ad714x-spi.c

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/*
 * AD714X CapTouch Programmable Controller driver (SPI bus)
 *
 * Copyright 2009-2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/input.h>    /* BUS_SPI */
#include <linux/module.h>
#include <linux/spi/spi.h>
#include <linux/pm.h>
#include <linux/types.h>
#include "ad714x.h"

#define AD714x_SPI_CMD_PREFIX      0xE000   /* bits 15:11 */
#define AD714x_SPI_READ            BIT(10)

#ifdef CONFIG_PM
static int ad714x_spi_suspend(struct device *dev)
{
    return ad714x_disable(spi_get_drvdata(to_spi_device(dev)));
}

static int ad714x_spi_resume(struct device *dev)
{
    return ad714x_enable(spi_get_drvdata(to_spi_device(dev)));
}
#endif

static SIMPLE_DEV_PM_OPS(ad714x_spi_pm, ad714x_spi_suspend, ad714x_spi_resume);

static int ad714x_spi_read(struct ad714x_chip *chip,
               unsigned short reg, unsigned short *data, size_t len)
{
    struct spi_device *spi = to_spi_device(chip->dev);
    struct spi_message message;
    struct spi_transfer xfer[2];
    int i;
    int error;

    spi_message_init(&message);
    memset(xfer, 0, sizeof(xfer));

    chip->xfer_buf[0] = cpu_to_be16(AD714x_SPI_CMD_PREFIX |
                    AD714x_SPI_READ | reg);
    xfer[0].tx_buf = &chip->xfer_buf[0];
    xfer[0].len = sizeof(chip->xfer_buf[0]);
    spi_message_add_tail(&xfer[0], &message);

    xfer[1].rx_buf = &chip->xfer_buf[1];
    xfer[1].len = sizeof(chip->xfer_buf[1]) * len;
    spi_message_add_tail(&xfer[1], &message);

    error = spi_sync(spi, &message);
    if (unlikely(error)) {
        dev_err(chip->dev, "SPI read error: %d\n", error);
        return error;
    }

    for (i = 0; i < len; i++)
        data[i] = be16_to_cpu(chip->xfer_buf[i + 1]);

    return 0;
}

static int ad714x_spi_write(struct ad714x_chip *chip,
                unsigned short reg, unsigned short data)
{
    struct spi_device *spi = to_spi_device(chip->dev);
    int error;

    chip->xfer_buf[0] = cpu_to_be16(AD714x_SPI_CMD_PREFIX | reg);
    chip->xfer_buf[1] = cpu_to_be16(data);

    error = spi_write(spi, (u8 *)chip->xfer_buf,
              2 * sizeof(*chip->xfer_buf));
    if (unlikely(error)) {
        dev_err(chip->dev, "SPI write error: %d\n", error);
        return error;
    }

    return 0;
}

static int __devinit ad714x_spi_probe(struct spi_device *spi)
{
    struct ad714x_chip *chip;
    int err;

    spi->bits_per_word = 8;
    err = spi_setup(spi);
    if (err < 0)
        return err;

    chip = ad714x_probe(&spi->dev, BUS_SPI, spi->irq,
                ad714x_spi_read, ad714x_spi_write);
    if (IS_ERR(chip))
        return PTR_ERR(chip);

    spi_set_drvdata(spi, chip);

    return 0;
}

static int __devexit ad714x_spi_remove(struct spi_device *spi)
{
    struct ad714x_chip *chip = spi_get_drvdata(spi);

    ad714x_remove(chip);
    spi_set_drvdata(spi, NULL);

    return 0;
}

static struct spi_driver ad714x_spi_driver = {
    .driver = {
        .name   = "ad714x_captouch",
        .owner  = THIS_MODULE,
        .pm = &ad714x_spi_pm,
    },
    .probe      = ad714x_spi_probe,
    .remove     = __devexit_p(ad714x_spi_remove),
};

module_spi_driver(ad714x_spi_driver);

MODULE_DESCRIPTION("Analog Devices AD714X Capacitance Touch Sensor SPI Bus Driver");
MODULE_AUTHOR("Barry Song <[email protected]>");
MODULE_LICENSE("GPL");