arch/arm/mach-sunxi/sunxi.c

   1 /*
   2  * Device Tree support for Allwinner A1X SoCs
   3  *
   4  * Copyright (C) 2012 Maxime Ripard
   5  *
   6  * Maxime Ripard <maxime.ripard@free-electrons.com>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2.  This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/clocksource.h>
  14 #include <linux/delay.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/of_address.h>
  18 #include <linux/of_irq.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/io.h>
  21 #include <linux/reboot.h>
  22
  23 #include <linux/clk/sunxi.h>
  24
  25 #include <asm/mach/arch.h>
  26 #include <asm/mach/map.h>
  27 #include <asm/system_misc.h>
  28
  29 #define SUN4I_WATCHDOG_CTRL_REG         0x00
  30 #define SUN4I_WATCHDOG_CTRL_RESTART             (1 << 0)
  31 #define SUN4I_WATCHDOG_MODE_REG         0x04
  32 #define SUN4I_WATCHDOG_MODE_ENABLE              (1 << 0)
  33 #define SUN4I_WATCHDOG_MODE_RESET_ENABLE        (1 << 1)
  34
  35 static void __iomem *wdt_base;
  36
  37 static void sun4i_restart(enum reboot_mode mode, const char *cmd)
  38 {
  39         if (!wdt_base)
  40                 return;
  41
  42         /* Enable timer and set reset bit in the watchdog */
  43         writel(SUN4I_WATCHDOG_MODE_ENABLE | SUN4I_WATCHDOG_MODE_RESET_ENABLE,
  44                wdt_base + SUN4I_WATCHDOG_MODE_REG);
  45
  46         /*
  47          * Restart the watchdog. The default (and lowest) interval
  48          * value for the watchdog is 0.5s.
  49          */
  50         writel(SUN4I_WATCHDOG_CTRL_RESTART, wdt_base + SUN4I_WATCHDOG_CTRL_REG);
  51
  52         while (1) {
  53                 mdelay(5);
  54                 writel(SUN4I_WATCHDOG_MODE_ENABLE | SUN4I_WATCHDOG_MODE_RESET_ENABLE,
  55                        wdt_base + SUN4I_WATCHDOG_MODE_REG);
  56         }
  57 }
  58
  59 static struct of_device_id sunxi_restart_ids[] = {
  60         { .compatible = "allwinner,sun4i-wdt", .data = sun4i_restart },
  61         { /*sentinel*/ }
  62 };
  63
  64 static void sunxi_setup_restart(void)
  65 {
  66         const struct of_device_id *of_id;
  67         struct device_node *np;
  68
  69         np = of_find_matching_node(NULL, sunxi_restart_ids);
  70         if (WARN(!np, "unable to setup watchdog restart"))
  71                 return;
  72
  73         wdt_base = of_iomap(np, 0);
  74         WARN(!wdt_base, "failed to map watchdog base address");
  75
  76         of_id = of_match_node(sunxi_restart_ids, np);
  77         WARN(!of_id, "restart function not available");
  78
  79         arm_pm_restart = of_id->data;
  80 }
  81
  82 static void __init sunxi_timer_init(void)
  83 {
  84         sunxi_init_clocks();
  85         clocksource_of_init();
  86 }
  87
  88 static void __init sunxi_dt_init(void)
  89 {
  90         sunxi_setup_restart();
  91
  92         of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
  93 }
  94
  95 static const char * const sunxi_board_dt_compat[] = {
  96         "allwinner,sun4i-a10",
  97         "allwinner,sun5i-a10s",
  98         "allwinner,sun5i-a13",
  99         NULL,
 100 };
 101
 102 DT_MACHINE_START(SUNXI_DT, "Allwinner A1X (Device Tree)")
 103         .init_machine   = sunxi_dt_init,
 104         .init_time      = sunxi_timer_init,
 105         .dt_compat      = sunxi_board_dt_compat,
 106 MACHINE_END