drivers/watchdog/moxart_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * MOXA ART SoCs watchdog driver.
   4  *
   5  * Copyright (C) 2013 Jonas Jensen
   6  *
   7  * Jonas Jensen <jonas.jensen@gmail.com>
   8  *
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/io.h>
  13 #include <linux/module.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/err.h>
  16 #include <linux/kernel.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/moduleparam.h>
  20
  21 #define REG_COUNT                       0x4
  22 #define REG_MODE                        0x8
  23 #define REG_ENABLE                      0xC
  24
  25 struct moxart_wdt_dev {
  26         struct watchdog_device dev;
  27         void __iomem *base;
  28         unsigned int clock_frequency;
  29 };
  30
  31 static int heartbeat;
  32
  33 static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
  34                               unsigned long action, void *data)
  35 {
  36         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  37
  38         writel(1, moxart_wdt->base + REG_COUNT);
  39         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  40         writel(0x03, moxart_wdt->base + REG_ENABLE);
  41
  42         return 0;
  43 }
  44
  45 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  46 {
  47         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  48
  49         writel(0, moxart_wdt->base + REG_ENABLE);
  50
  51         return 0;
  52 }
  53
  54 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  55 {
  56         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  57
  58         writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  59                moxart_wdt->base + REG_COUNT);
  60         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  61         writel(0x03, moxart_wdt->base + REG_ENABLE);
  62
  63         return 0;
  64 }
  65
  66 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  67                                   unsigned int timeout)
  68 {
  69         wdt_dev->timeout = timeout;
  70
  71         return 0;
  72 }
  73
  74 static const struct watchdog_info moxart_wdt_info = {
  75         .identity       = "moxart-wdt",
  76         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  77                           WDIOF_MAGICCLOSE,
  78 };
  79
  80 static const struct watchdog_ops moxart_wdt_ops = {
  81         .owner          = THIS_MODULE,
  82         .start          = moxart_wdt_start,
  83         .stop           = moxart_wdt_stop,
  84         .set_timeout    = moxart_wdt_set_timeout,
  85         .restart        = moxart_wdt_restart,
  86 };
  87
  88 static int moxart_wdt_probe(struct platform_device *pdev)
  89 {
  90         struct moxart_wdt_dev *moxart_wdt;
  91         struct device *dev = &pdev->dev;
  92         struct clk *clk;
  93         int err;
  94         unsigned int max_timeout;
  95         bool nowayout = WATCHDOG_NOWAYOUT;
  96
  97         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
  98         if (!moxart_wdt)
  99                 return -ENOMEM;
 100
 101         platform_set_drvdata(pdev, moxart_wdt);
 102
 103         moxart_wdt->base = devm_platform_ioremap_resource(pdev, 0);
 104         if (IS_ERR(moxart_wdt->base))
 105                 return PTR_ERR(moxart_wdt->base);
 106
 107         clk = devm_clk_get(dev, NULL);
 108         if (IS_ERR(clk)) {
 109                 pr_err("%s: of_clk_get failed\n", __func__);
 110                 return PTR_ERR(clk);
 111         }
 112
 113         moxart_wdt->clock_frequency = clk_get_rate(clk);
 114         if (moxart_wdt->clock_frequency == 0) {
 115                 pr_err("%s: incorrect clock frequency\n", __func__);
 116                 return -EINVAL;
 117         }
 118
 119         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 120
 121         moxart_wdt->dev.info = &moxart_wdt_info;
 122         moxart_wdt->dev.ops = &moxart_wdt_ops;
 123         moxart_wdt->dev.timeout = max_timeout;
 124         moxart_wdt->dev.min_timeout = 1;
 125         moxart_wdt->dev.max_timeout = max_timeout;
 126         moxart_wdt->dev.parent = dev;
 127
 128         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 129         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 130         watchdog_set_restart_priority(&moxart_wdt->dev, 128);
 131
 132         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 133
 134         watchdog_stop_on_unregister(&moxart_wdt->dev);
 135         err = devm_watchdog_register_device(dev, &moxart_wdt->dev);
 136         if (err)
 137                 return err;
 138
 139         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 140                 moxart_wdt->dev.timeout, nowayout);
 141
 142         return 0;
 143 }
 144
 145 static const struct of_device_id moxart_watchdog_match[] = {
 146         { .compatible = "moxa,moxart-watchdog" },
 147         { },
 148 };
 149 MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
 150
 151 static struct platform_driver moxart_wdt_driver = {
 152         .probe      = moxart_wdt_probe,
 153         .driver     = {
 154                 .name           = "moxart-watchdog",
 155                 .of_match_table = moxart_watchdog_match,
 156         },
 157 };
 158 module_platform_driver(moxart_wdt_driver);
 159
 160 module_param(heartbeat, int, 0);
 161 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 162
 163 MODULE_DESCRIPTION("MOXART watchdog driver");
 164 MODULE_LICENSE("GPL");
 165 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");