linux-imx

/*

 * si7005.c - Support for Silabs Si7005 humidity and temperature sensor

 *

 * Copyright (c) 2014 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 0x40)

 *

 * TODO: heater, fast mode, processed mode (temp. / linearity compensation)

 */

​

#include <linux/err.h>

#include <linux/i2c.h>

#include <linux/delay.h>

#include <linux/module.h>

#include <linux/pm.h>

​

#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>

​

#define SI7005_STATUS 0x00

#define SI7005_DATA 0x01 /* 16-bit, MSB */

#define SI7005_CONFIG 0x03

#define SI7005_ID 0x11

​

#define SI7005_STATUS_NRDY BIT(0)

#define SI7005_CONFIG_TEMP BIT(4)

#define SI7005_CONFIG_START BIT(0)

​

#define SI7005_ID_7005 0x50

#define SI7005_ID_7015 0xf0

​

struct si7005_data {

    struct i2c_client *client;

    struct mutex lock;

    u8 config;

};

​

static int si7005_read_measurement(struct si7005_data *data, bool temp)

{

    int tries = 50;

    int ret;

​

    mutex_lock(&data->lock);

​

    ret = i2c_smbus_write_byte_data(data->client, SI7005_CONFIG,

        data->config | SI7005_CONFIG_START |

        (temp ? SI7005_CONFIG_TEMP : 0));

    if (ret < 0)

        goto done;

​

    while (tries-- > 0) {

        msleep(20);

        ret = i2c_smbus_read_byte_data(data->client, SI7005_STATUS);

        if (ret < 0)

            goto done;

        if (!(ret & SI7005_STATUS_NRDY))

            break;

    }

    if (tries < 0) {