* [PATCH 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
@ 2026-05-16 16:44 Shubham Chakraborty
2026-05-16 16:44 ` [PATCH 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
` (2 more replies)
0 siblings, 3 replies; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-16 16:44 UTC (permalink / raw)
To: Florian Fainelli, Ray Jui, Scott Branden,
Broadcom internal kernel review list, linux-rpi-kernel,
linux-arm-kernel, linux-kernel
Add firmware voltage domain identifiers for the Raspberry Pi
mailbox property interface.
These IDs are used by firmware clients to query voltage rails
through the RPI_FIRMWARE_GET_VOLTAGE property.
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
---
include/soc/bcm2835/raspberrypi-firmware.h | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index e1f87fbfe554..fd2e051ce05b 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -156,6 +156,14 @@ enum rpi_firmware_clk_id {
RPI_FIRMWARE_NUM_CLK_ID,
};
+enum rpi_firmware_volt_id {
+ RPI_FIRMWARE_VOLT_ID_RESERVED = 0,
+ RPI_FIRMWARE_VOLT_ID_CORE = 1,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_C = 2,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_I = 3,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_P = 4,
+};
+
/**
* struct rpi_firmware_clk_rate_request - Firmware Request for a rate
* @id: ID of the clock being queried
--
2.54.0
^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH 2/2] hwmon: raspberrypi: Add voltage input support
2026-05-16 16:44 [PATCH 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
@ 2026-05-16 16:44 ` Shubham Chakraborty
2026-05-16 17:13 ` Guenter Roeck
2026-05-16 19:15 ` [PATCH v2 0/2] raspberrypi: firmware and hwmon voltage support Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 0/3] raspberrypi-hwmon voltage support and teardown fix Shubham Chakraborty
2 siblings, 1 reply; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-16 16:44 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli,
Broadcom internal kernel review list, linux-hwmon,
linux-rpi-kernel, linux-arm-kernel, linux-kernel
Extend the raspberrypi-hwmon driver to expose firmware-provided
voltage measurements through the hwmon subsystem.
The driver now exports the following voltage inputs:
- in0_input (core)
- in1_input (sdram_c)
- in2_input (sdram_i)
- in3_input (sdram_p)
Voltage values returned by firmware are converted from microvolts
to millivolts as expected by the hwmon subsystem.
The existing undervoltage sticky alarm handling is preserved and
associated with the first voltage channel.
Tested in -
- Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
---
drivers/hwmon/raspberrypi-hwmon.c | 112 +++++++++++++++++++++++++++++-
1 file changed, 109 insertions(+), 3 deletions(-)
diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
index a2938881ccd2..c73a970db025 100644
--- a/drivers/hwmon/raspberrypi-hwmon.c
+++ b/drivers/hwmon/raspberrypi-hwmon.c
@@ -5,6 +5,7 @@
* Based on firmware/raspberrypi.c by Noralf Trønnes
*
* Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se•com>
+ * Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail•com>
*/
#include <linux/device.h>
#include <linux/devm-helpers.h>
@@ -18,6 +19,11 @@
#define UNDERVOLTAGE_STICKY_BIT BIT(16)
+struct rpi_firmware_get_value {
+ __le32 id;
+ __le32 val;
+} __packed;
+
struct rpi_hwmon_data {
struct device *hwmon_dev;
struct rpi_firmware *fw;
@@ -56,6 +62,23 @@ static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
}
+static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
+ long *val)
+{
+ struct rpi_firmware_get_value packet;
+ int ret;
+
+ packet.id = cpu_to_le32(id);
+ packet.val = 0;
+ ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
+ &packet, sizeof(packet));
+ if (ret)
+ return ret;
+
+ *val = le32_to_cpu(packet.val) / 1000;
+ return 0;
+}
+
static void get_values_poll(struct work_struct *work)
{
struct rpi_hwmon_data *data;
@@ -77,19 +100,101 @@ static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
{
struct rpi_hwmon_data *data = dev_get_drvdata(dev);
- *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+ if (type == hwmon_in) {
+ switch (attr) {
+ case hwmon_in_input:
+ switch (channel) {
+ case 0:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_CORE,
+ val);
+ case 1:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_C,
+ val);
+ case 2:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_I,
+ val);
+ case 3:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_P,
+ val);
+ default:
+ return -EOPNOTSUPP;
+ }
+ case hwmon_in_lcrit_alarm:
+ if (channel == 0) {
+ *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+ return 0;
+ }
+ return -EOPNOTSUPP;
+ default:
+ return -EOPNOTSUPP;
+ }
+ }
+
+ return -EOPNOTSUPP;
+}
+
+static int rpi_read_string(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, const char **str)
+{
+ if (type == hwmon_in && attr == hwmon_in_label) {
+ switch (channel) {
+ case 0:
+ *str = "core";
+ return 0;
+ case 1:
+ *str = "sdram_c";
+ return 0;
+ case 2:
+ *str = "sdram_i";
+ return 0;
+ case 3:
+ *str = "sdram_p";
+ return 0;
+ default:
+ return -EOPNOTSUPP;
+ }
+ }
+
+ return -EOPNOTSUPP;
+}
+
+static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ if (type == hwmon_in) {
+ switch (attr) {
+ case hwmon_in_input:
+ case hwmon_in_label:
+ return 0444;
+ case hwmon_in_lcrit_alarm:
+ if (channel == 0)
+ return 0444;
+ return 0;
+ default:
+ return 0;
+ }
+ }
+
return 0;
}
static const struct hwmon_channel_info * const rpi_info[] = {
HWMON_CHANNEL_INFO(in,
- HWMON_I_LCRIT_ALARM),
+ HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_LCRIT_ALARM,
+ HWMON_I_INPUT | HWMON_I_LABEL,
+ HWMON_I_INPUT | HWMON_I_LABEL,
+ HWMON_I_INPUT | HWMON_I_LABEL),
NULL
};
static const struct hwmon_ops rpi_hwmon_ops = {
- .visible = 0444,
+ .is_visible = rpi_is_visible,
.read = rpi_read,
+ .read_string = rpi_read_string,
};
static const struct hwmon_chip_info rpi_chip_info = {
@@ -159,6 +264,7 @@ static struct platform_driver rpi_hwmon_driver = {
module_platform_driver(rpi_hwmon_driver);
MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx•net>");
+MODULE_AUTHOR("Shubham Chakraborty <chakrabortyshubham66@gmail•com>");
MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:raspberrypi-hwmon");
--
2.54.0
^ permalink raw reply related [flat|nested] 19+ messages in thread
* Re: [PATCH 2/2] hwmon: raspberrypi: Add voltage input support
2026-05-16 16:44 ` [PATCH 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
@ 2026-05-16 17:13 ` Guenter Roeck
2026-05-16 18:24 ` Guenter Roeck
0 siblings, 1 reply; 19+ messages in thread
From: Guenter Roeck @ 2026-05-16 17:13 UTC (permalink / raw)
To: Shubham Chakraborty, Florian Fainelli,
Broadcom internal kernel review list, linux-hwmon,
linux-rpi-kernel, linux-arm-kernel, linux-kernel
On 5/16/26 09:44, Shubham Chakraborty wrote:
> Extend the raspberrypi-hwmon driver to expose firmware-provided
> voltage measurements through the hwmon subsystem.
>
> The driver now exports the following voltage inputs:
>
> - in0_input (core)
> - in1_input (sdram_c)
> - in2_input (sdram_i)
> - in3_input (sdram_p)
>
> Voltage values returned by firmware are converted from microvolts
> to millivolts as expected by the hwmon subsystem.
>
> The existing undervoltage sticky alarm handling is preserved and
> associated with the first voltage channel.
