[PATCH] ACPI: fan: Add hwmon support

[PATCH] ACPI: fan: Add hwmon support

[Armin Wolf]

Currently, the driver does only supports a custom sysfs
interface to allow userspace to read the fan speed.
Add support for the standard hwmon interface so users
can read the fan speed with standard tools like "sensors".

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 drivers/acpi/Makefile    |  1 +
 drivers/acpi/fan.h       |  2 ++
 drivers/acpi/fan_core.c  |  7 ++++
 drivers/acpi/fan_hwmon.c | 78 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 88 insertions(+)
 create mode 100644 drivers/acpi/fan_hwmon.c

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index d69d5444acdb..9a2e03acc1be 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_ACPI_TINY_POWER_BUTTON)	+= tiny-power-button.o
 obj-$(CONFIG_ACPI_FAN)		+= fan.o
 fan-objs			:= fan_core.o
 fan-objs			+= fan_attr.o
+fan-objs			+= fan_hwmon.o

 obj-$(CONFIG_ACPI_VIDEO)	+= video.o
 obj-$(CONFIG_ACPI_TAD)		+= acpi_tad.o
diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
index e7b4b4e4a55e..45c2637566da 100644
--- a/drivers/acpi/fan.h
+++ b/drivers/acpi/fan.h
@@ -56,4 +56,6 @@ struct acpi_fan {
 int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst *fst);
 int acpi_fan_create_attributes(struct acpi_device *device);
 void acpi_fan_delete_attributes(struct acpi_device *device);
+
+int devm_acpi_fan_create_hwmon(struct acpi_device *device);
 #endif
diff --git a/drivers/acpi/fan_core.c b/drivers/acpi/fan_core.c
index ff72e4ef8738..6bbdbb914e95 100644
--- a/drivers/acpi/fan_core.c
+++ b/drivers/acpi/fan_core.c
@@ -7,6 +7,7 @@
  *  Copyright (C) 2022 Intel Corporation. All rights reserved.
  */

+#include <linux/kconfig.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -336,6 +337,12 @@ static int acpi_fan_probe(struct platform_device *pdev)
 		if (result)
 			return result;

+		if (IS_REACHABLE(CONFIG_HWMON)) {
+			result = devm_acpi_fan_create_hwmon(device);
+			if (result)
+				return result;
+		}
+
 		result = acpi_fan_create_attributes(device);
 		if (result)
 			return result;
diff --git a/drivers/acpi/fan_hwmon.c b/drivers/acpi/fan_hwmon.c
new file mode 100644
index 000000000000..4f2bec8664f4
--- /dev/null
+++ b/drivers/acpi/fan_hwmon.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * fan_hwmon.c - hwmon interface for the ACPI Fan driver
+ *
+ * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
+ */
+
+#include <linux/acpi.h>
+#include <linux/hwmon.h>
+#include <linux/limits.h>
+
+#include "fan.h"
+
+static umode_t acpi_fan_is_visible(const void *drvdata, enum hwmon_sensor_types type, u32 attr,
+				   int channel)
+{
+	return 0444;
+}
+
+static int acpi_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
+			 long *val)
+{
+	struct acpi_device *adev = dev_get_drvdata(dev);
+	struct acpi_fan_fst fst;
+	int ret;
+
+	switch (type) {
+	case hwmon_fan:
+		ret = acpi_fan_get_fst(adev, &fst);
+		if (ret < 0)
+			return ret;
+
+		switch (attr) {
+		case hwmon_fan_input:
+			if (fst.speed > LONG_MAX)
+				return -EOVERFLOW;
+
+			*val = fst.speed;
+			return 0;
+		case hwmon_fan_fault:
+			*val = (fst.speed == U32_MAX);
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static const struct hwmon_ops acpi_fan_ops = {
+	.is_visible = acpi_fan_is_visible,
+	.read = acpi_fan_read,
+};
+
+static const struct hwmon_channel_info * const acpi_fan_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT | HWMON_F_FAULT),
+	NULL
+};
+
+static const struct hwmon_chip_info acpi_fan_chip_info = {
+	.ops = &acpi_fan_ops,
+	.info = acpi_fan_info,
+};
+
+int devm_acpi_fan_create_hwmon(struct acpi_device *device)
+{
+	struct device *hdev;
+
+	hdev = devm_hwmon_device_register_with_info(&device->dev, "acpi_fan", device,
+						    &acpi_fan_chip_info, NULL);
+
+	return PTR_ERR_OR_ZERO(hdev);
+}
--
2.39.2

