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Sender: Guenter Roeck <groeck7@gmail.com>
Date: Wed, 31 Jan 2024 05:21:54 -0800
From: Guenter Roeck <linux@roeck-us.net>
To: Ivor Wanders <ivor@iwanders.net>
Cc: Jean Delvare <jdelvare@suse.com>, Jonathan Corbet <corbet@lwn.net>,
	Maximilian Luz <luzmaximilian@gmail.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Mark Gross <markgross@kernel.org>, linux-hwmon@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH v5 1/2] hwmon: add fan speed monitoring driver for
 Surface devices
Message-ID: <3fd2f349-90c6-4445-be2f-54b6cf07dfb8@roeck-us.net>
References: <20240131005856.10180-1-ivor@iwanders.net>
 <20240131005856.10180-2-ivor@iwanders.net>
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In-Reply-To: <20240131005856.10180-2-ivor@iwanders.net>

On Tue, Jan 30, 2024 at 07:58:55PM -0500, Ivor Wanders wrote:
> Adds a driver that provides read only access to the fan speed for Microsoft
> Surface Pro devices. The fan speed is always regulated by the EC and cannot
> be influenced directly.
> 
> Signed-off-by: Ivor Wanders <ivor@iwanders.net>
> Link: https://github.com/linux-surface/kernel/pull/144
> Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
> Reviewed-by: Armin Wolf <W_Armin@gmx.de>

Applied.

