diff options
67 files changed, 3148 insertions, 574 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index b8753f74af67..42d360fe66a5 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -493,7 +493,7 @@ Contact: linux-iio@vger.kernel.org Description: Specifies the output powerdown mode. DAC output stage is disconnected from the amplifier and - 1kohm_to_gnd: connected to ground via an 1kOhm resistor, + 1kohm_to_gnd: connected to ground via an 1kOhm resistor, 6kohm_to_gnd: connected to ground via a 6kOhm resistor, 20kohm_to_gnd: connected to ground via a 20kOhm resistor, 100kohm_to_gnd: connected to ground via an 100kOhm resistor, @@ -503,9 +503,9 @@ Description: outX_powerdown_mode_available. If Y is not present the mode is shared across all outputs. -What: /sys/.../iio:deviceX/out_votlageY_powerdown_mode_available +What: /sys/.../iio:deviceX/out_voltageY_powerdown_mode_available What: /sys/.../iio:deviceX/out_voltage_powerdown_mode_available -What: /sys/.../iio:deviceX/out_altvotlageY_powerdown_mode_available +What: /sys/.../iio:deviceX/out_altvoltageY_powerdown_mode_available What: /sys/.../iio:deviceX/out_altvoltage_powerdown_mode_available KernelVersion: 2.6.38 Contact: linux-iio@vger.kernel.org @@ -1040,13 +1040,6 @@ Contact: linux-iio@vger.kernel.org Description: Number of scans contained by the buffer. -What: /sys/bus/iio/devices/iio:deviceX/buffer/bytes_per_datum -KernelVersion: 2.6.37 -Contact: linux-iio@vger.kernel.org -Description: - Bytes per scan. Due to alignment fun, the scan may be larger - than implied directly by the scan_element parameters. - What: /sys/bus/iio/devices/iio:deviceX/buffer/enable KernelVersion: 2.6.35 Contact: linux-iio@vger.kernel.org diff --git a/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs b/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs index 5235e6c749ab..bbb039237a25 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs +++ b/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs @@ -9,3 +9,12 @@ Description: automated testing or in situations, where other trigger methods are not applicable. For example no RTC or spare GPIOs. X is the IIO index of the trigger. + +What: /sys/bus/iio/devices/triggerX/name +KernelVersion: 2.6.39 +Contact: linux-iio@vger.kernel.org +Description: + The name attribute holds a description string for the current + trigger. In order to associate the trigger with an IIO device + one should write this name string to + /sys/bus/iio/devices/iio:deviceY/trigger/current_trigger. diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index b6a6a2e0dd3b..9e086067b4ae 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -15,7 +15,7 @@ DOCBOOKS := z8530book.xml device-drivers.xml \ 80211.xml debugobjects.xml sh.xml regulator.xml \ alsa-driver-api.xml writing-an-alsa-driver.xml \ tracepoint.xml drm.xml media_api.xml w1.xml \ - writing_musb_glue_layer.xml crypto-API.xml + writing_musb_glue_layer.xml crypto-API.xml iio.xml include Documentation/DocBook/media/Makefile diff --git a/Documentation/DocBook/iio.tmpl b/Documentation/DocBook/iio.tmpl new file mode 100644 index 000000000000..06bb53de5a47 --- /dev/null +++ b/Documentation/DocBook/iio.tmpl @@ -0,0 +1,697 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" + "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> + +<book id="iioid"> + <bookinfo> + <title>Industrial I/O driver developer's guide </title> + + <authorgroup> + <author> + <firstname>Daniel</firstname> + <surname>Baluta</surname> + <affiliation> + <address> + <email>daniel.baluta@intel.com</email> + </address> + </affiliation> + </author> + </authorgroup> + + <copyright> + <year>2015</year> + <holder>Intel Corporation</holder> + </copyright> + + <legalnotice> + <para> + This documentation is free software; you can redistribute + it and/or modify it under the terms of the GNU General Public + License version 2. + </para> + </legalnotice> + </bookinfo> + + <toc></toc> + + <chapter id="intro"> + <title>Introduction</title> + <para> + The