[PATCH v4 8/8] reset: Renesas RZ/N1 reboot driver

[Michel Pollet <michel.pollet@bp.renesas.com>]

The Renesas RZ/N1 Family (Part #R9A06G0xx) needs a small driver
to reboot the Cortex-A7 cores. This driver is a sub driver of
the sysctrl MFD.

Signed-off-by: Michel Pollet <michel.pollet@bp.renesas.com>
---
 drivers/power/reset/Kconfig       |   7 +++
 drivers/power/reset/Makefile      |   1 +
 drivers/power/reset/rzn1-reboot.c | 105 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 113 insertions(+)
 create mode 100644 drivers/power/reset/rzn1-reboot.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index df58fc8..1416d88 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -144,6 +144,13 @@ 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_RZN1
+	bool "Renesas RZ/N1 reboot driver"
+	depends on ARCH_RZN1
+	help
+	  This driver allows rebooting the CA7 cores of the
+	  Renesas RZ/N1 Family of SoC (Part # R9A06G0xx).
+
 config POWER_RESET_ST
 	bool "ST restart driver"
 	depends on ARCH_STI
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 7778c74..bad9702 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
 obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
 obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
+obj-$(CONFIG_POWER_RESET_RZN1) += rzn1-reboot.o
 obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
 obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o
 obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
diff --git a/drivers/power/reset/rzn1-reboot.c b/drivers/power/reset/rzn1-reboot.c
new file mode 100644
index 0000000..29b568c
--- /dev/null
+++ b/drivers/power/reset/rzn1-reboot.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RZ/N1 reboot driver
+ *
+ * Copyright (C) 2018 Renesas Electronics Europe Limited
+ *
+ * Michel Pollet <michel.pollet@bp.renesas.com>, <buserror@gmail.com>
+ * Derived from zx-reboot.c
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+
+/* Definitions from the SDK rzn1-sysctrl.h autogenerated file */
+#define RZN1_SYSCTRL_REG_RSTEN			0x120
+#define RZN1_SYSCTRL_REG_RSTEN_MRESET_EN		0
+#define RZN1_SYSCTRL_REG_RSTEN_WDA7RST_EN		1
+#define RZN1_SYSCTRL_REG_RSTEN_WDA7RST_EN_MASK		0x6
+#define RZN1_SYSCTRL_REG_RSTEN_WDM3RST_EN		3
+#define RZN1_SYSCTRL_REG_RSTEN_CM3LOCKUPRST_EN		4
+#define RZN1_SYSCTRL_REG_RSTEN_CM3SYSRESET_EN		5
+#define RZN1_SYSCTRL_REG_RSTEN_SWRST_EN			6
+#define RZN1_SYSCTRL_REG_RSTCTRL		0x198
+#define RZN1_SYSCTRL_REG_RSTCTRL_WDA7RST_REQ		1
+#define RZN1_SYSCTRL_REG_RSTCTRL_WDA7RST_REQ_MASK	0x6
+#define RZN1_SYSCTRL_REG_RSTCTRL_WDM3RST_REQ		3
+#define RZN1_SYSCTRL_REG_RSTCTRL_CM3LOCKUPRST_REQ	4
+#define RZN1_SYSCTRL_REG_RSTCTRL_CM3SYSRESET_REQ	5
+#define RZN1_SYSCTRL_REG_RSTCTRL_SWRST_REQ		6
+
+static struct regmap *sysctrl;
+
+static int rzn1_reboot_handler(struct notifier_block *this,
+			      unsigned long mode, void *cmd)
+{
+	regmap_write_bits(sysctrl,
+			RZN1_SYSCTRL_REG_RSTEN,
+			BIT(RZN1_SYSCTRL_REG_RSTEN_SWRST_EN) |
+				BIT(RZN1_SYSCTRL_REG_RSTEN_MRESET_EN),
+			BIT(RZN1_SYSCTRL_REG_RSTEN_SWRST_EN) |
+				BIT(RZN1_SYSCTRL_REG_RSTEN_MRESET_EN));
+	regmap_write_bits(sysctrl,
+			RZN1_SYSCTRL_REG_RSTCTRL,
+			BIT(RZN1_SYSCTRL_REG_RSTCTRL_SWRST_REQ),
+			BIT(RZN1_SYSCTRL_REG_RSTCTRL_SWRST_REQ));
+
+	mdelay(50);
+	pr_emerg("Unable to restart system\n");
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rzn1_reboot_nb = {
+	.notifier_call = rzn1_reboot_handler,
+	.priority = 128,
+};
+
+static int rzn1_reboot_probe(struct platform_device *pdev)
+{
+	int err;
+	struct device *parent;
+
+	parent = pdev->dev.parent;
+	if (!parent || !parent->of_node) {
+		dev_err(&pdev->dev, "couldn't find sysctrl node\n");
+		return -ENODEV;
+	}
+	sysctrl = syscon_node_to_regmap(parent->of_node);
+	if (IS_ERR(sysctrl)) {
+		dev_err(&pdev->dev, "couldn't find find regmap\n");
+		return PTR_ERR(sysctrl);
+	}
+	err = register_restart_handler(&rzn1_reboot_nb);
+	if (err) {
+		dev_err(&pdev->dev, "register restart handler failed(err=%d)\n",
+			err);
+	}
+
+	return err;
+}
+
+static const struct of_device_id rzn1_reboot_of_match[] = {
+	{ .compatible = "renesas,rzn1-reboot" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rzn1_reboot_of_match);
+
+static struct platform_driver rzn1_reboot_driver = {
+	.probe = rzn1_reboot_probe,
+	.driver = {
+		.name = "rzn1-reboot",
+		.of_match_table = rzn1_reboot_of_match,
+	},
+};
+module_platform_driver(rzn1_reboot_driver);
+
+MODULE_DESCRIPTION("RZ/N1 reboot driver");
+MODULE_AUTHOR("Michel Pollet <michel.pollet@bp.renesas.com>, <buserror@gmail.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4