drivers/watchdog/moxart_wdt.c

   1 /*
   2  * MOXA ART SoCs watchdog driver.
   3  *
   4  * Copyright (C) 2013 Jonas Jensen
   5  *
   6  * Jonas Jensen <jonas.jensen@gmail.com>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2.  This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/io.h>
  15 #include <linux/module.h>
  16 #include <linux/mod_devicetable.h>
  17 #include <linux/err.h>
  18 #include <linux/kernel.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/watchdog.h>
  21 #include <linux/moduleparam.h>
  22
  23 #define REG_COUNT                       0x4
  24 #define REG_MODE                        0x8
  25 #define REG_ENABLE                      0xC
  26
  27 struct moxart_wdt_dev {
  28         struct watchdog_device dev;
  29         void __iomem *base;
  30         unsigned int clock_frequency;
  31 };
  32
  33 static int heartbeat;
  34
  35 static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
  36                               unsigned long action, void *data)
  37 {
  38         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  39
  40         writel(1, moxart_wdt->base + REG_COUNT);
  41         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  42         writel(0x03, moxart_wdt->base + REG_ENABLE);
  43
  44         return 0;
  45 }
  46
  47 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  48 {
  49         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  50
  51         writel(0, moxart_wdt->base + REG_ENABLE);
  52
  53         return 0;
  54 }
  55
  56 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  57 {
  58         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  59
  60         writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  61                moxart_wdt->base + REG_COUNT);
  62         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  63         writel(0x03, moxart_wdt->base + REG_ENABLE);
  64
  65         return 0;
  66 }
  67
  68 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  69                                   unsigned int timeout)
  70 {
  71         wdt_dev->timeout = timeout;
  72
  73         return 0;
  74 }
  75
  76 static const struct watchdog_info moxart_wdt_info = {
  77         .identity       = "moxart-wdt",
  78         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  79                           WDIOF_MAGICCLOSE,
  80 };
  81
  82 static const struct watchdog_ops moxart_wdt_ops = {
  83         .owner          = THIS_MODULE,
  84         .start          = moxart_wdt_start,
  85         .stop           = moxart_wdt_stop,
  86         .set_timeout    = moxart_wdt_set_timeout,
  87         .restart        = moxart_wdt_restart,
  88 };
  89
  90 static int moxart_wdt_probe(struct platform_device *pdev)
  91 {
  92         struct moxart_wdt_dev *moxart_wdt;
  93         struct device *dev = &pdev->dev;
  94         struct clk *clk;
  95         int err;
  96         unsigned int max_timeout;
  97         bool nowayout = WATCHDOG_NOWAYOUT;
  98
  99         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 100         if (!moxart_wdt)
 101                 return -ENOMEM;
 102
 103         platform_set_drvdata(pdev, moxart_wdt);
 104
 105         moxart_wdt->base = devm_platform_ioremap_resource(pdev, 0);
 106         if (IS_ERR(moxart_wdt->base))
 107                 return PTR_ERR(moxart_wdt->base);
 108
 109         clk = devm_clk_get(dev, NULL);
 110         if (IS_ERR(clk)) {
 111                 pr_err("%s: of_clk_get failed\n", __func__);
 112                 return PTR_ERR(clk);
 113         }
 114
 115         moxart_wdt->clock_frequency = clk_get_rate(clk);
 116         if (moxart_wdt->clock_frequency == 0) {
 117                 pr_err("%s: incorrect clock frequency\n", __func__);
 118                 return -EINVAL;
 119         }
 120
 121         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 122
 123         moxart_wdt->dev.info = &moxart_wdt_info;
 124         moxart_wdt->dev.ops = &moxart_wdt_ops;
 125         moxart_wdt->dev.timeout = max_timeout;
 126         moxart_wdt->dev.min_timeout = 1;
 127         moxart_wdt->dev.max_timeout = max_timeout;
 128         moxart_wdt->dev.parent = dev;
 129
 130         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 131         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 132         watchdog_set_restart_priority(&moxart_wdt->dev, 128);
 133
 134         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 135
 136         watchdog_stop_on_unregister(&moxart_wdt->dev);
 137         err = devm_watchdog_register_device(dev, &moxart_wdt->dev);
 138         if (err)
 139                 return err;
 140
 141         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 142                 moxart_wdt->dev.timeout, nowayout);
 143
 144         return 0;
 145 }
 146
 147 static const struct of_device_id moxart_watchdog_match[] = {
 148         { .compatible = "moxa,moxart-watchdog" },
 149         { },
 150 };
 151 MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
 152
 153 static struct platform_driver moxart_wdt_driver = {
 154         .probe      = moxart_wdt_probe,
 155         .driver     = {
 156                 .name           = "moxart-watchdog",
 157                 .of_match_table = moxart_watchdog_match,
 158         },
 159 };
 160 module_platform_driver(moxart_wdt_driver);
 161
 162 module_param(heartbeat, int, 0);
 163 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 164
 165 MODULE_DESCRIPTION("MOXART watchdog driver");
 166 MODULE_LICENSE("GPL");
 167 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");