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/notifier.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/reboot.h>
  21 #include <linux/watchdog.h>
  22 #include <linux/moduleparam.h>
  23
  24 #define REG_COUNT                       0x4
  25 #define REG_MODE                        0x8
  26 #define REG_ENABLE                      0xC
  27
  28 struct moxart_wdt_dev {
  29         struct watchdog_device dev;
  30         void __iomem *base;
  31         unsigned int clock_frequency;
  32         struct notifier_block restart_handler;
  33 };
  34
  35 static int heartbeat;
  36
  37 static int moxart_restart_handle(struct notifier_block *this,
  38                                  unsigned long mode, void *cmd)
  39 {
  40         struct moxart_wdt_dev *moxart_wdt = container_of(this,
  41                                                          struct moxart_wdt_dev,
  42                                                          restart_handler);
  43         writel(1, moxart_wdt->base + REG_COUNT);
  44         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  45         writel(0x03, moxart_wdt->base + REG_ENABLE);
  46
  47         return NOTIFY_DONE;
  48 }
  49
  50 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
  51 {
  52         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  53
  54         writel(0, moxart_wdt->base + REG_ENABLE);
  55
  56         return 0;
  57 }
  58
  59 static int moxart_wdt_start(struct watchdog_device *wdt_dev)
  60 {
  61         struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
  62
  63         writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
  64                moxart_wdt->base + REG_COUNT);
  65         writel(0x5ab9, moxart_wdt->base + REG_MODE);
  66         writel(0x03, moxart_wdt->base + REG_ENABLE);
  67
  68         return 0;
  69 }
  70
  71 static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
  72                                   unsigned int timeout)
  73 {
  74         wdt_dev->timeout = timeout;
  75
  76         return 0;
  77 }
  78
  79 static const struct watchdog_info moxart_wdt_info = {
  80         .identity       = "moxart-wdt",
  81         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  82                           WDIOF_MAGICCLOSE,
  83 };
  84
  85 static const struct watchdog_ops moxart_wdt_ops = {
  86         .owner          = THIS_MODULE,
  87         .start          = moxart_wdt_start,
  88         .stop           = moxart_wdt_stop,
  89         .set_timeout    = moxart_wdt_set_timeout,
  90 };
  91
  92 static int moxart_wdt_probe(struct platform_device *pdev)
  93 {
  94         struct moxart_wdt_dev *moxart_wdt;
  95         struct device *dev = &pdev->dev;
  96         struct device_node *node = dev->of_node;
  97         struct resource *res;
  98         struct clk *clk;
  99         int err;
 100         unsigned int max_timeout;
 101         bool nowayout = WATCHDOG_NOWAYOUT;
 102
 103         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 104         if (!moxart_wdt)
 105                 return -ENOMEM;
 106
 107         platform_set_drvdata(pdev, moxart_wdt);
 108
 109         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 110         moxart_wdt->base = devm_ioremap_resource(dev, res);
 111         if (IS_ERR(moxart_wdt->base))
 112                 return PTR_ERR(moxart_wdt->base);
 113
 114         clk = of_clk_get(node, 0);
 115         if (IS_ERR(clk)) {
 116                 pr_err("%s: of_clk_get failed\n", __func__);
 117                 return PTR_ERR(clk);
 118         }
 119
 120         moxart_wdt->clock_frequency = clk_get_rate(clk);
 121         if (moxart_wdt->clock_frequency == 0) {
 122                 pr_err("%s: incorrect clock frequency\n", __func__);
 123                 return -EINVAL;
 124         }
 125
 126         max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
 127
 128         moxart_wdt->dev.info = &moxart_wdt_info;
 129         moxart_wdt->dev.ops = &moxart_wdt_ops;
 130         moxart_wdt->dev.timeout = max_timeout;
 131         moxart_wdt->dev.min_timeout = 1;
 132         moxart_wdt->dev.max_timeout = max_timeout;
 133         moxart_wdt->dev.parent = dev;
 134
 135         watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
 136         watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
 137
 138         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 139
 140         err = watchdog_register_device(&moxart_wdt->dev);
 141         if (err)
 142                 return err;
 143
 144         moxart_wdt->restart_handler.notifier_call = moxart_restart_handle;
 145         moxart_wdt->restart_handler.priority = 128;
 146         err = register_restart_handler(&moxart_wdt->restart_handler);
 147         if (err)
 148                 dev_err(dev, "cannot register restart notifier (err=%d)\n",
 149                         err);
 150
 151         dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 152                 moxart_wdt->dev.timeout, nowayout);
 153
 154         return 0;
 155 }
 156
 157 static int moxart_wdt_remove(struct platform_device *pdev)
 158 {
 159         struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
 160
 161         unregister_restart_handler(&moxart_wdt->restart_handler);
 162         moxart_wdt_stop(&moxart_wdt->dev);
 163
 164         return 0;
 165 }
 166
 167 static const struct of_device_id moxart_watchdog_match[] = {
 168         { .compatible = "moxa,moxart-watchdog" },
 169         { },
 170 };
 171
 172 static struct platform_driver moxart_wdt_driver = {
 173         .probe      = moxart_wdt_probe,
 174         .remove     = moxart_wdt_remove,
 175         .driver     = {
 176                 .name           = "moxart-watchdog",
 177                 .of_match_table = moxart_watchdog_match,
 178         },
 179 };
 180 module_platform_driver(moxart_wdt_driver);
 181
 182 module_param(heartbeat, int, 0);
 183 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 184
 185 MODULE_DESCRIPTION("MOXART watchdog driver");
 186 MODULE_LICENSE("GPL");
 187 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");