>
> Tested in -
> - Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
> Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
I wasn't copied on patch 1/2, so I have no idea what is in there
and how it is related to this patch. Either way it seems unlikely that
the new functionality is supported by all versions of Raspberry Pi supported
by this driver. Just returning an error when the user tries to read a sensor
that is not supported is unacceptable. This needs either evidence that the
sensors are supported by all board variants and firmware versions supported
by this driver, or the is_visible function needs to selectively enable the
supported sensors.
> ---
> drivers/hwmon/raspberrypi-hwmon.c | 112 +++++++++++++++++++++++++++++-
Documentation/hwmon/raspberrypi-hwmon.rst needs to be updated as well.
> 1 file changed, 109 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
> index a2938881ccd2..c73a970db025 100644
> --- a/drivers/hwmon/raspberrypi-hwmon.c
> +++ b/drivers/hwmon/raspberrypi-hwmon.c
> @@ -5,6 +5,7 @@
> * Based on firmware/raspberrypi.c by Noralf Trønnes
> *
> * Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se•com>
> + * Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail•com>
> */
> #include <linux/device.h>
> #include <linux/devm-helpers.h>
> @@ -18,6 +19,11 @@
>
> #define UNDERVOLTAGE_STICKY_BIT BIT(16)
>
> +struct rpi_firmware_get_value {
> + __le32 id;
> + __le32 val;
> +} __packed;
> +
> struct rpi_hwmon_data {
> struct device *hwmon_dev;
> struct rpi_firmware *fw;
> @@ -56,6 +62,23 @@ static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
> hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
> }
>
> +static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
> + long *val)
> +{
> + struct rpi_firmware_get_value packet;
> + int ret;
> +
> + packet.id = cpu_to_le32(id);
> + packet.val = 0;
> + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
> + &packet, sizeof(packet));
> + if (ret)
> + return ret;
> +
> + *val = le32_to_cpu(packet.val) / 1000;
> + return 0;
> +}
> +
> static void get_values_poll(struct work_struct *work)
> {
> struct rpi_hwmon_data *data;
> @@ -77,19 +100,101 @@ static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
> {
> struct rpi_hwmon_data *data = dev_get_drvdata(dev);
>
> - *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
> + if (type == hwmon_in) {
> + switch (attr) {
> + case hwmon_in_input:
> + switch (channel) {
> + case 0:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_CORE,
> + val);
> + case 1:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_C,
> + val);
> + case 2:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_I,
> + val);
> + case 3:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_P,
> + val);
> + default:
> + return -EOPNOTSUPP;
> + }
> + case hwmon_in_lcrit_alarm:
> + if (channel == 0) {
> + *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
> + return 0;
> + }
> + return -EOPNOTSUPP;
> + default:
> + return -EOPNOTSUPP;
> + }
> + }
> +
> + return -EOPNOTSUPP;
> +}
> +
> +static int rpi_read_string(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, const char **str)
> +{
> + if (type == hwmon_in && attr == hwmon_in_label) {
> + switch (channel) {
> + case 0:
> + *str = "core";
> + return 0;
> + case 1:
> + *str = "sdram_c";
> + return 0;
> + case 2:
> + *str = "sdram_i";
> + return 0;
> + case 3:
> + *str = "sdram_p";
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
This can be implemented as string array.
> + }
> +
> + return -EOPNOTSUPP;
> +}
> +
> +static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + if (type == hwmon_in) {
> + switch (attr) {
> + case hwmon_in_input:
> + case hwmon_in_label:
> + return 0444;
> + case hwmon_in_lcrit_alarm:
> + if (channel == 0)
> + return 0444;
> + return 0;
> + default:
> + return 0;
> + }
> + }
> +
> return 0;
> }
>
> static const struct hwmon_channel_info * const rpi_info[] = {
> HWMON_CHANNEL_INFO(in,
> - HWMON_I_LCRIT_ALARM),
> + HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_LCRIT_ALARM,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL),
> NULL
> };
>
> static const struct hwmon_ops rpi_hwmon_ops = {
> - .visible = 0444,
> + .is_visible = rpi_is_visible,
> .read = rpi_read,
> + .read_string = rpi_read_string,
> };
>
> static const struct hwmon_chip_info rpi_chip_info = {
> @@ -159,6 +264,7 @@ static struct platform_driver rpi_hwmon_driver = {
> module_platform_driver(rpi_hwmon_driver);
>
> MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx•net>");
> +MODULE_AUTHOR("Shubham Chakraborty <chakrabortyshubham66@gmail•com>");
> MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
> MODULE_LICENSE("GPL v2");
> MODULE_ALIAS("platform:raspberrypi-hwmon");
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH 2/2] hwmon: raspberrypi: Add voltage input support
2026-05-16 17:13 ` Guenter Roeck
@ 2026-05-16 18:24 ` Guenter Roeck
0 siblings, 0 replies; 19+ messages in thread
From: Guenter Roeck @ 2026-05-16 18:24 UTC (permalink / raw)
To: Shubham Chakraborty, Florian Fainelli,
Broadcom internal kernel review list, linux-hwmon,
linux-rpi-kernel, linux-arm-kernel, linux-kernel
On 5/16/26 10:13, Guenter Roeck wrote:
> On 5/16/26 09:44, Shubham Chakraborty wrote:
>> Extend the raspberrypi-hwmon driver to expose firmware-provided
>> voltage measurements through the hwmon subsystem.
>>
>> The driver now exports the following voltage inputs:
>>
>> - in0_input (core)
>> - in1_input (sdram_c)
>> - in2_input (sdram_i)
>> - in3_input (sdram_p)
>>
>> Voltage values returned by firmware are converted from microvolts
>> to millivolts as expected by the hwmon subsystem.
>>
>> The existing undervoltage sticky alarm handling is preserved and
>> associated with the first voltage channel.
>>
>> Tested in -
>> - Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
>> Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
>>
>> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
>
> I wasn't copied on patch 1/2, so I have no idea what is in there
> and how it is related to this patch. Either way it seems unlikely that
> the new functionality is supported by all versions of Raspberry Pi supported
> by this driver. Just returning an error when the user tries to read a sensor
> that is not supported is unacceptable. This needs either evidence that the
> sensors are supported by all board variants and firmware versions supported
> by this driver, or the is_visible function needs to selectively enable the
> supported sensors.
>
>> ---
>> drivers/hwmon/raspberrypi-hwmon.c | 112 +++++++++++++++++++++++++++++-
>
> Documentation/hwmon/raspberrypi-hwmon.rst needs to be updated as well.
>
>> 1 file changed, 109 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
>> index a2938881ccd2..c73a970db025 100644
>> --- a/drivers/hwmon/raspberrypi-hwmon.c
>> +++ b/drivers/hwmon/raspberrypi-hwmon.c
>> @@ -5,6 +5,7 @@
>> * Based on firmware/raspberrypi.c by Noralf Trønnes
>> *
>> * Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se•com>
>> + * Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail•com>
>> */
>> #include <linux/device.h>
>> #include <linux/devm-helpers.h>
>> @@ -18,6 +19,11 @@
>> #define UNDERVOLTAGE_STICKY_BIT BIT(16)
>> +struct rpi_firmware_get_value {
>> + __le32 id;
>> + __le32 val;
>> +} __packed;
>> +
More feedback:
Why define this here but RPI_FIRMWARE_VOLT_ID_CORE etc. in the
firmware API include file ? struct rpi_firmware_clk_rate_request
is quite similar and defined (and documented) in the include file.
Also, the name is quite generic, suggesting a common structure.
rpi_firmware_clk_rate_request, as used for the clock, is much more
specific. I would suggest to either use a single structure for all
requests or clarify that this is for voltages only (i.e., name the
structure and the returned value appropriately).
Last but not least, please send both patches to the same set of people
and mailing lists.
