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