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/err.h>
  17 #include <linux/kernel.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/watchdog.h>
  20 #include <linux/moduleparam.h>
  21
  22 #define REG_COUNT                       0x4
  23 #define REG_MODE                        0x8
  24 #define REG_ENABLE                      0xC
  25
  26 struct moxart_wdt_dev {
  27         struct watchdog_device dev;
  28         void __iomem *base;
  29         unsigned int clock_frequency;
  30 };
  31
  32 static int heartbeat;
  33
  34 static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
  35                               unsigned long action, void *data)
  36 {
  37         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  38
  39         writel(1, moxart_wdt->base + REG_COUNT);
  40         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  41         writel(0x03, moxart_wdt->base + REG_ENABLE);
  42
  43         return 0;
  44 }
  45
  46 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  47 {
  48         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  49
  50         writel(0, moxart_wdt->base + REG_ENABLE);
  51
  52         return 0;
  53 }
  54
  55 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  56 {
  57         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  58
  59         writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  60                moxart_wdt->base + REG_COUNT);
  61         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  62         writel(0x03, moxart_wdt->base + REG_ENABLE);
  63
  64         return 0;
  65 }
  66
  67 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  68                                   unsigned int timeout)
  69 {
  70         wdt_dev->timeout = timeout;
  71
  72         return 0;
  73 }
  74
  75 static const struct watchdog_info moxart_wdt_info = {
  76         .identity       = "moxart-wdt",
  77         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  78                           WDIOF_MAGICCLOSE,
  79 };
  80
  81 static const struct watchdog_ops moxart_wdt_ops = {
  82         .owner          = THIS_MODULE,
  83         .start          = moxart_wdt_start,
  84         .stop           = moxart_wdt_stop,
  85         .set_timeout    = moxart_wdt_set_timeout,
  86         .restart        = moxart_wdt_restart,
  87 };
  88
  89 static int moxart_wdt_probe(struct platform_device *pdev)
  90 {
  91         struct moxart_wdt_dev *moxart_wdt;
  92         struct device *dev = &pdev->dev;
  93         struct device_node *node = dev->of_node;
  94         struct resource *res;
  95         struct clk *clk;
  96         int err;
  97         unsigned int max_timeout;
  98         bool nowayout = WATCHDOG_NOWAYOUT;
  99
 100         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 101         if (!moxart_wdt)
 102                 return -ENOMEM;
 103
 104         platform_set_drvdata(pdev, moxart_wdt);
 105
 106         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 107         moxart_wdt->base = devm_ioremap_resource(dev, res);
 108         if (IS_ERR(moxart_wdt->base))
 109                 return PTR_ERR(moxart_wdt->base);
 110
 111         clk = of_clk_get(node, 0);
 112         if (IS_ERR(clk)) {
 113                 pr_err("%s: of_clk_get failed\n", __func__);
 114                 return PTR_ERR(clk);
 115         }
 116
 117         moxart_wdt->clock_frequency = clk_get_rate(clk);
 118         if (moxart_wdt->clock_frequency == 0) {
 119                 pr_err("%s: incorrect clock frequency\n", __func__);
 120                 return -EINVAL;
 121         }
 122
 123         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 124
 125         moxart_wdt->dev.info = &moxart_wdt_info;
 126         moxart_wdt->dev.ops = &moxart_wdt_ops;
 127         moxart_wdt->dev.timeout = max_timeout;
 128         moxart_wdt->dev.min_timeout = 1;
 129         moxart_wdt->dev.max_timeout = max_timeout;
 130         moxart_wdt->dev.parent = dev;
 131
 132         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 133         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 134         watchdog_set_restart_priority(&moxart_wdt->dev, 128);
 135
 136         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 137
 138         err = watchdog_register_device(&moxart_wdt->dev);
 139         if (err)
 140                 return err;
 141
 142         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 143                 moxart_wdt->dev.timeout, nowayout);
 144
 145         return 0;
 146 }
 147
 148 static int moxart_wdt_remove(struct platform_device *pdev)
 149 {
 150         struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
 151
 152         moxart_wdt_stop(&moxart_wdt->dev);
 153
 154         return 0;
 155 }
 156
 157 static const struct of_device_id moxart_watchdog_match[] = {
 158         { .compatible = "moxa,moxart-watchdog" },
 159         { },
 160 };
 161 MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
 162
 163 static struct platform_driver moxart_wdt_driver = {
 164         .probe      = moxart_wdt_probe,
 165         .remove     = moxart_wdt_remove,
 166         .driver     = {
 167                 .name           = "moxart-watchdog",
 168                 .of_match_table = moxart_watchdog_match,
 169         },
 170 };
 171 module_platform_driver(moxart_wdt_driver);
 172
 173 module_param(heartbeat, int, 0);
 174 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 175
 176 MODULE_DESCRIPTION("MOXART watchdog driver");
 177 MODULE_LICENSE("GPL");
 178 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");