linux-imx

/*

 * AD7303 Digital to analog converters driver

 *

 * Copyright 2013 Analog Devices Inc.

 *

 * Licensed under the GPL-2.

 */

​

#include <linux/err.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/spi/spi.h>

#include <linux/slab.h>

#include <linux/sysfs.h>

#include <linux/regulator/consumer.h>

#include <linux/of.h>

​

#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>

​

#include <linux/platform_data/ad7303.h>

​

#define AD7303_CFG_EXTERNAL_VREF BIT(15)

#define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))

#define AD7303_CFG_ADDR_OFFSET  10

​

#define AD7303_CMD_UPDATE_DAC   (0x3 << 8)

​

/**

 * struct ad7303_state - driver instance specific data

 * @spi:        the device for this driver instance

 * @config:     cached config register value

 * @dac_cache:      current DAC raw value (chip does not support readback)

 * @data:       spi transfer buffer

 */

​

struct ad7303_state {

    struct spi_device *spi;

    uint16_t config;

    uint8_t dac_cache[2];

​

    struct regulator *vdd_reg;

    struct regulator *vref_reg;

​

    /*

     * DMA (thus cache coherency maintenance) requires the

     * transfer buffers to live in their own cache lines.

     */

    __be16 data ____cacheline_aligned;

};

​

static int ad7303_write(struct ad7303_state *st, unsigned int chan,

    uint8_t val)

{

    st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |

        (chan << AD7303_CFG_ADDR_OFFSET) |

        st->config | val);

​

    return spi_write(st->spi, &st->data, sizeof(st->data));

}

​

static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,

    uintptr_t private, const struct iio_chan_spec *chan, char *buf)

{

    struct ad7303_state *st = iio_priv(indio_dev);

​

    return sprintf(buf, "%d\n", (bool)(st->config &

        AD7303_CFG_POWER_DOWN(chan->channel)));

}

​

static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,

     uintptr_t private, const struct iio_chan_spec *chan, const char *buf,

     size_t len)

{

    struct ad7303_state *st = iio_priv(indio_dev);

    bool pwr_down;

    int ret;

​

    ret = strtobool(buf, &pwr_down);

    if (ret)

        return ret;

​

    mutex_lock(&indio_dev->mlock);

​

    if (pwr_down)

        st->config |= AD7303_CFG_POWER_DOWN(chan->channel);

    else

        st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);

​

    /* There is no noop cmd which allows us to only update the powerdown

     * mode, so just write one of the DAC channels again */

    ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);