linux-imx

/*

 * ti-dac082s085.c - Texas Instruments 8/10/12-bit 2/4-channel DAC driver

 *

 * Copyright (C) 2017 KUNBUS GmbH

 *

 * http://www.ti.com/lit/ds/symlink/dac082s085.pdf

 * http://www.ti.com/lit/ds/symlink/dac102s085.pdf

 * http://www.ti.com/lit/ds/symlink/dac122s085.pdf

 * http://www.ti.com/lit/ds/symlink/dac084s085.pdf

 * http://www.ti.com/lit/ds/symlink/dac104s085.pdf

 * http://www.ti.com/lit/ds/symlink/dac124s085.pdf

 *

 * 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.

 */

​

#include <linux/iio/iio.h>

#include <linux/module.h>

#include <linux/regulator/consumer.h>

#include <linux/spi/spi.h>

​

enum { dual_8bit, dual_10bit, dual_12bit, quad_8bit, quad_10bit, quad_12bit };

​

struct ti_dac_spec {

    u8 num_channels;

    u8 resolution;

};

​

static const struct ti_dac_spec ti_dac_spec[] = {

    [dual_8bit]  = { .num_channels = 2, .resolution = 8  },

    [dual_10bit] = { .num_channels = 2, .resolution = 10 },

    [dual_12bit] = { .num_channels = 2, .resolution = 12 },

    [quad_8bit]  = { .num_channels = 4, .resolution = 8  },

    [quad_10bit] = { .num_channels = 4, .resolution = 10 },

    [quad_12bit] = { .num_channels = 4, .resolution = 12 },

};

​

/**

 * struct ti_dac_chip - TI DAC chip

 * @lock: protects write sequences

 * @vref: regulator generating Vref

 * @mesg: SPI message to perform a write

 * @xfer: SPI transfer used by @mesg

 * @val: cached value of each output

 * @powerdown: whether the chip is powered down

 * @powerdown_mode: selected by the user

 * @resolution: resolution of the chip

 * @buf: buffer for @xfer

 */

struct ti_dac_chip {

    struct mutex lock;

    struct regulator *vref;

    struct spi_message mesg;

    struct spi_transfer xfer;

    u16 val[4];

    bool powerdown;

    u8 powerdown_mode;

    u8 resolution;

    u8 buf[2] ____cacheline_aligned;

};

​

#define WRITE_NOT_UPDATE(chan)  (0x00 | (chan) << 6)

#define WRITE_AND_UPDATE(chan)  (0x10 | (chan) << 6)

#define WRITE_ALL_UPDATE     0x20

#define POWERDOWN(mode)     (0x30 | ((mode) + 1) << 6)

​

static int ti_dac_cmd(struct ti_dac_chip *ti_dac, u8 cmd, u16 val)

{

    u8 shift = 12 - ti_dac->resolution;

​

    ti_dac->buf[0] = cmd | (val >> (8 - shift));

    ti_dac->buf[1] = (val << shift) & 0xff;

    return spi_sync(ti_dac->mesg.spi, &ti_dac->mesg);

}

​

static const char * const ti_dac_powerdown_modes[] = {

    "2.5kohm_to_gnd", "100kohm_to_gnd", "three_state",

};

​

static int ti_dac_get_powerdown_mode(struct iio_dev *indio_dev,

                     const struct iio_chan_spec *chan)

{

    struct ti_dac_chip *ti_dac = iio_priv(indio_dev);

​

    return ti_dac->powerdown_mode;

}

​

static int ti_dac_set_powerdown_mode(struct iio_dev *indio_dev,

                     const struct iio_chan_spec *chan,

                     unsigned int mode)

{