[PATCH v2 0/6] firmware: raspberrypi: Style cleanups and fix child device lifetime

[PATCH v2 0/6] firmware: raspberrypi: Style cleanups and fix child device lifetime

[Sander Speetjens]

This series does minor style cleanups in the Raspberry Pi firmware
driver and fixes the lifetime handling of the hwmon and clock child
devices.

The first five patches address checkpatch warnings (missing blank lines
after declarations, incorrect indentation, unnecessary braces, and
undocumented memory barriers).

The final patch moves the hwmon and clock platform device pointers from
globals into struct rpi_firmware.  This pairs their lifetime with the
parent device and prevents leaks or incorrect unregistration if the
driver is probed more than once.  It also checks the return value of
platform_device_register_data() so that an error pointer is never
stored.  Registration failures are not propagated because the child
devices are optional.

---
Changes in v2:
- Move platform device pointers to rpi firmware struct
- Link to v1: https://lore.kernel.org/r/20261107-fix-raspberrypi-firmware-v1-0-707362c710cd@gmail.com

---
Sander Speetjens (6):
      firmware: raspberrypi: Add blank line after declaration in response_callback
      firmware: raspberrypi: Fix indentation of return statement
      firmware: raspberrypi: Add blank line after declaration in probe error path
      firmware: raspberrypi: Remove unnecessary braces in transaction helper
      firmware: raspberrypi: Document memory barriers in property list path
      firmware: raspberrypi: Store child devices in struct rpi_firmware

 drivers/firmware/raspberrypi.c | 61 ++++++++++++++++++++++++++----------------
 1 file changed, 38 insertions(+), 23 deletions(-)
---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20261107-fix-raspberrypi-firmware-be9c602d6755

Best regards,
-- 
Sander Speetjens <sander.speetjens@gmail.com>

[PATCH v2 1/6] firmware: raspberrypi: Add blank line after declaration in response_callback

[Sander Speetjens]

Add a blank line after the local variable declaration.

Signed-off-by: Sander Speetjens <sander.speetjens@gmail.com>
---
 drivers/firmware/raspberrypi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 443459c8c90f..8f3653c4a669 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -40,6 +40,7 @@ static DEFINE_MUTEX(transaction_lock);
 static void response_callback(struct mbox_client *cl, void *msg)
 {
 	struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
+
 	complete(&fw->c);
 }
 

-- 
2.56.0

[PATCH v2 2/6] firmware: raspberrypi: Fix indentation of return statement

[Sander Speetjens]

The return was over-indented; statements should start on a tab stop.

Signed-off-by: Sander Speetjens <sander.speetjens@gmail.com>
---
 drivers/firmware/raspberrypi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 8f3653c4a669..e0c91719b4d0 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -267,7 +267,7 @@ unsigned int rpi_firmware_clk_get_max_rate(struct rpi_firmware *fw, unsigned int
 		 * assume the maximum clock rate is absolute maximum we can
 		 * store over our type.
 		 */
-		 return UINT_MAX;
+		return UINT_MAX;
 
 	return le32_to_cpu(msg.rate);
 }

-- 
2.56.0

[PATCH v2 3/6] firmware: raspberrypi: Add blank line after declaration in probe error path

[Sander Speetjens]

Add the conventional blank line after the local variable declaration.

Signed-off-by: Sander Speetjens <sander.speetjens@gmail.com>
---
 drivers/firmware/raspberrypi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index e0c91719b4d0..04163c3f385d 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -315,6 +315,7 @@ static int rpi_firmware_probe(struct platform_device *pdev)
 	fw->chan = mbox_request_channel(&fw->cl, 0);
 	if (IS_ERR(fw->chan)) {
 		int ret = PTR_ERR(fw->chan);
+
 		kfree(fw);
 		return dev_err_probe(dev, ret, "Failed to get mbox channel\n");
 	}

-- 
2.56.0

[PATCH v2 4/6] firmware: raspberrypi: Remove unnecessary braces in transaction helper

[Sander Speetjens]

Braces are not needed around the single-statement arms of the
wait_for_completion_timeout() check.

