From 9332ee103244674cb611fde69b8c959cd95ba8e6 Mon Sep 17 00:00:00 2001
From: Nikita Shubin <nikita.shubin@maquefel.me>
Date: Wed, 26 May 2021 14:25:59 +0300
Subject: [PATCH] power: reset: Add a driver for the ep93xx reset

Implement the reset behaviour of the various EP93xx SoCS in drivers/power/reset.

It used to be located in arch/arm/mach-ep93xx.

Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
---
 drivers/power/reset/Kconfig          | 10 +++++
 drivers/power/reset/Makefile         |  1 +
 drivers/power/reset/ep93xx-restart.c | 65 ++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)
 create mode 100644 drivers/power/reset/ep93xx-restart.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 8c87eeda0feca..2a61afbb047bb 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -75,6 +75,16 @@ config POWER_RESET_BRCMSTB
 	  Say Y here if you have a Broadcom STB board and you wish
 	  to have restart support.
 
+config POWER_RESET_EP93XX
+	bool "Cirrus EP93XX reset driver" if COMPILE_TEST
+	depends on MFD_SYSCON
+	default ARCH_EP93XX
+	help
+	  This driver provides restart support for Cirrus EP93XX SoC.
+
+	  Say Y here if you have a Cirrus EP93XX SoC and you wish
+	  to have restart support.
+
 config POWER_RESET_GEMINI_POWEROFF
 	bool "Cortina Gemini power-off driver"
 	depends on ARCH_GEMINI || COMPILE_TEST
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index d763e6735ee39..61f4e11619b2b 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_POWER_RESET_ATC260X) += atc260x-poweroff.o
 obj-$(CONFIG_POWER_RESET_AXXIA) += axxia-reset.o
 obj-$(CONFIG_POWER_RESET_BRCMKONA) += brcm-kona-reset.o
 obj-$(CONFIG_POWER_RESET_BRCMSTB) += brcmstb-reboot.o
+obj-$(CONFIG_POWER_RESET_EP93XX) += ep93xx-restart.o
 obj-$(CONFIG_POWER_RESET_GEMINI_POWEROFF) += gemini-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
diff --git a/drivers/power/reset/ep93xx-restart.c b/drivers/power/reset/ep93xx-restart.c
new file mode 100644
index 0000000000000..0dab09d4fd3c0
--- /dev/null
+++ b/drivers/power/reset/ep93xx-restart.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: (GPL-2.0)
+/*
+ * Cirrus EP93xx SoC reset driver
+ *
+ * Copyright (C) 2021 Nikita Shubin <nikita.shubin@maquefel.me>
+ */
+
+#include <linux/delay.h>
+#include <linux/notifier.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+
+#include <linux/soc/cirrus/ep93xx.h>
+
+#define EP93XX_SYSCON_DEVCFG_SWRST	BIT(31)
+
+static int ep93xx_restart_handle(struct notifier_block *this,
+				 unsigned long mode, void *cmd)
+{
+	/* Issue the reboot */
+	ep93xx_devcfg_set_clear(EP93XX_SYSCON_DEVCFG_SWRST, 0x00);
+	ep93xx_devcfg_set_clear(0x00, EP93XX_SYSCON_DEVCFG_SWRST);
+
+	mdelay(1000);
+
+	pr_emerg("Unable to restart system\n");
+	return NOTIFY_DONE;
+}
+
+static int ep93xx_reboot_probe(struct platform_device *pdev)
+{
+	struct notifier_block *res_han;
+	struct device *dev = &pdev->dev;
+	int err;
+
+	res_han = devm_kzalloc(&pdev->dev, sizeof(*res_han), GFP_KERNEL);
+	if (!res_han)
+		return -ENOMEM;
+
+	res_han->notifier_call = ep93xx_restart_handle;
+	res_han->priority = 128;
+
+	err = register_restart_handler(res_han);
+	if (err)
+		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
+
+	return err;
+}
+
+static const struct of_device_id ep93xx_reboot_of_match[] = {
+	{
+		.compatible = "cirrus,ep9301-reboot",
+	},
+	{}
+};
+
+static struct platform_driver ep93xx_reboot_driver = {
+	.probe = ep93xx_reboot_probe,
+	.driver = {
+		.name = "ep9301-reboot",
+		.of_match_table = ep93xx_reboot_of_match,
+	},
+};
+builtin_platform_driver(ep93xx_reboot_driver);
-- 
2.30.2