linux-imx

/*

 * Industrial I/O driver for Microchip digital potentiometers

 *

 * Copyright (c) 2016 Slawomir Stepien

 * Based on: Peter Rosin's code from mcp4531.c

 *

 * Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/22060b.pdf

 *

 * DEVID    #Wipers #Positions  Resistor Opts (kOhm)

 * mcp4131  1   129     5, 10, 50, 100

 * mcp4132  1   129     5, 10, 50, 100

 * mcp4141  1   129     5, 10, 50, 100

 * mcp4142  1   129     5, 10, 50, 100

 * mcp4151  1   257     5, 10, 50, 100

 * mcp4152  1   257     5, 10, 50, 100

 * mcp4161  1   257     5, 10, 50, 100

 * mcp4162  1   257     5, 10, 50, 100

 * mcp4231  2   129     5, 10, 50, 100

 * mcp4232  2   129     5, 10, 50, 100

 * mcp4241  2   129     5, 10, 50, 100

 * mcp4242  2   129     5, 10, 50, 100

 * mcp4251  2   257     5, 10, 50, 100

 * mcp4252  2   257     5, 10, 50, 100

 * mcp4261  2   257     5, 10, 50, 100

 * mcp4262  2   257     5, 10, 50, 100

 *

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

 * under the terms of the GNU General Public License version 2 as published by

 * the Free Software Foundation.

 */

​

/*

 * TODO:

 * 1. Write wiper setting to EEPROM for EEPROM capable models.

 */

​

#include <linux/cache.h>

#include <linux/err.h>

#include <linux/export.h>

#include <linux/iio/iio.h>

#include <linux/iio/types.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/spi/spi.h>

​

#define MCP4131_WRITE       (0x00 << 2)

#define MCP4131_READ        (0x03 << 2)

​

#define MCP4131_WIPER_SHIFT 4

#define MCP4131_CMDERR(r)   ((r[0]) & 0x02)

#define MCP4131_RAW(r)      ((r[0]) == 0xff ? 0x100 : (r[1]))

​

struct mcp4131_cfg {

    int wipers;

    int max_pos;

    int kohms;

};

​

enum mcp4131_type {

    MCP413x_502 = 0,

    MCP413x_103,