linux-imx

/*

 *  ads7871 - driver for TI ADS7871 A/D converter

 *

 *  Copyright (c) 2010 Paul Thomas <pthomas8589@gmail.com>

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 *  GNU General Public License for more details.

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License version 2 or

 *  later as publishhed by the Free Software Foundation.

 *

 *  You need to have something like this in struct spi_board_info

 *  {

 *      .modalias   = "ads7871",

 *      .max_speed_hz   = 2*1000*1000,

 *      .chip_select    = 0,

 *      .bus_num    = 1,

 *  },

 */

​

/*From figure 18 in the datasheet*/

/*Register addresses*/

#define REG_LS_BYTE 0 /*A/D Output Data, LS Byte*/

#define REG_MS_BYTE 1 /*A/D Output Data, MS Byte*/

#define REG_PGA_VALID   2 /*PGA Valid Register*/

#define REG_AD_CONTROL  3 /*A/D Control Register*/

#define REG_GAIN_MUX    4 /*Gain/Mux Register*/

#define REG_IO_STATE    5 /*Digital I/O State Register*/

#define REG_IO_CONTROL  6 /*Digital I/O Control Register*/

#define REG_OSC_CONTROL 7 /*Rev/Oscillator Control Register*/

#define REG_SER_CONTROL 24 /*Serial Interface Control Register*/

#define REG_ID      31 /*ID Register*/

​

/*

 * From figure 17 in the datasheet

 * These bits get ORed with the address to form

 * the instruction byte

 */

/*Instruction Bit masks*/

#define INST_MODE_BM    (1 << 7)

#define INST_READ_BM    (1 << 6)

#define INST_16BIT_BM   (1 << 5)

​

/*From figure 18 in the datasheet*/

/*bit masks for Rev/Oscillator Control Register*/

#define MUX_CNV_BV  7

#define MUX_CNV_BM  (1 << MUX_CNV_BV)

#define MUX_M3_BM   (1 << 3) /*M3 selects single ended*/

#define MUX_G_BV    4 /*allows for reg = (gain << MUX_G_BV) | ...*/

​

/*From figure 18 in the datasheet*/

/*bit masks for Rev/Oscillator Control Register*/

#define OSC_OSCR_BM (1 << 5)

#define OSC_OSCE_BM (1 << 4)

#define OSC_REFE_BM (1 << 3)

#define OSC_BUFE_BM (1 << 2)

#define OSC_R2V_BM  (1 << 1)

#define OSC_RBG_BM  (1 << 0)

​

#include <linux/module.h>

#include <linux/init.h>

#include <linux/spi/spi.h>

#include <linux/hwmon.h>

#include <linux/hwmon-sysfs.h>

#include <linux/err.h>

#include <linux/delay.h>

​

#define DEVICE_NAME "ads7871"

​

struct ads7871_data {

    struct spi_device *spi;

};

​

static int ads7871_read_reg8(struct spi_device *spi, int reg)

{

    int ret;

    reg = reg | INST_READ_BM;

    ret = spi_w8r8(spi, reg);

    return ret;

}

​

static int ads7871_read_reg16(struct spi_device *spi, int reg)

{

    int ret;

    reg = reg | INST_READ_BM | INST_16BIT_BM;

    ret = spi_w8r16(spi, reg);

    return ret;

}

​