drivers/watchdog/ep93xx_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Watchdog driver for Cirrus Logic EP93xx family of devices.
   4  *
   5  * Copyright (c) 2004 Ray Lehtiniemi
   6  * Copyright (c) 2006 Tower Technologies
   7  * Based on ep93xx driver, bits from alim7101_wdt.c
   8  *
   9  * Authors: Ray Lehtiniemi <rayl@mail.com>,
  10  *      Alessandro Zummo <a.zummo@towertech.it>
  11  *
  12  * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
  13  *      Convert to a platform device and use the watchdog framework API
  14  *
  15  * This watchdog fires after 250msec, which is a too short interval
  16  * for us to rely on the user space daemon alone. So we ping the
  17  * wdt each ~200msec and eventually stop doing it if the user space
  18  * daemon dies.
  19  */
  20
  21 #include <linux/platform_device.h>
  22 #include <linux/module.h>
  23 #include <linux/watchdog.h>
  24 #include <linux/io.h>
  25
  26 /* default timeout (secs) */
  27 #define WDT_TIMEOUT 30
  28
  29 static bool nowayout = WATCHDOG_NOWAYOUT;
  30 module_param(nowayout, bool, 0);
  31 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  32
  33 static unsigned int timeout;
  34 module_param(timeout, uint, 0);
  35 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds.");
  36
  37 #define EP93XX_WATCHDOG         0x00
  38 #define EP93XX_WDSTATUS         0x04
  39
  40 struct ep93xx_wdt_priv {
  41         void __iomem *mmio;
  42         struct watchdog_device wdd;
  43 };
  44
  45 static int ep93xx_wdt_start(struct watchdog_device *wdd)
  46 {
  47         struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  48
  49         writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);
  50
  51         return 0;
  52 }
  53
  54 static int ep93xx_wdt_stop(struct watchdog_device *wdd)
  55 {
  56         struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  57
  58         writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);
  59
  60         return 0;
  61 }
  62
  63 static int ep93xx_wdt_ping(struct watchdog_device *wdd)
  64 {
  65         struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  66
  67         writel(0x5555, priv->mmio + EP93XX_WATCHDOG);
  68
  69         return 0;
  70 }
  71
  72 static const struct watchdog_info ep93xx_wdt_ident = {
  73         .options        = WDIOF_CARDRESET |
  74                           WDIOF_SETTIMEOUT |
  75                           WDIOF_MAGICCLOSE |
  76                           WDIOF_KEEPALIVEPING,
  77         .identity       = "EP93xx Watchdog",
  78 };
  79
  80 static const struct watchdog_ops ep93xx_wdt_ops = {
  81         .owner          = THIS_MODULE,
  82         .start          = ep93xx_wdt_start,
  83         .stop           = ep93xx_wdt_stop,
  84         .ping           = ep93xx_wdt_ping,
  85 };
  86
  87 static int ep93xx_wdt_probe(struct platform_device *pdev)
  88 {
  89         struct device *dev = &pdev->dev;
  90         struct ep93xx_wdt_priv *priv;
  91         struct watchdog_device *wdd;
  92         unsigned long val;
  93         int ret;
  94
  95         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
  96         if (!priv)
  97                 return -ENOMEM;
  98
  99         priv->mmio = devm_platform_ioremap_resource(pdev, 0);
 100         if (IS_ERR(priv->mmio))
 101                 return PTR_ERR(priv->mmio);
 102
 103         val = readl(priv->mmio + EP93XX_WATCHDOG);
 104
 105         wdd = &priv->wdd;
 106         wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
 107         wdd->info = &ep93xx_wdt_ident;
 108         wdd->ops = &ep93xx_wdt_ops;
 109         wdd->min_timeout = 1;
 110         wdd->max_hw_heartbeat_ms = 200;
 111         wdd->parent = dev;
 112
 113         watchdog_set_nowayout(wdd, nowayout);
 114
 115         wdd->timeout = WDT_TIMEOUT;
 116         watchdog_init_timeout(wdd, timeout, dev);
 117
 118         watchdog_set_drvdata(wdd, priv);
 119
 120         ret = devm_watchdog_register_device(dev, wdd);
 121         if (ret)
 122                 return ret;
 123
 124         dev_info(dev, "EP93XX watchdog driver %s\n",
 125                  (val & 0x08) ? " (nCS1 disable detected)" : "");
 126
 127         return 0;
 128 }
 129
 130 static struct platform_driver ep93xx_wdt_driver = {
 131         .driver         = {
 132                 .name   = "ep93xx-wdt",
 133         },
 134         .probe          = ep93xx_wdt_probe,
 135 };
 136
 137 module_platform_driver(ep93xx_wdt_driver);
 138
 139 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
 140 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 141 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 142 MODULE_DESCRIPTION("EP93xx Watchdog");
 143 MODULE_LICENSE("GPL");