Re: [PATCH v5 1/2] hwmon: add fan speed monitoring driver for Surface devices
From: Guenter Roeck
Date: Wed Jan 31 2024 - 08:22:11 EST
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@xxxxxxxxxxxx>
> Link: https://github.com/linux-surface/kernel/pull/144
> Reviewed-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>
> Reviewed-by: Armin Wolf <W_Armin@xxxxxx>
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@xxxxxxxxxxxx>
> +
> +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@xxxxxxxxx>
> +M: Ivor Wanders <ivor@xxxxxxxxxxxx>
> +L: linux-hwmon@xxxxxxxxxxxxxxx
> +S: Maintained
> +F: Documentation/hwmon/surface_fan.rst
> +F: drivers/hwmon/surface_fan.c
> +
> MICROSOFT SURFACE GPE LID SUPPORT DRIVER
> M: Maximilian Luz <luzmaximilian@xxxxxxxxx>
> L: platform-driver-x86@xxxxxxxxxxxxxxx
> 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@xxxxxxxxxxxx>
> + */
> +
> +#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@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
> +MODULE_LICENSE("GPL");