Thanks,
Guenter
>> struct rpi_hwmon_data {
>> struct device *hwmon_dev;
>> struct rpi_firmware *fw;
>> @@ -56,6 +62,23 @@ static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
>> hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
>> }
>> +static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
>> + long *val)
>> +{
>> + struct rpi_firmware_get_value packet;
>> + int ret;
>> +
>> + packet.id = cpu_to_le32(id);
>> + packet.val = 0;
>> + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
>> + &packet, sizeof(packet));
>> + if (ret)
>> + return ret;
>> +
>> + *val = le32_to_cpu(packet.val) / 1000;
>> + return 0;
>> +}
>> +
>> static void get_values_poll(struct work_struct *work)
>> {
>> struct rpi_hwmon_data *data;
>> @@ -77,19 +100,101 @@ static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
>> {
>> struct rpi_hwmon_data *data = dev_get_drvdata(dev);
>> - *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
>> + if (type == hwmon_in) {
>> + switch (attr) {
>> + case hwmon_in_input:
>> + switch (channel) {
>> + case 0:
>> + return rpi_firmware_get_voltage(data,
>> + RPI_FIRMWARE_VOLT_ID_CORE,
>> + val);
>> + case 1:
>> + return rpi_firmware_get_voltage(data,
>> + RPI_FIRMWARE_VOLT_ID_SDRAM_C,
>> + val);
>> + case 2:
>> + return rpi_firmware_get_voltage(data,
>> + RPI_FIRMWARE_VOLT_ID_SDRAM_I,
>> + val);
>> + case 3:
>> + return rpi_firmware_get_voltage(data,
>> + RPI_FIRMWARE_VOLT_ID_SDRAM_P,
>> + val);
>> + default:
>> + return -EOPNOTSUPP;
>> + }
>> + case hwmon_in_lcrit_alarm:
>> + if (channel == 0) {
>> + *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
>> + return 0;
>> + }
>> + return -EOPNOTSUPP;
>> + default:
>> + return -EOPNOTSUPP;
>> + }
>> + }
>> +
>> + return -EOPNOTSUPP;
>> +}
>> +
>> +static int rpi_read_string(struct device *dev, enum hwmon_sensor_types type,
>> + u32 attr, int channel, const char **str)
>> +{
>> + if (type == hwmon_in && attr == hwmon_in_label) {
>> + switch (channel) {
>> + case 0:
>> + *str = "core";
>> + return 0;
>> + case 1:
>> + *str = "sdram_c";
>> + return 0;
>> + case 2:
>> + *str = "sdram_i";
>> + return 0;
>> + case 3:
>> + *str = "sdram_p";
>> + return 0;
>> + default:
>> + return -EOPNOTSUPP;
>> + }
>
> This can be implemented as string array.
>
>> + }
>> +
>> + return -EOPNOTSUPP;
>> +}
>> +
>> +static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
>> + u32 attr, int channel)
>> +{
>> + if (type == hwmon_in) {
>> + switch (attr) {
>> + case hwmon_in_input:
>> + case hwmon_in_label:
>> + return 0444;
>> + case hwmon_in_lcrit_alarm:
>> + if (channel == 0)
>> + return 0444;
>> + return 0;
>> + default:
>> + return 0;
>> + }
>> + }
>> +
>> return 0;
>> }
>> static const struct hwmon_channel_info * const rpi_info[] = {
>> HWMON_CHANNEL_INFO(in,
>> - HWMON_I_LCRIT_ALARM),
>> + HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_LCRIT_ALARM,
>> + HWMON_I_INPUT | HWMON_I_LABEL,
>> + HWMON_I_INPUT | HWMON_I_LABEL,
>> + HWMON_I_INPUT | HWMON_I_LABEL),
>> NULL
>> };
>> static const struct hwmon_ops rpi_hwmon_ops = {
>> - .visible = 0444,
>> + .is_visible = rpi_is_visible,
>> .read = rpi_read,
>> + .read_string = rpi_read_string,
>> };
>> static const struct hwmon_chip_info rpi_chip_info = {
>> @@ -159,6 +264,7 @@ static struct platform_driver rpi_hwmon_driver = {
>> module_platform_driver(rpi_hwmon_driver);
>> MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx•net>");
>> +MODULE_AUTHOR("Shubham Chakraborty <chakrabortyshubham66@gmail•com>");
>> MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
>> MODULE_LICENSE("GPL v2");
>> MODULE_ALIAS("platform:raspberrypi-hwmon");
>
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v2 0/2] raspberrypi: firmware and hwmon voltage support
2026-05-16 16:44 [PATCH 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-16 16:44 ` [PATCH 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
@ 2026-05-16 19:15 ` Shubham Chakraborty
2026-05-16 19:15 ` [PATCH v2 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-16 19:15 ` [PATCH v2 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 0/3] raspberrypi-hwmon voltage support and teardown fix Shubham Chakraborty
2 siblings, 2 replies; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-16 19:15 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel, Shubham Chakraborty
Changes in v2:
- Patch 1/2: no changes
- Patch 2/2:
- hide unsupported voltage sensors using .is_visible()
- replace the label switch with a string array
- update raspberrypi-hwmon documentation
Shubham Chakraborty (2):
soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
hwmon: raspberrypi: Add voltage input support
Documentation/hwmon/raspberrypi-hwmon.rst | 15 ++-
drivers/hwmon/raspberrypi-hwmon.c | 134 ++++++++++++++++++++-
include/soc/bcm2835/raspberrypi-firmware.h | 8 ++
3 files changed, 152 insertions(+), 5 deletions(-)
--
2.54.0
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v2 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
2026-05-16 19:15 ` [PATCH v2 0/2] raspberrypi: firmware and hwmon voltage support Shubham Chakraborty
@ 2026-05-16 19:15 ` Shubham Chakraborty
2026-05-16 23:09 ` Guenter Roeck
2026-05-16 19:15 ` [PATCH v2 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
1 sibling, 1 reply; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-16 19:15 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel, Shubham Chakraborty
Add firmware voltage domain identifiers for the Raspberry Pi
mailbox property interface.
These IDs are used by firmware clients to query voltage rails
through the RPI_FIRMWARE_GET_VOLTAGE property.
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
---
include/soc/bcm2835/raspberrypi-firmware.h | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index e1f87fbfe554..fd2e051ce05b 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -156,6 +156,14 @@ enum rpi_firmware_clk_id {
RPI_FIRMWARE_NUM_CLK_ID,
};
+enum rpi_firmware_volt_id {
+ RPI_FIRMWARE_VOLT_ID_RESERVED = 0,
+ RPI_FIRMWARE_VOLT_ID_CORE = 1,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_C = 2,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_I = 3,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_P = 4,
+};
+
/**
* struct rpi_firmware_clk_rate_request - Firmware Request for a rate
* @id: ID of the clock being queried
--
2.54.0
^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH v2 2/2] hwmon: raspberrypi: Add voltage input support
2026-05-16 19:15 ` [PATCH v2 0/2] raspberrypi: firmware and hwmon voltage support Shubham Chakraborty
2026-05-16 19:15 ` [PATCH v2 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
@ 2026-05-16 19:15 ` Shubham Chakraborty
2026-05-16 23:20 ` Guenter Roeck
1 sibling, 1 reply; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-16 19:15 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel, Shubham Chakraborty
Extend the raspberrypi-hwmon driver to expose firmware-provided
voltage measurements through the hwmon subsystem.
The driver now exports the following voltage inputs:
- in0_input (core)
- in1_input (sdram_c)
- in2_input (sdram_i)
- in3_input (sdram_p)
Voltage values returned by firmware are converted from microvolts
to millivolts as expected by the hwmon subsystem.
Update the documentation related to it.
The existing undervoltage sticky alarm handling is preserved and
associated with the first voltage channel.