main purpose of the Industrial I/O subsystem (IIO) is to provide + support for devices that in some sense perform either analog-to-digital + conversion (ADC) or digital-to-analog conversion (DAC) or both. The aim + is to fill the gap between the somewhat similar hwmon and input + subsystems. + Hwmon is directed at low sample rate sensors used to monitor and + control the system itself, like fan speed control or temperature + measurement. Input is, as its name suggests, focused on human interaction + input devices (keyboard, mouse, touchscreen). In some cases there is + considerable overlap between these and IIO. + </para> + <para> + Devices that fall into this category include: + <itemizedlist> + <listitem> + analog to digital converters (ADCs) + </listitem> + <listitem> + accelerometers + </listitem> + <listitem> + capacitance to digital converters (CDCs) + </listitem> + <listitem> + digital to analog converters (DACs) + </listitem> + <listitem> + gyroscopes + </listitem> + <listitem> + inertial measurement units (IMUs) + </listitem> + <listitem> + color and light sensors + </listitem> + <listitem> + magnetometers + </listitem> + <listitem> + pressure sensors + </listitem> + <listitem> + proximity sensors + </listitem> + <listitem> + temperature sensors + </listitem> + </itemizedlist> + Usually these sensors are connected via SPI or I2C. A common use case of the + sensors devices is to have combined functionality (e.g. light plus proximity + sensor). + </para> + </chapter> + <chapter id='iiosubsys'> + <title>Industrial I/O core</title> + <para> + The Industrial I/O core offers: + <itemizedlist> + <listitem> + a unified framework for writing drivers for many different types of + embedded sensors. + </listitem> + <listitem> + a standard interface to user space applications manipulating sensors. + </listitem> + </itemizedlist> + The implementation can be found under <filename> + drivers/iio/industrialio-*</filename> + </para> + <sect1 id="iiodevice"> + <title> Industrial I/O devices </title> + +!Finclude/linux/iio/iio.h iio_dev +!Fdrivers/iio/industrialio-core.c iio_device_alloc +!Fdrivers/iio/industrialio-core.c iio_device_free +!Fdrivers/iio/industrialio-core.c iio_device_register +!Fdrivers/iio/industrialio-core.c iio_device_unregister + + <para> + An IIO device usually corresponds to a single hardware sensor and it + provides all the information needed by a driver handling a device. + Let's first have a look at the functionality embedded in an IIO + device then we will show how a device driver makes use of an IIO + device. + </para> + <para> + There are two ways for a user space application to interact + with an IIO driver. + <itemizedlist> + <listitem> + <filename>/sys/bus/iio/iio:deviceX/</filename>, this + represents a hardware sensor and groups together the data + channels of the same chip. + </listitem> + <listitem> + <filename>/dev/iio:deviceX</filename>, character device node + interface used for buffered data transfer and for events information + retrieval. + </listitem> + </itemizedlist> + </para> + A typical IIO driver will register itself as an I2C or SPI driver and will + create two routines, <function> probe </function> and <function> remove + </function>. At <function>probe</function>: + <itemizedlist> + <listitem>call <function>iio_device_alloc</function>, which allocates memory + for an IIO device. + </listitem> + <listitem> initialize IIO device fields with driver specific information + (e.g. device name, device channels). + </listitem> + <listitem>call <function> iio_device_register</function>, this registers the + device with the IIO core. After this call the device is ready to accept + requests from user space applications. + </listitem> + </itemizedlist> + At <function>remove</function>, we free the resources allocated in + <function>probe</function> in reverse order: + <itemizedlist> + <listitem><function>iio_device_unregister</function>, unregister the device + from the IIO