[PATCH 2/6] power: reset: Add Allwinner A31 reset code

[Maxime Ripard <maxime.ripard@free-electrons.com>]

That code used to be in the machine code, but it's more fit here with other
restart hooks.

That will allow to cleanup the machine directory, while waiting for a proper
watchdog driver for the A31.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/power/reset/Kconfig        |  7 ++++
 drivers/power/reset/Makefile       |  1 +
 drivers/power/reset/sun6i-reboot.c | 85 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 drivers/power/reset/sun6i-reboot.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index fa0e4e057b99..67aeb6ec08f9 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -43,6 +43,13 @@ config POWER_RESET_RESTART
 	  Instead they restart, and u-boot holds the SoC until the
 	  user presses a key. u-boot then boots into Linux.
 
+config POWER_RESET_SUN6I
+	bool "Allwinner A31 SoC reset driver"
+	depends on ARCH_SUNXI
+	depends on POWER_RESET
+	help
+	  Reboot support for the Allwinner A31 SoCs.
+
 config POWER_RESET_VEXPRESS
 	bool "ARM Versatile Express power-off and reset driver"
 	depends on ARM || ARM64
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index a5b4a77d1a41..950fdc011c7a 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -3,5 +3,6 @@ obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
 obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
 obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
+obj-$(CONFIG_POWER_RESET_SUN6I) += sun6i-reboot.o
 obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
 obj-$(CONFIG_POWER_RESET_XGENE) += xgene-reboot.o
diff --git a/drivers/power/reset/sun6i-reboot.c b/drivers/power/reset/sun6i-reboot.c
new file mode 100644
index 000000000000..af2cd7ff2fe8
--- /dev/null
+++ b/drivers/power/reset/sun6i-reboot.c
@@ -0,0 +1,85 @@
+/*
+ * Allwinner A31 SoCs reset code
+ *
+ * Copyright (C) 2012-2014 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/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+
+#include <asm/system_misc.h>
+
+#define SUN6I_WATCHDOG1_IRQ_REG		0x00
+#define SUN6I_WATCHDOG1_CTRL_REG	0x10
+#define SUN6I_WATCHDOG1_CTRL_RESTART		BIT(0)
+#define SUN6I_WATCHDOG1_CONFIG_REG	0x14
+#define SUN6I_WATCHDOG1_CONFIG_RESTART		BIT(0)
+#define SUN6I_WATCHDOG1_CONFIG_IRQ		BIT(1)
+#define SUN6I_WATCHDOG1_MODE_REG	0x18
+#define SUN6I_WATCHDOG1_MODE_ENABLE		BIT(0)
+
+static void __iomem *wdt_base;
+
+static void sun6i_wdt_restart(enum reboot_mode mode, const char *cmd)
+{
+	if (!wdt_base)
+		return;
+
+	/* Disable interrupts */
+	writel(0, wdt_base + SUN6I_WATCHDOG1_IRQ_REG);
+
+	/* We want to disable the IRQ and just reset the whole system */
+	writel(SUN6I_WATCHDOG1_CONFIG_RESTART,
+		wdt_base + SUN6I_WATCHDOG1_CONFIG_REG);
+
+	/* Enable timer. The default and lowest interval value is 0.5s */
+	writel(SUN6I_WATCHDOG1_MODE_ENABLE,
+		wdt_base + SUN6I_WATCHDOG1_MODE_REG);
+
+	/* Restart the watchdog. */
+	writel(SUN6I_WATCHDOG1_CTRL_RESTART,
+		wdt_base + SUN6I_WATCHDOG1_CTRL_REG);
+
+	while (1) {
+		mdelay(5);
+		writel(SUN6I_WATCHDOG1_MODE_ENABLE,
+			wdt_base + SUN6I_WATCHDOG1_MODE_REG);
+	}
+}
+
+static int sun6i_reboot_probe(struct platform_device *pdev)
+{
+	wdt_base = of_iomap(pdev->dev.of_node, 0);
+	if (!wdt_base) {
+		WARN(1, "failed to map watchdog base address");
+		return -ENODEV;
+	}
+
+	arm_pm_restart = sun6i_wdt_restart;
+
+	return 0;
+}
+
+static struct of_device_id sun6i_reboot_of_match[] = {
+	{ .compatible = "allwinner,sun6i-a31-wdt" },
+	{}
+};
+
+static struct platform_driver sun6i_reboot_driver = {
+	.probe = sun6i_reboot_probe,
+	.driver = {
+		.name = "sun6i-reboot",
+		.of_match_table = sun6i_reboot_of_match,
+	},
+};
+module_platform_driver(sun6i_reboot_driver);
-- 
1.9.1