reboot-mode: read the boot mode from GPIOs status

A use case for controlling the boot mode is when the user wants
to control the device boot by pushing a button without needing to
go in user-space.

Add a new backed for reboot mode where GPIOs are used to control the
reboot-mode. The driver is able to scan a predefined list of GPIOs
and return the magic value. Having the modes associated with
the magic value generated based on the GPIO values, allows the
reboot mode uclass to select the proper mode.

Signed-off-by: Nandor Han <nandor.han@vaisala.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

3 files changed, 138 insertions, 0 deletions

diff --git a/drivers/reboot-mode/Kconfig b/drivers/reboot-mode/Kconfig
index 0edc3209d7..ff65e2031a 100644
--- a/drivers/reboot-mode/Kconfig
+++ b/drivers/reboot-mode/Kconfig
@@ -15,4 +15,13 @@ config DM_REBOOT_MODE
 		adjust the boot process based on reboot mode parameter
 		passed to U-Boot.
 
+config DM_REBOOT_MODE_GPIO
+	bool "Use GPIOs as reboot mode backend"
+	depends on DM_REBOOT_MODE
+	default n
+	help
+		Use GPIOs to control the reboot mode. This will allow users to boot
+		a device in a specific mode by using a GPIO that can be controlled
+		outside U-Boot.
+
 endmenu
diff --git a/drivers/reboot-mode/Makefile b/drivers/reboot-mode/Makefile
index 2ab0fddac9..04917be4f4 100644
--- a/drivers/reboot-mode/Makefile
+++ b/drivers/reboot-mode/Makefile
@@ -5,3 +5,4 @@
 #
 
 obj-$(CONFIG_DM_REBOOT_MODE) += reboot-mode-uclass.o
+obj-$(CONFIG_DM_REBOOT_MODE_GPIO) += reboot-mode-gpio.o
diff --git a/drivers/reboot-mode/reboot-mode-gpio.c b/drivers/reboot-mode/reboot-mode-gpio.c
new file mode 100644
index 0000000000..305174736e
--- /dev/null
+++ b/drivers/reboot-mode/reboot-mode-gpio.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c), Vaisala Oyj
+ */
+
+#include <common.h>
+#include <asm/gpio.h>
+#include <dm.h>
+#include <dm/devres.h>
+#include <errno.h>
+#include <reboot-mode/reboot-mode-gpio.h>
+#include <reboot-mode/reboot-mode.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static int reboot_mode_get(struct udevice *dev, u32 *buf)
+{
+	int ret;
+	struct reboot_mode_gpio_platdata *plat_data;
+
+	if (!buf)
+		return -EINVAL;
+
+	plat_data = dev_get_plat(dev);
+	if (!plat_data)
+		return -EINVAL;
+
+	ret = dm_gpio_get_values_as_int(plat_data->gpio_desc,
+					plat_data->gpio_count);
+	if (ret < 0)
+		return ret;
+
+	*buf = ret;
+
+	return 0;
+}
+
+static int reboot_mode_probe(struct udevice *dev)
+{
+	struct reboot_mode_gpio_platdata *plat_data;
+
+	plat_data = dev_get_plat(dev);
+	if (!plat_data)
+		return -EINVAL;
+
+	int ret;
+
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+	ret = gpio_get_list_count(dev, "gpios");
+	if (ret < 0)
+		return ret;
+
+	plat_data->gpio_count = ret;
+#endif
+
+	if (plat_data->gpio_count <= 0)
+		return -EINVAL;
+
+	plat_data->gpio_desc = devm_kcalloc(dev, plat_data->gpio_count,
+					    sizeof(struct gpio_desc), 0);
+	if (!plat_data->gpio_desc)
+		return -ENOMEM;
+
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+	ret = gpio_request_list_by_name(dev, "gpios", plat_data->gpio_desc,
+					plat_data->gpio_count, GPIOD_IS_IN);
+	if (ret < 0)
+		return ret;
+#else
+	for (int i = 0; i < plat_data->gpio_count; i++) {
+		struct reboot_mode_gpio_config *gpio =
+			plat_data->gpios_config + i;
+		struct gpio_desc *desc = plat_data->gpio_desc + i;
+
+		ret = uclass_get_device_by_seq(UCLASS_GPIO,
+					       gpio->gpio_dev_offset,
+					       &desc->dev);
+		if (ret < 0)
+			return ret;
+
+		desc->flags = gpio->flags;
+		desc->offset = gpio->gpio_offset;
+
+		ret = dm_gpio_request(desc, "");
+		if (ret < 0)
+			return ret;
+
+		ret = dm_gpio_set_dir(desc);
+		if (ret < 0)
+			return ret;
+	}
+#endif
+	return 0;
+}
+
+static int reboot_mode_remove(struct udevice *dev)
+{
+	struct reboot_mode_gpio_platdata *plat_data;
+
+	plat_data = dev_get_plat(dev);
+	if (!plat_data)
+		return -EINVAL;
+
+	return gpio_free_list(dev, plat_data->gpio_desc, plat_data->gpio_count);
+}
+
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+static const struct udevice_id reboot_mode_ids[] = {
+	{ .compatible = "reboot-mode-gpio", 0 },
+	{ }
+};
+#endif
+
+static const struct reboot_mode_ops reboot_mode_gpio_ops = {
+	.get = reboot_mode_get,
+};
+
+U_BOOT_DRIVER(reboot_mode_gpio) = {
+	.name = "reboot-mode-gpio",
+	.id = UCLASS_REBOOT_MODE,
+	.probe = reboot_mode_probe,
+	.remove = reboot_mode_remove,
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+	.of_match = reboot_mode_ids,
+#endif
+	.plat_auto = sizeof(struct reboot_mode_gpio_platdata),
+	.ops = &reboot_mode_gpio_ops,
+};