drivers/watchdog/msc313e_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * MStar WDT driver
   4  *
   5  * Copyright (C) 2019 - 2021 Daniel Palmer
   6  * Copyright (C) 2021 Romain Perier
   7  *
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/io.h>
  12 #include <linux/mod_devicetable.h>
  13 #include <linux/module.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/watchdog.h>
  16
  17 #define REG_WDT_CLR                     0x0
  18 #define REG_WDT_MAX_PRD_L               0x10
  19 #define REG_WDT_MAX_PRD_H               0x14
  20
  21 #define MSC313E_WDT_MIN_TIMEOUT         1
  22 #define MSC313E_WDT_DEFAULT_TIMEOUT     30
  23
  24 static unsigned int timeout;
  25
  26 module_param(timeout, int, 0);
  27 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  28
  29 struct msc313e_wdt_priv {
  30         void __iomem *base;
  31         struct watchdog_device wdev;
  32         struct clk *clk;
  33 };
  34
  35 static int msc313e_wdt_start(struct watchdog_device *wdev)
  36 {
  37         struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
  38         u32 timeout;
  39         int err;
  40
  41         err = clk_prepare_enable(priv->clk);
  42         if (err)
  43                 return err;
  44
  45         timeout = wdev->timeout * clk_get_rate(priv->clk);
  46         writew(timeout & 0xffff, priv->base + REG_WDT_MAX_PRD_L);
  47         writew((timeout >> 16) & 0xffff, priv->base + REG_WDT_MAX_PRD_H);
  48         writew(1, priv->base + REG_WDT_CLR);
  49         return 0;
  50 }
  51
  52 static int msc313e_wdt_ping(struct watchdog_device *wdev)
  53 {
  54         struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
  55
  56         writew(1, priv->base + REG_WDT_CLR);
  57         return 0;
  58 }
  59
  60 static int msc313e_wdt_stop(struct watchdog_device *wdev)
  61 {
  62         struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
  63
  64         writew(0, priv->base + REG_WDT_MAX_PRD_L);
  65         writew(0, priv->base + REG_WDT_MAX_PRD_H);
  66         writew(0, priv->base + REG_WDT_CLR);
  67         clk_disable_unprepare(priv->clk);
  68         return 0;
  69 }
  70
  71 static int msc313e_wdt_settimeout(struct watchdog_device *wdev, unsigned int new_time)
  72 {
  73         wdev->timeout = new_time;
  74
  75         return msc313e_wdt_start(wdev);
  76 }
  77
  78 static const struct watchdog_info msc313e_wdt_ident = {
  79         .identity = "MSC313e watchdog",
  80         .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
  81 };
  82
  83 static const struct watchdog_ops msc313e_wdt_ops = {
  84         .owner = THIS_MODULE,
  85         .start = msc313e_wdt_start,
  86         .stop = msc313e_wdt_stop,
  87         .ping = msc313e_wdt_ping,
  88         .set_timeout = msc313e_wdt_settimeout,
  89 };
  90
  91 static const struct of_device_id msc313e_wdt_of_match[] = {
  92         { .compatible = "mstar,msc313e-wdt", },
  93         { /* sentinel */ }
  94 };
  95 MODULE_DEVICE_TABLE(of, msc313e_wdt_of_match);
  96
  97 static int msc313e_wdt_probe(struct platform_device *pdev)
  98 {
  99         struct device *dev = &pdev->dev;
 100         struct msc313e_wdt_priv *priv;
 101
 102         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 103         if (!priv)
 104                 return -ENOMEM;
 105
 106         priv->base = devm_platform_ioremap_resource(pdev, 0);
 107         if (IS_ERR(priv->base))
 108                 return PTR_ERR(priv->base);
 109
 110         priv->clk = devm_clk_get(dev, NULL);
 111         if (IS_ERR(priv->clk)) {
 112                 dev_err(dev, "No input clock\n");
 113                 return PTR_ERR(priv->clk);
 114         }
 115
 116         priv->wdev.info = &msc313e_wdt_ident,
 117         priv->wdev.ops = &msc313e_wdt_ops,
 118         priv->wdev.parent = dev;
 119         priv->wdev.min_timeout = MSC313E_WDT_MIN_TIMEOUT;
 120         priv->wdev.max_timeout = U32_MAX / clk_get_rate(priv->clk);
 121         priv->wdev.timeout = MSC313E_WDT_DEFAULT_TIMEOUT;
 122
 123         /* If the period is non-zero the WDT is running */
 124         if (readw(priv->base + REG_WDT_MAX_PRD_L) | (readw(priv->base + REG_WDT_MAX_PRD_H) << 16))
 125                 set_bit(WDOG_HW_RUNNING, &priv->wdev.status);
 126
 127         watchdog_set_drvdata(&priv->wdev, priv);
 128
 129         watchdog_init_timeout(&priv->wdev, timeout, dev);
 130         watchdog_stop_on_reboot(&priv->wdev);
 131         watchdog_stop_on_unregister(&priv->wdev);
 132
 133         return devm_watchdog_register_device(dev, &priv->wdev);
 134 }
 135
 136 static int __maybe_unused msc313e_wdt_suspend(struct device *dev)
 137 {
 138         struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
 139
 140         if (watchdog_active(&priv->wdev))
 141                 msc313e_wdt_stop(&priv->wdev);
 142
 143         return 0;
 144 }
 145
 146 static int __maybe_unused msc313e_wdt_resume(struct device *dev)
 147 {
 148         struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
 149
 150         if (watchdog_active(&priv->wdev))
 151                 msc313e_wdt_start(&priv->wdev);
 152
 153         return 0;
 154 }
 155
 156 static SIMPLE_DEV_PM_OPS(msc313e_wdt_pm_ops, msc313e_wdt_suspend, msc313e_wdt_resume);
 157
 158 static struct platform_driver msc313e_wdt_driver = {
 159         .driver = {
 160                 .name = "msc313e-wdt",
 161                 .of_match_table = msc313e_wdt_of_match,
 162                 .pm = &msc313e_wdt_pm_ops,
 163         },
 164         .probe = msc313e_wdt_probe,
 165 };
 166 module_platform_driver(msc313e_wdt_driver);
 167
 168 MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
 169 MODULE_DESCRIPTION("Watchdog driver for MStar MSC313e");
 170 MODULE_LICENSE("GPL v2");