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 #include <asm/system_misc.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 };
  33
  34 static struct moxart_wdt_dev *moxart_restart_ctx;
  35
  36 static int heartbeat;
  37
  38 static void moxart_wdt_restart(enum reboot_mode reboot_mode, const char *cmd)
  39 {
  40         writel(1, moxart_restart_ctx->base + REG_COUNT);
  41         writel(0x5ab9, moxart_restart_ctx->base + REG_MODE);
  42         writel(0x03, moxart_restart_ctx->base + REG_ENABLE);
  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 };
  86
  87 static int moxart_wdt_probe(struct platform_device *pdev)
  88 {
  89         struct moxart_wdt_dev *moxart_wdt;
  90         struct device *dev = &pdev->dev;
  91         struct device_node *node = dev->of_node;
  92         struct resource *res;
  93         struct clk *clk;
  94         int err;
  95         unsigned int max_timeout;
  96         bool nowayout = WATCHDOG_NOWAYOUT;
  97
  98         moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
  99         if (!moxart_wdt)
 100                 return -ENOMEM;
 101
 102         platform_set_drvdata(pdev, moxart_wdt);
 103
 104         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 105         moxart_wdt->base = devm_ioremap_resource(dev, res);
 106         if (IS_ERR(moxart_wdt->base))
 107                 return PTR_ERR(moxart_wdt->base);
 108
 109         clk = of_clk_get(node, 0);
 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
 133         watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
 134
 135         err = watchdog_register_device(&moxart_wdt->dev);
 136         if (err)
 137                 return err;
 138
 139         moxart_restart_ctx = moxart_wdt;
 140         arm_pm_restart = moxart_wdt_restart;
 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         arm_pm_restart = NULL;
 153         moxart_wdt_stop(&moxart_wdt->dev);
 154         watchdog_unregister_device(&moxart_wdt->dev);
 155
 156         return 0;
 157 }
 158
 159 static const struct of_device_id moxart_watchdog_match[] = {
 160         { .compatible = "moxa,moxart-watchdog" },
 161         { },
 162 };
 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                 .owner          = THIS_MODULE,
 170                 .of_match_table = moxart_watchdog_match,
 171         },
 172 };
 173 module_platform_driver(moxart_wdt_driver);
 174
 175 module_param(heartbeat, int, 0);
 176 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
 177
 178 MODULE_DESCRIPTION("MOXART watchdog driver");
 179 MODULE_LICENSE("GPL");
 180 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");