04、IIO相关API

IIO相关接口位于linux/iio/consumer.h

一、API 原型

/**
 * struct iio_channel - everything needed for a consumer to use a channel
 * @indio_dev:          Device on which the channel exists.
 * @channel:            Full description of the channel.
 * @data:               Data about the channel used by consumer.
 */
struct iio_channel {
        struct iio_dev *indio_dev;
        const struct iio_chan_spec *channel;
        void *data;
};

/**
 * iio_channel_get() - get description of all that is needed to access channel.
 * @dev:                Pointer to consumer device. Device name must match
 *                      the name of the device as provided in the iio_map
 *                      with which the desired provider to consumer mapping
 *                      was registered.
 * @consumer_channel:   Unique name to identify the channel on the consumer
 *                      side. This typically describes the channels use within
 *                      the consumer. E.g. 'battery_voltage'
 */
struct iio_channel *iio_channel_get(struct device *dev,
                                    const char *consumer_channel);

/**
 * iio_channel_release() - release channels obtained via iio_channel_get
 * @chan:               The channel to be released.
 */
void iio_channel_release(struct iio_channel *chan);

/**
 * devm_iio_channel_get() - Resource managed version of iio_channel_get().
 * @dev:                Pointer to consumer device. Device name must match
 *                      the name of the device as provided in the iio_map
 *                      with which the desired provider to consumer mapping
 *                      was registered.
 * @consumer_channel:   Unique name to identify the channel on the consumer
 *                      side. This typically describes the channels use within
 *                      the consumer. E.g. 'battery_voltage'
 *
 * Returns a pointer to negative errno if it is not able to get the iio channel
 * otherwise returns valid pointer for iio channel.
 *
 * The allocated iio channel is automatically released when the device is
 * unbound.
 */
struct iio_channel *devm_iio_channel_get(struct device *dev,
                                         const char *consumer_channel);

/**
 * iio_channel_get_all() - get all channels associated with a client
 * @dev:                Pointer to consumer device.
 *
 * Returns an array of iio_channel structures terminated with one with
 * null iio_dev pointer.
 * This function is used by fairly generic consumers to get all the
 * channels registered as having this consumer.
 */
struct iio_channel *iio_channel_get_all(struct device *dev);

二、常用API

2.1、功能：获取 iio 通道描述

参数：

• dev: 使用该通道的设备描述指针
• consumer_channel: 该设备所使用的 IIO 通道描述指针

struct iio_channel *iio_channel_get(struct device *dev, const char *consumer_channel);

2.2、功能：释放 iio_channel_get 函数获取到的通道

参数：

• chan：要被释放的通道描述指针

void iio_channel_release(struct iio_channel *chan);

2.3、功能：读取 chan 通道 AD 采集的原始数据。

参数：

• chan：要读取的采集通道指针
• val：存放读取结果的指针

int iio_read_channel_raw(struct iio_channel *chan, int *val);