Tested in -
- Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
---
Documentation/hwmon/raspberrypi-hwmon.rst | 15 ++-
drivers/hwmon/raspberrypi-hwmon.c | 134 +++++++++++++++++++++-
2 files changed, 144 insertions(+), 5 deletions(-)
diff --git a/Documentation/hwmon/raspberrypi-hwmon.rst b/Documentation/hwmon/raspberrypi-hwmon.rst
index 8038ade36490..db315184b861 100644
--- a/Documentation/hwmon/raspberrypi-hwmon.rst
+++ b/Documentation/hwmon/raspberrypi-hwmon.rst
@@ -20,6 +20,17 @@ undervoltage conditions.
Sysfs entries
-------------
-======================= ==================
+======================= ======================================================
+in0_input Core voltage in millivolts
+in1_input SDRAM controller voltage in millivolts
+in2_input SDRAM I/O voltage in millivolts
+in3_input SDRAM PHY voltage in millivolts
+in0_label "core"
+in1_label "sdram_c"
+in2_label "sdram_i"
+in3_label "sdram_p"
in0_lcrit_alarm Undervoltage alarm
-======================= ==================
+======================= ======================================================
+
+The voltage inputs and labels are only exposed if the firmware reports support
+for the corresponding voltage ID.
diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
index a2938881ccd2..4f96f37116f3 100644
--- a/drivers/hwmon/raspberrypi-hwmon.c
+++ b/drivers/hwmon/raspberrypi-hwmon.c
@@ -5,6 +5,7 @@
* Based on firmware/raspberrypi.c by Noralf Trønnes
*
* Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se•com>
+ * Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail•com>
*/
#include <linux/device.h>
#include <linux/devm-helpers.h>
@@ -18,13 +19,26 @@
#define UNDERVOLTAGE_STICKY_BIT BIT(16)
+struct rpi_firmware_get_value {
+ __le32 id;
+ __le32 val;
+} __packed;
+
struct rpi_hwmon_data {
struct device *hwmon_dev;
struct rpi_firmware *fw;
+ u32 valid_inputs;
u32 last_throttled;
struct delayed_work get_values_poll_work;
};
+static const char * const rpi_hwmon_labels[] = {
+ "core",
+ "sdram_c",
+ "sdram_i",
+ "sdram_p",
+};
+
static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
{
u32 new_uv, old_uv, value;
@@ -56,6 +70,23 @@ static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
}
+static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
+ long *val)
+{
+ struct rpi_firmware_get_value packet;
+ int ret;
+
+ packet.id = cpu_to_le32(id);
+ packet.val = 0;
+ ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
+ &packet, sizeof(packet));
+ if (ret)
+ return ret;
+
+ *val = le32_to_cpu(packet.val) / 1000;
+ return 0;
+}
+
static void get_values_poll(struct work_struct *work)
{
struct rpi_hwmon_data *data;
@@ -77,19 +108,94 @@ static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
{
struct rpi_hwmon_data *data = dev_get_drvdata(dev);
- *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+ if (type == hwmon_in) {
+ switch (attr) {
+ case hwmon_in_input:
+ switch (channel) {
+ case 0:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_CORE,
+ val);
+ case 1:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_C,
+ val);
+ case 2:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_I,
+ val);
+ case 3:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_P,
+ val);
+ default:
+ return -EOPNOTSUPP;
+ }
+ case hwmon_in_lcrit_alarm:
+ if (channel == 0) {
+ *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+ return 0;
+ }
+ return -EOPNOTSUPP;
+ default:
+ return -EOPNOTSUPP;
+ }
+ }
+
+ return -EOPNOTSUPP;
+}
+
+static int rpi_read_string(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, const char **str)
+{
+ if (type == hwmon_in && attr == hwmon_in_label) {
+ if (channel >= ARRAY_SIZE(rpi_hwmon_labels))
+ return -EOPNOTSUPP;
+
+ *str = rpi_hwmon_labels[channel];
+ return 0;
+ }
+
+ return -EOPNOTSUPP;
+}
+
+static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ const struct rpi_hwmon_data *data = _data;
+
+ if (type == hwmon_in) {
+ switch (attr) {
+ case hwmon_in_input:
+ case hwmon_in_label:
+ if (!(data->valid_inputs & BIT(channel)))
+ return 0;
+ return 0444;
+ case hwmon_in_lcrit_alarm:
+ if (channel == 0)
+ return 0444;
+ return 0;
+ default:
+ return 0;
+ }
+ }
+
return 0;
}
static const struct hwmon_channel_info * const rpi_info[] = {
HWMON_CHANNEL_INFO(in,
- HWMON_I_LCRIT_ALARM),
+ HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_LCRIT_ALARM,
+ HWMON_I_INPUT | HWMON_I_LABEL,
+ HWMON_I_INPUT | HWMON_I_LABEL,
+ HWMON_I_INPUT | HWMON_I_LABEL),
NULL
};
static const struct hwmon_ops rpi_hwmon_ops = {
- .visible = 0444,
+ .is_visible = rpi_is_visible,
.read = rpi_read,
+ .read_string = rpi_read_string,
};
static const struct hwmon_chip_info rpi_chip_info = {
@@ -101,6 +207,7 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rpi_hwmon_data *data;
+ long voltage;
int ret;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
@@ -110,6 +217,26 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
/* Parent driver assure that firmware is correct */
data->fw = dev_get_drvdata(dev->parent);
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_CORE,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(0);
+
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_C,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(1);
+
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_I,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(2);
+
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_P,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(3);
+
data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
data,
&rpi_chip_info,
@@ -159,6 +286,7 @@ static struct platform_driver rpi_hwmon_driver = {
module_platform_driver(rpi_hwmon_driver);
MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx•net>");
+MODULE_AUTHOR("Shubham Chakraborty <chakrabortyshubham66@gmail•com>");
MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:raspberrypi-hwmon");
--
2.54.0
^ permalink raw reply related [flat|nested] 19+ messages in thread
* Re: [PATCH v2 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
2026-05-16 19:15 ` [PATCH v2 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
@ 2026-05-16 23:09 ` Guenter Roeck
0 siblings, 0 replies; 19+ messages in thread
From: Guenter Roeck @ 2026-05-16 23:09 UTC (permalink / raw)
To: Shubham Chakraborty, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel
On 5/16/26 12:15, Shubham Chakraborty wrote:
> Add firmware voltage domain identifiers for the Raspberry Pi
> mailbox property interface.
>
> These IDs are used by firmware clients to query voltage rails
> through the RPI_FIRMWARE_GET_VOLTAGE property.
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
> ---
> include/soc/bcm2835/raspberrypi-firmware.h | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
> index e1f87fbfe554..fd2e051ce05b 100644
> --- a/include/soc/bcm2835/raspberrypi-firmware.h
> +++ b/include/soc/bcm2835/raspberrypi-firmware.h
> @@ -156,6 +156,14 @@ enum rpi_firmware_clk_id {
> RPI_FIRMWARE_NUM_CLK_ID,
> };
>
> +enum rpi_firmware_volt_id {
> + RPI_FIRMWARE_VOLT_ID_RESERVED = 0,
Is that needed ?
> + RPI_FIRMWARE_VOLT_ID_CORE = 1,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_C = 2,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_I = 3,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_P = 4,
Regarding Sashiko's feedback: I don't know where it got the
information from, but a web search suggests that it has a point;
RPI_FIRMWARE_VOLT_ID_SDRAM_I and RPI_FIRMWARE_VOLT_ID_SDRAM_P appear
to be swapped. If that is not the case, please provide evidence.
Thanks,
Guenter
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v2 2/2] hwmon: raspberrypi: Add voltage input support
2026-05-16 19:15 ` [PATCH v2 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
@ 2026-05-16 23:20 ` Guenter Roeck
0 siblings, 0 replies; 19+ messages in thread
From: Guenter Roeck @ 2026-05-16 23:20 UTC (permalink / raw)
To: Shubham Chakraborty, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel
On 5/16/26 12:15, Shubham Chakraborty wrote:
> Extend the raspberrypi-hwmon driver to expose firmware-provided
> voltage measurements through the hwmon subsystem.
