wd_timer.c

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/*
 * OMAP2+ MPU WD_TIMER-specific code
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/err.h>

#include <plat/omap_hwmod.h>

#include "wd_timer.h"
#include "common.h"

/*
 * In order to avoid any assumptions from bootloader regarding WDT
 * settings, WDT module is reset during init. This enables the watchdog
 * timer. Hence it is required to disable the watchdog after the WDT reset
 * during init. Otherwise the system would reboot as per the default
 * watchdog timer registers settings.
 */
#define OMAP_WDT_WPS        0x34
#define OMAP_WDT_SPR        0x48

/* Maximum microseconds to wait for OMAP module to softreset */
#define MAX_MODULE_SOFTRESET_WAIT   10000

int omap2_wd_timer_disable(struct omap_hwmod *oh)
{
    void __iomem *base;

    if (!oh) {
        pr_err("%s: Could not look up wdtimer_hwmod\n", __func__);
        return -EINVAL;
    }

    base = omap_hwmod_get_mpu_rt_va(oh);
    if (!base) {
        pr_err("%s: Could not get the base address for %s\n",
                oh->name, __func__);
        return -EINVAL;
    }

    /* sequence required to disable watchdog */
    __raw_writel(0xAAAA, base + OMAP_WDT_SPR);
    while (__raw_readl(base + OMAP_WDT_WPS) & 0x10)
        cpu_relax();

    __raw_writel(0x5555, base + OMAP_WDT_SPR);
    while (__raw_readl(base + OMAP_WDT_WPS) & 0x10)
        cpu_relax();

    return 0;
}

int omap2_wd_timer_reset(struct omap_hwmod *oh)
{
    int c = 0;

    /* Write to the SOFTRESET bit */
    omap_hwmod_softreset(oh);

    /* Poll on RESETDONE bit */
    omap_test_timeout((omap_hwmod_read(oh,
                       oh->class->sysc->syss_offs)
               & SYSS_RESETDONE_MASK),
              MAX_MODULE_SOFTRESET_WAIT, c);

    if (oh->class->sysc->srst_udelay)
        udelay(oh->class->sysc->srst_udelay);

    if (c == MAX_MODULE_SOFTRESET_WAIT)
        pr_warning("%s: %s: softreset failed (waited %d usec)\n",
               __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
    else
        pr_debug("%s: %s: softreset in %d usec\n", __func__,
             oh->name, c);

    return (c == MAX_MODULE_SOFTRESET_WAIT) ? -ETIMEDOUT :
        omap2_wd_timer_disable(oh);
}