linux/drivers/watchdog/rtd119x_wdt.c
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   1/*
   2 * Realtek RTD129x watchdog
   3 *
   4 * Copyright (c) 2017 Andreas F\xC3\xA4rber
   5 *
   6 * SPDX-License-Identifier: GPL-2.0+
   7 */
   8
   9#include <linux/bitops.h>
  10#include <linux/clk.h>
  11#include <linux/io.h>
  12#include <linux/of.h>
  13#include <linux/of_address.h>
  14#include <linux/platform_device.h>
  15#include <linux/watchdog.h>
  16
  17#define RTD119X_TCWCR           0x0
  18#define RTD119X_TCWTR           0x4
  19#define RTD119X_TCWOV           0xc
  20
  21#define RTD119X_TCWCR_WDEN_DISABLED             0xa5
  22#define RTD119X_TCWCR_WDEN_ENABLED              0xff
  23#define RTD119X_TCWCR_WDEN_MASK                 0xff
  24
  25#define RTD119X_TCWTR_WDCLR                     BIT(0)
  26
  27struct rtd119x_watchdog_device {
  28        struct watchdog_device wdt_dev;
  29        void __iomem *base;
  30        struct clk *clk;
  31};
  32
  33static int rtd119x_wdt_start(struct watchdog_device *wdev)
  34{
  35        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  36        u32 val;
  37
  38        val = readl_relaxed(data->base + RTD119X_TCWCR);
  39        val &= ~RTD119X_TCWCR_WDEN_MASK;
  40        val |= RTD119X_TCWCR_WDEN_ENABLED;
  41        writel(val, data->base + RTD119X_TCWCR);
  42
  43        return 0;
  44}
  45
  46static int rtd119x_wdt_stop(struct watchdog_device *wdev)
  47{
  48        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  49        u32 val;
  50
  51        val = readl_relaxed(data->base + RTD119X_TCWCR);
  52        val &= ~RTD119X_TCWCR_WDEN_MASK;
  53        val |= RTD119X_TCWCR_WDEN_DISABLED;
  54        writel(val, data->base + RTD119X_TCWCR);
  55
  56        return 0;
  57}
  58
  59static int rtd119x_wdt_ping(struct watchdog_device *wdev)
  60{
  61        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  62
  63        writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
  64
  65        return rtd119x_wdt_start(wdev);
  66}
  67
  68static int rtd119x_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val)
  69{
  70        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  71
  72        writel(val * clk_get_rate(data->clk), data->base + RTD119X_TCWOV);
  73
  74        data->wdt_dev.timeout = val;
  75
  76        return 0;
  77}
  78
  79static const struct watchdog_ops rtd119x_wdt_ops = {
  80        .owner = THIS_MODULE,
  81        .start          = rtd119x_wdt_start,
  82        .stop           = rtd119x_wdt_stop,
  83        .ping           = rtd119x_wdt_ping,
  84        .set_timeout    = rtd119x_wdt_set_timeout,
  85};
  86
  87static const struct watchdog_info rtd119x_wdt_info = {
  88        .identity = "rtd119x-wdt",
  89        .options = 0,
  90};
  91
  92static const struct of_device_id rtd119x_wdt_dt_ids[] = {
  93         { .compatible = "realtek,rtd1295-watchdog" },
  94         { }
  95};
  96
  97static void rtd119x_clk_disable_unprepare(void *data)
  98{
  99        clk_disable_unprepare(data);
 100}
 101
 102static int rtd119x_wdt_probe(struct platform_device *pdev)
 103{
 104        struct device *dev = &pdev->dev;
 105        struct rtd119x_watchdog_device *data;
 106        int ret;
 107
 108        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 109        if (!data)
 110                return -ENOMEM;
 111
 112        data->base = devm_platform_ioremap_resource(pdev, 0);
 113        if (IS_ERR(data->base))
 114                return PTR_ERR(data->base);
 115
 116        data->clk = devm_clk_get(dev, NULL);
 117        if (IS_ERR(data->clk))
 118                return PTR_ERR(data->clk);
 119
 120        ret = clk_prepare_enable(data->clk);
 121        if (ret)
 122                return ret;
 123        ret = devm_add_action_or_reset(dev, rtd119x_clk_disable_unprepare,
 124                                       data->clk);
 125        if (ret)
 126                return ret;
 127
 128        data->wdt_dev.info = &rtd119x_wdt_info;
 129        data->wdt_dev.ops = &rtd119x_wdt_ops;
 130        data->wdt_dev.timeout = 120;
 131        data->wdt_dev.max_timeout = 0xffffffff / clk_get_rate(data->clk);
 132        data->wdt_dev.min_timeout = 1;
 133        data->wdt_dev.parent = dev;
 134
 135        watchdog_stop_on_reboot(&data->wdt_dev);
 136        watchdog_set_drvdata(&data->wdt_dev, data);
 137        platform_set_drvdata(pdev, data);
 138
 139        writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
 140        rtd119x_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
 141        rtd119x_wdt_stop(&data->wdt_dev);
 142
 143        return devm_watchdog_register_device(dev, &data->wdt_dev);
 144}
 145
 146static struct platform_driver rtd119x_wdt_driver = {
 147        .probe = rtd119x_wdt_probe,
 148        .driver = {
 149                .name = "rtd1295-watchdog",
 150                .of_match_table = rtd119x_wdt_dt_ids,
 151        },
 152};
 153builtin_platform_driver(rtd119x_wdt_driver);
 154