iio: documentation: Document proximity sensor label use

[linux-2.6-microblaze.git] / Documentation / ABI / testing / sysfs-bus-iio

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 0890bd1..c42fe98 100644 (file)
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -33,6 +33,45 @@ Description:
                Description of the physical chip / device for device X.
                Typically a part number.
 
+What:          /sys/bus/iio/devices/iio:deviceX/label
+KernelVersion: 5.8
+Contact:       linux-iio@vger.kernel.org
+Description:
+               Optional symbolic label for a device.
+               This is useful for userspace to be able to better identify an
+               individual device.
+
+               The contents of the label are free-form, but there are some
+               standardized uses:
+
+               For proximity sensors which give the proximity (of a person) to
+               a certain wlan or wwan antenna the following standardized labels
+               are used:
+
+               * "proximity-wifi"
+               * "proximity-lte"
+               * "proximity-wifi-lte"
+               * "proximity-wifi-left"
+               * "proximity-wifi-right"
+
+               These are used to indicate to userspace that these proximity
+               sensors may be used to tune transmit power to ensure that
+               Specific Absorption Rate (SAR) limits are honored.
+               The "-left" and "-right" labels are for devices with multiple
+               antennas.
+
+               In some laptops/tablets the standardized proximity sensor labels
+               instead indicate proximity to a specific part of the device:
+
+               * "proximity-palmrest" indicates proximity to the keyboard's palmrest
+               * "proximity-palmrest-left" indicates proximity to the left part of the palmrest
+               * "proximity-palmrest-right" indicates proximity to the right part of the palmrest
+               * "proximity-lap" indicates the device is being used on someone's lap
+
+               Note "proximity-lap" is special in that its value may be
+               calculated by firmware from other sensor readings, rather then
+               being a raw sensor reading.
+
 What:          /sys/bus/iio/devices/iio:deviceX/current_timestamp_clock
 KernelVersion: 4.5
 Contact:       linux-iio@vger.kernel.org