linux-imx

/*

 * Driver for Atmel SAMA5D4 Watchdog Timer

 *

 * Copyright (C) 2015 Atmel Corporation

 *

 * Licensed under GPLv2.

 */

​

#include <linux/delay.h>

#include <linux/interrupt.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/of_irq.h>

#include <linux/platform_device.h>

#include <linux/reboot.h>

#include <linux/watchdog.h>

​

#include "at91sam9_wdt.h"

​

/* minimum and maximum watchdog timeout, in seconds */

#define MIN_WDT_TIMEOUT     1

#define MAX_WDT_TIMEOUT     16

#define WDT_DEFAULT_TIMEOUT MAX_WDT_TIMEOUT

​

#define WDT_SEC2TICKS(s)    ((s) ? (((s) << 8) - 1) : 0)

​

struct sama5d4_wdt {

    struct watchdog_device  wdd;

    void __iomem        *reg_base;

    u32         mr;

    unsigned long       last_ping;

};

​

static int wdt_timeout;

static bool nowayout = WATCHDOG_NOWAYOUT;

​

module_param(wdt_timeout, int, 0);

MODULE_PARM_DESC(wdt_timeout,

    "Watchdog timeout in seconds. (default = "

    __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");

​

module_param(nowayout, bool, 0);

MODULE_PARM_DESC(nowayout,

    "Watchdog cannot be stopped once started (default="

    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

​

#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))

​

#define wdt_read(wdt, field) \

    readl_relaxed((wdt)->reg_base + (field))

​

/* 4 slow clock periods is 4/32768 = 122.07µs*/

#define WDT_DELAY   usecs_to_jiffies(123)

​

static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)

{

    /*

     * WDT_CR and WDT_MR must not be modified within three slow clock

     * periods following a restart of the watchdog performed by a write

     * access in WDT_CR.

     */

    while (time_before(jiffies, wdt->last_ping + WDT_DELAY))

        usleep_range(30, 125);

    writel_relaxed(val, wdt->reg_base + field);

    wdt->last_ping = jiffies;

}

​

static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)

{

    if (time_before(jiffies, wdt->last_ping + WDT_DELAY))

        udelay(123);

    writel_relaxed(val, wdt->reg_base + field);

    wdt->last_ping = jiffies;

}

​

static int sama5d4_wdt_start(struct watchdog_device *wdd)

{

    struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);

​

    wdt->mr &= ~AT91_WDT_WDDIS;

    wdt_write(wdt, AT91_WDT_MR, wdt->mr);

​

    return 0;

}

​

static int sama5d4_wdt_stop(struct watchdog_device *wdd)

{

    struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);

​

    wdt->mr |= AT91_WDT_WDDIS;