drivers/watchdog/ep93xx_wdt.c

0001 /*
0002  * Watchdog driver for Cirrus Logic EP93xx family of devices.
0003  *
0004  * Copyright (c) 2004 Ray Lehtiniemi
0005  * Copyright (c) 2006 Tower Technologies
0006  * Based on ep93xx driver, bits from alim7101_wdt.c
0007  *
0008  * Authors: Ray Lehtiniemi <rayl@mail.com>,
0009  *  Alessandro Zummo <a.zummo@towertech.it>
0010  *
0011  * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
0012  *  Convert to a platform device and use the watchdog framework API
0013  *
0014  * This file is licensed under the terms of the GNU General Public
0015  * License version 2. This program is licensed "as is" without any
0016  * warranty of any kind, whether express or implied.
0017  *
0018  * This watchdog fires after 250msec, which is a too short interval
0019  * for us to rely on the user space daemon alone. So we ping the
0020  * wdt each ~200msec and eventually stop doing it if the user space
0021  * daemon dies.
0022  */
0023
0024 #include <linux/platform_device.h>
0025 #include <linux/module.h>
0026 #include <linux/watchdog.h>
0027 #include <linux/io.h>
0028
0029 /* default timeout (secs) */
0030 #define WDT_TIMEOUT 30
0031
0032 static bool nowayout = WATCHDOG_NOWAYOUT;
0033 module_param(nowayout, bool, 0);
0034 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
0035
0036 static unsigned int timeout;
0037 module_param(timeout, uint, 0);
0038 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds.");
0039
0040 #define EP93XX_WATCHDOG     0x00
0041 #define EP93XX_WDSTATUS     0x04
0042
0043 struct ep93xx_wdt_priv {
0044     void __iomem *mmio;
0045     struct watchdog_device wdd;
0046 };
0047
0048 static int ep93xx_wdt_start(struct watchdog_device *wdd)
0049 {
0050     struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
0051
0052     writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);
0053
0054     return 0;
0055 }
0056
0057 static int ep93xx_wdt_stop(struct watchdog_device *wdd)
0058 {
0059     struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
0060
0061     writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);
0062
0063     return 0;
0064 }
0065
0066 static int ep93xx_wdt_ping(struct watchdog_device *wdd)
0067 {
0068     struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
0069
0070     writel(0x5555, priv->mmio + EP93XX_WATCHDOG);
0071
0072     return 0;
0073 }
0074
0075 static const struct watchdog_info ep93xx_wdt_ident = {
0076     .options    = WDIOF_CARDRESET |
0077               WDIOF_SETTIMEOUT |
0078               WDIOF_MAGICCLOSE |
0079               WDIOF_KEEPALIVEPING,
0080     .identity   = "EP93xx Watchdog",
0081 };
0082
0083 static const struct watchdog_ops ep93xx_wdt_ops = {
0084     .owner      = THIS_MODULE,
0085     .start      = ep93xx_wdt_start,
0086     .stop       = ep93xx_wdt_stop,
0087     .ping       = ep93xx_wdt_ping,
0088 };
0089
0090 static int ep93xx_wdt_probe(struct platform_device *pdev)
0091 {
0092     struct device *dev = &pdev->dev;
0093     struct ep93xx_wdt_priv *priv;
0094     struct watchdog_device *wdd;
0095     unsigned long val;
0096     int ret;
0097
0098     priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
0099     if (!priv)
0100         return -ENOMEM;
0101
0102     priv->mmio = devm_platform_ioremap_resource(pdev, 0);
0103     if (IS_ERR(priv->mmio))
0104         return PTR_ERR(priv->mmio);
0105
0106     val = readl(priv->mmio + EP93XX_WATCHDOG);
0107
0108     wdd = &priv->wdd;
0109     wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
0110     wdd->info = &ep93xx_wdt_ident;
0111     wdd->ops = &ep93xx_wdt_ops;
0112     wdd->min_timeout = 1;
0113     wdd->max_hw_heartbeat_ms = 200;
0114     wdd->parent = dev;
0115
0116     watchdog_set_nowayout(wdd, nowayout);
0117
0118     wdd->timeout = WDT_TIMEOUT;
0119     watchdog_init_timeout(wdd, timeout, dev);
0120
0121     watchdog_set_drvdata(wdd, priv);
0122
0123     ret = devm_watchdog_register_device(dev, wdd);
0124     if (ret)
0125         return ret;
0126
0127     dev_info(dev, "EP93XX watchdog driver %s\n",
0128          (val & 0x08) ? " (nCS1 disable detected)" : "");
0129
0130     return 0;
0131 }
0132
0133 static struct platform_driver ep93xx_wdt_driver = {
0134     .driver     = {
0135         .name   = "ep93xx-wdt",
0136     },
0137     .probe      = ep93xx_wdt_probe,
0138 };
0139
0140 module_platform_driver(ep93xx_wdt_driver);
0141
0142 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
0143 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
0144 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
0145 MODULE_DESCRIPTION("EP93xx Watchdog");
0146 MODULE_LICENSE("GPL");