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/module.h>
  13 #include <linux/of.h>
  14 #include <linux/of_address.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/watchdog.h>
  17
  18 #define RTD119X_TCWCR           0x0
  19 #define RTD119X_TCWTR           0x4
  20 #define RTD119X_TCWOV           0xc
  21
  22 #define RTD119X_TCWCR_WDEN_DISABLED             0xa5
  23 #define RTD119X_TCWCR_WDEN_ENABLED              0xff
  24 #define RTD119X_TCWCR_WDEN_MASK                 0xff
  25
  26 #define RTD119X_TCWTR_WDCLR                     BIT(0)
  27
  28 struct rtd119x_watchdog_device {
  29         struct watchdog_device wdt_dev;
  30         void __iomem *base;
  31         struct clk *clk;
  32 };
  33
  34 static int rtd119x_wdt_start(struct watchdog_device *wdev)
  35 {
  36         struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  37         u32 val;
  38
  39         val = readl_relaxed(data->base + RTD119X_TCWCR);
  40         val &= ~RTD119X_TCWCR_WDEN_MASK;
  41         val |= RTD119X_TCWCR_WDEN_ENABLED;
  42         writel(val, data->base + RTD119X_TCWCR);
  43
  44         return 0;
  45 }
  46
  47 static int rtd119x_wdt_stop(struct watchdog_device *wdev)
  48 {
  49         struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  50         u32 val;
  51
  52         val = readl_relaxed(data->base + RTD119X_TCWCR);
  53         val &= ~RTD119X_TCWCR_WDEN_MASK;
  54         val |= RTD119X_TCWCR_WDEN_DISABLED;
  55         writel(val, data->base + RTD119X_TCWCR);
  56
  57         return 0;
  58 }
  59
  60 static int rtd119x_wdt_ping(struct watchdog_device *wdev)
  61 {
  62         struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  63
  64         writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
  65
  66         return rtd119x_wdt_start(wdev);
  67 }
  68
  69 static int rtd119x_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val)
  70 {
  71         struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
  72
  73         writel(val * clk_get_rate(data->clk), data->base + RTD119X_TCWOV);
  74
  75         data->wdt_dev.timeout = val;
  76
  77         return 0;
  78 }
  79
  80 static const struct watchdog_ops rtd119x_wdt_ops = {
  81         .owner = THIS_MODULE,
  82         .start          = rtd119x_wdt_start,
  83         .stop           = rtd119x_wdt_stop,
  84         .ping           = rtd119x_wdt_ping,
  85         .set_timeout    = rtd119x_wdt_set_timeout,
  86 };
  87
  88 static const struct watchdog_info rtd119x_wdt_info = {
  89         .identity = "rtd119x-wdt",
  90         .options = 0,
  91 };
  92
  93 static const struct of_device_id rtd119x_wdt_dt_ids[] = {
  94          { .compatible = "realtek,rtd1295-watchdog" },
  95          { }
  96 };
  97
  98 static int rtd119x_wdt_probe(struct platform_device *pdev)
  99 {
 100         struct rtd119x_watchdog_device *data;
 101         int ret;
 102
 103         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 104         if (!data)
 105                 return -ENOMEM;
 106
 107         data->base = devm_platform_ioremap_resource(pdev, 0);
 108         if (IS_ERR(data->base))
 109                 return PTR_ERR(data->base);
 110
 111         data->clk = of_clk_get(pdev->dev.of_node, 0);
 112         if (IS_ERR(data->clk))
 113                 return PTR_ERR(data->clk);
 114
 115         ret = clk_prepare_enable(data->clk);
 116         if (ret) {
 117                 clk_put(data->clk);
 118                 return ret;
 119         }
 120
 121         data->wdt_dev.info = &rtd119x_wdt_info;
 122         data->wdt_dev.ops = &rtd119x_wdt_ops;
 123         data->wdt_dev.timeout = 120;
 124         data->wdt_dev.max_timeout = 0xffffffff / clk_get_rate(data->clk);
 125         data->wdt_dev.min_timeout = 1;
 126         data->wdt_dev.parent = &pdev->dev;
 127
 128         watchdog_stop_on_reboot(&data->wdt_dev);
 129         watchdog_set_drvdata(&data->wdt_dev, data);
 130         platform_set_drvdata(pdev, data);
 131
 132         writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
 133         rtd119x_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
 134         rtd119x_wdt_stop(&data->wdt_dev);
 135
 136         ret = devm_watchdog_register_device(&pdev->dev, &data->wdt_dev);
 137         if (ret) {
 138                 clk_disable_unprepare(data->clk);
 139                 clk_put(data->clk);
 140                 return ret;
 141         }
 142
 143         return 0;
 144 }
 145
 146 static int rtd119x_wdt_remove(struct platform_device *pdev)
 147 {
 148         struct rtd119x_watchdog_device *data = platform_get_drvdata(pdev);
 149
 150         watchdog_unregister_device(&data->wdt_dev);
 151
 152         clk_disable_unprepare(data->clk);
 153         clk_put(data->clk);
 154
 155         return 0;
 156 }
 157
 158 static struct platform_driver rtd119x_wdt_driver = {
 159         .probe = rtd119x_wdt_probe,
 160         .remove = rtd119x_wdt_remove,
 161         .driver = {
 162                 .name = "rtd1295-watchdog",
 163                 .of_match_table = rtd119x_wdt_dt_ids,
 164         },
 165 };
 166 builtin_platform_driver(rtd119x_wdt_driver);