Re: [PATCH] ACPI: fan: Add hwmon support

[Thomas Weißschuh]

Hi,

On 2024-04-08 14:37:18+0200, Armin Wolf wrote:
> Currently, the driver does only supports a custom sysfs
> interface to allow userspace to read the fan speed.
> Add support for the standard hwmon interface so users
> can read the fan speed with standard tools like "sensors".
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
>  drivers/acpi/Makefile    |  1 +
>  drivers/acpi/fan.h       |  2 ++
>  drivers/acpi/fan_core.c  |  7 ++++
>  drivers/acpi/fan_hwmon.c | 78 ++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 88 insertions(+)
>  create mode 100644 drivers/acpi/fan_hwmon.c

[snip]

> +
> +int devm_acpi_fan_create_hwmon(struct acpi_device *device)
> +{
> +	struct device *hdev;
> +
> +	hdev = devm_hwmon_device_register_with_info(&device->dev, "acpi_fan", device,
> +						    &acpi_fan_chip_info, NULL);

This fails to link if CONFIG_ACPI_FAN=y and CONFIG_HWMON=n:

ld: vmlinux.o: in function `devm_acpi_fan_create_hwmon':
.../drivers/acpi/fan_hwmon.c:74:(.text+0x819e65): undefined reference to `devm_hwmon_device_register_with_info'

With this fixed:

Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>

> +
> +	return PTR_ERR_OR_ZERO(hdev);
> +}
> --
> 2.39.2
> 
> 

Re: [PATCH] ACPI: fan: Add hwmon support

[Ilpo Järvinen]

On Mon, 8 Apr 2024, Armin Wolf wrote:

> Currently, the driver does only supports a custom sysfs
> interface to allow userspace to read the fan speed.
> Add support for the standard hwmon interface so users
> can read the fan speed with standard tools like "sensors".
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
>  drivers/acpi/Makefile    |  1 +
>  drivers/acpi/fan.h       |  2 ++
>  drivers/acpi/fan_core.c  |  7 ++++
>  drivers/acpi/fan_hwmon.c | 78 ++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 88 insertions(+)
>  create mode 100644 drivers/acpi/fan_hwmon.c
> 
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index d69d5444acdb..9a2e03acc1be 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -83,6 +83,7 @@ obj-$(CONFIG_ACPI_TINY_POWER_BUTTON)	+= tiny-power-button.o
>  obj-$(CONFIG_ACPI_FAN)		+= fan.o
>  fan-objs			:= fan_core.o
>  fan-objs			+= fan_attr.o
> +fan-objs			+= fan_hwmon.o
> 
>  obj-$(CONFIG_ACPI_VIDEO)	+= video.o
>  obj-$(CONFIG_ACPI_TAD)		+= acpi_tad.o
> diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
> index e7b4b4e4a55e..45c2637566da 100644
> --- a/drivers/acpi/fan.h
> +++ b/drivers/acpi/fan.h
> @@ -56,4 +56,6 @@ struct acpi_fan {
>  int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst *fst);
>  int acpi_fan_create_attributes(struct acpi_device *device);
>  void acpi_fan_delete_attributes(struct acpi_device *device);
> +
> +int devm_acpi_fan_create_hwmon(struct acpi_device *device);
>  #endif
> diff --git a/drivers/acpi/fan_core.c b/drivers/acpi/fan_core.c
> index ff72e4ef8738..6bbdbb914e95 100644
> --- a/drivers/acpi/fan_core.c
> +++ b/drivers/acpi/fan_core.c
> @@ -7,6 +7,7 @@
>   *  Copyright (C) 2022 Intel Corporation. All rights reserved.
>   */
> 
> +#include <linux/kconfig.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/init.h>
> @@ -336,6 +337,12 @@ static int acpi_fan_probe(struct platform_device *pdev)
>  		if (result)
>  			return result;
> 
> +		if (IS_REACHABLE(CONFIG_HWMON)) {
> +			result = devm_acpi_fan_create_hwmon(device);
> +			if (result)
> +				return result;
> +		}
> +
>  		result = acpi_fan_create_attributes(device);
>  		if (result)
>  			return result;
> diff --git a/drivers/acpi/fan_hwmon.c b/drivers/acpi/fan_hwmon.c
> new file mode 100644
> index 000000000000..4f2bec8664f4
> --- /dev/null
> +++ b/drivers/acpi/fan_hwmon.c
> @@ -0,0 +1,78 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * fan_hwmon.c - hwmon interface for the ACPI Fan driver
> + *
> + * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/hwmon.h>
> +#include <linux/limits.h>
> +
> +#include "fan.h"
> +
> +static umode_t acpi_fan_is_visible(const void *drvdata, enum hwmon_sensor_types type, u32 attr,
> +				   int channel)
> +{
> +	return 0444;
> +}
> +
> +static int acpi_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
> +			 long *val)
> +{
> +	struct acpi_device *adev = dev_get_drvdata(dev);
> +	struct acpi_fan_fst fst;
> +	int ret;
> +
> +	switch (type) {
> +	case hwmon_fan:
> +		ret = acpi_fan_get_fst(adev, &fst);
> +		if (ret < 0)
> +			return ret;
> +
> +		switch (attr) {
> +		case hwmon_fan_input:
> +			if (fst.speed > LONG_MAX)
> +				return -EOVERFLOW;
> +
> +			*val = fst.speed;
> +			return 0;
> +		case hwmon_fan_fault:
> +			*val = (fst.speed == U32_MAX);
> +			return 0;

