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 device_node *node = dev->of_node;
  95         struct resource *res;
  96         struct clk *clk;
  97         int err;
  98         unsigned int max_timeout;
  99         bool nowayout = WATCHDOG_NOWAYOUT;
 100
 101         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 102         if (!moxart_wdt)
 103                 return -ENOMEM;
 104
 105         platform_set_drvdata(pdev, moxart_wdt);
 106
 107         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 108         moxart_wdt->base = devm_ioremap_resource(dev, res);
 109         if (IS_ERR(moxart_wdt->base))
 110                 return PTR_ERR(moxart_wdt->base);
 111
 112         clk = of_clk_get(node, 0);
 113         if (IS_ERR(clk)) {
 114                 pr_err("%s: of_clk_get failed\n", __func__);
 115                 return PTR_ERR(clk);
 116         }
 117
 118         moxart_wdt->clock_frequency = clk_get_rate(clk);
 119         if (moxart_wdt->clock_frequency == 0) {
 120                 pr_err("%s: incorrect clock frequency\n", __func__);
 121                 return -EINVAL;
 122         }
 123
 124         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 125
 126         moxart_wdt->dev.info = &moxart_wdt_info;
 127         moxart_wdt->dev.ops = &moxart_wdt_ops;
 128         moxart_wdt->dev.timeout = max_timeout;
 129         moxart_wdt->dev.min_timeout = 1;
 130         moxart_wdt->dev.max_timeout = max_timeout;
 131         moxart_wdt->dev.parent = dev;
 132
 133         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 134         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 135         watchdog_set_restart_priority(&moxart_wdt->dev, 128);
 136
 137         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 138
 139         err = watchdog_register_device(&moxart_wdt->dev);
 140         if (err)
 141                 return err;
 142
 143         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 144                 moxart_wdt->dev.timeout, nowayout);
 145
 146         return 0;
 147 }
 148
 149 static int moxart_wdt_remove(struct platform_device *pdev)
 150 {
 151         struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
 152
 153         moxart_wdt_stop(&moxart_wdt->dev);
 154
 155         return 0;
 156 }
 157
 158 static const struct of_device_id moxart_watchdog_match[] = {
 159         { .compatible = "moxa,moxart-watchdog" },
 160         { },
 161 };
 162 MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
 163
 164 static struct platform_driver moxart_wdt_driver = {
 165         .probe      = moxart_wdt_probe,
 166         .remove     = moxart_wdt_remove,
 167         .driver     = {
 168                 .name           = "moxart-watchdog",
 169                 .of_match_table = moxart_watchdog_match,
 170         },
 171 };
 172 module_platform_driver(moxart_wdt_driver);
 173
 174 module_param(heartbeat, int, 0);
 175 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 176
 177 MODULE_DESCRIPTION("MOXART watchdog driver");
 178 MODULE_LICENSE("GPL");
 179 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");