On 20/03/15 21:58, Srinivas Pandruvada wrote: > Added custom sensor documentation > > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx> (now with the name attribute ;) > --- > Documentation/hid/hid-sensor.txt | 84 ++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 84 insertions(+) > > diff --git a/Documentation/hid/hid-sensor.txt b/Documentation/hid/hid-sensor.txt > index 948b098..073052f 100644 > --- a/Documentation/hid/hid-sensor.txt > +++ b/Documentation/hid/hid-sensor.txt > @@ -138,3 +138,87 @@ accelerometer wants to poll X axis value, then it can call this function with > the usage id of X axis. HID sensors can provide events, so this is not necessary > to poll for any field. If there is some new sample, the core driver will call > registered callback function to process the sample. > + > + > +---------- > + > +HID Custom and generic Sensors > + > +HID Sensor specification defines two special sensor usage types. Since they > +don't represent a standard sensor, it is not possible to define using Linux IIO > +type interfaces. > +The purpose of these sensors is to extend the functionality or provide a > +way to obfuscate the data being communicated by a sensor. Without knowing the > +mapping between the data and its encapsulated form, it is difficult for > +an application/driver to determine what data is being communicated by the sensor. > +This allows some differentiating use cases, where vendor can provide applications. > +Some common use cases are debug other sensors or to provide some events like > +keyboard attached/detached or lid open/close. > + > +To allow application to utilize these sensors, here they are exported uses sysfs > +attribute groups, attributes and misc device interface. > + > +An example of this representation on sysfs: > +/sys/devices/pci0000:00/INT33C2:00/i2c-0/i2c-INT33D1:00/0018:8086:09FA.0001/HID-SENSOR-2000e1.6.auto$ tree -R > +. > +├── enable_sensor > +├── feature-0-200316 > +│ ├── feature-0-200316-maximum > +│ ├── feature-0-200316-minimum > +│ ├── feature-0-200316-name > +│ ├── feature-0-200316-size > +│ ├── feature-0-200316-unit-expo > +│ ├── feature-0-200316-units > +│ └── feature-0-200316-value > +├── feature-1-200201 > +│ ├── feature-1-200201-maximum > +│ ├── feature-1-200201-minimum > +│ ├── feature-1-200201-name > +│ ├── feature-1-200201-size > +│ ├── feature-1-200201-unit-expo > +│ ├── feature-1-200201-units > +│ └── feature-1-200201-value > +├── input-0-200201 > +│ ├── input-0-200201-maximum > +│ ├── input-0-200201-minimum > +│ ├── input-0-200201-name > +│ ├── input-0-200201-size > +│ ├── input-0-200201-unit-expo > +│ ├── input-0-200201-units > +│ └── input-0-200201-value > +├── input-1-200202 > +│ ├── input-1-200202-maximum > +│ ├── input-1-200202-minimum > +│ ├── input-1-200202-name > +│ ├── input-1-200202-size > +│ ├── input-1-200202-unit-expo > +│ ├── input-1-200202-units > +│ └── input-1-200202-value > + > +Here there is a custom sensors with four fields, two feature and two inputs. > +Each field is represented by a set of attributes. All fields except the "value" > +are read only. The value field is a RW field. > +Example > +/sys/bus/platform/devices/HID-SENSOR-2000e1.6.auto/feature-0-200316$ grep -r . * > +feature-0-200316-maximum:6 > +feature-0-200316-minimum:0 > +feature-0-200316-name:property-reporting-state > +feature-0-200316-size:1 > +feature-0-200316-unit-expo:0 > +feature-0-200316-units:25 > +feature-0-200316-value:1 > + > +How to enable such sensor? > +By default sensor can be power gated. To enable sysfs attribute "enable" can be > +used. > +$ echo 1 > enable_sensor > + > +Once enabled and powered on, sensor can report value using HID reports. > +These reports are pushed using misc device interface in a FIFO order. > +/dev$ tree | grep HID-SENSOR-2000e1.6.auto > +│ ├── 10:53 -> ../HID-SENSOR-2000e1.6.auto > +├── HID-SENSOR-2000e1.6.auto > + > +Each reports can be of variable length preceded by a header. This header > +consist of a 32 bit usage id, 64 bit time stamp and 32 bit length field of raw > +data. > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
