drivers/watchdog/ep93xx_wdt.c

   1 /*
   2  * Watchdog driver for Cirrus Logic EP93xx family of devices.
   3  *
   4  * Copyright (c) 2004 Ray Lehtiniemi
   5  * Copyright (c) 2006 Tower Technologies
   6  * Based on ep93xx driver, bits from alim7101_wdt.c
   7  *
   8  * Authors: Ray Lehtiniemi <rayl@mail.com>,
   9  *      Alessandro Zummo <a.zummo@towertech.it>
  10  *
  11  * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
  12  *      Convert to a platform device and use the watchdog framework API
  13  *
  14  * This file is licensed under the terms of the GNU General Public
  15  * License version 2. This program is licensed "as is" without any
  16  * warranty of any kind, whether express or implied.
  17  *
  18  * This watchdog fires after 250msec, which is a too short interval
  19  * for us to rely on the user space daemon alone. So we ping the
  20  * wdt each ~200msec and eventually stop doing it if the user space
  21  * daemon dies.
  22  */
  23
  24 #include <linux/platform_device.h>
  25 #include <linux/module.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/io.h>
  28
  29 /* default timeout (secs) */
  30 #define WDT_TIMEOUT 30
  31
  32 static bool nowayout = WATCHDOG_NOWAYOUT;
  33 module_param(nowayout, bool, 0);
  34 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  35
  36 static unsigned int timeout;
  37 module_param(timeout, uint, 0);
  38 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds.");
  39
  40 #define EP93XX_WATCHDOG         0x00
  41 #define EP93XX_WDSTATUS         0x04
  42
  43 struct ep93xx_wdt_priv {
  44         void __iomem *mmio;
  45         struct watchdog_device wdd;
  46 };
  47
  48 static int ep93xx_wdt_start(struct watchdog_device *wdd)
  49 {
  50         struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  51
  52         writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);
  53
  54         return 0;
  55 }
  56
  57 static int ep93xx_wdt_stop(struct watchdog_device *wdd)
  58 {
  59         struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  60
  61         writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);
  62
  63         return 0;
  64 }
  65
  66 static int ep93xx_wdt_ping(struct watchdog_device *wdd)
  67 {
  68         struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  69
  70         writel(0x5555, priv->mmio + EP93XX_WATCHDOG);
  71
  72         return 0;
  73 }
  74
  75 static const struct watchdog_info ep93xx_wdt_ident = {
  76         .options        = WDIOF_CARDRESET |
  77                           WDIOF_SETTIMEOUT |
  78                           WDIOF_MAGICCLOSE |
  79                           WDIOF_KEEPALIVEPING,
  80         .identity       = "EP93xx Watchdog",
  81 };
  82
  83 static const struct watchdog_ops ep93xx_wdt_ops = {
  84         .owner          = THIS_MODULE,
  85         .start          = ep93xx_wdt_start,
  86         .stop           = ep93xx_wdt_stop,
  87         .ping           = ep93xx_wdt_ping,
  88 };
  89
  90 static int ep93xx_wdt_probe(struct platform_device *pdev)
  91 {
  92         struct device *dev = &pdev->dev;
  93         struct ep93xx_wdt_priv *priv;
  94         struct watchdog_device *wdd;
  95         unsigned long val;
  96         int ret;
  97
  98         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
  99         if (!priv)
 100                 return -ENOMEM;
 101
 102         priv->mmio = devm_platform_ioremap_resource(pdev, 0);
 103         if (IS_ERR(priv->mmio))
 104                 return PTR_ERR(priv->mmio);
 105
 106         val = readl(priv->mmio + EP93XX_WATCHDOG);
 107
 108         wdd = &priv->wdd;
 109         wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
 110         wdd->info = &ep93xx_wdt_ident;
 111         wdd->ops = &ep93xx_wdt_ops;
 112         wdd->min_timeout = 1;
 113         wdd->max_hw_heartbeat_ms = 200;
 114         wdd->parent = dev;
 115
 116         watchdog_set_nowayout(wdd, nowayout);
 117
 118         wdd->timeout = WDT_TIMEOUT;
 119         watchdog_init_timeout(wdd, timeout, dev);
 120
 121         watchdog_set_drvdata(wdd, priv);
 122
 123         ret = devm_watchdog_register_device(dev, wdd);
 124         if (ret)
 125                 return ret;
 126
 127         dev_info(dev, "EP93XX watchdog driver %s\n",
 128                  (val & 0x08) ? " (nCS1 disable detected)" : "");
 129
 130         return 0;
 131 }
 132
 133 static struct platform_driver ep93xx_wdt_driver = {
 134         .driver         = {
 135                 .name   = "ep93xx-wdt",
 136         },
 137         .probe          = ep93xx_wdt_probe,
 138 };
 139
 140 module_platform_driver(ep93xx_wdt_driver);
 141
 142 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
 143 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 144 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 145 MODULE_DESCRIPTION("EP93xx Watchdog");
 146 MODULE_LICENSE("GPL");