linux/arch/arm/mach-sunxi/sunxi.c

/*
 * Device Tree support for Allwinner A1X SoCs
 *
 * Copyright (C) 2012 Maxime Ripard
 *
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clocksource.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/io.h>

#include <linux/clk/sunxi.h>

#include <asm/mach/arch.h>
#include <asm/mach/map.h>
#include <asm/system_misc.h>

#define SUN4I_WATCHDOG_CTRL_REG		0x00
#define SUN4I_WATCHDOG_CTRL_RESTART		(1 << 0)
#define SUN4I_WATCHDOG_MODE_REG		0x04
#define SUN4I_WATCHDOG_MODE_ENABLE		(1 << 0)
#define SUN4I_WATCHDOG_MODE_RESET_ENABLE	(1 << 1)

static void __iomem *wdt_base;

static void sun4i_restart(char mode, const char *cmd)
{
	if (!wdt_base)
		return;

	/* Enable timer and set reset bit in the watchdog */
	writel(SUN4I_WATCHDOG_MODE_ENABLE | SUN4I_WATCHDOG_MODE_RESET_ENABLE,
	       wdt_base + SUN4I_WATCHDOG_MODE_REG);

	/*
	 * Restart the watchdog. The default (and lowest) interval
	 * value for the watchdog is 0.5s.
	 */
	writel(SUN4I_WATCHDOG_CTRL_RESTART, wdt_base + SUN4I_WATCHDOG_CTRL_REG);

	while (1) {
		mdelay(5);
		writel(SUN4I_WATCHDOG_MODE_ENABLE | SUN4I_WATCHDOG_MODE_RESET_ENABLE,
		       wdt_base + SUN4I_WATCHDOG_MODE_REG);
	}
}

static struct of_device_id sunxi_restart_ids[] = {
	{ .compatible = "allwinner,sun4i-wdt", .data = sun4i_restart },
	{ /*sentinel*/ }
};

static void sunxi_setup_restart(void)
{
	const struct of_device_id *of_id;
	struct device_node *np;

	np = of_find_matching_node(NULL, sunxi_restart_ids);
	if (WARN(!np, "unable to setup watchdog restart"))
		return;

	wdt_base = of_iomap(np, 0);
	WARN(!wdt_base, "failed to map watchdog base address");

	of_id = of_match_node(sunxi_restart_ids, np);
	WARN(!of_id, "restart function not available");

	arm_pm_restart = of_id->data;
}

static void __init sunxi_timer_init(void)
{
	sunxi_init_clocks();
	clocksource_of_init();
}

static void __init sunxi_dt_init(void)
{
	sunxi_setup_restart();

	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
}

static const char * const sunxi_board_dt_compat[] = {
	"allwinner,sun4i-a10",
	"allwinner,sun5i-a10s",
	"allwinner,sun5i-a13",
	NULL,
};

DT_MACHINE_START(SUNXI_DT, "Allwinner A1X (Device Tree)")
	.init_machine	= sunxi_dt_init,
	.init_time	= sunxi_timer_init,
	.dt_compat	= sunxi_board_dt_compat,
MACHINE_END