[PATCH 0/3] hwmon: (cros_ec) Synchronize EC access from the thermal device callbacks

[PATCH 0/3] hwmon: (cros_ec) Synchronize EC access from the thermal device callbacks

[Thomas Weißschuh]

To guarantee consistency for the read-modify-write access in
cros_ec_hwmon_cooling_set_cur_state(), locking is necessary.

Use the existing hwmon device lock to do so.

Sung-Chi: Could you test this? I do not have access to hardware which
triggers this code path.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Thomas Weißschuh (3):
      hwmon: (cros_ec) Register the thermal devices after the hwmon ones
      hwmon: (cros_ec) Store the hwmon device in cros_ec_hwmon_priv
      hwmon: (cros_ec) Synchronize EC access from the thermal device callbacks

 drivers/hwmon/cros_ec_hwmon.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)
---
base-commit: ca078d004cf58137bcf8cb24a8b271397431ba58
change-id: 20260630-cros_ec-hwmon-locking-d32263db1c94

Best regards,
--  
Thomas Weißschuh <linux@weissschuh.net>

[PATCH 1/3] hwmon: (cros_ec) Register the thermal devices after the hwmon ones

[Thomas Weißschuh]

To guarantee consistency for the read-modify-write access in
cros_ec_hwmon_cooling_set_cur_state(), locking is necessary.
The locking will use standard hwmon device locks, which requires
the hwmon device to be ready before the fan devices are set up.

Reorder the initialization so this works.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 drivers/hwmon/cros_ec_hwmon.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
index 44291799dd8e..f9b19da50472 100644
--- a/drivers/hwmon/cros_ec_hwmon.c
+++ b/drivers/hwmon/cros_ec_hwmon.c
@@ -579,13 +579,17 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
 	priv->fan_control_supported = cros_ec_hwmon_probe_fan_control_supported(priv->cros_ec);
 	priv->temp_threshold_supported = is_cros_ec_cmd_available(priv->cros_ec,
 								  EC_CMD_THERMAL_GET_THRESHOLD, 1);
-	cros_ec_hwmon_register_fan_cooling_devices(dev, priv);
 
 	hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
 							 &cros_ec_hwmon_chip_info, NULL);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	cros_ec_hwmon_register_fan_cooling_devices(dev, priv);
+
 	platform_set_drvdata(pdev, priv);
 
-	return PTR_ERR_OR_ZERO(hwmon_dev);
+	return 0;
 }
 
 static int cros_ec_hwmon_suspend(struct platform_device *pdev, pm_message_t state)

-- 
2.55.0

[PATCH 2/3] hwmon: (cros_ec) Store the hwmon device in cros_ec_hwmon_priv

[Thomas Weißschuh]

The upcoming locking scheme for thermal devices will require access
to the hwmon device.

Add it do the priv struct.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 drivers/hwmon/cros_ec_hwmon.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
index f9b19da50472..fb5daa9f80d1 100644
--- a/drivers/hwmon/cros_ec_hwmon.c
+++ b/drivers/hwmon/cros_ec_hwmon.c
@@ -25,6 +25,7 @@
 
 struct cros_ec_hwmon_priv {
 	struct cros_ec_device *cros_ec;
+	struct device *hwmon_dev;
 	const char *temp_sensor_names[EC_TEMP_SENSOR_ENTRIES + EC_TEMP_SENSOR_B_ENTRIES];
 	u8 usable_fans;
 	bool fan_control_supported;
@@ -556,7 +557,6 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
 	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
 	struct cros_ec_device *cros_ec = ec_dev->ec_dev;
 	struct cros_ec_hwmon_priv *priv;
-	struct device *hwmon_dev;
 	u8 thermal_version;
 	int ret;
 
@@ -580,10 +580,10 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
 	priv->temp_threshold_supported = is_cros_ec_cmd_available(priv->cros_ec,
 								  EC_CMD_THERMAL_GET_THRESHOLD, 1);
 
-	hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
-							 &cros_ec_hwmon_chip_info, NULL);
-	if (IS_ERR(hwmon_dev))
-		return PTR_ERR(hwmon_dev);
+	priv->hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
+							       &cros_ec_hwmon_chip_info, NULL);
+	if (IS_ERR(priv->hwmon_dev))
+		return PTR_ERR(priv->hwmon_dev);
 
 	cros_ec_hwmon_register_fan_cooling_devices(dev, priv);
 

-- 
2.55.0

[PATCH 3/3] hwmon: (cros_ec) Synchronize EC access from the thermal device callbacks

[Thomas Weißschuh]

To guarantee consistency for the read-modify-write access in
cros_ec_hwmon_cooling_set_cur_state(), locking is necessary.

Use the existing hwmon device lock to do so.

