1 Industrial I/O Subsystem in kernel consumers.
3 The IIO subsystem can act as a layer under other elements of the kernel
4 providing a means of obtaining ADC type readings or of driving DAC type
5 signals. The functionality supported will grow as use cases arise.
7 Describing the channel mapping (iio/machine.h)
9 Channel associations are described using:
12 const char *adc_channel_label;
13 const char *consumer_dev_name;
14 const char *consumer_channel;
17 adc_channel_label identifies the channel on the IIO device by being
18 matched against the datasheet_name field of the iio_chan_spec.
20 consumer_dev_name allows identification of the consumer device.
21 This are then used to find the channel mapping from the consumer device (see
24 Finally consumer_channel is a string identifying the channel to the consumer.
25 (Perhaps 'battery_voltage' or similar).
27 An array of these structures is then passed to the IIO driver.
29 Supporting in kernel interfaces in the driver (driver.h)
31 The driver must provide datasheet_name values for its channels and
32 must pass the iio_map structures and a pointer to its own iio_dev structure
33 on to the core via a call to iio_map_array_register. On removal,
34 iio_map_array_unregister reverses this process.
36 The result of this is that the IIO core now has all the information needed
37 to associate a given channel with the consumer requesting it.
39 Acting as an IIO consumer (consumer.h)
41 The consumer first has to obtain an iio_channel structure from the core
42 by calling iio_channel_get(). The correct channel is identified by:
44 * matching dev or dev_name against consumer_dev and consumer_dev_name
45 * matching consumer_channel against consumer_channel in the map
47 There are then a number of functions that can be used to get information
48 about this channel such as it's current reading.
51 iio_read_channel_raw() - get a reading
52 iio_get_channel_type() - get the type of channel
54 There is also provision for retrieving all of the channels associated
55 with a given consumer. This is useful for generic drivers such as
56 iio_hwmon where the number and naming of channels is not known by the
57 consumer driver. To do this, use iio_channel_get_all.