core. + </listitem> + <listitem><function>iio_device_free</function>, free the memory allocated + for the IIO device. + </listitem> + </itemizedlist> + + <sect2 id="iioattr"> <title> IIO device sysfs interface </title> + <para> + Attributes are sysfs files used to expose chip info and also allowing + applications to set various configuration parameters. For device + with index X, attributes can be found under + <filename>/sys/bus/iio/iio:deviceX/ </filename> directory. + Common attributes are: + <itemizedlist> + <listitem><filename>name</filename>, description of the physical + chip. + </listitem> + <listitem><filename>dev</filename>, shows the major:minor pair + associated with <filename>/dev/iio:deviceX</filename> node. + </listitem> + <listitem><filename>sampling_frequency_available</filename>, + available discrete set of sampling frequency values for + device. + </listitem> + </itemizedlist> + Available standard attributes for IIO devices are described in the + <filename>Documentation/ABI/testing/sysfs-bus-iio </filename> file + in the Linux kernel sources. + </para> + </sect2> + <sect2 id="iiochannel"> <title> IIO device channels </title> +!Finclude/linux/iio/iio.h iio_chan_spec structure. + <para> + An IIO device channel is a representation of a data channel. An + IIO device can have one or multiple channels. For example: + <itemizedlist> + <listitem> + a thermometer sensor has one channel representing the + temperature measurement. + </listitem> + <listitem> + a light sensor with two channels indicating the measurements in + the visible and infrared spectrum. + </listitem> + <listitem> + an accelerometer can have up to 3 channels representing + acceleration on X, Y and Z axes. + </listitem> + </itemizedlist> + An IIO channel is described by the <type> struct iio_chan_spec + </type>. A thermometer driver for the temperature sensor in the + example above would have to describe its channel as follows: + <programlisting> + static const struct iio_chan_spec temp_channel[] = { + { + .type = IIO_TEMP, + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), + }, + }; + + </programlisting> + Channel sysfs attributes exposed to userspace are specified in + the form of <emphasis>bitmasks</emphasis>. Depending on their + shared info, attributes can be set in one of the following masks: + <itemizedlist> + <listitem><emphasis>info_mask_separate</emphasis>, attributes will + be specific to this channel</listitem> + <listitem><emphasis>info_mask_shared_by_type</emphasis>, + attributes are shared by all channels of the same type</listitem> + <listitem><emphasis>info_mask_shared_by_dir</emphasis>, attributes + are shared by all channels of the same direction </listitem> + <listitem><emphasis>info_mask_shared_by_all</emphasis>, + attributes are shared by all channels</listitem> + </itemizedlist> + When there are multiple data channels per channel type we have two + ways to distinguish between them: + <itemizedlist> + <listitem> set <emphasis> .modified</emphasis> field of <type> + iio_chan_spec</type> to 1. Modifiers are specified using + <emphasis>.channel2</emphasis> field of the same + <type>iio_chan_spec</type> structure and are used to indicate a + physically unique characteristic of the channel such as its direction + or spectral response. For example, a light sensor can have two channels, + one for infrared light and one for both infrared and visible light. + </listitem> + <listitem> set <emphasis>.indexed </emphasis> field of + <type>iio_chan_spec</type> to 1. In this case the channel is + simply another instance with an index specified by the + <emphasis>.channel</emphasis> field. + </listitem> + </itemizedlist> + Here is how we can make use of the channel's modifiers: + <programlisting> + static const struct iio_chan_spec light_channels[] = { + { + .type = IIO_INTENSITY, + .modified = 1, + .channel2 = IIO_MOD_LIGHT_IR, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .info_mask_shared = BIT(IIO_CHAN_INFO_SAMP_FREQ), + }, + { + .type = IIO_INTENSITY, + .modified = 1, + .channel2 = IIO_MOD_LIGHT_BOTH, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .info_mask_shared = BIT(IIO_CHAN_INFO_SAMP_FREQ), + }, + { + .type = IIO_LIGHT, + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), + .info_mask_shared = BIT(IIO_CHAN_INFO_SAMP_FREQ), + }, + + } + </programlisting> + This channel's definition will generate two separate sysfs files + for raw data retrieval: + <itemizedlist> + <listitem> + <filename>/sys/bus/iio/iio:deviceX/in_intensity_ir_raw</filename> + </listitem> + <listitem> + <filename>/sys/bus/iio/iio:deviceX/in_intensity_both_raw</filename> + </listitem> + </itemizedlist> + one file for processed data: + <itemizedlist> + <listitem> + <filename>/sys/bus/iio/iio:deviceX/in_illuminance_input + </filename> + </listitem> + </itemizedlist> + and one shared sysfs file for sampling frequency: + <itemizedlist> + <listitem> + <filename>/sys/bus/iio/iio:deviceX/sampling_frequency. + </filename> + </listitem> + </itemizedlist> + </para> + <para> + Here is how we can make use of the channel's indexing: + <programlisting> + static const struct iio_chan_spec light_channels[] = { + { + .type = IIO_VOLTAGE, + .indexed = 1, + .channel = 0, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + }, + { + .type = IIO_VOLTAGE, + .indexed = 1, + .channel = 1, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + }, + } + </programlisting> + This will generate two separate attributes files for raw data + retrieval: + <itemizedlist> + <listitem> + <filename>/sys/bus/iio/devices/iio:deviceX/in_voltage0_raw</filename>, + representing voltage measurement for channel 0. + </listitem> + <listitem> + <filename>/sys/bus/iio/devices/iio:deviceX/in_voltage1_raw</filename>, + representing voltage measurement for channel 1. + </listitem> + </itemizedlist> + </para> + </sect2> + </sect1> + + <sect1 id="iiobuffer"> <title> Industrial I/O buffers </title> +!Finclude/linux/iio/buffer.h iio_buffer +!Edrivers/iio/industrialio-buffer.c + + <para> + The Industrial I/O core offers a way for continuous data capture + based on a trigger source. Multiple data channels can be read at once + from <filename>/dev/iio:deviceX</filename> character device node, + thus reducing the CPU load. + </para> + + <sect2 id="iiobuffersysfs"> + <title>IIO buffer sysfs interface </title> + <para> + An IIO buffer has an associated attributes directory under <filename> + /sys/bus/iio/iio:deviceX/buffer/</filename>. Here are the existing + attributes: + <itemizedlist> + <listitem> + <emphasis>length</emphasis>, the total number of data samples + (capacity) that can be stored by the buffer. + </listitem> + <listitem> + <emphasis>enable</emphasis>, activate buffer capture. + </listitem> + </itemizedlist> + + </para> + </sect2> + <sect2 id="iiobuffersetup"> <title> IIO buffer setup </title> + <para>The meta information associated with a channel reading + placed in a buffer is called a <emphasis> scan element </emphasis>. + The important bits configuring scan elements are exposed to + userspace applications via the <filename> + /sys/bus/iio/iio:deviceX/scan_elements/</filename> directory. This + file contains attributes of the following form: + <itemizedlist> + <listitem><emphasis>enable</emphasis>, used for enabling a channel. + If and only if its attribute is non zero, then a triggered capture + will contain data samples for this channel. + </listitem> + <listitem><emphasis>type</emphasis>, description of the scan element + data storage within the buffer and hence the form in which it is + read from user space. Format is <emphasis> + [be|le]:[s|u]bits/storagebitsXrepeat[>>shift] </emphasis>. + <itemizedlist> + <listitem> <emphasis>be</emphasis> or <emphasis>le</emphasis>, specifies + big or little endian. + </listitem> + <listitem> + <emphasis>s </emphasis>or <emphasis>u</emphasis>, specifies if + signed (2's complement) or unsigned. + </listitem> + <listitem><emphasis>bits</emphasis>, is the number of valid data + bits. + </listitem> + <listi |