reset.c

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/io.h>
#include <asm/proc-fns.h>
#include <asm/system_misc.h>

#include <mach/regs-ost.h>
#include <mach/reset.h>

unsigned int reset_status;
EXPORT_SYMBOL(reset_status);

static void do_hw_reset(void);

static int reset_gpio = -1;

int init_gpio_reset(int gpio, int output, int level)
{
    int rc;

    rc = gpio_request(gpio, "reset generator");
    if (rc) {
        printk(KERN_ERR "Can't request reset_gpio\n");
        goto out;
    }

    if (output)
        rc = gpio_direction_output(gpio, level);
    else
        rc = gpio_direction_input(gpio);
    if (rc) {
        printk(KERN_ERR "Can't configure reset_gpio\n");
        gpio_free(gpio);
        goto out;
    }

out:
    if (!rc)
        reset_gpio = gpio;

    return rc;
}

/*
 * Trigger GPIO reset.
 * This covers various types of logic connecting gpio pin
 * to RESET pins (nRESET or GPIO_RESET):
 */
static void do_gpio_reset(void)
{
    BUG_ON(reset_gpio == -1);

    /* drive it low */
    gpio_direction_output(reset_gpio, 0);
    mdelay(2);
    /* rising edge or drive high */
    gpio_set_value(reset_gpio, 1);
    mdelay(2);
    /* falling edge */
    gpio_set_value(reset_gpio, 0);

    /* give it some time */
    mdelay(10);

    WARN_ON(1);
    /* fallback */
    do_hw_reset();
}

static void do_hw_reset(void)
{
    /* Initialize the watchdog and let it fire */
    writel_relaxed(OWER_WME, OWER);
    writel_relaxed(OSSR_M3, OSSR);
    /* ... in 100 ms */
    writel_relaxed(readl_relaxed(OSCR) + 368640, OSMR3);
}

void pxa_restart(char mode, const char *cmd)
{
    local_irq_disable();
    local_fiq_disable();

    clear_reset_status(RESET_STATUS_ALL);

    switch (mode) {
    case 's':
        /* Jump into ROM at address 0 */
        soft_restart(0);
        break;
    case 'g':
        do_gpio_reset();
        break;
    case 'h':
    default:
        do_hw_reset();
        break;
    }
}