adcxx.c

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/*
 * adcxx.c
 *
 * The adcxx4s is an AD converter family from National Semiconductor (NS).
 *
 * Copyright (c) 2008 Marc Pignat <[email protected]>
 *
 * The adcxx4s communicates with a host processor via an SPI/Microwire Bus
 * interface. This driver supports the whole family of devices with name
 * ADC<bb><c>S<sss>, where
 * * bb is the resolution in number of bits (8, 10, 12)
 * * c is the number of channels (1, 2, 4, 8)
 * * sss is the maximum conversion speed (021 for 200 kSPS, 051 for 500 kSPS
 *   and 101 for 1 MSPS)
 *
 * Complete datasheets are available at National's website here:
 * http://www.national.com/ds/DC/ADC<bb><c>S<sss>.pdf
 *
 * Handling of 8, 10 and 12 bits converters are the same, the
 * unavailable bits are 0 :)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/sysfs.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/mutex.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>

#define DRVNAME     "adcxx"

struct adcxx {
    struct device *hwmon_dev;
    struct mutex lock;
    u32 channels;
    u32 reference; /* in millivolts */
};

/* sysfs hook function */
static ssize_t adcxx_read(struct device *dev,
        struct device_attribute *devattr, char *buf)
{
    struct spi_device *spi = to_spi_device(dev);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
    struct adcxx *adc = spi_get_drvdata(spi);
    u8 tx_buf[2];
    u8 rx_buf[2];
    int status;
    u32 value;

    if (mutex_lock_interruptible(&adc->lock))
        return -ERESTARTSYS;

    if (adc->channels == 1) {
        status = spi_read(spi, rx_buf, sizeof(rx_buf));
    } else {
        tx_buf[0] = attr->index << 3; /* other bits are don't care */
        status = spi_write_then_read(spi, tx_buf, sizeof(tx_buf),
                        rx_buf, sizeof(rx_buf));
    }
    if (status < 0) {
        dev_warn(dev, "SPI synch. transfer failed with status %d\n",
                status);
        goto out;
    }

    value = (rx_buf[0] << 8) + rx_buf[1];
    dev_dbg(dev, "raw value = 0x%x\n", value);

    value = value * adc->reference >> 12;
    status = sprintf(buf, "%d\n", value);
out:
    mutex_unlock(&adc->lock);
    return status;
}

static ssize_t adcxx_show_min(struct device *dev,
        struct device_attribute *devattr, char *buf)
{
    /* The minimum reference is 0 for this chip family */
    return sprintf(buf, "0\n");
}

static ssize_t adcxx_show_max(struct device *dev,
        struct device_attribute *devattr, char *buf)
{
    struct spi_device *spi = to_spi_device(dev);
    struct adcxx *adc = spi_get_drvdata(spi);
    u32 reference;

    if (mutex_lock_interruptible(&adc->lock))
        return -ERESTARTSYS;

    reference = adc->reference;

    mutex_unlock(&adc->lock);

    return sprintf(buf, "%d\n", reference);
}

static ssize_t adcxx_set_max(struct device *dev,
    struct device_attribute *devattr, const char *buf, size_t count)
{
    struct spi_device *spi = to_spi_device(dev);
    struct adcxx *adc = spi_get_drvdata(spi);
    unsigned long value;

    if (kstrtoul(buf, 10, &value))
        return -EINVAL;

    if (mutex_lock_interruptible(&adc->lock))
        return -ERESTARTSYS;

    adc->reference = value;

    mutex_unlock(&adc->lock);

    return count;
}

static ssize_t adcxx_show_name(struct device *dev, struct device_attribute
                  *devattr, char *buf)
{
    return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
}

static struct sensor_device_attribute ad_input[] = {
    SENSOR_ATTR(name, S_IRUGO, adcxx_show_name, NULL, 0),
    SENSOR_ATTR(in_min, S_IRUGO, adcxx_show_min, NULL, 0),
    SENSOR_ATTR(in_max, S_IWUSR | S_IRUGO, adcxx_show_max,
                    adcxx_set_max, 0),
    SENSOR_ATTR(in0_input, S_IRUGO, adcxx_read, NULL, 0),
    SENSOR_ATTR(in1_input, S_IRUGO, adcxx_read, NULL, 1),
    SENSOR_ATTR(in2_input, S_IRUGO, adcxx_read, NULL, 2),
    SENSOR_ATTR(in3_input, S_IRUGO, adcxx_read, NULL, 3),
    SENSOR_ATTR(in4_input, S_IRUGO, adcxx_read, NULL, 4),
    SENSOR_ATTR(in5_input, S_IRUGO, adcxx_read, NULL, 5),
    SENSOR_ATTR(in6_input, S_IRUGO, adcxx_read, NULL, 6),
    SENSOR_ATTR(in7_input, S_IRUGO, adcxx_read, NULL, 7),
};

/*----------------------------------------------------------------------*/

static int __devinit adcxx_probe(struct spi_device *spi)
{
    int channels = spi_get_device_id(spi)->driver_data;
    struct adcxx *adc;
    int status;
    int i;

    adc = devm_kzalloc(&spi->dev, sizeof(*adc), GFP_KERNEL);
    if (!adc)
        return -ENOMEM;

    /* set a default value for the reference */
    adc->reference = 3300;
    adc->channels = channels;
    mutex_init(&adc->lock);

    mutex_lock(&adc->lock);

    spi_set_drvdata(spi, adc);

    for (i = 0; i < 3 + adc->channels; i++) {
        status = device_create_file(&spi->dev, &ad_input[i].dev_attr);
        if (status) {
            dev_err(&spi->dev, "device_create_file failed.\n");
            goto out_err;
        }
    }

    adc->hwmon_dev = hwmon_device_register(&spi->dev);
    if (IS_ERR(adc->hwmon_dev)) {
        dev_err(&spi->dev, "hwmon_device_register failed.\n");
        status = PTR_ERR(adc->hwmon_dev);
        goto out_err;
    }

    mutex_unlock(&adc->lock);
    return 0;

out_err:
    for (i--; i >= 0; i--)
        device_remove_file(&spi->dev, &ad_input[i].dev_attr);

    spi_set_drvdata(spi, NULL);
    mutex_unlock(&adc->lock);
    return status;
}

static int __devexit adcxx_remove(struct spi_device *spi)
{
    struct adcxx *adc = spi_get_drvdata(spi);
    int i;

    mutex_lock(&adc->lock);
    hwmon_device_unregister(adc->hwmon_dev);
    for (i = 0; i < 3 + adc->channels; i++)
        device_remove_file(&spi->dev, &ad_input[i].dev_attr);

    spi_set_drvdata(spi, NULL);
    mutex_unlock(&adc->lock);

    return 0;
}

static const struct spi_device_id adcxx_ids[] = {
    { "adcxx1s", 1 },
    { "adcxx2s", 2 },
    { "adcxx4s", 4 },
    { "adcxx8s", 8 },
    { },
};
MODULE_DEVICE_TABLE(spi, adcxx_ids);

static struct spi_driver adcxx_driver = {
    .driver = {
        .name   = "adcxx",
        .owner  = THIS_MODULE,
    },
    .id_table = adcxx_ids,
    .probe  = adcxx_probe,
    .remove = __devexit_p(adcxx_remove),
};

module_spi_driver(adcxx_driver);

MODULE_AUTHOR("Marc Pignat");
MODULE_DESCRIPTION("National Semiconductor adcxx8sxxx Linux driver");
MODULE_LICENSE("GPL");