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
  17 unsigned int reset_status;
  18 EXPORT_SYMBOL(reset_status);
  19
  20 static void do_hw_reset(void);
  21
  22 static int reset_gpio = -1;
  23
  24 int 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
  44 out:
  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  */
  56 static 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
  77 static 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
  86 void pxa_restart(char 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 's':
  95                 /* Jump into ROM at address 0 */
  96                 soft_restart(0);
  97                 break;
  98         case 'g':
  99                 do_gpio_reset();
 100                 break;
 101         case 'h':
 102         default:
 103                 do_hw_reset();
 104                 break;
 105         }
 106 }
 107