linux-imx

/*

 * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver

 *

 * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com>

 *

 * This file is subject to the terms and conditions of version 2 of

 * the GNU General Public License.  See the file COPYING in the main

 * directory of this archive for more details.

 *

 * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf

 *

 * SPI interface connections

 *

 * SPI                MAXIM

 * Master  Direction  MAX1117/8/9

 * ------  ---------  -----------

 * nCS        -->     CNVST

 * SCK        -->     SCLK

 * MISO       <--     DOUT

 * ------  ---------  -----------

 */

​

#include <linux/module.h>

#include <linux/spi/spi.h>

#include <linux/iio/iio.h>

#include <linux/iio/buffer.h>

#include <linux/iio/triggered_buffer.h>

#include <linux/iio/trigger_consumer.h>

#include <linux/regulator/consumer.h>

​

enum max1118_id {

    max1117,

    max1118,

    max1119,

};

​

struct max1118 {

    struct spi_device *spi;

    struct mutex lock;

    struct regulator *reg;

​

    u8 data ____cacheline_aligned;

};

​

#define MAX1118_CHANNEL(ch)                     \

    {                               \

        .type = IIO_VOLTAGE,                    \

        .indexed = 1,                       \

        .channel = (ch),                    \

        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),       \

        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \

        .scan_index = ch,                   \

        .scan_type = {                      \

            .sign = 'u',                    \

            .realbits = 8,                  \

            .storagebits = 8,               \

        },                          \

    }

​

static const struct iio_chan_spec max1118_channels[] = {

    MAX1118_CHANNEL(0),

    MAX1118_CHANNEL(1),

    IIO_CHAN_SOFT_TIMESTAMP(2),

};

​

static int max1118_read(struct spi_device *spi, int channel)

{

    struct iio_dev *indio_dev = spi_get_drvdata(spi);

    struct max1118 *adc = iio_priv(indio_dev);

    struct spi_transfer xfers[] = {

        /*

         * To select CH1 for conversion, CNVST pin must be brought high

         * and low for a second time.

         */

        {

            .len = 0,

            .delay_usecs = 1,   /* > CNVST Low Time 100 ns */

            .cs_change = 1,

        },

        /*

         * The acquisition interval begins with the falling edge of

         * CNVST.  The total acquisition and conversion process takes

         * <7.5us.

         */

        {

            .len = 0,

            .delay_usecs = 8,

        },

        {

            .rx_buf = &adc->data,

            .len = 1,

        },