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#define REG_COUNT                       0x4
  23#define REG_MODE                        0x8
  24#define REG_ENABLE                      0xC
  25
  26struct moxart_wdt_dev {
  27        struct watchdog_device dev;
  28        void __iomem *base;
  29        unsigned int clock_frequency;
  30};
  31
  32static int heartbeat;
  33
  34static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
  35                              unsigned long action, void *data)
  36{
  37        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  38
  39        writel(1, moxart_wdt->base + REG_COUNT);
  40        writel(0x5ab9, moxart_wdt->base + REG_MODE);
  41        writel(0x03, moxart_wdt->base + REG_ENABLE);
  42
  43        return 0;
  44}
  45
  46static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  47{
  48        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  49
  50        writel(0, moxart_wdt->base + REG_ENABLE);
  51
  52        return 0;
  53}
  54
  55static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  56{
  57        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  58
  59        writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  60               moxart_wdt->base + REG_COUNT);
  61        writel(0x5ab9, moxart_wdt->base + REG_MODE);
  62        writel(0x03, moxart_wdt->base + REG_ENABLE);
  63
  64        return 0;
  65}
  66
  67static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  68                                  unsigned int timeout)
  69{
  70        wdt_dev->timeout = timeout;
  71
  72        return 0;
  73}
  74
  75static const struct watchdog_info moxart_wdt_info = {
  76        .identity       = "moxart-wdt",
  77        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  78                          WDIOF_MAGICCLOSE,
  79};
  80
  81static const struct watchdog_ops moxart_wdt_ops = {
  82        .owner          = THIS_MODULE,
  83        .start          = moxart_wdt_start,
  84        .stop           = moxart_wdt_stop,
  85        .set_timeout    = moxart_wdt_set_timeout,
  86        .restart        = moxart_wdt_restart,
  87};
  88
  89static int moxart_wdt_probe(struct platform_device *pdev)
  90{
  91        struct moxart_wdt_dev *moxart_wdt;
  92        struct device *dev = &pdev->dev;
  93        struct device_node *node = dev->of_node;
  94        struct resource *res;
  95        struct clk *clk;
  96        int err;
  97        unsigned int max_timeout;
  98        bool nowayout = WATCHDOG_NOWAYOUT;
  99
 100        moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 101        if (!moxart_wdt)
 102                return -ENOMEM;
 103
 104        platform_set_drvdata(pdev, moxart_wdt);
 105
 106        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 107        moxart_wdt->base = devm_ioremap_resource(dev, res);
 108        if (IS_ERR(moxart_wdt->base))
 109                return PTR_ERR(moxart_wdt->base);
 110
 111        clk = of_clk_get(node, 0);
 112        if (IS_ERR(clk)) {
 113                pr_err("%s: of_clk_get failed\n", __func__);
 114                return PTR_ERR(clk);
 115        }
 116
 117        moxart_wdt->clock_frequency = clk_get_rate(clk);
 118        if (moxart_wdt->clock_frequency == 0) {
 119                pr_err("%s: incorrect clock frequency\n", __func__);
 120                return -EINVAL;
 121        }
 122
 123        max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 124
 125        moxart_wdt->dev.info = &moxart_wdt_info;
 126        moxart_wdt->dev.ops = &moxart_wdt_ops;
 127        moxart_wdt->dev.timeout = max_timeout;
 128        moxart_wdt->dev.min_timeout = 1;
 129        moxart_wdt->dev.max_timeout = max_timeout;
 130        moxart_wdt->dev.parent = dev;
 131
 132        watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 133        watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 134        watchdog_set_restart_priority(&moxart_wdt->dev, 128);
 135
 136        watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 137
 138        err = watchdog_register_device(&moxart_wdt->dev);
 139        if (err)
 140                return err;
 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        moxart_wdt_stop(&moxart_wdt->dev);
 153
 154        return 0;
 155}
 156
 157static const struct of_device_id moxart_watchdog_match[] = {
 158        { .compatible = "moxa,moxart-watchdog" },
 159        { },
 160};
 161MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
 162
 163static struct platform_driver moxart_wdt_driver = {
 164        .probe      = moxart_wdt_probe,
 165        .remove     = moxart_wdt_remove,
 166        .driver     = {
 167                .name           = "moxart-watchdog",
 168                .of_match_table = moxart_watchdog_match,
 169        },
 170};
 171module_platform_driver(moxart_wdt_driver);
 172
 173module_param(heartbeat, int, 0);
 174MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 175
 176MODULE_DESCRIPTION("MOXART watchdog driver");
 177MODULE_LICENSE("GPL");
 178MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
 179
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