Signed-off-by: Sander Speetjens <sander.speetjens@gmail.com>
---
 drivers/firmware/raspberrypi.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 04163c3f385d..d9a569a6dae7 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -60,11 +60,10 @@ rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
 	reinit_completion(&fw->c);
 	ret = mbox_send_message(fw->chan, &message);
 	if (ret >= 0) {
-		if (wait_for_completion_timeout(&fw->c, HZ)) {
+		if (wait_for_completion_timeout(&fw->c, HZ))
 			ret = 0;
-		} else {
+		else
 			ret = -ETIMEDOUT;
-		}
 	} else {
 		dev_err(fw->cl.dev, "mbox_send_message returned %d\n", ret);
 	}

-- 
2.56.0

[PATCH v2 5/6] firmware: raspberrypi: Document memory barriers in property list path

[Sander Speetjens]

Add comments explaining the wmb() before the firmware transaction and
the rmb() before reading the response, as required by coding style.

Signed-off-by: Sander Speetjens <sander.speetjens@gmail.com>
---
 drivers/firmware/raspberrypi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index d9a569a6dae7..57f21e4e65d6 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -110,10 +110,12 @@ int rpi_firmware_property_list(struct rpi_firmware *fw,
 	buf[1] = RPI_FIRMWARE_STATUS_REQUEST;
 	memcpy(&buf[2], data, tag_size);
 	buf[size / 4 - 1] = RPI_FIRMWARE_PROPERTY_END;
+	/* Make sure the writes to the buffer are visible to the firmware. */
 	wmb();
 
 	ret = rpi_firmware_transaction(fw, MBOX_CHAN_PROPERTY, bus_addr);
 
+	/* Make sure we see the firmware's response before reading it. */
 	rmb();
 	memcpy(data, &buf[2], tag_size);
 	if (ret == 0 && buf[1] != RPI_FIRMWARE_STATUS_SUCCESS) {

-- 
2.56.0

[PATCH v2 6/6] firmware: raspberrypi: Store child devices in struct rpi_firmware

[Sander Speetjens]

The hwmon and clock platform devices were kept in global variables.
Move them into struct rpi_firmware so each instance owns its own
children and their lifetimes are correctly paired with the parent.

Also check the return value of platform_device_register_data() so that
an error pointer is never stored.  The child devices are optional; do
not propagate registration failures so the main firmware interface
remains available.

Signed-off-by: Sander Speetjens <sander.speetjens@gmail.com>
---
 drivers/firmware/raspberrypi.c | 50 ++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 57f21e4e65d6..d44b2c9f0d96 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -22,10 +22,6 @@
 #define MBOX_DATA28(msg)		((msg) & ~0xf)
 #define MBOX_CHAN_PROPERTY		8
 
-static struct platform_device *rpi_hwmon;
-static struct platform_device *rpi_clk;
-static struct platform_device *rpi_rtc;
-
 struct rpi_firmware {
 	struct mbox_client cl;
 	struct mbox_chan *chan; /* The property channel. */
@@ -33,6 +29,10 @@ struct rpi_firmware {
 	u32 enabled;
 
 	struct kref consumers;
+
+	struct platform_device *hwmon_dev;
+	struct platform_device *clk_dev;
+	struct platform_device *rtc_dev;
 };
 
 static DEFINE_MUTEX(transaction_lock);
@@ -203,6 +203,7 @@ rpi_firmware_print_firmware_revision(struct rpi_firmware *fw)
 static void
 rpi_register_hwmon_driver(struct device *dev, struct rpi_firmware *fw)
 {
+	struct platform_device *pdev;
 	u32 packet;
 	int ret = rpi_firmware_property(fw, RPI_FIRMWARE_GET_THROTTLED,
 					&packet, sizeof(packet));
@@ -210,13 +211,19 @@ rpi_register_hwmon_driver(struct device *dev, struct rpi_firmware *fw)
 	if (ret)
 		return;
 
-	rpi_hwmon = platform_device_register_data(dev, "raspberrypi-hwmon",
-						  -1, NULL, 0);
+	pdev = platform_device_register_data(dev, "raspberrypi-hwmon",
+					     -1, NULL, 0);
+
+	if (IS_ERR(pdev))
+		return;
+
+	 fw->hwmon_dev = pdev;
 }
 
