linux/drivers/watchdog/ep93xx_wdt.c
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   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 * TODO:
  24 *
  25 *      - Test last reset from watchdog status
  26 *      - Add a few missing ioctls
  27 */
  28
  29#include <linux/platform_device.h>
  30#include <linux/module.h>
  31#include <linux/miscdevice.h>
  32#include <linux/watchdog.h>
  33#include <linux/timer.h>
  34#include <linux/io.h>
  35
  36#define WDT_VERSION     "0.4"
  37
  38/* default timeout (secs) */
  39#define WDT_TIMEOUT 30
  40
  41static bool nowayout = WATCHDOG_NOWAYOUT;
  42module_param(nowayout, bool, 0);
  43MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  44
  45static unsigned int timeout = WDT_TIMEOUT;
  46module_param(timeout, uint, 0);
  47MODULE_PARM_DESC(timeout,
  48        "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  49                                __MODULE_STRING(WDT_TIMEOUT) ")");
  50
  51static void __iomem *mmio_base;
  52static struct timer_list timer;
  53static unsigned long next_heartbeat;
  54
  55#define EP93XX_WATCHDOG         0x00
  56#define EP93XX_WDSTATUS         0x04
  57
  58/* reset the wdt every ~200ms - the heartbeat of the device is 0.250 seconds*/
  59#define WDT_INTERVAL (HZ/5)
  60
  61static void ep93xx_wdt_timer_ping(unsigned long data)
  62{
  63        if (time_before(jiffies, next_heartbeat))
  64                writel(0x5555, mmio_base + EP93XX_WATCHDOG);
  65
  66        /* Re-set the timer interval */
  67        mod_timer(&timer, jiffies + WDT_INTERVAL);
  68}
  69
  70static int ep93xx_wdt_start(struct watchdog_device *wdd)
  71{
  72        next_heartbeat = jiffies + (timeout * HZ);
  73
  74        writel(0xaaaa, mmio_base + EP93XX_WATCHDOG);
  75        mod_timer(&timer, jiffies + WDT_INTERVAL);
  76
  77        return 0;
  78}
  79
  80static int ep93xx_wdt_stop(struct watchdog_device *wdd)
  81{
  82        del_timer_sync(&timer);
  83        writel(0xaa55, mmio_base + EP93XX_WATCHDOG);
  84
  85        return 0;
  86}
  87
  88static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
  89{
  90        /* user land ping */
  91        next_heartbeat = jiffies + (timeout * HZ);
  92
  93        return 0;
  94}
  95
  96static const struct watchdog_info ep93xx_wdt_ident = {
  97        .options        = WDIOF_CARDRESET |
  98                          WDIOF_MAGICCLOSE |
  99                          WDIOF_KEEPALIVEPING,
 100        .identity       = "EP93xx Watchdog",
 101};
 102
 103static struct watchdog_ops ep93xx_wdt_ops = {
 104        .owner          = THIS_MODULE,
 105        .start          = ep93xx_wdt_start,
 106        .stop           = ep93xx_wdt_stop,
 107        .ping           = ep93xx_wdt_keepalive,
 108};
 109
 110static struct watchdog_device ep93xx_wdt_wdd = {
 111        .info           = &ep93xx_wdt_ident,
 112        .ops            = &ep93xx_wdt_ops,
 113};
 114
 115static int ep93xx_wdt_probe(struct platform_device *pdev)
 116{
 117        struct resource *res;
 118        unsigned long val;
 119        int err;
 120
 121        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 122        if (!res)
 123                return -ENXIO;
 124
 125        if (!devm_request_mem_region(&pdev->dev, res->start,
 126                                     resource_size(res), pdev->name))
 127                return -EBUSY;
 128
 129        mmio_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
 130        if (!mmio_base)
 131                return -ENXIO;
 132
 133        if (timeout < 1 || timeout > 3600) {
 134                timeout = WDT_TIMEOUT;
 135                dev_warn(&pdev->dev,
 136                        "timeout value must be 1<=x<=3600, using %d\n",
 137                        timeout);
 138        }
 139
 140        val = readl(mmio_base + EP93XX_WATCHDOG);
 141        ep93xx_wdt_wdd.bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
 142        ep93xx_wdt_wdd.timeout = timeout;
 143
 144        watchdog_set_nowayout(&ep93xx_wdt_wdd, nowayout);
 145
 146        setup_timer(&timer, ep93xx_wdt_timer_ping, 1);
 147
 148        err = watchdog_register_device(&ep93xx_wdt_wdd);
 149        if (err)
 150                return err;
 151
 152        dev_info(&pdev->dev,
 153                "EP93XX watchdog, driver version " WDT_VERSION "%s\n",
 154                (val & 0x08) ? " (nCS1 disable detected)" : "");
 155
 156        return 0;
 157}
 158
 159static int ep93xx_wdt_remove(struct platform_device *pdev)
 160{
 161        watchdog_unregister_device(&ep93xx_wdt_wdd);
 162        return 0;
 163}
 164
 165static struct platform_driver ep93xx_wdt_driver = {
 166        .driver         = {
 167                .owner  = THIS_MODULE,
 168                .name   = "ep93xx-wdt",
 169        },
 170        .probe          = ep93xx_wdt_probe,
 171        .remove         = ep93xx_wdt_remove,
 172};
 173
 174module_platform_driver(ep93xx_wdt_driver);
 175
 176MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
 177                "Alessandro Zummo <a.zummo@towertech.it>,"
 178                "H Hartley Sweeten <hsweeten@visionengravers.com>");
 179MODULE_DESCRIPTION("EP93xx Watchdog");
 180MODULE_LICENSE("GPL");
 181MODULE_VERSION(WDT_VERSION);
 182MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 183
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