LXR linux/drivers/watchdog/moxart

   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/mod_devicetable.h>
  17#include <linux/err.h>
  18#include <linux/kernel.h>
  19#include <linux/platform_device.h>
  20#include <linux/watchdog.h>
  21#include <linux/moduleparam.h>
  22
  23#define REG_COUNT                       0x4
  24#define REG_MODE                        0x8
  25#define REG_ENABLE                      0xC
  26
  27struct moxart_wdt_dev {
  28        struct watchdog_device dev;
  29        void __iomem *base;
  30        unsigned int clock_frequency;
  31};
  32
  33static int heartbeat;
  34
  35static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
  36                              unsigned long action, void *data)
  37{
  38        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  39
  40        writel(1, moxart_wdt->base + REG_COUNT);
  41        writel(0x5ab9, moxart_wdt->base + REG_MODE);
  42        writel(0x03, moxart_wdt->base + REG_ENABLE);
  43
  44        return 0;
  45}
  46
  47static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  48{
  49        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  50
  51        writel(0, moxart_wdt->base + REG_ENABLE);
  52
  53        return 0;
  54}
  55
  56static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  57{
  58        struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  59
  60        writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  61               moxart_wdt->base + REG_COUNT);
  62        writel(0x5ab9, moxart_wdt->base + REG_MODE);
  63        writel(0x03, moxart_wdt->base + REG_ENABLE);
  64
  65        return 0;
  66}
  67
  68static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  69                                  unsigned int timeout)
  70{
  71        wdt_dev->timeout = timeout;
  72
  73        return 0;
  74}
  75
  76static const struct watchdog_info moxart_wdt_info = {
  77        .identity       = "moxart-wdt",
  78        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  79                          WDIOF_MAGICCLOSE,
  80};
  81
  82static const struct watchdog_ops moxart_wdt_ops = {
  83        .owner          = THIS_MODULE,
  84        .start          = moxart_wdt_start,
  85        .stop           = moxart_wdt_stop,
  86        .set_timeout    = moxart_wdt_set_timeout,
  87        .restart        = moxart_wdt_restart,
  88};
  89
  90static int moxart_wdt_probe(struct platform_device *pdev)
  91{
  92        struct moxart_wdt_dev *moxart_wdt;
  93        struct device *dev = &pdev->dev;
  94        struct clk *clk;
  95        int err;
  96        unsigned int max_timeout;
  97        bool nowayout = WATCHDOG_NOWAYOUT;
  98
  99        moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 100        if (!moxart_wdt)
 101                return -ENOMEM;
 102
 103        platform_set_drvdata(pdev, moxart_wdt);
 104
 105        moxart_wdt->base = devm_platform_ioremap_resource(pdev, 0);
 106        if (IS_ERR(moxart_wdt->base))
 107                return PTR_ERR(moxart_wdt->base);
 108
 109        clk = devm_clk_get(dev, NULL);
 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        watchdog_set_restart_priority(&moxart_wdt->dev, 128);
 133
 134        watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 135
 136        watchdog_stop_on_unregister(&moxart_wdt->dev);
 137        err = devm_watchdog_register_device(dev, &moxart_wdt->dev);
 138        if (err)
 139                return err;
 140
 141        dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 142                moxart_wdt->dev.timeout, nowayout);
 143
 144        return 0;
 145}
 146
 147static const struct of_device_id moxart_watchdog_match[] = {
 148        { .compatible = "moxa,moxart-watchdog" },
 149        { },
 150};
 151MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
 152
 153static struct platform_driver moxart_wdt_driver = {
 154        .probe      = moxart_wdt_probe,
 155        .driver     = {
 156                .name           = "moxart-watchdog",
 157                .of_match_table = moxart_watchdog_match,
 158        },
 159};
 160module_platform_driver(moxart_wdt_driver);
 161
 162module_param(heartbeat, int, 0);
 163MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 164
 165MODULE_DESCRIPTION("MOXART watchdog driver");
 166MODULE_LICENSE("GPL");
 167MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
 168