LXR linux/arch/arm/mach-pxa/reset.c

   1/*
   2 * This program is free software; you can redistribute it and/or modify
   3 * it under the terms of the GNU General Public License version 2 as
   4 * published by the Free Software Foundation.
   5 */
   6#include <linux/kernel.h>
   7#include <linux/module.h>
   8#include <linux/delay.h>
   9#include <linux/gpio.h>
  10#include <linux/io.h>
  11#include <asm/proc-fns.h>
  12#include <asm/system_misc.h>
  13
  14#include <mach/regs-ost.h>
  15#include <mach/reset.h>
  16
  17unsigned int reset_status;
  18EXPORT_SYMBOL(reset_status);
  19
  20static void do_hw_reset(void);
  21
  22static int reset_gpio = -1;
  23
  24int init_gpio_reset(int gpio, int output, int level)
  25{
  26        int rc;
  27
  28        rc = gpio_request(gpio, "reset generator");
  29        if (rc) {
  30                printk(KERN_ERR "Can't request reset_gpio\n");
  31                goto out;
  32        }
  33
  34        if (output)
  35                rc = gpio_direction_output(gpio, level);
  36        else
  37                rc = gpio_direction_input(gpio);
  38        if (rc) {
  39                printk(KERN_ERR "Can't configure reset_gpio\n");
  40                gpio_free(gpio);
  41                goto out;
  42        }
  43
  44out:
  45        if (!rc)
  46                reset_gpio = gpio;
  47
  48        return rc;
  49}
  50
  51/*
  52 * Trigger GPIO reset.
  53 * This covers various types of logic connecting gpio pin
  54 * to RESET pins (nRESET or GPIO_RESET):
  55 */
  56static void do_gpio_reset(void)
  57{
  58        BUG_ON(reset_gpio == -1);
  59
  60        /* drive it low */
  61        gpio_direction_output(reset_gpio, 0);
  62        mdelay(2);
  63        /* rising edge or drive high */
  64        gpio_set_value(reset_gpio, 1);
  65        mdelay(2);
  66        /* falling edge */
  67        gpio_set_value(reset_gpio, 0);
  68
  69        /* give it some time */
  70        mdelay(10);
  71
  72        WARN_ON(1);
  73        /* fallback */
  74        do_hw_reset();
  75}
  76
  77static void do_hw_reset(void)
  78{
  79        /* Initialize the watchdog and let it fire */
  80        writel_relaxed(OWER_WME, OWER);
  81        writel_relaxed(OSSR_M3, OSSR);
  82        /* ... in 100 ms */
  83        writel_relaxed(readl_relaxed(OSCR) + 368640, OSMR3);
  84}
  85
  86void pxa_restart(enum reboot_mode mode, const char *cmd)
  87{
  88        local_irq_disable();
  89        local_fiq_disable();
  90
  91        clear_reset_status(RESET_STATUS_ALL);
  92
  93        switch (mode) {
  94        case REBOOT_SOFT:
  95                /* Jump into ROM at address 0 */
  96                soft_restart(0);
  97                break;
  98        case REBOOT_GPIO:
  99                do_gpio_reset();
 100                break;
 101        case REBOOT_HARD:
 102        default:
 103                do_hw_reset();
 104                break;
 105        }
 106}
 107
 108