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#include <mach/smemc.h>
  17
  18unsigned int reset_status;
  19EXPORT_SYMBOL(reset_status);
  20
  21static void do_hw_reset(void);
  22
  23static int reset_gpio = -1;
  24
  25int init_gpio_reset(int gpio, int output, int level)
  26{
  27        int rc;
  28
  29        rc = gpio_request(gpio, "reset generator");
  30        if (rc) {
  31                printk(KERN_ERR "Can't request reset_gpio\n");
  32                goto out;
  33        }
  34
  35        if (output)
  36                rc = gpio_direction_output(gpio, level);
  37        else
  38                rc = gpio_direction_input(gpio);
  39        if (rc) {
  40                printk(KERN_ERR "Can't configure reset_gpio\n");
  41                gpio_free(gpio);
  42                goto out;
  43        }
  44
  45out:
  46        if (!rc)
  47                reset_gpio = gpio;
  48
  49        return rc;
  50}
  51
  52/*
  53 * Trigger GPIO reset.
  54 * This covers various types of logic connecting gpio pin
  55 * to RESET pins (nRESET or GPIO_RESET):
  56 */
  57static void do_gpio_reset(void)
  58{
  59        BUG_ON(reset_gpio == -1);
  60
  61        /* drive it low */
  62        gpio_direction_output(reset_gpio, 0);
  63        mdelay(2);
  64        /* rising edge or drive high */
  65        gpio_set_value(reset_gpio, 1);
  66        mdelay(2);
  67        /* falling edge */
  68        gpio_set_value(reset_gpio, 0);
  69
  70        /* give it some time */
  71        mdelay(10);
  72
  73        WARN_ON(1);
  74        /* fallback */
  75        do_hw_reset();
  76}
  77
  78static void do_hw_reset(void)
  79{
  80        /* Initialize the watchdog and let it fire */
  81        writel_relaxed(OWER_WME, OWER);
  82        writel_relaxed(OSSR_M3, OSSR);
  83        /* ... in 100 ms */
  84        writel_relaxed(readl_relaxed(OSCR) + 368640, OSMR3);
  85        /*
  86         * SDRAM hangs on watchdog reset on Marvell PXA270 (erratum 71)
  87         * we put SDRAM into self-refresh to prevent that
  88         */
  89        while (1)
  90                writel_relaxed(MDREFR_SLFRSH, MDREFR);
  91}
  92
  93void pxa_restart(enum reboot_mode mode, const char *cmd)
  94{
  95        local_irq_disable();
  96        local_fiq_disable();
  97
  98        clear_reset_status(RESET_STATUS_ALL);
  99
 100        switch (mode) {
 101        case REBOOT_SOFT:
 102                /* Jump into ROM at address 0 */
 103                soft_restart(0);
 104                break;
 105        case REBOOT_GPIO:
 106                do_gpio_reset();
 107                break;
 108        case REBOOT_HARD:
 109        default:
 110                do_hw_reset();
 111                break;
 112        }
 113}
 114