ARM: Exynos: fix reboot hang on Odroid X2/U2/U3 with eMMC memory

Odroid X/X2/U2/U3 require special handling of SD4_nRESET_OUT line for eMMC
memory to perform complete reboot. This patch adds code for performing such
reset.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Change-id: I0dd05288da3d5e661772914cc853a1267609fc6d

3 files changed, 102 insertions, 0 deletions

diff --git a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
index 16000370198..9eac03cd858 100644
--- a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
+++ b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
@@ -516,6 +516,11 @@
 		vdd_pll-supply = <&ldo8_reg>;
 		status = "okay";
 	};
+
+	odroid_reboot {
+		compatible = "hardkernel,odroid-reboot";
+		reset-gpio = <&gpk1 2 0>;
+	};
 };
 
 &pinctrl_1 {
diff --git a/arch/arm/mach-exynos/Makefile b/arch/arm/mach-exynos/Makefile
index 0b539ea1bda..9f6844cf498 100644
--- a/arch/arm/mach-exynos/Makefile
+++ b/arch/arm/mach-exynos/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_MACH_EXYNOS4_DT)		+= mach-exynos4-dt.o
 obj-$(CONFIG_MACH_EXYNOS5_DT)		+= mach-exynos5-dt.o
 
 obj-$(CONFIG_ARCH_EXYNOS4)		+= sec-reboot.o
+obj-$(CONFIG_ARCH_EXYNOS4)		+= odroid-reboot.o
 
 # device support
 
diff --git a/arch/arm/mach-exynos/odroid-reboot.c b/arch/arm/mach-exynos/odroid-reboot.c
new file mode 100644
index 00000000000..a81a5cb863a
--- /dev/null
+++ b/arch/arm/mach-exynos/odroid-reboot.c
@@ -0,0 +1,96 @@
+#include <linux/delay.h>
+#include <linux/pm.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <asm/cacheflush.h>
+#include <asm/system.h>
+#include <mach/regs-pmu.h>
+#include <linux/gpio.h>
+#include "common.h"
+#include <linux/extcon.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+
+struct odroid_reboot_platform_data {
+	struct device *dev;
+	int power_gpio;
+};
+
+static struct odroid_reboot_platform_data *g_pdata;
+
+static void odroid_reboot(char str, const char *cmd)
+{
+	local_irq_disable();
+
+	writel(0x12345678, S5P_INFORM2);	/* Don't enter lpm mode */
+	writel(0x0, S5P_INFORM4);		/* Reset reboot count */
+
+        gpio_set_value(g_pdata->power_gpio, 0);
+        mdelay(150);
+        gpio_set_value(g_pdata->power_gpio, 1);
+
+	flush_cache_all();
+	outer_flush_all();
+
+	exynos4_restart(0, 0);
+
+	pr_emerg("%s: waiting for reboot\n", __func__);
+	while (1)
+		;
+}
+
+static struct odroid_reboot_platform_data *odroid_reboot_parse_dt(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct odroid_reboot_platform_data *pdata;
+
+	pdata = devm_kzalloc(dev, sizeof(struct odroid_reboot_platform_data),
+			     GFP_KERNEL);
+	if (!pdata)
+		return NULL;
+
+	pdata->power_gpio = of_get_named_gpio(np, "reset-gpio", 0);
+	if (!gpio_is_valid(pdata->power_gpio)) {
+		dev_err(dev, "invalied power-gpio\n");
+		return NULL;
+	}
+	devm_gpio_request(dev, pdata->power_gpio, "reset-gpio");
+
+	return pdata;
+}
+
+static int odroid_reboot_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	if (pdev->dev.of_node)
+		g_pdata = odroid_reboot_parse_dt(dev);
+
+	if (!g_pdata) {
+		dev_err(&pdev->dev, "failed to get platform data\n");
+		return -EINVAL;
+	}
+
+	g_pdata->dev = &pdev->dev;
+
+	/* Set machine specific functions */
+	arm_pm_restart = odroid_reboot;
+
+	return 0;
+}
+
+static struct of_device_id odroid_reboot_of_match[] = {
+	{ .compatible = "hardkernel,odroid-reboot", },
+	{ },
+};
+
+static struct platform_driver odroid_reboot_driver = {
+	.probe		= odroid_reboot_probe,
+	.driver		= {
+		.name	= "odroid-reboot",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(odroid_reboot_of_match),
+	}
+};
+
+module_platform_driver(odroid_reboot_driver);