>
> The driver now exports the following voltage inputs:
>
> - in0_input (core)
> - in1_input (sdram_c)
> - in2_input (sdram_i)
> - in3_input (sdram_p)
>
> Voltage values returned by firmware are converted from microvolts
> to millivolts as expected by the hwmon subsystem.
>
> Update the documentation related to it.
>
> The existing undervoltage sticky alarm handling is preserved and
> associated with the first voltage channel.
>
> Tested in -
> - Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
> Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
> ---
> Documentation/hwmon/raspberrypi-hwmon.rst | 15 ++-
> drivers/hwmon/raspberrypi-hwmon.c | 134 +++++++++++++++++++++-
> 2 files changed, 144 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/hwmon/raspberrypi-hwmon.rst b/Documentation/hwmon/raspberrypi-hwmon.rst
> index 8038ade36490..db315184b861 100644
> --- a/Documentation/hwmon/raspberrypi-hwmon.rst
> +++ b/Documentation/hwmon/raspberrypi-hwmon.rst
> @@ -20,6 +20,17 @@ undervoltage conditions.
> Sysfs entries
> -------------
>
> -======================= ==================
> +======================= ======================================================
> +in0_input Core voltage in millivolts
> +in1_input SDRAM controller voltage in millivolts
> +in2_input SDRAM I/O voltage in millivolts
> +in3_input SDRAM PHY voltage in millivolts
> +in0_label "core"
> +in1_label "sdram_c"
> +in2_label "sdram_i"
> +in3_label "sdram_p"
> in0_lcrit_alarm Undervoltage alarm
> -======================= ==================
> +======================= ======================================================
> +
> +The voltage inputs and labels are only exposed if the firmware reports support
> +for the corresponding voltage ID.
> diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
> index a2938881ccd2..4f96f37116f3 100644
> --- a/drivers/hwmon/raspberrypi-hwmon.c
> +++ b/drivers/hwmon/raspberrypi-hwmon.c
> @@ -5,6 +5,7 @@
> * Based on firmware/raspberrypi.c by Noralf Trønnes
> *
> * Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se•com>
> + * Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail•com>
> */
> #include <linux/device.h>
> #include <linux/devm-helpers.h>
> @@ -18,13 +19,26 @@
>
> #define UNDERVOLTAGE_STICKY_BIT BIT(16)
>
> +struct rpi_firmware_get_value {
> + __le32 id;
> + __le32 val;
> +} __packed;
My earlier comment is still valid: This should be defined in
the include file, and it should be query-specific, just like
struct rpi_firmware_clk_rate_request.
> +
> struct rpi_hwmon_data {
> struct device *hwmon_dev;
> struct rpi_firmware *fw;
> + u32 valid_inputs;
> u32 last_throttled;
> struct delayed_work get_values_poll_work;
> };
>
> +static const char * const rpi_hwmon_labels[] = {
> + "core",
> + "sdram_c",
> + "sdram_i",
> + "sdram_p",
> +};
> +
> static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
> {
> u32 new_uv, old_uv, value;
> @@ -56,6 +70,23 @@ static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
> hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
> }
>
> +static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
> + long *val)
> +{
> + struct rpi_firmware_get_value packet;
> + int ret;
> +
> + packet.id = cpu_to_le32(id);
> + packet.val = 0;
> + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
> + &packet, sizeof(packet));
> + if (ret)
> + return ret;
> +
> + *val = le32_to_cpu(packet.val) / 1000;
I would suggest to use DIV_ROUND_CLOSEST().
> + return 0;
> +}
> +
> static void get_values_poll(struct work_struct *work)
> {
> struct rpi_hwmon_data *data;
> @@ -77,19 +108,94 @@ static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
> {
> struct rpi_hwmon_data *data = dev_get_drvdata(dev);
>
> - *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
> + if (type == hwmon_in) {
> + switch (attr) {
> + case hwmon_in_input:
> + switch (channel) {
> + case 0:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_CORE,
> + val);
> + case 1:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_C,
> + val);
> + case 2:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_I,
> + val);
> + case 3:
> + return rpi_firmware_get_voltage(data,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_P,
> + val);
> + default:
> + return -EOPNOTSUPP;
With
static const int voltage_regs[] = {
RPI_FIRMWARE_VOLT_ID_CORE, RPI_FIRMWARE_VOLT_ID_SDRAM_C, RPI_FIRMWARE_VOLT_ID_SDRAM_I,
RPI_FIRMWARE_VOLT_ID_SDRAM_P };
this can be simplified to
return rpi_firmware_get_voltage(data, voltage_regs[channel];
> + }
> + case hwmon_in_lcrit_alarm:
> + if (channel == 0) {
> + *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
> + return 0;
> + }
The channel check is not really necessary.
> + return -EOPNOTSUPP;
> + default:
> + return -EOPNOTSUPP;
> + }
> + }
> +
> + return -EOPNOTSUPP;
> +}
> +
> +static int rpi_read_string(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, const char **str)
> +{
> + if (type == hwmon_in && attr == hwmon_in_label) {
> + if (channel >= ARRAY_SIZE(rpi_hwmon_labels))
> + return -EOPNOTSUPP;
Unnecessary check.
> +
> + *str = rpi_hwmon_labels[channel];
> + return 0;
> + }
> +
> + return -EOPNOTSUPP;
> +}
> +
> +static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + const struct rpi_hwmon_data *data = _data;
> +
> + if (type == hwmon_in) {
> + switch (attr) {
> + case hwmon_in_input:
> + case hwmon_in_label:
> + if (!(data->valid_inputs & BIT(channel)))
> + return 0;
> + return 0444;
> + case hwmon_in_lcrit_alarm:
> + if (channel == 0)
> + return 0444;
> + return 0;
> + default:
> + return 0;
> + }
> + }
> +
> return 0;
> }
>
> static const struct hwmon_channel_info * const rpi_info[] = {
> HWMON_CHANNEL_INFO(in,
> - HWMON_I_LCRIT_ALARM),
> + HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_LCRIT_ALARM,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL),
> NULL
> };
>
> static const struct hwmon_ops rpi_hwmon_ops = {
> - .visible = 0444,
> + .is_visible = rpi_is_visible,
> .read = rpi_read,
> + .read_string = rpi_read_string,
> };
>
> static const struct hwmon_chip_info rpi_chip_info = {
> @@ -101,6 +207,7 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> struct rpi_hwmon_data *data;
> + long voltage;
> int ret;
>
> data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> @@ -110,6 +217,26 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
> /* Parent driver assure that firmware is correct */
> data->fw = dev_get_drvdata(dev->parent);
>
> + ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_CORE,
> + &voltage);
> + if (!ret)
> + data->valid_inputs |= BIT(0);
> +
> + ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_C,
> + &voltage);
> + if (!ret)
> + data->valid_inputs |= BIT(1);
> +
> + ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_I,
> + &voltage);
> + if (!ret)
> + data->valid_inputs |= BIT(2);
> +
> + ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_P,
> + &voltage);
> + if (!ret)
> + data->valid_inputs |= BIT(3);
> +
This can be implemented in a loop, using the above voltage_regs array.