Is it okay to return 0 in this case?

> +		default:
> +			break;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return -EOPNOTSUPP;
> +}
> +
> +static const struct hwmon_ops acpi_fan_ops = {
> +	.is_visible = acpi_fan_is_visible,
> +	.read = acpi_fan_read,
> +};
> +
> +static const struct hwmon_channel_info * const acpi_fan_info[] = {
> +	HWMON_CHANNEL_INFO(fan,
> +			   HWMON_F_INPUT | HWMON_F_FAULT),

One line.

-- 
 i.


> +	NULL
> +};
> +
> +static const struct hwmon_chip_info acpi_fan_chip_info = {
> +	.ops = &acpi_fan_ops,
> +	.info = acpi_fan_info,
> +};
> +
> +int devm_acpi_fan_create_hwmon(struct acpi_device *device)
> +{
> +	struct device *hdev;
> +
> +	hdev = devm_hwmon_device_register_with_info(&device->dev, "acpi_fan", device,
> +						    &acpi_fan_chip_info, NULL);
> +
> +	return PTR_ERR_OR_ZERO(hdev);
> +}
> --
> 2.39.2
> 
> 

Re: [PATCH] ACPI: fan: Add hwmon support

[Armin Wolf]

Am 08.04.24 um 17:48 schrieb Ilpo Järvinen:

