[PATCH 3/4] firmware: raspberrypi: Add reboot mode support
From: Gregor Herburger
Date: Fri Jun 26 2026 - 03:35:26 EST
The Raspberry Pi firmware has a tryboot mode where it tries to boot from
another partition. This can be used to create a A/B update schema.
To enable this on the next boot the RPI_FIRMWARE_SET_REBOOT_FLAGS
message must be send to the firmware.
Add support for this by registering a reboot mode driver.
Signed-off-by: Gregor Herburger <gregor.herburger@xxxxxxxxxxxxx>
---
drivers/firmware/Kconfig | 1 +
drivers/firmware/raspberrypi.c | 25 +++++++++++++++++++++++++
include/soc/bcm2835/raspberrypi-firmware.h | 2 ++
3 files changed, 28 insertions(+)
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index bbd2155d84838..04bc8263e0017 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -115,6 +115,7 @@ config ISCSI_IBFT
config RASPBERRYPI_FIRMWARE
tristate "Raspberry Pi Firmware Driver"
depends on BCM2835_MBOX
+ select REBOOT_MODE
help
This option enables support for communicating with the firmware on the
Raspberry Pi.
diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 0aa322e9a2e73..ba4f723751ef8 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -14,6 +14,7 @@
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
+#include <linux/reboot-mode.h>
#include <linux/slab.h>
#include <soc/bcm2835/raspberrypi-firmware.h>
@@ -29,6 +30,7 @@ struct rpi_firmware {
struct mbox_client cl;
struct mbox_chan *chan; /* The property channel. */
struct completion c;
+ struct reboot_mode_driver reboot_mode;
u32 enabled;
struct kref consumers;
@@ -273,10 +275,25 @@ static void devm_rpi_firmware_put(void *data)
rpi_firmware_put(fw);
}
+static int rpi_firmware_reboot_mode_write(struct reboot_mode_driver *reboot,
+ unsigned int magic)
+{
+ struct rpi_firmware *fw = container_of(reboot, struct rpi_firmware,
+ reboot_mode);
+ int ret = 0;
+
+ if (magic)
+ ret = rpi_firmware_property(fw, RPI_FIRMWARE_SET_REBOOT_FLAGS,
+ &magic, sizeof(magic));
+
+ return ret;
+}
+
static int rpi_firmware_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rpi_firmware *fw;
+ int ret;
/*
* Memory will be freed by rpi_firmware_delete() once all users have
@@ -306,6 +323,12 @@ static int rpi_firmware_probe(struct platform_device *pdev)
rpi_register_hwmon_driver(dev, fw);
rpi_register_clk_driver(dev);
+ fw->reboot_mode.dev = dev;
+ fw->reboot_mode.write = rpi_firmware_reboot_mode_write;
+ ret = devm_reboot_mode_register(dev, &fw->reboot_mode);
+ if (ret)
+ dev_err(dev, "Failed to register reboot mode: %d\n", ret);
+
return 0;
}
@@ -323,6 +346,8 @@ static void rpi_firmware_remove(struct platform_device *pdev)
{
struct rpi_firmware *fw = platform_get_drvdata(pdev);
+ reboot_mode_unregister(&fw->reboot_mode);
+
platform_device_unregister(rpi_hwmon);
rpi_hwmon = NULL;
platform_device_unregister(rpi_clk);
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index 66cc5a426c3c5..f905bff0fb3ea 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -81,6 +81,7 @@ enum rpi_firmware_property_tag {
RPI_FIRMWARE_GET_POE_HAT_VAL = 0x00030049,
RPI_FIRMWARE_SET_POE_HAT_VAL = 0x00030050,
RPI_FIRMWARE_NOTIFY_XHCI_RESET = 0x00030058,
+ RPI_FIRMWARE_GET_REBOOT_FLAGS = 0x00030064,
RPI_FIRMWARE_NOTIFY_DISPLAY_DONE = 0x00030066,
RPI_FIRMWARE_SET_CLOCK_STATE = 0x00038001,
RPI_FIRMWARE_SET_CLOCK_RATE = 0x00038002,
@@ -92,6 +93,7 @@ enum rpi_firmware_property_tag {
RPI_FIRMWARE_SET_SDHOST_CLOCK = 0x00038042,
RPI_FIRMWARE_SET_GPIO_CONFIG = 0x00038043,
RPI_FIRMWARE_SET_PERIPH_REG = 0x00038045,
+ RPI_FIRMWARE_SET_REBOOT_FLAGS = 0x00038064,
/* Dispmanx TAGS */
RPI_FIRMWARE_FRAMEBUFFER_ALLOCATE = 0x00040001,
--
2.47.3