Thanks,
Guenter
> data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
> data,
> &rpi_chip_info,
> @@ -159,6 +286,7 @@ static struct platform_driver rpi_hwmon_driver = {
> module_platform_driver(rpi_hwmon_driver);
>
> MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx•net>");
> +MODULE_AUTHOR("Shubham Chakraborty <chakrabortyshubham66@gmail•com>");
> MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
> MODULE_LICENSE("GPL v2");
> MODULE_ALIAS("platform:raspberrypi-hwmon");
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 0/3] raspberrypi-hwmon voltage support and teardown fix
2026-05-16 16:44 [PATCH 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-16 16:44 ` [PATCH 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
2026-05-16 19:15 ` [PATCH v2 0/2] raspberrypi: firmware and hwmon voltage support Shubham Chakraborty
@ 2026-05-17 8:04 ` Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
` (2 more replies)
2 siblings, 3 replies; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-17 8:04 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel, Shubham Chakraborty
This series adds firmware-backed voltage inputs to raspberrypi-hwmon and
includes a separate fix for the delayed polling work teardown path.
Patch 1 adds the firmware voltage IDs and the shared voltage request
structure to the Raspberry Pi firmware API header.
Patch 2 extends raspberrypi-hwmon to expose the firmware-provided core
and SDRAM voltage inputs through hwmon and documents the new sysfs
entries.
Patch 3 addresses the delayed polling work teardown concern raised
during review.
Changes in v3:
- corrected the SDRAM_P and SDRAM_I voltage ID mapping
- moved the voltage request structure into the firmware API header
- made the voltage request structure voltage-specific
- split the delayed-work teardown change into a separate patch
Tested on:
- Raspberry Pi 3B+ running Linux 6.12.75+rpt-rpi-v8
Shubham Chakraborty (3):
soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
hwmon: raspberrypi: Add voltage input support
hwmon: raspberrypi: Fix delayed-work teardown race
Documentation/hwmon/raspberrypi-hwmon.rst | 15 ++-
drivers/hwmon/raspberrypi-hwmon.c | 139 ++++++++++++++++++++-
include/soc/bcm2835/raspberrypi-firmware.h | 25 ++++
3 files changed, 171 insertions(+), 8 deletions(-)
--
2.54.0
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
2026-05-17 8:04 ` [PATCH v3 0/3] raspberrypi-hwmon voltage support and teardown fix Shubham Chakraborty
@ 2026-05-17 8:04 ` Shubham Chakraborty
2026-05-18 22:17 ` Guenter Roeck
` (2 more replies)
2026-05-17 8:04 ` [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 3/3] hwmon: raspberrypi: Fix delayed-work teardown race Shubham Chakraborty
2 siblings, 3 replies; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-17 8:04 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel, Shubham Chakraborty
Add Raspberry Pi firmware voltage domain identifiers for the mailbox
property interface.
Also add the voltage request structure used with
RPI_FIRMWARE_GET_VOLTAGE so firmware clients can share the common API
definition from the firmware header.
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
---
include/soc/bcm2835/raspberrypi-firmware.h | 25 ++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index e1f87fbfe554..975bef529854 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -156,6 +156,31 @@ enum rpi_firmware_clk_id {
RPI_FIRMWARE_NUM_CLK_ID,
};
+enum rpi_firmware_volt_id {
+ RPI_FIRMWARE_VOLT_ID_CORE = 1,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_C = 2,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_P = 3,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_I = 4,
+ RPI_FIRMWARE_NUM_VOLT_ID,
+};
+
+/**
+ * struct rpi_firmware_get_voltage_request - Firmware request for a voltage
+ * @id: ID of the voltage being queried
+ * @value: Voltage in microvolts. Set by the firmware.
+ *
+ * Used by @RPI_FIRMWARE_GET_VOLTAGE.
+ */
+struct rpi_firmware_get_voltage_request {
+ __le32 id;
+ __le32 value;
+} __packed;
+
+#define RPI_FIRMWARE_GET_VOLTAGE_REQUEST(_id) \
+ { \
+ .id = cpu_to_le32(_id), \
+ }
+
/**
* struct rpi_firmware_clk_rate_request - Firmware Request for a rate
* @id: ID of the clock being queried
--
2.54.0
^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support
2026-05-17 8:04 ` [PATCH v3 0/3] raspberrypi-hwmon voltage support and teardown fix Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
@ 2026-05-17 8:04 ` Shubham Chakraborty
2026-05-19 15:28 ` Florian Fainelli
2026-05-20 13:37 ` Guenter Roeck
2026-05-17 8:04 ` [PATCH v3 3/3] hwmon: raspberrypi: Fix delayed-work teardown race Shubham Chakraborty
2 siblings, 2 replies; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-17 8:04 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel, Shubham Chakraborty
Extend the raspberrypi-hwmon driver to expose firmware-provided
voltage measurements through the hwmon subsystem.
The driver now exports the following voltage inputs:
- in0_input (core)
- in1_input (sdram_c)
- in2_input (sdram_i)
- in3_input (sdram_p)
Voltage values returned by firmware are converted from microvolts
to millivolts as expected by the hwmon subsystem.
Update the documentation related to it.
The existing undervoltage sticky alarm handling is preserved and
associated with the first voltage channel.
Tested in -
- Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
---
Documentation/hwmon/raspberrypi-hwmon.rst | 15 ++-
drivers/hwmon/raspberrypi-hwmon.c | 127 +++++++++++++++++++++-
2 files changed, 137 insertions(+), 5 deletions(-)
diff --git a/Documentation/hwmon/raspberrypi-hwmon.rst b/Documentation/hwmon/raspberrypi-hwmon.rst
index 8038ade36490..db315184b861 100644
--- a/Documentation/hwmon/raspberrypi-hwmon.rst
+++ b/Documentation/hwmon/raspberrypi-hwmon.rst
@@ -20,6 +20,17 @@ undervoltage conditions.
Sysfs entries
-------------
-======================= ==================
+======================= ======================================================
+in0_input Core voltage in millivolts
+in1_input SDRAM controller voltage in millivolts
+in2_input SDRAM I/O voltage in millivolts
+in3_input SDRAM PHY voltage in millivolts
+in0_label "core"
+in1_label "sdram_c"
+in2_label "sdram_i"
+in3_label "sdram_p"
in0_lcrit_alarm Undervoltage alarm
-======================= ==================
+======================= ======================================================
+
+The voltage inputs and labels are only exposed if the firmware reports support
+for the corresponding voltage ID.
diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
index a2938881ccd2..8ce6dacc19b0 100644
--- a/drivers/hwmon/raspberrypi-hwmon.c
+++ b/drivers/hwmon/raspberrypi-hwmon.c
@@ -5,6 +5,7 @@
* Based on firmware/raspberrypi.c by Noralf Trønnes
*
* Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se•com>
+ * Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail•com>
*/
#include <linux/device.h>
#include <linux/devm-helpers.h>
@@ -21,10 +22,18 @@
struct rpi_hwmon_data {
struct device *hwmon_dev;
struct rpi_firmware *fw;
+ u32 valid_inputs;
u32 last_throttled;
struct delayed_work get_values_poll_work;
};
+static const char * const rpi_hwmon_labels[] = {
+ "core",
+ "sdram_c",
+ "sdram_i",
+ "sdram_p",
+};
+
static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
{
u32 new_uv, old_uv, value;
@@ -56,6 +65,21 @@ static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
}
+static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
+ long *val)
+{
+ struct rpi_firmware_get_voltage_request packet =
+ RPI_FIRMWARE_GET_VOLTAGE_REQUEST(id);
+ int ret;
+ ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
+ &packet, sizeof(packet));
+ if (ret)
+ return ret;
+
+ *val = le32_to_cpu(packet.value) / 1000;
+ return 0;
+}
+
static void get_values_poll(struct work_struct *work)
{
struct rpi_hwmon_data *data;
@@ -77,19 +101,94 @@ static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
{
struct rpi_hwmon_data *data = dev_get_drvdata(dev);
- *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+ if (type == hwmon_in) {
+ switch (attr) {
+ case hwmon_in_input:
+ switch (channel) {
+ case 0:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_CORE,
+ val);
+ case 1:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_C,
+ val);
+ case 2:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_I,
+ val);
+ case 3:
+ return rpi_firmware_get_voltage(data,
+ RPI_FIRMWARE_VOLT_ID_SDRAM_P,
+ val);
+ default:
+ return -EOPNOTSUPP;
+ }
+ case hwmon_in_lcrit_alarm:
+ if (channel == 0) {
+ *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+ return 0;
+ }
+ return -EOPNOTSUPP;
+ default:
+ return -EOPNOTSUPP;
+ }
+ }
+
+ return -EOPNOTSUPP;
+}
+
+static int rpi_read_string(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, const char **str)
+{
+ if (type == hwmon_in && attr == hwmon_in_label) {
+ if (channel >= ARRAY_SIZE(rpi_hwmon_labels))
+ return -EOPNOTSUPP;
+
+ *str = rpi_hwmon_labels[channel];
+ return 0;
+ }
+
+ return -EOPNOTSUPP;
+}
+
+static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ const struct rpi_hwmon_data *data = _data;
+
+ if (type == hwmon_in) {
+ switch (attr) {
+ case hwmon_in_input:
+ case hwmon_in_label:
+ if (!(data->valid_inputs & BIT(channel)))
+ return 0;
+ return 0444;
+ case hwmon_in_lcrit_alarm:
+ if (channel == 0)
+ return 0444;
+ return 0;
+ default:
+ return 0;
+ }
+ }
+
return 0;
}
static const struct hwmon_channel_info * const rpi_info[] = {
HWMON_CHANNEL_INFO(in,
- HWMON_I_LCRIT_ALARM),
+ HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_LCRIT_ALARM,
+ HWMON_I_INPUT | HWMON_I_LABEL,
+ HWMON_I_INPUT | HWMON_I_LABEL,
+ HWMON_I_INPUT | HWMON_I_LABEL),
NULL
};
static const struct hwmon_ops rpi_hwmon_ops = {
- .visible = 0444,
+ .is_visible = rpi_is_visible,
.read = rpi_read,
+ .read_string = rpi_read_string,
};
static const struct hwmon_chip_info rpi_chip_info = {
@@ -101,6 +200,7 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rpi_hwmon_data *data;
+ long voltage;
int ret;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
@@ -110,6 +210,26 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
/* Parent driver assure that firmware is correct */
data->fw = dev_get_drvdata(dev->parent);
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_CORE,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(0);
+
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_C,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(1);
+
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_I,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(2);
+
+ ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_P,
+ &voltage);
+ if (!ret)
+ data->valid_inputs |= BIT(3);
+
data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
data,
&rpi_chip_info,
@@ -159,6 +279,7 @@ static struct platform_driver rpi_hwmon_driver = {
module_platform_driver(rpi_hwmon_driver);
MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx•net>");
+MODULE_AUTHOR("Shubham Chakraborty <chakrabortyshubham66@gmail•com>");
MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:raspberrypi-hwmon");
--
2.54.0
^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH v3 3/3] hwmon: raspberrypi: Fix delayed-work teardown race
2026-05-17 8:04 ` [PATCH v3 0/3] raspberrypi-hwmon voltage support and teardown fix Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
@ 2026-05-17 8:04 ` Shubham Chakraborty
2026-05-20 13:39 ` Guenter Roeck
2 siblings, 1 reply; 19+ messages in thread
From: Shubham Chakraborty @ 2026-05-17 8:04 UTC (permalink / raw)
To: Guenter Roeck, Florian Fainelli, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel, Shubham Chakraborty
The delayed polling work rearms itself from the work function, so use
explicit delayed-work setup and cleanup instead of
devm_delayed_work_autocancel().
Initialize the delayed work with INIT_DELAYED_WORK() and register a
devres cleanup action that calls disable_delayed_work_sync() during
teardown.
This addresses the concern raised during review about the polling work
being able to requeue itself while the driver is being removed.
Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
---
drivers/hwmon/raspberrypi-hwmon.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
index 8ce6dacc19b0..0bbc735f74a4 100644
--- a/drivers/hwmon/raspberrypi-hwmon.c
+++ b/drivers/hwmon/raspberrypi-hwmon.c
@@ -8,7 +8,6 @@
* Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail•com>
*/
#include <linux/device.h>
-#include <linux/devm-helpers.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/module.h>
@@ -96,6 +95,13 @@ static void get_values_poll(struct work_struct *work)
schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
}
+static void rpi_hwmon_cancel_poll_work(void *res)
+{
+ struct rpi_hwmon_data *data = res;
+
+ disable_delayed_work_sync(&data->get_values_poll_work);
+}
+
static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long *val)
{
@@ -237,8 +243,8 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
if (IS_ERR(data->hwmon_dev))
return PTR_ERR(data->hwmon_dev);
- ret = devm_delayed_work_autocancel(dev, &data->get_values_poll_work,
- get_values_poll);
+ INIT_DELAYED_WORK(&data->get_values_poll_work, get_values_poll);
+ ret = devm_add_action_or_reset(dev, rpi_hwmon_cancel_poll_work, data);
if (ret)
return ret;
platform_set_drvdata(pdev, data);
--
2.54.0
^ permalink raw reply related [flat|nested] 19+ messages in thread
* Re: [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
2026-05-17 8:04 ` [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
@ 2026-05-18 22:17 ` Guenter Roeck
2026-05-19 15:29 ` Florian Fainelli
2026-05-20 13:35 ` Guenter Roeck
2 siblings, 0 replies; 19+ messages in thread
From: Guenter Roeck @ 2026-05-18 22:17 UTC (permalink / raw)
To: Shubham Chakraborty
Cc: Florian Fainelli, Jonathan Corbet, Shuah Khan,
Broadcom internal kernel review list, Ray Jui, Scott Branden,
linux-hwmon, linux-doc, linux-rpi-kernel, linux-arm-kernel,
linux-kernel
On Sun, May 17, 2026 at 01:34:43PM +0530, Shubham Chakraborty wrote:
> Add Raspberry Pi firmware voltage domain identifiers for the mailbox
> property interface.
>
> Also add the voltage request structure used with
> RPI_FIRMWARE_GET_VOLTAGE so firmware clients can share the common API
> definition from the firmware header.
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
I'll need an Acked-by: from a maintainer to apply this patch,
or some other maintainer will have to pick it up.
Thanks,
Guenter
> ---
> include/soc/bcm2835/raspberrypi-firmware.h | 25 ++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
> index e1f87fbfe554..975bef529854 100644
> --- a/include/soc/bcm2835/raspberrypi-firmware.h
> +++ b/include/soc/bcm2835/raspberrypi-firmware.h
> @@ -156,6 +156,31 @@ enum rpi_firmware_clk_id {
> RPI_FIRMWARE_NUM_CLK_ID,
> };
>
> +enum rpi_firmware_volt_id {
> + RPI_FIRMWARE_VOLT_ID_CORE = 1,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_C = 2,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_P = 3,
> + RPI_FIRMWARE_VOLT_ID_SDRAM_I = 4,
> + RPI_FIRMWARE_NUM_VOLT_ID,
> +};
> +
> +/**
> + * struct rpi_firmware_get_voltage_request - Firmware request for a voltage
> + * @id: ID of the voltage being queried
> + * @value: Voltage in microvolts. Set by the firmware.
> + *
> + * Used by @RPI_FIRMWARE_GET_VOLTAGE.
