[PATCH 4/5] power: reset: add GPIO restart driver

[Ahmad Fatoum <ahmad@a3f.at>]

This is a straight port from Linux v5.11.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
---
 drivers/power/reset/Kconfig        |  8 +++
 drivers/power/reset/Makefile       |  1 +
 drivers/power/reset/gpio-restart.c | 99 ++++++++++++++++++++++++++++++
 3 files changed, 108 insertions(+)
 create mode 100644 drivers/power/reset/gpio-restart.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index cadcc0b13f2f..dec1482ccd0c 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -36,3 +36,11 @@ config POWER_RESET_GPIO
 	  This driver supports turning off your board via a GPIO line.
 	  If your board needs a GPIO high/low to power down, say Y and
 	  create a binding in your devicetree.
+
+config POWER_RESET_GPIO_RESTART
+	bool "GPIO restart driver"
+	depends on OF_GPIO
+	help
+	  This driver supports restarting your board via a GPIO line.
+	  If your board needs a GPIO high/low to restart, say Y and
+	  create a binding in your devicetree.
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 438c85970028..33d29d2d9546 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o
 obj-$(CONFIG_POWER_RESET_SYSCON) += syscon-reboot.o
 obj-$(CONFIG_POWER_RESET_SYSCON_POWEROFF) += syscon-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
+obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
diff --git a/drivers/power/reset/gpio-restart.c b/drivers/power/reset/gpio-restart.c
new file mode 100644
index 000000000000..72c690a3cf4c
--- /dev/null
+++ b/drivers/power/reset/gpio-restart.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Toggles a GPIO pin to restart a device
+ *
+ * Copyright (C) 2014 Google, Inc.
+ *
+ * Based on the gpio-poweroff driver.
+ */
+#include <common.h>
+#include <driver.h>
+#include <restart.h>
+#include <gpiod.h>
+
+struct gpio_restart {
+	int reset_gpio;
+	struct restart_handler restart_handler;
+	u32 active_delay_ms;
+	u32 inactive_delay_ms;
+	u32 wait_delay_ms;
+};
+
+static void __noreturn gpio_restart_handle(struct restart_handler *this)
+{
+	struct gpio_restart *gpio_restart =
+		container_of(this, struct gpio_restart, restart_handler);
+
+	/* drive it active, also inactive->active edge */
+	gpio_direction_active(gpio_restart->reset_gpio, true);
+	mdelay(gpio_restart->active_delay_ms);
+
+	/* drive inactive, also active->inactive edge */
+	gpio_set_active(gpio_restart->reset_gpio, false);
+	mdelay(gpio_restart->inactive_delay_ms);
+
+	/* drive it active, also inactive->active edge */
+	gpio_set_active(gpio_restart->reset_gpio, true);
+
+	/* give it some time */
+	mdelay(gpio_restart->wait_delay_ms);
+
+	mdelay(1000);
+
+	panic("Unable to restart system\n");
+}
+
+static int gpio_restart_probe(struct device_d *dev)
+{
+	struct device_node *np = dev->device_node;
+	struct gpio_restart *gpio_restart;
+	bool open_source = false;
+	u32 property;
+	int ret;
+
+	gpio_restart = xzalloc(sizeof(*gpio_restart));
+
+	open_source = of_property_read_bool(np, "open-source");
+
+	gpio_restart->reset_gpio = gpiod_get(dev, NULL,
+			open_source ? GPIOD_IN : GPIOD_OUT_LOW);
+	ret = gpio_restart->reset_gpio;
+	if (ret < 0) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Could not get reset GPIO\n");
+		return ret;
+	}
+
+	gpio_restart->restart_handler.restart = gpio_restart_handle;
+	gpio_restart->restart_handler.name = "gpio-restart";
+	gpio_restart->restart_handler.priority = 129;
+	gpio_restart->active_delay_ms = 100;
+	gpio_restart->inactive_delay_ms = 100;
+	gpio_restart->wait_delay_ms = 3000;
+
+	ret = of_property_read_u32(dev->device_node, "priority", &property);
+	if (!ret)
+		gpio_restart->restart_handler.priority = property;
+
+	of_property_read_u32(np, "active-delay", &gpio_restart->active_delay_ms);
+	of_property_read_u32(np, "inactive-delay", &gpio_restart->inactive_delay_ms);
+	of_property_read_u32(np, "wait-delay", &gpio_restart->wait_delay_ms);
+
+	return restart_handler_register(&gpio_restart->restart_handler);
+}
+
+static const struct of_device_id of_gpio_restart_match[] = {
+	{ .compatible = "gpio-restart", },
+	{},
+};
+
+static struct driver_d gpio_restart_driver = {
+	.name = "restart-gpio",
+	.of_compatible = of_gpio_restart_match,
+	.probe = gpio_restart_probe,
+};
+device_platform_driver(gpio_restart_driver);
+
+MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
+MODULE_DESCRIPTION("GPIO restart driver");
+MODULE_LICENSE("GPL");
-- 
2.30.0


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