linux/drivers/iio/adc/mcp320x.c

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/*
* Copyright (C) 2013 Oskar Andero <oskar.andero@gmail.com>
*
* Driver for Microchip Technology's MCP3204 and MCP3208 ADC chips.
* Datasheet can be found here:
* http://ww1.microchip.com/downloads/en/devicedoc/21298c.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/err.h>
#include <linux/spi/spi.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/regulator/consumer.h>
#define MCP_SINGLE_ENDED (1 << 3)
#define MCP_START_BIT (1 << 4)
enum {
mcp3204,
mcp3208,
};
struct mcp320x {
struct spi_device *spi;
struct spi_message msg;
struct spi_transfer transfer[2];
u8 tx_buf;
u8 rx_buf[2];
struct regulator *reg;
struct mutex lock;
};
static int mcp320x_adc_conversion(struct mcp320x *adc, u8 msg)
{
int ret;
adc->tx_buf = msg;
ret = spi_sync(adc->spi, &adc->msg);
if (ret < 0)
return ret;
return ((adc->rx_buf[0] & 0x3f) << 6) |
(adc->rx_buf[1] >> 2);
}
static int mcp320x_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *channel, int *val,
int *val2, long mask)
{
struct mcp320x *adc = iio_priv(indio_dev);
int ret = -EINVAL;
mutex_lock(&adc->lock);
switch (mask) {
case IIO_CHAN_INFO_RAW:
if (channel->differential)
ret = mcp320x_adc_conversion(adc,
MCP_START_BIT | channel->address);
else
ret = mcp320x_adc_conversion(adc,
MCP_START_BIT | MCP_SINGLE_ENDED |
channel->address);
if (ret < 0)
goto out;
*val = ret;
ret = IIO_VAL_INT;
break;
case IIO_CHAN_INFO_SCALE:
/* Digital output code = (4096 * Vin) / Vref */
ret = regulator_get_voltage(adc->reg);
if (ret < 0)
goto out;
*val = ret / 1000;
*val2 = 12;
ret = IIO_VAL_FRACTIONAL_LOG2;
break;
default:
break;
}
out:
mutex_unlock(&adc->lock);
return ret;
}
#define MCP320X_VOLTAGE_CHANNEL(num) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (num), \
.address = (num), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
}
#define MCP320X_VOLTAGE_CHANNEL_DIFF(num) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (num * 2), \
.channel2 = (num * 2 + 1), \
.address = (num * 2), \
.differential = 1, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
}
static const struct iio_chan_spec mcp3204_channels[] = {
MCP320X_VOLTAGE_CHANNEL(0),
MCP320X_VOLTAGE_CHANNEL(1),
MCP320X_VOLTAGE_CHANNEL(2),
MCP320X_VOLTAGE_CHANNEL(3),
MCP320X_VOLTAGE_CHANNEL_DIFF(0),
MCP320X_VOLTAGE_CHANNEL_DIFF(1),
};
static const struct iio_chan_spec mcp3208_channels[] = {
MCP320X_VOLTAGE_CHANNEL(0),
MCP320X_VOLTAGE_CHANNEL(1),
MCP320X_VOLTAGE_CHANNEL(2),
MCP320X_VOLTAGE_CHANNEL(3),
MCP320X_VOLTAGE_CHANNEL(4),
MCP320X_VOLTAGE_CHANNEL(5),
MCP320X_VOLTAGE_CHANNEL(6),
MCP320X_VOLTAGE_CHANNEL(7),
MCP320X_VOLTAGE_CHANNEL_DIFF(0),
MCP320X_VOLTAGE_CHANNEL_DIFF(1),
MCP320X_VOLTAGE_CHANNEL_DIFF(2),
MCP320X_VOLTAGE_CHANNEL_DIFF(3),
};
static const struct iio_info mcp320x_info = {
.read_raw = mcp320x_read_raw,
.driver_module = THIS_MODULE,
};
struct mcp3208_chip_info {
const struct iio_chan_spec *channels;
unsigned int num_channels;
};
static const struct mcp3208_chip_info mcp3208_chip_infos[] = {
[mcp3204] = {
.channels = mcp3204_channels,
.num_channels = ARRAY_SIZE(mcp3204_channels)
},
[mcp3208] = {
.channels = mcp3208_channels,
.num_channels = ARRAY_SIZE(mcp3208_channels)
},
};
static int mcp320x_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct mcp320x *adc;
const struct mcp3208_chip_info *chip_info;
int ret;
indio_dev = iio_device_alloc(sizeof(*adc));
if (!indio_dev)
return -ENOMEM;
adc = iio_priv(indio_dev);
adc->spi = spi;
indio_dev->dev.parent = &spi->dev;
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &mcp320x_info;
chip_info = &mcp3208_chip_infos[spi_get_device_id(spi)->driver_data];
indio_dev->channels = chip_info->channels;
indio_dev->num_channels = chip_info->num_channels;
adc->transfer[0].tx_buf = &adc->tx_buf;
adc->transfer[0].len = sizeof(adc->tx_buf);
adc->transfer[1].rx_buf = adc->rx_buf;
adc->transfer[1].len = sizeof(adc->rx_buf);
spi_message_init_with_transfers(&adc->msg, adc->transfer,
ARRAY_SIZE(adc->transfer));
adc->reg = regulator_get(&spi->dev, "vref");
if (IS_ERR(adc->reg)) {
ret = PTR_ERR(adc->reg);
goto iio_free;
}
ret = regulator_enable(adc->reg);
if (ret < 0)
goto reg_free;
mutex_init(&adc->lock);
ret = iio_device_register(indio_dev);
if (ret < 0)
goto reg_disable;
return 0;
reg_disable:
regulator_disable(adc->reg);
reg_free:
regulator_put(adc->reg);
iio_free:
iio_device_free(indio_dev);
return ret;
}
static int mcp320x_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct mcp320x *adc = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
regulator_disable(adc->reg);
regulator_put(adc->reg);
iio_device_free(indio_dev);
return 0;
}
static const struct spi_device_id mcp320x_id[] = {
{ "mcp3204", mcp3204 },
{ "mcp3208", mcp3208 },
{ }
};
MODULE_DEVICE_TABLE(spi, mcp320x_id);
static struct spi_driver mcp320x_driver = {
.driver = {
.name = "mcp320x",
.owner = THIS_MODULE,
},
.probe = mcp320x_probe,
.remove = mcp320x_remove,
.id_table = mcp320x_id,
};
module_spi_driver(mcp320x_driver);
MODULE_AUTHOR("Oskar Andero <oskar.andero@gmail.com>");
MODULE_DESCRIPTION("Microchip Technology MCP3204/08");
MODULE_LICENSE("GPL v2");