> On Mon, 8 Apr 2024, Armin Wolf wrote:
>
>> Currently, the driver does only supports a custom sysfs
>> interface to allow userspace to read the fan speed.
>> Add support for the standard hwmon interface so users
>> can read the fan speed with standard tools like "sensors".
>>
>> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
>> ---
>>   drivers/acpi/Makefile    |  1 +
>>   drivers/acpi/fan.h       |  2 ++
>>   drivers/acpi/fan_core.c  |  7 ++++
>>   drivers/acpi/fan_hwmon.c | 78 ++++++++++++++++++++++++++++++++++++++++
>>   4 files changed, 88 insertions(+)
>>   create mode 100644 drivers/acpi/fan_hwmon.c
>>
>> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
>> index d69d5444acdb..9a2e03acc1be 100644
>> --- a/drivers/acpi/Makefile
>> +++ b/drivers/acpi/Makefile
>> @@ -83,6 +83,7 @@ obj-$(CONFIG_ACPI_TINY_POWER_BUTTON)	+= tiny-power-button.o
>>   obj-$(CONFIG_ACPI_FAN)		+= fan.o
>>   fan-objs			:= fan_core.o
>>   fan-objs			+= fan_attr.o
>> +fan-objs			+= fan_hwmon.o
>>
>>   obj-$(CONFIG_ACPI_VIDEO)	+= video.o
>>   obj-$(CONFIG_ACPI_TAD)		+= acpi_tad.o
>> diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
>> index e7b4b4e4a55e..45c2637566da 100644
>> --- a/drivers/acpi/fan.h
>> +++ b/drivers/acpi/fan.h
>> @@ -56,4 +56,6 @@ struct acpi_fan {
>>   int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst *fst);
>>   int acpi_fan_create_attributes(struct acpi_device *device);
>>   void acpi_fan_delete_attributes(struct acpi_device *device);
>> +
>> +int devm_acpi_fan_create_hwmon(struct acpi_device *device);
>>   #endif
>> diff --git a/drivers/acpi/fan_core.c b/drivers/acpi/fan_core.c
>> index ff72e4ef8738..6bbdbb914e95 100644
>> --- a/drivers/acpi/fan_core.c
>> +++ b/drivers/acpi/fan_core.c
>> @@ -7,6 +7,7 @@
>>    *  Copyright (C) 2022 Intel Corporation. All rights reserved.
>>    */
>>
>> +#include <linux/kconfig.h>
>>   #include <linux/kernel.h>
>>   #include <linux/module.h>
>>   #include <linux/init.h>
>> @@ -336,6 +337,12 @@ static int acpi_fan_probe(struct platform_device *pdev)
>>   		if (result)
>>   			return result;
>>
>> +		if (IS_REACHABLE(CONFIG_HWMON)) {
>> +			result = devm_acpi_fan_create_hwmon(device);
>> +			if (result)
>> +				return result;
>> +		}
>> +
>>   		result = acpi_fan_create_attributes(device);
>>   		if (result)
>>   			return result;
>> diff --git a/drivers/acpi/fan_hwmon.c b/drivers/acpi/fan_hwmon.c
>> new file mode 100644
>> index 000000000000..4f2bec8664f4
>> --- /dev/null
>> +++ b/drivers/acpi/fan_hwmon.c
>> @@ -0,0 +1,78 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * fan_hwmon.c - hwmon interface for the ACPI Fan driver
>> + *
>> + * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
>> + */
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/hwmon.h>
>> +#include <linux/limits.h>
>> +
>> +#include "fan.h"
>> +
>> +static umode_t acpi_fan_is_visible(const void *drvdata, enum hwmon_sensor_types type, u32 attr,
>> +				   int channel)
>> +{
>> +	return 0444;
>> +}
>> +
>> +static int acpi_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
>> +			 long *val)
>> +{
>> +	struct acpi_device *adev = dev_get_drvdata(dev);
>> +	struct acpi_fan_fst fst;
>> +	int ret;
>> +
>> +	switch (type) {
>> +	case hwmon_fan:
>> +		ret = acpi_fan_get_fst(adev, &fst);
>> +		if (ret < 0)
>> +			return ret;
>> +
>> +		switch (attr) {
>> +		case hwmon_fan_input:
>> +			if (fst.speed > LONG_MAX)
>> +				return -EOVERFLOW;
>> +
>> +			*val = fst.speed;
>> +			return 0;
>> +		case hwmon_fan_fault:
>> +			*val = (fst.speed == U32_MAX);
>> +			return 0;
> Is it okay to return 0 in this case?

Hi,

i think so, since the value of the attribute (with the meaning of "is the rpm value ok?") is being
correctly stored in val. If acpi_fan_get_fst() fails, we already return a negative error code.

Thanks,
Armin Wolf

>> +		default:
>> +			break;
>> +		}
>> +		break;
>> +	default:
>> +		break;
>> +	}
>> +
>> +	return -EOPNOTSUPP;
>> +}
>> +
>> +static const struct hwmon_ops acpi_fan_ops = {
>> +	.is_visible = acpi_fan_is_visible,
>> +	.read = acpi_fan_read,
>> +};
>> +
>> +static const struct hwmon_channel_info * const acpi_fan_info[] = {
>> +	HWMON_CHANNEL_INFO(fan,
>> +			   HWMON_F_INPUT | HWMON_F_FAULT),
> One line.
>

Re: [PATCH] ACPI: fan: Add hwmon support

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 4968 bytes --]

