linux-imx

/*

 * mpl3115.c - Support for Freescale MPL3115A2 pressure/temperature sensor

 *

 * Copyright (c) 2013 Peter Meerwald <pmeerw@pmeerw.net>

 *

 * 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.

 *

 * (7-bit I2C slave address 0x60)

 *

 * TODO: FIFO buffer, altimeter mode, oversampling, continuous mode,

 * interrupts, user offset correction, raw mode

 */

​

#include <linux/module.h>

#include <linux/i2c.h>

#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>

#include <linux/iio/trigger_consumer.h>

#include <linux/iio/buffer.h>

#include <linux/iio/triggered_buffer.h>

#include <linux/delay.h>

​

#define MPL3115_STATUS 0x00

#define MPL3115_OUT_PRESS 0x01 /* MSB first, 20 bit */

#define MPL3115_OUT_TEMP 0x04 /* MSB first, 12 bit */

#define MPL3115_WHO_AM_I 0x0c

#define MPL3115_CTRL_REG1 0x26

​

#define MPL3115_DEVICE_ID 0xc4

​

#define MPL3115_STATUS_PRESS_RDY BIT(2)

#define MPL3115_STATUS_TEMP_RDY BIT(1)

​

#define MPL3115_CTRL_RESET BIT(2) /* software reset */

#define MPL3115_CTRL_OST BIT(1) /* initiate measurement */

#define MPL3115_CTRL_ACTIVE BIT(0) /* continuous measurement */

#define MPL3115_CTRL_OS_258MS (BIT(5) | BIT(4)) /* 64x oversampling */

​

struct mpl3115_data {

    struct i2c_client *client;

    struct mutex lock;

    u8 ctrl_reg1;

};

​

static int mpl3115_request(struct mpl3115_data *data)

{

    int ret, tries = 15;

​

    /* trigger measurement */

    ret = i2c_smbus_write_byte_data(data->client, MPL3115_CTRL_REG1,

        data->ctrl_reg1 | MPL3115_CTRL_OST);

    if (ret < 0)

        return ret;

​

    while (tries-- > 0) {

        ret = i2c_smbus_read_byte_data(data->client, MPL3115_CTRL_REG1);

        if (ret < 0)

            return ret;

        /* wait for data ready, i.e. OST cleared */

        if (!(ret & MPL3115_CTRL_OST))

            break;

        msleep(20);

    }

​

    if (tries < 0) {

        dev_err(&data->client->dev, "data not ready\n");

        return -EIO;

    }

​

    return 0;

}

​

static int mpl3115_read_raw(struct iio_dev *indio_dev,

                struct iio_chan_spec const *chan,

                int *val, int *val2, long mask)

{

    struct mpl3115_data *data = iio_priv(indio_dev);

    __be32 tmp = 0;

    int ret;

​

    switch (mask) {

    case IIO_CHAN_INFO_RAW:

        ret = iio_device_claim_direct_mode(indio_dev);

        if (ret)

            return ret;

​

        switch (chan->type) {

        case IIO_PRESSURE: /* in 0.25 pascal / LSB */

            mutex_lock(&data->lock);

            ret = mpl3115_request(data);