linux-imx

/*

 * max1111.c - +2.7V, Low-Power, Multichannel, Serial 8-bit ADCs

 *

 * Based on arch/arm/mach-pxa/corgi_ssp.c

 *

 * Copyright (C) 2004-2005 Richard Purdie

 *

 * Copyright (C) 2008 Marvell International Ltd.

 *  Eric Miao <eric.miao@marvell.com>

 *

 *  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

 *  publishhed by the Free Software Foundation.

 */

​

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/err.h>

#include <linux/hwmon.h>

#include <linux/hwmon-sysfs.h>

#include <linux/spi/spi.h>

#include <linux/slab.h>

​

enum chips { max1110, max1111, max1112, max1113 };

​

#define MAX1111_TX_BUF_SIZE 1

#define MAX1111_RX_BUF_SIZE 2

​

/* MAX1111 Commands */

#define MAX1111_CTRL_PD0      (1u << 0)

#define MAX1111_CTRL_PD1      (1u << 1)

#define MAX1111_CTRL_SGL      (1u << 2)

#define MAX1111_CTRL_UNI      (1u << 3)

#define MAX1110_CTRL_SEL_SH   (4)

#define MAX1111_CTRL_SEL_SH   (5)   /* NOTE: bit 4 is ignored */

#define MAX1111_CTRL_STR      (1u << 7)

​

struct max1111_data {

    struct spi_device   *spi;

    struct device       *hwmon_dev;

    struct spi_message  msg;

    struct spi_transfer xfer[2];

    uint8_t tx_buf[MAX1111_TX_BUF_SIZE];

    uint8_t rx_buf[MAX1111_RX_BUF_SIZE];

    struct mutex        drvdata_lock;

    /* protect msg, xfer and buffers from multiple access */

    int         sel_sh;

    int         lsb;

};

​

static int max1111_read(struct device *dev, int channel)

{

    struct max1111_data *data = dev_get_drvdata(dev);

    uint8_t v1, v2;

    int err;

​

    /* writing to drvdata struct is not thread safe, wait on mutex */

    mutex_lock(&data->drvdata_lock);

​

    data->tx_buf[0] = (channel << data->sel_sh) |

        MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |

        MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;

​

    err = spi_sync(data->spi, &data->msg);

    if (err < 0) {

        dev_err(dev, "spi_sync failed with %d\n", err);

        mutex_unlock(&data->drvdata_lock);

        return err;

    }

​

    v1 = data->rx_buf[0];

    v2 = data->rx_buf[1];

​

    mutex_unlock(&data->drvdata_lock);

​

    if ((v1 & 0xc0) || (v2 & 0x3f))

        return -EINVAL;

​

    return (v1 << 2) | (v2 >> 6);

}

​

#ifdef CONFIG_SHARPSL_PM

static struct max1111_data *the_max1111;

​

int max1111_read_channel(int channel)

{

    if (!the_max1111 || !the_max1111->spi)

        return -ENODEV;

​

    return max1111_read(&the_max1111->spi->dev, channel);

}