On Mon, 8 Apr 2024, Armin Wolf wrote:
> Am 08.04.24 um 17:48 schrieb Ilpo Järvinen:
> > On Mon, 8 Apr 2024, Armin Wolf wrote:
> > 
> > > Currently, the driver does only supports a custom sysfs
> > > interface to allow userspace to read the fan speed.
> > > Add support for the standard hwmon interface so users
> > > can read the fan speed with standard tools like "sensors".
> > > 
> > > Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> > > ---
> > >   drivers/acpi/Makefile    |  1 +
> > >   drivers/acpi/fan.h       |  2 ++
> > >   drivers/acpi/fan_core.c  |  7 ++++
> > >   drivers/acpi/fan_hwmon.c | 78 ++++++++++++++++++++++++++++++++++++++++
> > >   4 files changed, 88 insertions(+)
> > >   create mode 100644 drivers/acpi/fan_hwmon.c
> > > 
> > > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> > > index d69d5444acdb..9a2e03acc1be 100644
> > > --- a/drivers/acpi/Makefile
> > > +++ b/drivers/acpi/Makefile
> > > @@ -83,6 +83,7 @@ obj-$(CONFIG_ACPI_TINY_POWER_BUTTON)	+=
> > > tiny-power-button.o
> > >   obj-$(CONFIG_ACPI_FAN)		+= fan.o
> > >   fan-objs			:= fan_core.o
> > >   fan-objs			+= fan_attr.o
> > > +fan-objs			+= fan_hwmon.o
> > > 
> > >   obj-$(CONFIG_ACPI_VIDEO)	+= video.o
> > >   obj-$(CONFIG_ACPI_TAD)		+= acpi_tad.o
> > > diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
> > > index e7b4b4e4a55e..45c2637566da 100644
> > > --- a/drivers/acpi/fan.h
> > > +++ b/drivers/acpi/fan.h
> > > @@ -56,4 +56,6 @@ struct acpi_fan {
> > >   int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst
> > > *fst);
> > >   int acpi_fan_create_attributes(struct acpi_device *device);
> > >   void acpi_fan_delete_attributes(struct acpi_device *device);
> > > +
> > > +int devm_acpi_fan_create_hwmon(struct acpi_device *device);
> > >   #endif
> > > diff --git a/drivers/acpi/fan_core.c b/drivers/acpi/fan_core.c
> > > index ff72e4ef8738..6bbdbb914e95 100644
> > > --- a/drivers/acpi/fan_core.c
> > > +++ b/drivers/acpi/fan_core.c
> > > @@ -7,6 +7,7 @@
> > >    *  Copyright (C) 2022 Intel Corporation. All rights reserved.
> > >    */
> > > 
> > > +#include <linux/kconfig.h>
> > >   #include <linux/kernel.h>
> > >   #include <linux/module.h>
> > >   #include <linux/init.h>
> > > @@ -336,6 +337,12 @@ static int acpi_fan_probe(struct platform_device
> > > *pdev)
> > >   		if (result)
> > >   			return result;
> > > 
> > > +		if (IS_REACHABLE(CONFIG_HWMON)) {
> > > +			result = devm_acpi_fan_create_hwmon(device);
> > > +			if (result)
> > > +				return result;
> > > +		}
> > > +
> > >   		result = acpi_fan_create_attributes(device);
> > >   		if (result)
> > >   			return result;
> > > diff --git a/drivers/acpi/fan_hwmon.c b/drivers/acpi/fan_hwmon.c
> > > new file mode 100644
> > > index 000000000000..4f2bec8664f4
> > > --- /dev/null
> > > +++ b/drivers/acpi/fan_hwmon.c
> > > @@ -0,0 +1,78 @@
> > > +// SPDX-License-Identifier: GPL-2.0-or-later
> > > +/*
> > > + * fan_hwmon.c - hwmon interface for the ACPI Fan driver
> > > + *
> > > + * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
> > > + */
> > > +
> > > +#include <linux/acpi.h>
> > > +#include <linux/hwmon.h>
> > > +#include <linux/limits.h>
> > > +
> > > +#include "fan.h"
> > > +
> > > +static umode_t acpi_fan_is_visible(const void *drvdata, enum
> > > hwmon_sensor_types type, u32 attr,
> > > +				   int channel)
> > > +{
> > > +	return 0444;
> > > +}
> > > +
> > > +static int acpi_fan_read(struct device *dev, enum hwmon_sensor_types
> > > type, u32 attr, int channel,
> > > +			 long *val)
> > > +{
> > > +	struct acpi_device *adev = dev_get_drvdata(dev);
> > > +	struct acpi_fan_fst fst;
> > > +	int ret;
> > > +
> > > +	switch (type) {
> > > +	case hwmon_fan:
> > > +		ret = acpi_fan_get_fst(adev, &fst);
> > > +		if (ret < 0)
> > > +			return ret;
> > > +
> > > +		switch (attr) {
> > > +		case hwmon_fan_input:
> > > +			if (fst.speed > LONG_MAX)
> > > +				return -EOVERFLOW;
> > > +
> > > +			*val = fst.speed;
> > > +			return 0;
> > > +		case hwmon_fan_fault:
> > > +			*val = (fst.speed == U32_MAX);
> > > +			return 0;
> > Is it okay to return 0 in this case?
> 
> Hi,
> 
> i think so, since the value of the attribute (with the meaning of "is the rpm
> value ok?") is being
> correctly stored in val. If acpi_fan_get_fst() fails, we already return a
> negative error code.

