linux-imx

/*

 * mcp3021.c - driver for Microchip MCP3021 and MCP3221

 *

 * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.

 * Author: Mingkai Hu <Mingkai.hu@freescale.com>

 * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>

 * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>

 *

 * This driver export the value of analog input voltage to sysfs, the

 * voltage unit is mV. Through the sysfs interface, lm-sensors tool

 * can also display the input voltage.

 *

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

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 */

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/hwmon.h>

#include <linux/slab.h>

#include <linux/i2c.h>

#include <linux/err.h>

#include <linux/device.h>

#include <linux/of.h>

#include <linux/of_device.h>

​

/* Vdd / reference voltage in millivolt */

#define MCP3021_VDD_REF_MAX 5500

#define MCP3021_VDD_REF_MIN 2700

#define MCP3021_VDD_REF_DEFAULT 3300

​

/* output format */

#define MCP3021_SAR_SHIFT   2

#define MCP3021_SAR_MASK    0x3ff

#define MCP3021_OUTPUT_RES  10  /* 10-bit resolution */

​

#define MCP3221_SAR_SHIFT   0

#define MCP3221_SAR_MASK    0xfff

#define MCP3221_OUTPUT_RES  12  /* 12-bit resolution */

​

enum chips {

    mcp3021,

    mcp3221

};

​

/*

 * Client data (each client gets its own)

 */

struct mcp3021_data {

    struct device *hwmon_dev;

    u32 vdd;        /* supply and reference voltage in millivolt */

    u16 sar_shift;

    u16 sar_mask;

    u8 output_res;

};

​

static int mcp3021_read16(struct i2c_client *client)

{

    struct mcp3021_data *data = i2c_get_clientdata(client);

    int ret;

    u16 reg;

    __be16 buf;

​

    ret = i2c_master_recv(client, (char *)&buf, 2);

    if (ret < 0)

        return ret;

    if (ret != 2)

        return -EIO;

​

    /* The output code of the MCP3021 is transmitted with MSB first. */

    reg = be16_to_cpu(buf);

​

    /*

     * The ten-bit output code is composed of the lower 4-bit of the

     * first byte and the upper 6-bit of the second byte.

     */

    reg = (reg >> data->sar_shift) & data->sar_mask;

​

    return reg;

}

​

static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)

{

    return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);

}

​

static ssize_t in0_input_show(struct device *dev,

                  struct device_attribute *attr, char *buf)

{

    struct i2c_client *client = to_i2c_client(dev);