An overview document about thermal iio binding. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> --- Documentation/thermal/thermal_iio_binding | 88 +++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 Documentation/thermal/thermal_iio_binding diff --git a/Documentation/thermal/thermal_iio_binding b/Documentation/thermal/thermal_iio_binding new file mode 100644 index 0000000..df501f1 --- /dev/null +++ b/Documentation/thermal/thermal_iio_binding @@ -0,0 +1,88 @@ + +Thermal IIO Bindings + +When CONFIG_THERMAL_IIO is enabled, in addition to the regular thermal +zone attributes, an additional entry for an IIO device is created. +IIO sysfs ABI documents is available at Documentation/ABI/sysfs-bus-iio. + +The following example shows the contents of the IIO:device in a thermal +zone. + +thermal_zoneX +├── iio:device9 +│ ├── buffer +│ │ ├── enable +│ │ ├── length +│ │ └── watermark +│ ├── events +│ │ ├── in_temp_thresh_either_en +│ │ └── in_temp_thresh_either_value +│ ├── in_temp_raw +│ ├── name +│ ├── scan_elements +│ │ ├── in_temp_en +│ │ ├── in_temp_index +│ │ ├── in_temp_type +│ │ ├── in_timestamp_en +│ │ ├── in_timestamp_index +│ │ └── in_timestamp_type +│ ├── subsystem -> ../../../../../bus/iio +│ ├── trigger0 +│ │ └── name +│ ├── trigger +│ │ └── current_trigger +│ └── uevent +├── integral_cutoff +... +... other thermal_zone attributes +... + + +IIO Attributes + +name: This shows iio device name, which will match thermal_zone/type attribute +in_temp_raw: This will show raw temperature values same as thermal_zone/temp +attribute. + +trigger/current_trigger: This is IIO way of specifying data ready indication. +If the thermal client can provide asynchronous notifications, then a iio trigger +device is created under trigger0. The name of this trigger will be thermal +device name suffixed with devX. To enable iio buffer notifications, +trigger/current_trigger cab be updated with this trigger. For example + +#echo "x86_pkg_temp-dev9" > trigger/current_trigger + +In addition of samples can be pushed to iio buffers with external standard IIO +device triggers, E.g. sysfs trigger. + +How to enable events? +To enable events a suitable threshold temperature can be written to +in_temp_thresh_either_value +and enable by writing 1 to in_temp_thresh_either_en. + +To monitor events a good user space program is here: +tools/iio/iio_event_monitor.c + +For example +# echo 50000 > /sys/devices/virtual/thermal/thermal_zone9/iio:device9/events/in_temp_thresh_either_value +# echo 1 > /sys/devices/virtual/thermal/thermal_zone9/iio:device9/events/in_temp_thresh_either_en +# ./iio_event_monitor x86_pkg_temp +Found IIO device with name x86_pkg_temp with device number 9 +Event: time: 1443297126626859289, type: temp, channel: 0, evtype: thresh, direction: either + +How to read temperature samples? +When thermal client or core driver calls thermal_zone_device_update, this will +result in sample pushed to iio buffers. These samples can be read from +/dev/iio:deviceX file. + +To enable buffer select scan_elements +# echo 1 > scan_elements/in_temp_en + +Set buffer length to n samples and enable buffer. +# echo 2 > buffer/length +# echo 1 > buffer/enable + +Then user can poll/select or /dev/iio:deviceX (Here X correspond to iio device number), +and read temperature samples. A good example is at tools/iio/generic_buffer.c. + + -- 2.4.3 -- 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