> + */
> +struct rpi_firmware_get_voltage_request {
> + __le32 id;
> + __le32 value;
> +} __packed;
> +
> +#define RPI_FIRMWARE_GET_VOLTAGE_REQUEST(_id) \
> + { \
> + .id = cpu_to_le32(_id), \
> + }
> +
> /**
> * struct rpi_firmware_clk_rate_request - Firmware Request for a rate
> * @id: ID of the clock being queried
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support
2026-05-17 8:04 ` [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
@ 2026-05-19 15:28 ` Florian Fainelli
2026-05-20 13:37 ` Guenter Roeck
1 sibling, 0 replies; 19+ messages in thread
From: Florian Fainelli @ 2026-05-19 15:28 UTC (permalink / raw)
To: Shubham Chakraborty, Guenter Roeck, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel
On 5/17/26 01:04, Shubham Chakraborty wrote:
> Extend the raspberrypi-hwmon driver to expose firmware-provided
> voltage measurements through the hwmon subsystem.
>
> The driver now exports the following voltage inputs:
>
> - in0_input (core)
> - in1_input (sdram_c)
> - in2_input (sdram_i)
> - in3_input (sdram_p)
>
> Voltage values returned by firmware are converted from microvolts
> to millivolts as expected by the hwmon subsystem.
>
> Update the documentation related to it.
>
> The existing undervoltage sticky alarm handling is preserved and
> associated with the first voltage channel.
>
> Tested in -
> - Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
> Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom•com>
--
Florian
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
2026-05-17 8:04 ` [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-18 22:17 ` Guenter Roeck
@ 2026-05-19 15:29 ` Florian Fainelli
2026-05-20 13:35 ` Guenter Roeck
2 siblings, 0 replies; 19+ messages in thread
From: Florian Fainelli @ 2026-05-19 15:29 UTC (permalink / raw)
To: Shubham Chakraborty, Guenter Roeck, Jonathan Corbet
Cc: Shuah Khan, Broadcom internal kernel review list, Ray Jui,
Scott Branden, linux-hwmon, linux-doc, linux-rpi-kernel,
linux-arm-kernel, linux-kernel
On 5/17/26 01:04, Shubham Chakraborty wrote:
> Add Raspberry Pi firmware voltage domain identifiers for the mailbox
> property interface.
>
> Also add the voltage request structure used with
> RPI_FIRMWARE_GET_VOLTAGE so firmware clients can share the common API
> definition from the firmware header.
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
Acked-by: Florian Fainelli <florian.fainelli@broadcom•com>
--
Florian
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs
2026-05-17 8:04 ` [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-18 22:17 ` Guenter Roeck
2026-05-19 15:29 ` Florian Fainelli
@ 2026-05-20 13:35 ` Guenter Roeck
2 siblings, 0 replies; 19+ messages in thread
From: Guenter Roeck @ 2026-05-20 13:35 UTC (permalink / raw)
To: Shubham Chakraborty
Cc: Florian Fainelli, Jonathan Corbet, Shuah Khan,
Broadcom internal kernel review list, Ray Jui, Scott Branden,
linux-hwmon, linux-doc, linux-rpi-kernel, linux-arm-kernel,
linux-kernel
On Sun, May 17, 2026 at 01:34:43PM +0530, Shubham Chakraborty wrote:
> Add Raspberry Pi firmware voltage domain identifiers for the mailbox
> property interface.
>
> Also add the voltage request structure used with
> RPI_FIRMWARE_GET_VOLTAGE so firmware clients can share the common API
> definition from the firmware header.
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
> Acked-by: Florian Fainelli <florian.fainelli@broadcom•com>
Applied.
Thanks,
Guenter
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support
2026-05-17 8:04 ` [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
2026-05-19 15:28 ` Florian Fainelli
@ 2026-05-20 13:37 ` Guenter Roeck
1 sibling, 0 replies; 19+ messages in thread
From: Guenter Roeck @ 2026-05-20 13:37 UTC (permalink / raw)
To: Shubham Chakraborty
Cc: Florian Fainelli, Jonathan Corbet, Shuah Khan,
Broadcom internal kernel review list, Ray Jui, Scott Branden,
linux-hwmon, linux-doc, linux-rpi-kernel, linux-arm-kernel,
linux-kernel
On Sun, May 17, 2026 at 01:34:44PM +0530, Shubham Chakraborty wrote:
> Extend the raspberrypi-hwmon driver to expose firmware-provided
> voltage measurements through the hwmon subsystem.
>
> The driver now exports the following voltage inputs:
>
> - in0_input (core)
> - in1_input (sdram_c)
> - in2_input (sdram_i)
> - in3_input (sdram_p)
>
> Voltage values returned by firmware are converted from microvolts
> to millivolts as expected by the hwmon subsystem.
>
> Update the documentation related to it.
>
> The existing undervoltage sticky alarm handling is preserved and
> associated with the first voltage channel.
>
> Tested in -
> - Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT
> Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux)
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
> Reviewed-by: Florian Fainelli <florian.fainelli@broadcom•com>
Applied, after fixing:
WARNING: Missing a blank line after declarations
#207: FILE: drivers/hwmon/raspberrypi-hwmon.c:74:
+ int ret;
+ ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
Please run checkpatch on your patches.
Thanks,
Guenter
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 3/3] hwmon: raspberrypi: Fix delayed-work teardown race
2026-05-17 8:04 ` [PATCH v3 3/3] hwmon: raspberrypi: Fix delayed-work teardown race Shubham Chakraborty
@ 2026-05-20 13:39 ` Guenter Roeck
0 siblings, 0 replies; 19+ messages in thread
From: Guenter Roeck @ 2026-05-20 13:39 UTC (permalink / raw)
To: Shubham Chakraborty
Cc: Florian Fainelli, Jonathan Corbet, Shuah Khan,
Broadcom internal kernel review list, Ray Jui, Scott Branden,
linux-hwmon, linux-doc, linux-rpi-kernel, linux-arm-kernel,
linux-kernel
On Sun, May 17, 2026 at 01:34:45PM +0530, Shubham Chakraborty wrote:
> The delayed polling work rearms itself from the work function, so use
> explicit delayed-work setup and cleanup instead of
> devm_delayed_work_autocancel().
>
> Initialize the delayed work with INIT_DELAYED_WORK() and register a
> devres cleanup action that calls disable_delayed_work_sync() during
> teardown.
>
> This addresses the concern raised during review about the polling work
> being able to requeue itself while the driver is being removed.
>
> Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail•com>
Applied.
Thanks,
Guenter
^ permalink raw reply [flat|nested] 19+ messages in thread
end of thread, other threads:[~2026-05-20 13:39 UTC | newest]
Thread overview: 19+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-05-16 16:44 [PATCH 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-16 16:44 ` [PATCH 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
2026-05-16 17:13 ` Guenter Roeck
2026-05-16 18:24 ` Guenter Roeck
2026-05-16 19:15 ` [PATCH v2 0/2] raspberrypi: firmware and hwmon voltage support Shubham Chakraborty
2026-05-16 19:15 ` [PATCH v2 1/2] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-16 23:09 ` Guenter Roeck
2026-05-16 19:15 ` [PATCH v2 2/2] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
2026-05-16 23:20 ` Guenter Roeck
2026-05-17 8:04 ` [PATCH v3 0/3] raspberrypi-hwmon voltage support and teardown fix Shubham Chakraborty
2026-05-17 8:04 ` [PATCH v3 1/3] soc: bcm2835: raspberrypi-firmware: Add voltage domain IDs Shubham Chakraborty
2026-05-18 22:17 ` Guenter Roeck
2026-05-19 15:29 ` Florian Fainelli
2026-05-20 13:35 ` Guenter Roeck
2026-05-17 8:04 ` [PATCH v3 2/3] hwmon: raspberrypi: Add voltage input support Shubham Chakraborty
2026-05-19 15:28 ` Florian Fainelli
2026-05-20 13:37 ` Guenter Roeck
2026-05-17 8:04 ` [PATCH v3 3/3] hwmon: raspberrypi: Fix delayed-work teardown race Shubham Chakraborty
2026-05-20 13:39 ` Guenter Roeck
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