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 <asm/arch/pxa-regs.h>
  14 #include <asm/arch/pxa2xx-regs.h>
  15
  16 static void do_hw_reset(void);
  17
  18 static int reset_gpio = -1;
  19
  20 int init_gpio_reset(int gpio)
  21 {
  22         int rc;
  23
  24         rc = gpio_request(gpio, "reset generator");
  25         if (rc) {
  26                 printk(KERN_ERR "Can't request reset_gpio\n");
  27                 goto out;
  28         }
  29
  30         rc = gpio_direction_input(gpio);
  31         if (rc) {
  32                 printk(KERN_ERR "Can't configure reset_gpio for input\n");
  33                 gpio_free(gpio);
  34                 goto out;
  35         }
  36
  37 out:
  38         if (!rc)
  39                 reset_gpio = gpio;
  40
  41         return rc;
  42 }
  43
  44 /*
  45  * Trigger GPIO reset.
  46  * This covers various types of logic connecting gpio pin
  47  * to RESET pins (nRESET or GPIO_RESET):
  48  */
  49 static void do_gpio_reset(void)
  50 {
  51         BUG_ON(reset_gpio == -1);
  52
  53         /* drive it low */
  54         gpio_direction_output(reset_gpio, 0);
  55         mdelay(2);
  56         /* rising edge or drive high */
  57         gpio_set_value(reset_gpio, 1);
  58         mdelay(2);
  59         /* falling edge */
  60         gpio_set_value(reset_gpio, 0);
  61
  62         /* give it some time */
  63         mdelay(10);
  64
  65         WARN_ON(1);
  66         /* fallback */
  67         do_hw_reset();
  68 }
  69
  70 static void do_hw_reset(void)
  71 {
  72         /* Initialize the watchdog and let it fire */
  73         OWER = OWER_WME;
  74         OSSR = OSSR_M3;
  75         OSMR3 = OSCR + 368640;  /* ... in 100 ms */
  76 }
  77
  78 void arch_reset(char mode)
  79 {
  80         if (cpu_is_pxa2xx())
  81                 RCSR = RCSR_HWR | RCSR_WDR | RCSR_SMR | RCSR_GPR;
  82
  83         switch (mode) {
  84         case 's':
  85                 /* Jump into ROM at address 0 */
  86                 cpu_reset(0);
  87                 break;
  88         case 'h':
  89                 do_hw_reset();
  90                 break;
  91         case 'g':
  92                 do_gpio_reset();
  93                 break;
  94         }
  95 }
  96