Ah, right. It seems fine.

-- 
 i.

> > > +		default:
> > > +			break;
> > > +		}
> > > +		break;
> > > +	default:
> > > +		break;
> > > +	}
> > > +
> > > +	return -EOPNOTSUPP;
> > > +}
> > > +
> > > +static const struct hwmon_ops acpi_fan_ops = {
> > > +	.is_visible = acpi_fan_is_visible,
> > > +	.read = acpi_fan_read,
> > > +};
> > > +
> > > +static const struct hwmon_channel_info * const acpi_fan_info[] = {
> > > +	HWMON_CHANNEL_INFO(fan,
> > > +			   HWMON_F_INPUT | HWMON_F_FAULT),
> > One line.
> > 
> 

[PATCH] ACPI: fan: Add hwmon support

[Armin Wolf]

Currently, the driver does only support a custom sysfs
interface to allow userspace to read the fan speed.
Add support for the standard hwmon interface so users
can read the fan speed with standard tools like "sensors".

Tested with a custom ACPI SSDT.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
Changes since v4:
- fix spelling issues
- check power values for overflow condition too

Changes since v3:
- drop fault attrs
- rework initialization

Changes since v2:
- add support for fanX_target and power attrs

Changes since v1:
- fix undefined reference error
- fix fan speed validation
- coding style fixes
- clarify that the changes are compile-tested only
- add hwmon maintainers to cc list
---
 drivers/acpi/Makefile    |   1 +
 drivers/acpi/fan.h       |   9 ++
 drivers/acpi/fan_core.c  |   4 +
 drivers/acpi/fan_hwmon.c | 173 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 187 insertions(+)
 create mode 100644 drivers/acpi/fan_hwmon.c

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 39ea5cfa8326..61ca4afe83dc 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -77,6 +77,7 @@ obj-$(CONFIG_ACPI_TINY_POWER_BUTTON)	+= tiny-power-button.o
 obj-$(CONFIG_ACPI_FAN)		+= fan.o
 fan-objs			:= fan_core.o
 fan-objs			+= fan_attr.o
+fan-$(CONFIG_HWMON)		+= fan_hwmon.o

 obj-$(CONFIG_ACPI_VIDEO)	+= video.o
 obj-$(CONFIG_ACPI_TAD)		+= acpi_tad.o
diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
index f89d19c922dc..db25a3898af7 100644
--- a/drivers/acpi/fan.h
+++ b/drivers/acpi/fan.h
@@ -10,6 +10,8 @@
 #ifndef _ACPI_FAN_H_
 #define _ACPI_FAN_H_

+#include <linux/kconfig.h>
+
 #define ACPI_FAN_DEVICE_IDS	\
 	{"INT3404", }, /* Fan */ \
 	{"INTC1044", }, /* Fan for Tiger Lake generation */ \
@@ -57,4 +59,11 @@ struct acpi_fan {
 int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst *fst);
 int acpi_fan_create_attributes(struct acpi_device *device);
 void acpi_fan_delete_attributes(struct acpi_device *device);
+
+#if IS_REACHABLE(CONFIG_HWMON)
+int devm_acpi_fan_create_hwmon(struct acpi_device *device);
+#else
+static inline int devm_acpi_fan_create_hwmon(struct acpi_device *device) { return 0; };
+#endif
+
 #endif
diff --git a/drivers/acpi/fan_core.c b/drivers/acpi/fan_core.c
index ff72e4ef8738..7cea4495f19b 100644
--- a/drivers/acpi/fan_core.c
+++ b/drivers/acpi/fan_core.c
@@ -336,6 +336,10 @@ static int acpi_fan_probe(struct platform_device *pdev)
 		if (result)
 			return result;

