power: reset: Add restart functionality for STiH41x platforms

This driver adds the restart functionality for STiH415 and STiH416
platforms from STMicroelectronics.  This driver registers an
arm_pm_restart function to reset the platform.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/reset/Kconfig

@@ -82,6 +82,12 @@ config POWER_RESET_SUN6I
 	help
 	  Reboot support for the Allwinner A31 SoCs.
 
+config POWER_RESET_ST
+	bool "ST restart power-off driver"
+	depends on POWER_RESET && ARCH_STI
+	help
+	  Power off and reset support for STMicroelectronics boards.
+
 config POWER_RESET_VEXPRESS
 	bool "ARM Versatile Express power-off and reset driver"
 	depends on ARM || ARM64

drivers/power/reset/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
 obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
 obj-$(CONFIG_POWER_RESET_SUN6I) += sun6i-reboot.o
+obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
 obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
 obj-$(CONFIG_POWER_RESET_XGENE) += xgene-reboot.o
 obj-$(CONFIG_POWER_RESET_KEYSTONE) += keystone-reset.o

drivers/power/reset/st-poweroff.c

@@ -0,0 +1,151 @@
+/*
+ * Copyright (C) 2014 STMicroelectronics
+ *
+ * Power off Restart driver, used in STMicroelectronics devices.
+ *
+ * Author: Christophe Kerello <christophe.kerello@st.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+
+#include <asm/system_misc.h>
+
+struct reset_syscfg {
+	struct regmap *regmap;
+	/* syscfg used for reset */
+	unsigned int offset_rst;
+	unsigned int mask_rst;
+	/* syscfg used for unmask the reset */
+	unsigned int offset_rst_msk;
+	unsigned int mask_rst_msk;
+};
+
+/* STiH415 */
+#define STIH415_SYSCFG_11	0x2c
+#define STIH415_SYSCFG_15	0x3c
+
+static struct reset_syscfg stih415_reset = {
+	.offset_rst = STIH415_SYSCFG_11,
+	.mask_rst = BIT(0),
+	.offset_rst_msk = STIH415_SYSCFG_15,
+	.mask_rst_msk = BIT(0)
+};
+
+/* STiH416 */
+#define STIH416_SYSCFG_500	0x7d0
+#define STIH416_SYSCFG_504	0x7e0
+
+static struct reset_syscfg stih416_reset = {
+	.offset_rst = STIH416_SYSCFG_500,
+	.mask_rst = BIT(0),
+	.offset_rst_msk = STIH416_SYSCFG_504,
+	.mask_rst_msk = BIT(0)
+};
+
+/* STiH407 */
+#define STIH407_SYSCFG_4000	0x0
+#define STIH407_SYSCFG_4008	0x20
+
+static struct reset_syscfg stih407_reset = {
+	.offset_rst = STIH407_SYSCFG_4000,
+	.mask_rst = BIT(0),
+	.offset_rst_msk = STIH407_SYSCFG_4008,
+	.mask_rst_msk = BIT(0)
+};
+
+/* STiD127 */
+#define STID127_SYSCFG_700	0x0
+#define STID127_SYSCFG_773	0x124
+
+static struct reset_syscfg stid127_reset = {
+	.offset_rst = STID127_SYSCFG_773,
+	.mask_rst = BIT(0),
+	.offset_rst_msk = STID127_SYSCFG_700,
+	.mask_rst_msk = BIT(8)
+};
+
+static struct reset_syscfg *st_restart_syscfg;
+
+static void st_restart(enum reboot_mode reboot_mode, const char *cmd)
+{
+	/* reset syscfg updated */
+	regmap_update_bits(st_restart_syscfg->regmap,
+			   st_restart_syscfg->offset_rst,
+			   st_restart_syscfg->mask_rst,
+			   0);
+
+	/* unmask the reset */
+	regmap_update_bits(st_restart_syscfg->regmap,
+			   st_restart_syscfg->offset_rst_msk,
+			   st_restart_syscfg->mask_rst_msk,
+			   0);
+}
+
+static struct of_device_id st_reset_of_match[] = {
+	{
+		.compatible = "st,stih415-restart",
+		.data = (void *)&stih415_reset,
+	}, {
+		.compatible = "st,stih416-restart",
+		.data = (void *)&stih416_reset,
+	}, {
+		.compatible = "st,stih407-restart",
+		.data = (void *)&stih407_reset,
+	}, {
+		.compatible = "st,stid127-restart",
+		.data = (void *)&stid127_reset,
+	},
+	{}
+};
+
+static int st_reset_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	const struct of_device_id *match;
+	struct device *dev = &pdev->dev;
+
+	match = of_match_device(st_reset_of_match, dev);
+	if (!match)
+		return -ENODEV;
+
+	st_restart_syscfg = (struct reset_syscfg *)match->data;
+
+	st_restart_syscfg->regmap =
+		syscon_regmap_lookup_by_phandle(np, "st,syscfg");
+	if (IS_ERR(st_restart_syscfg->regmap)) {
+		dev_err(dev, "No syscfg phandle specified\n");
+		return PTR_ERR(st_restart_syscfg->regmap);
+	}
+
+	arm_pm_restart = st_restart;
+
+	return 0;
+}
+
+static struct platform_driver st_reset_driver = {
+	.probe = st_reset_probe,
+	.driver = {
+		.name = "st_reset",
+		.of_match_table = st_reset_of_match,
+	},
+};
+
+static int __init st_reset_init(void)
+{
+	return platform_driver_register(&st_reset_driver);
+}
+
+device_initcall(st_reset_init);
+
+MODULE_AUTHOR("Christophe Kerello <christophe.kerello@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics Power off Restart driver");
+MODULE_LICENSE("GPL v2");