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
  18 unsigned int reset_status;
  19 EXPORT_SYMBOL(reset_status);
  20
  21 static void do_hw_reset(void);
  22
  23 static int reset_gpio = -1;
  24
  25 int 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
  45 out:
  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  */
  57 static 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
  78 static 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
  93 void 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 }