linux-imx

/*

 * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface

 *

 * Author: James Chapman <jchapman@katalix.com>

 *

 * Platform-specific setup code should configure the dog to generate

 * interrupt or reset as required.  This code only enables/disables

 * and services the watchdog.

 *

 * Derived from mpc8xx_wdt.c, with the following copyright.

 *

 * 2002 (c) Florian Schirmer <jolt@tuxbox.org> This file is licensed under

 * the terms of the GNU General Public License version 2. This program

 * is licensed "as is" without any warranty of any kind, whether express

 * or implied.

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/miscdevice.h>

#include <linux/module.h>

#include <linux/watchdog.h>

#include <linux/platform_device.h>

#include <linux/mv643xx.h>

#include <linux/uaccess.h>

#include <linux/io.h>

​

#define MV64x60_WDT_WDC_OFFSET  0

​

/*

 * The watchdog configuration register contains a pair of 2-bit fields,

 *   1.  a reload field, bits 27-26, which triggers a reload of

 *       the countdown register, and

 *   2.  an enable field, bits 25-24, which toggles between

 *       enabling and disabling the watchdog timer.

 * Bit 31 is a read-only field which indicates whether the

 * watchdog timer is currently enabled.

 *

 * The low 24 bits contain the timer reload value.

 */

#define MV64x60_WDC_ENABLE_SHIFT    24

#define MV64x60_WDC_SERVICE_SHIFT   26

#define MV64x60_WDC_ENABLED_SHIFT   31

​

#define MV64x60_WDC_ENABLED_TRUE    1

#define MV64x60_WDC_ENABLED_FALSE   0

​

/* Flags bits */

#define MV64x60_WDOG_FLAG_OPENED    0

​

static unsigned long wdt_flags;

static int wdt_status;

static void __iomem *mv64x60_wdt_regs;

static int mv64x60_wdt_timeout;

static int mv64x60_wdt_count;

static unsigned int bus_clk;

static char expect_close;

static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);

​

static bool nowayout = WATCHDOG_NOWAYOUT;

module_param(nowayout, bool, 0);

MODULE_PARM_DESC(nowayout,

        "Watchdog cannot be stopped once started (default="

                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

​

static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)

{

    u32 data;

    u32 enabled;

    int ret = 0;

​

    spin_lock(&mv64x60_wdt_spinlock);

    data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);

    enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;

​

    /* only toggle the requested field if enabled state matches predicate */

    if ((enabled ^ enabled_predicate) == 0) {

        /* We write a 1, then a 2 -- to the appropriate field */

        data = (1 << field_shift) | mv64x60_wdt_count;

        writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);

​

        data = (2 << field_shift) | mv64x60_wdt_count;

        writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);

        ret = 1;

    }

    spin_unlock(&mv64x60_wdt_spinlock);

​

    return ret;

}