drivers/watchdog/rtd119x_wdt.c

   1 /*
   2  * Realtek RTD129x watchdog
   3  *
   4  * Copyright (c) 2017 Andreas Färber
   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
  27 struct rtd119x_watchdog_device {
  28         struct watchdog_device wdt_dev;
  29         void __iomem *base;
  30         struct clk *clk;
  31 };
  32
  33 static 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
  46 static 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
  59 static 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
  68 static 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
  79 static 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
  87 static const struct watchdog_info rtd119x_wdt_info = {
  88         .identity = "rtd119x-wdt",
  89         .options = 0,
  90 };
  91
  92 static const struct of_device_id rtd119x_wdt_dt_ids[] = {
  93          { .compatible = "realtek,rtd1295-watchdog" },
  94          { }
  95 };
  96
  97 static void rtd119x_clk_disable_unprepare(void *data)
  98 {
  99         clk_disable_unprepare(data);
 100 }
 101
 102 static 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
 146 static 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 };
 153 builtin_platform_driver(rtd119x_wdt_driver);