Fixes: 5798b62867b4 ("hwmon: (cros_ec) register fans into thermal framework cooling devices")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 drivers/hwmon/cros_ec_hwmon.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
index fb5daa9f80d1..76d83e1c68cf 100644
--- a/drivers/hwmon/cros_ec_hwmon.c
+++ b/drivers/hwmon/cros_ec_hwmon.c
@@ -5,6 +5,7 @@
  *  Copyright (C) 2024 Thomas Weißschuh <linux@weissschuh.net>
  */
 
+#include <linux/cleanup.h>
 #include <linux/device.h>
 #include <linux/hwmon.h>
 #include <linux/math.h>
@@ -411,6 +412,8 @@ static int cros_ec_hwmon_cooling_get_cur_state(struct thermal_cooling_device *cd
 	u8 read_val;
 	int ret;
 
+	guard(hwmon_lock)(priv->hwmon_priv->hwmon_dev);
+
 	ret = cros_ec_hwmon_read_pwm_value(priv->hwmon_priv->cros_ec, priv->index, &read_val);
 	if (ret)
 		return ret;
@@ -424,6 +427,8 @@ static int cros_ec_hwmon_cooling_set_cur_state(struct thermal_cooling_device *cd
 {
 	const struct cros_ec_hwmon_cooling_priv *priv = cdev->devdata;
 
+	guard(hwmon_lock)(priv->hwmon_priv->hwmon_dev);
+
 	return cros_ec_hwmon_write_pwm_input(priv->hwmon_priv->cros_ec, priv->index, val);
 }
 

-- 
2.55.0

Re: [PATCH 1/3] hwmon: (cros_ec) Register the thermal devices after the hwmon ones

[Guenter Roeck]

On Sat, Jul 11, 2026 at 11:59:05AM +0200, Thomas Weißschuh wrote:
> To guarantee consistency for the read-modify-write access in
> cros_ec_hwmon_cooling_set_cur_state(), locking is necessary.
> The locking will use standard hwmon device locks, which requires
> the hwmon device to be ready before the fan devices are set up.
> 
> Reorder the initialization so this works.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Applied.

Thanks,
Guenter

Re: [PATCH 2/3] hwmon: (cros_ec) Store the hwmon device in cros_ec_hwmon_priv

[Guenter Roeck]

On Sat, Jul 11, 2026 at 11:59:06AM +0200, Thomas Weißschuh wrote:
> The upcoming locking scheme for thermal devices will require access
> to the hwmon device.
> 
> Add it do the priv struct.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/cros_ec_hwmon.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
> index f9b19da50472..fb5daa9f80d1 100644
> --- a/drivers/hwmon/cros_ec_hwmon.c
> +++ b/drivers/hwmon/cros_ec_hwmon.c
> @@ -25,6 +25,7 @@
>  
>  struct cros_ec_hwmon_priv {
>  	struct cros_ec_device *cros_ec;
> +	struct device *hwmon_dev;
>  	const char *temp_sensor_names[EC_TEMP_SENSOR_ENTRIES + EC_TEMP_SENSOR_B_ENTRIES];
>  	u8 usable_fans;
>  	bool fan_control_supported;
> @@ -556,7 +557,6 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
>  	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
>  	struct cros_ec_device *cros_ec = ec_dev->ec_dev;
>  	struct cros_ec_hwmon_priv *priv;
> -	struct device *hwmon_dev;
>  	u8 thermal_version;
>  	int ret;
>  
> @@ -580,10 +580,10 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
>  	priv->temp_threshold_supported = is_cros_ec_cmd_available(priv->cros_ec,
>  								  EC_CMD_THERMAL_GET_THRESHOLD, 1);
>  
> -	hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
> -							 &cros_ec_hwmon_chip_info, NULL);
> -	if (IS_ERR(hwmon_dev))
> -		return PTR_ERR(hwmon_dev);
> +	priv->hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
> +							       &cros_ec_hwmon_chip_info, NULL);
> +	if (IS_ERR(priv->hwmon_dev))
> +		return PTR_ERR(priv->hwmon_dev);
>  
>  	cros_ec_hwmon_register_fan_cooling_devices(dev, priv);
>  

Re: [PATCH 3/3] hwmon: (cros_ec) Synchronize EC access from the thermal device callbacks

[Guenter Roeck]

On Sat, Jul 11, 2026 at 11:59:07AM +0200, Thomas Weißschuh wrote:
> To guarantee consistency for the read-modify-write access in
> cros_ec_hwmon_cooling_set_cur_state(), locking is necessary.
> 
> Use the existing hwmon device lock to do so.
> 
> Fixes: 5798b62867b4 ("hwmon: (cros_ec) register fans into thermal framework cooling devices")
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Applied.

Thanks,
Guenter