arch/arm/mach-pxa/reset.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/kernel.h>
   3 #include <linux/module.h>
   4 #include <linux/delay.h>
   5 #include <linux/gpio.h>
   6 #include <linux/io.h>
   7 #include <asm/proc-fns.h>
   8 #include <asm/system_misc.h>
   9
  10 #include "regs-ost.h"
  11 #include "reset.h"
  12 #include "smemc.h"
  13 #include "generic.h"
  14
  15 static void do_hw_reset(void);
  16
  17 static int reset_gpio = -1;
  18
  19 int init_gpio_reset(int gpio, int output, int level)
  20 {
  21         int rc;
  22
  23         rc = gpio_request(gpio, "reset generator");
  24         if (rc) {
  25                 printk(KERN_ERR "Can't request reset_gpio\n");
  26                 goto out;
  27         }
  28
  29         if (output)
  30                 rc = gpio_direction_output(gpio, level);
  31         else
  32                 rc = gpio_direction_input(gpio);
  33         if (rc) {
  34                 printk(KERN_ERR "Can't configure reset_gpio\n");
  35                 gpio_free(gpio);
  36                 goto out;
  37         }
  38
  39 out:
  40         if (!rc)
  41                 reset_gpio = gpio;
  42
  43         return rc;
  44 }
  45
  46 /*
  47  * Trigger GPIO reset.
  48  * This covers various types of logic connecting gpio pin
  49  * to RESET pins (nRESET or GPIO_RESET):
  50  */
  51 static void do_gpio_reset(void)
  52 {
  53         BUG_ON(reset_gpio == -1);
  54
  55         /* drive it low */
  56         gpio_direction_output(reset_gpio, 0);
  57         mdelay(2);
  58         /* rising edge or drive high */
  59         gpio_set_value(reset_gpio, 1);
  60         mdelay(2);
  61         /* falling edge */
  62         gpio_set_value(reset_gpio, 0);
  63
  64         /* give it some time */
  65         mdelay(10);
  66
  67         WARN_ON(1);
  68         /* fallback */
  69         do_hw_reset();
  70 }
  71
  72 static void do_hw_reset(void)
  73 {
  74         /* Initialize the watchdog and let it fire */
  75         writel_relaxed(OWER_WME, OWER);
  76         writel_relaxed(OSSR_M3, OSSR);
  77         /* ... in 100 ms */
  78         writel_relaxed(readl_relaxed(OSCR) + 368640, OSMR3);
  79         /*
  80          * SDRAM hangs on watchdog reset on Marvell PXA270 (erratum 71)
  81          * we put SDRAM into self-refresh to prevent that
  82          */
  83         while (1)
  84                 writel_relaxed(MDREFR_SLFRSH, MDREFR);
  85 }
  86
  87 void pxa_restart(enum reboot_mode mode, const char *cmd)
  88 {
  89         local_irq_disable();
  90         local_fiq_disable();
  91
  92         clear_reset_status(RESET_STATUS_ALL);
  93
  94         switch (mode) {
  95         case REBOOT_SOFT:
  96                 /* Jump into ROM at address 0 */
  97                 soft_restart(0);
  98                 break;
  99         case REBOOT_GPIO:
 100                 do_gpio_reset();
 101                 break;
 102         case REBOOT_HARD:
 103         default:
 104                 do_hw_reset();
 105                 break;
 106         }
 107 }