  65        writel(0x5ab9, moxart_wdt->base + REG_MODE);
  66        writel(0x03, moxart_wdt->base + REG_ENABLE);
  67
  68        return 0;
  69}
  70
  71static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  72                                  unsigned int timeout)
  73{
  74        wdt_dev->timeout = timeout;
  75
  76        return 0;
  77}
  78
  79static const struct watchdog_info moxart_wdt_info = {
  80        .identity       = "moxart-wdt",
  81        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  82                          WDIOF_MAGICCLOSE,
  83};
  84
  85static const struct watchdog_ops moxart_wdt_ops = {
  86        .owner          = THIS_MODULE,
  87        .start          = moxart_wdt_start,
  88        .stop           = moxart_wdt_stop,
  89        .set_timeout    = moxart_wdt_set_timeout,
  90};
  91
  92static int moxart_wdt_probe(struct platform_device *pdev)
  93{
  94        struct moxart_wdt_dev *moxart_wdt;
  95        struct device *dev = &pdev->dev;
  96        struct device_node *node = dev->of_node;
  97        struct resource *res;
  98        struct clk *clk;
  99        int err;
 100        unsigned int max_timeout;
 101        bool nowayout = WATCHDOG_NOWAYOUT;
 102
 103        moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 104        if (!moxart_wdt)
 105                return -ENOMEM;
 106
 107        platform_set_drvdata(pdev, moxart_wdt);
 108
 109        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 110        moxart_wdt->base = devm_ioremap_resource(dev, res);
 111        if (IS_ERR(moxart_wdt->base))
 112                return PTR_ERR(moxart_wdt->base);
 113
 114        clk = of_clk_get(node, 0);
 115        if (IS_ERR(clk)) {
 116                pr_err("%s: of_clk_get failed\n", __func__);
 117                return PTR_ERR(clk);
 118        }
 119
 120        moxart_wdt->clock_frequency = clk_get_rate(clk);
 121        if (moxart_wdt->clock_frequency == 0) {
 122                pr_err("%s: incorrect clock frequency\n", __func__);
 123                return -EINVAL;
 124        }
 125
 126        max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 127
 128        moxart_wdt->dev.info = &moxart_wdt_info;
 129        moxart_wdt->dev.ops = &moxart_wdt_ops;
 130        moxart_wdt->dev.timeout = max_timeout;
 131        moxart_wdt->dev.min_timeout = 1;
 132        moxart_wdt->dev.max_timeout = max_timeout;
 133        moxart_wdt->dev.parent = dev;
 134
 135        watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 136        watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 137
 138        watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 139
 140        err = watchdog_register_device(&moxart_wdt->dev);
 141        if (err)
 142                return err;
 143
 144        moxart_wdt->restart_handler.notifier_call = moxart_restart_handle;
 145        moxart_wdt->restart_handler.priority = 128;
 146        err = register_restart_handler(&moxart_wdt->restart_handler);
 147        if (err)
 148                dev_err(dev, "cannot register restart notifier (err=%d)\n",
 149                        err);
 150
 151        dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 152                moxart_wdt->dev.timeout, nowayout);
 153
 154        return 0;
 155}
 156
 157static int moxart_wdt_remove(struct platform_device *pdev)
 158{
 159        struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
 160
 161        unregister_restart_handler(&moxart_wdt->restart_handler);
 162        moxart_wdt_stop(&moxart_wdt->dev);
 163
 164        return 0;
 165}
 166
 167static const struct of_device_id moxart_watchdog_match[] = {
 168        { .compatible = "moxa,moxart-watchdog" },
 169        { },
 170};
 171
 172static struct platform_driver moxart_wdt_driver = {
 173        .probe      = moxart_wdt_probe,
 174        .remove     = moxart_wdt_remove,
 175        .driver     = {
 176                .name           = "moxart-watchdog",
 177                .of_match_table = moxart_watchdog_match,
 178        },
 179};
 180module_platform_driver(moxart_wdt_driver);
 181
 182module_param(heartbeat, int, 0);
 183MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 184
 185MODULE_DESCRIPTION("MOXART watchdog driver");
 186MODULE_LICENSE("GPL");
 187MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
 188
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