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
  13 #include <mach/pxa-regs.h>
  14 #include <mach/reset.h>
  15
  16 unsigned int reset_status;
  17 EXPORT_SYMBOL(reset_status);
  18
  19 static void do_hw_reset(void);
  20
  21 static int reset_gpio = -1;
  22
  23 int init_gpio_reset(int gpio, int output)
  24 {
  25         int rc;
  26
  27         rc = gpio_request(gpio, "reset generator");
  28         if (rc) {
  29                 printk(KERN_ERR "Can't request reset_gpio\n");
  30                 goto out;
  31         }
  32
  33         if (output)
  34                 rc = gpio_direction_output(gpio, 0);
  35         else
  36                 rc = gpio_direction_input(gpio);
  37         if (rc) {
  38                 printk(KERN_ERR "Can't configure reset_gpio\n");
  39                 gpio_free(gpio);
  40                 goto out;
  41         }
  42
  43 out:
  44         if (!rc)
  45                 reset_gpio = gpio;
  46
  47         return rc;
  48 }
  49
  50 /*
  51  * Trigger GPIO reset.
  52  * This covers various types of logic connecting gpio pin
  53  * to RESET pins (nRESET or GPIO_RESET):
  54  */
  55 static void do_gpio_reset(void)
  56 {
  57         BUG_ON(reset_gpio == -1);
  58
  59         /* drive it low */
  60         gpio_direction_output(reset_gpio, 0);
  61         mdelay(2);
  62         /* rising edge or drive high */
  63         gpio_set_value(reset_gpio, 1);
  64         mdelay(2);
  65         /* falling edge */
  66         gpio_set_value(reset_gpio, 0);
  67
  68         /* give it some time */
  69         mdelay(10);
  70
  71         WARN_ON(1);
  72         /* fallback */
  73         do_hw_reset();
  74 }
  75
  76 static void do_hw_reset(void)
  77 {
  78         /* Initialize the watchdog and let it fire */
  79         OWER = OWER_WME;
  80         OSSR = OSSR_M3;
  81         OSMR3 = OSCR + 368640;  /* ... in 100 ms */
  82 }
  83
  84 void arch_reset(char mode)
  85 {
  86         clear_reset_status(RESET_STATUS_ALL);
  87
  88         switch (mode) {
  89         case 's':
  90                 /* Jump into ROM at address 0 */
  91                 cpu_reset(0);
  92                 break;
  93         case 'h':
  94                 do_hw_reset();
  95                 break;
  96         case 'g':
  97                 do_gpio_reset();
  98                 break;
  99         }
 100 }
 101