Thanks,
Guenter

> ---
> Changes in v5:
>   - No changes in this patch.
> Changes in v4:
>   - Return 0 from surface_fan_hwmon_read instead of ret.
>   - Use PTR_ERR_OR_ZERO in probe instead of if statement.
> Changes in v3:
>   - Removed type and attr checks in read and is_visible.
>   - Removed assigning sdev to ssam_device drvdata.
>   - Propagate return from __ssam_fan_rpm_get.
>   - Renamed hwmon chip name from 'fan' to 'surface_fan'.
>   - Removed unnecessary platform_device header.
> Changes in v2:
>   - Removed all sysfs attributes except fan1_input. Simplified code
>     and updated documentation accordingly.
> ---
>  Documentation/hwmon/index.rst       |  1 +
>  Documentation/hwmon/surface_fan.rst | 25 ++++++++
>  MAINTAINERS                         |  8 +++
>  drivers/hwmon/Kconfig               | 13 +++++
>  drivers/hwmon/Makefile              |  1 +
>  drivers/hwmon/surface_fan.c         | 91 +++++++++++++++++++++++++++++
>  6 files changed, 139 insertions(+)
>  create mode 100644 Documentation/hwmon/surface_fan.rst
>  create mode 100644 drivers/hwmon/surface_fan.c
> 
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index c7ed1f73a..58be92e94 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -208,6 +208,7 @@ Hardware Monitoring Kernel Drivers
>     smsc47m1
>     sparx5-temp
>     stpddc60
> +   surface_fan
>     sy7636a-hwmon
>     tc654
>     tc74
> diff --git a/Documentation/hwmon/surface_fan.rst b/Documentation/hwmon/surface_fan.rst
> new file mode 100644
> index 000000000..07942574c
> --- /dev/null
> +++ b/Documentation/hwmon/surface_fan.rst
> @@ -0,0 +1,25 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Kernel driver surface_fan
> +=========================
> +
> +Supported Devices:
> +
> +  * Microsoft Surface Pro 9
> +
> +Author: Ivor Wanders <ivor@iwanders.net>
> +
> +Description
> +-----------
> +
> +This provides monitoring of the fan found in some Microsoft Surface Pro devices,
> +like the Surface Pro 9. The fan is always controlled by the onboard controller.
> +
> +Sysfs interface
> +---------------
> +
> +======================= ======= =========================================
> +Name                    Perm    Description
> +======================= ======= =========================================
> +``fan1_input``          RO      Current fan speed in RPM.
> +======================= ======= =========================================
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c4828ab15..2c5c4d7e5 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -14560,6 +14560,14 @@ F:	Documentation/driver-api/surface_aggregator/clients/dtx.rst
>  F:	drivers/platform/surface/surface_dtx.c
>  F:	include/uapi/linux/surface_aggregator/dtx.h
>  
> +MICROSOFT SURFACE SENSOR FAN DRIVER
> +M:	Maximilian Luz <luzmaximilian@gmail.com>
> +M:	Ivor Wanders <ivor@iwanders.net>
> +L:	linux-hwmon@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/hwmon/surface_fan.rst
> +F:	drivers/hwmon/surface_fan.c
> +
>  MICROSOFT SURFACE GPE LID SUPPORT DRIVER
>  M:	Maximilian Luz <luzmaximilian@gmail.com>
>  L:	platform-driver-x86@vger.kernel.org
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index a608264da..e762f6138 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1994,6 +1994,19 @@ config SENSORS_SFCTEMP
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called sfctemp.
>  
> +config SENSORS_SURFACE_FAN
> +	tristate "Surface Fan Driver"
> +	depends on SURFACE_AGGREGATOR
> +	help
> +	  Driver that provides monitoring of the fan on Surface Pro devices that
> +	  have a fan, like the Surface Pro 9.
> +
> +	  This makes the fan's current speed accessible through the hwmon
> +	  system. It does not provide control over the fan, the firmware is
> +	  responsible for that, this driver merely provides monitoring.
> +
> +	  Select M or Y here, if you want to be able to read the fan's speed.
> +
>  config SENSORS_ADC128D818
>  	tristate "Texas Instruments ADC128D818"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 47be39af5..30cc90f40 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -201,6 +201,7 @@ obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
>  obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
>  obj-$(CONFIG_SENSORS_SPARX5)	+= sparx5-temp.o
>  obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
> +obj-$(CONFIG_SENSORS_SURFACE_FAN)+= surface_fan.o
>  obj-$(CONFIG_SENSORS_SY7636A)	+= sy7636a-hwmon.o
>  obj-$(CONFIG_SENSORS_AMC6821)	+= amc6821.o
>  obj-$(CONFIG_SENSORS_TC74)	+= tc74.o
> diff --git a/drivers/hwmon/surface_fan.c b/drivers/hwmon/surface_fan.c
> new file mode 100644
> index 000000000..31cd5da9e
> --- /dev/null
> +++ b/drivers/hwmon/surface_fan.c
> @@ -0,0 +1,91 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Surface Fan driver for Surface System Aggregator Module. It provides access
> + * to the fan's rpm through the hwmon system.
> + *
> + * Copyright (C) 2023 Ivor Wanders <ivor@iwanders.net>
> + */
> +
> +#include <linux/hwmon.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/surface_aggregator/device.h>
> +#include <linux/types.h>
> +
> +// SSAM
> +SSAM_DEFINE_SYNC_REQUEST_CL_R(__ssam_fan_rpm_get, __le16, {
> +	.target_category = SSAM_SSH_TC_FAN,
> +	.command_id      = 0x01,
> +});
> +
> +// hwmon
> +umode_t surface_fan_hwmon_is_visible(const void *drvdata,
> +				     enum hwmon_sensor_types type, u32 attr,
> +				     int channel)
> +{
> +	return 0444;
> +}
> +
> +static int surface_fan_hwmon_read(struct device *dev,
> +				  enum hwmon_sensor_types type, u32 attr,
> +				  int channel, long *val)
> +{
> +	struct ssam_device *sdev = dev_get_drvdata(dev);
> +	int ret;
> +	__le16 value;
> +
> +	ret = __ssam_fan_rpm_get(sdev, &value);
> +	if (ret)
> +		return ret;
> +
> +	*val = le16_to_cpu(value);
> +
> +	return 0;
> +}
> +
> +static const struct hwmon_channel_info *const surface_fan_info[] = {
> +	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
> +	NULL
> +};
> +
> +static const struct hwmon_ops surface_fan_hwmon_ops = {
> +	.is_visible = surface_fan_hwmon_is_visible,
> +	.read = surface_fan_hwmon_read,
> +};
> +
> +static const struct hwmon_chip_info surface_fan_chip_info = {
> +	.ops = &surface_fan_hwmon_ops,
> +	.info = surface_fan_info,
> +};
> +
> +static int surface_fan_probe(struct ssam_device *sdev)
> +{
> +	struct device *hdev;
> +
> +	hdev = devm_hwmon_device_register_with_info(&sdev->dev,
> +						    "surface_fan", sdev,
> +						    &surface_fan_chip_info,
> +						    NULL);
> +
> +	return PTR_ERR_OR_ZERO(hdev);
> +}
> +
> +static const struct ssam_device_id ssam_fan_match[] = {
> +	{ SSAM_SDEV(FAN, SAM, 0x01, 0x01) },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(ssam, ssam_fan_match);
> +
> +static struct ssam_device_driver surface_fan = {
> +	.probe = surface_fan_probe,
> +	.match_table = ssam_fan_match,
> +	.driver = {
> +		.name = "surface_fan",
> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +	},
> +};
> +module_ssam_device_driver(surface_fan);
> +
> +MODULE_AUTHOR("Ivor Wanders <ivor@iwanders.net>");
> +MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
> +MODULE_LICENSE("GPL");