+		result = devm_acpi_fan_create_hwmon(device);
+		if (result)
+			return result;
+
 		result = acpi_fan_create_attributes(device);
 		if (result)
 			return result;
diff --git a/drivers/acpi/fan_hwmon.c b/drivers/acpi/fan_hwmon.c
new file mode 100644
index 000000000000..e7e5b6a29e7f
--- /dev/null
+++ b/drivers/acpi/fan_hwmon.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * fan_hwmon.c - hwmon interface for the ACPI Fan driver
+ *
+ * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
+ */
+
+#include <linux/acpi.h>
+#include <linux/hwmon.h>
+#include <linux/limits.h>
+#include <linux/units.h>
+
+#include "fan.h"
+
+/* Returned when the ACPI fan does not support speed reporting */
+#define FAN_SPEED_UNAVAILABLE	0xffffffff
+#define FAN_POWER_UNAVAILABLE	0xffffffff
+
+static struct acpi_fan_fps *acpi_fan_get_current_fps(struct acpi_fan *fan, u64 control)
+{
+	int i;
+
+	for (i = 0; i < fan->fps_count; i++) {
+		if (fan->fps[i].control == control)
+			return &fan->fps[i];
+	}
+
+	return NULL;
+}
+
+static umode_t acpi_fan_is_visible(const void *drvdata, enum hwmon_sensor_types type, u32 attr,
+				   int channel)
+{
+	const struct acpi_fan *fan = drvdata;
+	int i;
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			return 0444;
+		case hwmon_fan_target:
+			/* When in fine grain control mode, not every fan control value
+			 * has an associated fan performance state.
+			 */
+			if (fan->fif.fine_grain_ctrl)
+				return 0;
+
+			return 0444;
+		default:
+			break;
+		}
+		break;
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_input:
+			/* When in fine grain control mode, not every fan control value
+			 * has an associated fan performance state.
+			 */
+			if (fan->fif.fine_grain_ctrl)
+				return 0;
+
+			/* When all fan performance states contain no valid power data,
+			 * when the associated attribute should not be created.
+			 */
+			for (i = 0; i < fan->fps_count; i++) {
+				if (fan->fps[i].power != FAN_POWER_UNAVAILABLE)
+					return 0444;
+			}
+
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int acpi_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
+			 long *val)
+{
+	struct acpi_device *adev = to_acpi_device(dev->parent);
+	struct acpi_fan *fan = dev_get_drvdata(dev);
+	struct acpi_fan_fps *fps;
+	struct acpi_fan_fst fst;
+	int ret;
+
+	ret = acpi_fan_get_fst(adev, &fst);
+	if (ret < 0)
+		return ret;
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			if (fst.speed == FAN_SPEED_UNAVAILABLE)
+				return -ENODATA;
+
+			if (fst.speed > LONG_MAX)
+				return -EOVERFLOW;
+
+			*val = fst.speed;
+			return 0;
+		case hwmon_fan_target:
+			fps = acpi_fan_get_current_fps(fan, fst.control);
+			if (!fps)
+				return -ENODATA;
+
+			if (fps->speed > LONG_MAX)
+				return -EOVERFLOW;
+
+			*val = fps->speed;
+			return 0;
+		default:
+			break;
+		}
+		break;
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_input:
+			fps = acpi_fan_get_current_fps(fan, fst.control);
+			if (!fps)
+				return -ENODATA;
+
+			if (fps->power == FAN_POWER_UNAVAILABLE)
+				return -ENODATA;
+
+			if (fps->power > LONG_MAX / MICROWATT_PER_MILLIWATT)
+				return -EOVERFLOW;
+
+			*val = fps->power * MICROWATT_PER_MILLIWATT;
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static const struct hwmon_ops acpi_fan_ops = {
+	.is_visible = acpi_fan_is_visible,
+	.read = acpi_fan_read,
+};
+
+static const struct hwmon_channel_info * const acpi_fan_info[] = {
+	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT | HWMON_F_TARGET),
+	HWMON_CHANNEL_INFO(power, HWMON_P_INPUT),
+	NULL
+};
+
+static const struct hwmon_chip_info acpi_fan_chip_info = {
+	.ops = &acpi_fan_ops,
+	.info = acpi_fan_info,
+};
+
+int devm_acpi_fan_create_hwmon(struct acpi_device *device)
+{
+	struct acpi_fan *fan = acpi_driver_data(device);
+	struct device *hdev;
+
+	hdev = devm_hwmon_device_register_with_info(&device->dev, "acpi_fan", fan,
+						    &acpi_fan_chip_info, NULL);
+
+	return PTR_ERR_OR_ZERO(hdev);
+}
--
2.39.2