-static void rpi_register_clk_driver(struct device *dev)
+static void rpi_register_clk_driver(struct device *dev, struct rpi_firmware *fw)
 {
 	struct device_node *firmware;
+	struct platform_device *pdev;
 
 	/*
 	 * Earlier DTs don't have a node for the firmware clocks but
@@ -230,11 +237,16 @@ static void rpi_register_clk_driver(struct device *dev)
 		return;
 	}
 
-	rpi_clk = platform_device_register_data(dev, "raspberrypi-clk",
-						-1, NULL, 0);
+	pdev = platform_device_register_data(dev, "raspberrypi-clk",
+					     -1, NULL, 0);
+
+	if (IS_ERR(pdev))
+		return;
+
+	 fw->clk_dev = pdev;
 }
 
-static void rpi_register_rtc_driver(struct device *dev)
+static void rpi_register_rtc_driver(struct device *dev, struct rpi_firmware *fw)
 {
 	struct platform_device *pdev;
 
@@ -251,7 +263,7 @@ static void rpi_register_rtc_driver(struct device *dev)
 	if (IS_ERR(pdev))
 		return;
 
-	rpi_rtc = pdev;
+	 fw->rtc_dev = pdev;
 }
 
 unsigned int rpi_firmware_clk_get_max_rate(struct rpi_firmware *fw, unsigned int id)
@@ -328,8 +340,8 @@ static int rpi_firmware_probe(struct platform_device *pdev)
 
 	rpi_firmware_print_firmware_revision(fw);
 	rpi_register_hwmon_driver(dev, fw);
-	rpi_register_clk_driver(dev);
-	rpi_register_rtc_driver(dev);
+	rpi_register_clk_driver(dev, fw);
+	rpi_register_rtc_driver(dev, fw);
 
 	return 0;
 }
@@ -348,12 +360,12 @@ static void rpi_firmware_remove(struct platform_device *pdev)
 {
 	struct rpi_firmware *fw = platform_get_drvdata(pdev);
 
-	platform_device_unregister(rpi_hwmon);
-	rpi_hwmon = NULL;
-	platform_device_unregister(rpi_clk);
-	rpi_clk = NULL;
-	platform_device_unregister(rpi_rtc);
-	rpi_rtc = NULL;
+	platform_device_unregister(fw->hwmon_dev);
+	fw->hwmon_dev = NULL;
+	platform_device_unregister(fw->clk_dev);
+	fw->clk_dev = NULL;
+	platform_device_unregister(fw->rtc_dev);
+	fw->rtc_dev = NULL;
 
 	rpi_firmware_put(fw);
 }

-- 
2.56.0

Re: [PATCH v2 5/6] firmware: raspberrypi: Document memory barriers in property list path

[Manuel Ebner]

Hi Sander,

On Sat, 2026-11-07 at 19:21 +0100, Sander Speetjens wrote:
> Add comments explaining the wmb() before the firmware transaction and
> the rmb() before reading the response, as required by coding style.
> 
> Signed-off-by: Sander Speetjens <sander.speetjens@gmail.com>

For Patches 1-5/6:
Reviewed-by: Manuel Ebner <manuelebnerli@mailbox.org>

Thanks
 Manuel 

> ---
>  drivers/firmware/raspberrypi.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
> index d9a569a6dae7..57f21e4e65d6 100644
> --- a/drivers/firmware/raspberrypi.c
> +++ b/drivers/firmware/raspberrypi.c
> @@ -110,10 +110,12 @@ int rpi_firmware_property_list(struct rpi_firmware *fw,
>  	buf[1] = RPI_FIRMWARE_STATUS_REQUEST;
>  	memcpy(&buf[2], data, tag_size);
>  	buf[size / 4 - 1] = RPI_FIRMWARE_PROPERTY_END;
> +	/* Make sure the writes to the buffer are visible to the firmware. */
>  	wmb();
>  
>  	ret = rpi_firmware_transaction(fw, MBOX_CHAN_PROPERTY, bus_addr);
>  
> +	/* Make sure we see the firmware's response before reading it. */
>  	rmb();
>  	memcpy(data, &buf[2], tag_size);
>  	if (ret == 0 && buf[1] != RPI_FIRMWARE_STATUS_SUCCESS) {