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linux/drivers/iio/adc/mcp320x.c
Lukas Wunner e6f4794371 iio: adc: mcp320x: Fix readout of negative voltages 
Commit f686a36b4b79 ("iio: adc: mcp320x: Add support for mcp3301")
returns a signed voltage from mcp320x_adc_conversion() but neglects that
the caller interprets a negative return value as failure.  Only mcp3301
(and the upcoming mcp3550/1/3) is affected as the other chips are
incapable of measuring negative voltages.

Fix and while at it, add mcp3301 to the list of supported chips at the
top of the file.

Fixes: f686a36b4b79 ("iio: adc: mcp320x: Add support for mcp3301")
Cc: Andrea Galbusera <gizero@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2017-09-24 16:58:10 +01:00

461 lines
11 KiB
C
Raw Blame History

/*
* Copyright (C) 2013 Oskar Andero <oskar.andero@gmail.com>
* Copyright (C) 2014 Rose Technology
* Allan Bendorff Jensen <abj@rosetechnology.dk>
* Soren Andersen <san@rosetechnology.dk>
*
* Driver for following ADC chips from Microchip Technology's:
* 10 Bit converter
* MCP3001
* MCP3002
* MCP3004
* MCP3008
* ------------
* 12 bit converter
* MCP3201
* MCP3202
* MCP3204
* MCP3208
* ------------
* 13 bit converter
* MCP3301
*
* Datasheet can be found here:
* http://ww1.microchip.com/downloads/en/DeviceDoc/21293C.pdf mcp3001
* http://ww1.microchip.com/downloads/en/DeviceDoc/21294E.pdf mcp3002
* http://ww1.microchip.com/downloads/en/DeviceDoc/21295d.pdf mcp3004/08
* http://ww1.microchip.com/downloads/en/DeviceDoc/21290D.pdf mcp3201
* http://ww1.microchip.com/downloads/en/DeviceDoc/21034D.pdf mcp3202
* http://ww1.microchip.com/downloads/en/DeviceDoc/21298c.pdf mcp3204/08
* http://ww1.microchip.com/downloads/en/DeviceDoc/21700E.pdf mcp3301
*
* 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/delay.h>
#include <linux/spi/spi.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/regulator/consumer.h>
enum {
mcp3001,
mcp3002,
mcp3004,
mcp3008,
mcp3201,
mcp3202,
mcp3204,
mcp3208,
mcp3301,
};
struct mcp320x_chip_info {
const struct iio_chan_spec *channels;
unsigned int num_channels;
unsigned int resolution;
};
struct mcp320x {
struct spi_device *spi;
struct spi_message msg;
struct spi_transfer transfer[2];
struct regulator *reg;
struct mutex lock;
const struct mcp320x_chip_info *chip_info;
u8 tx_buf ____cacheline_aligned;
u8 rx_buf[2];
};
static int mcp320x_channel_to_tx_data(int device_index,
const unsigned int channel, bool differential)
{
int start_bit = 1;
switch (device_index) {
case mcp3001:
case mcp3201:
case mcp3301:
return 0;
case mcp3002:
case mcp3202:
return ((start_bit << 4) | (!differential << 3) |
(channel << 2));
case mcp3004:
case mcp3204:
case mcp3008:
case mcp3208:
return ((start_bit << 6) | (!differential << 5) |
(channel << 2));
default:
return -EINVAL;
}
}
static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel,
bool differential, int device_index, int *val)
{
int ret;
adc->rx_buf[0] = 0;
adc->rx_buf[1] = 0;
adc->tx_buf = mcp320x_channel_to_tx_data(device_index,
channel, differential);
if (device_index != mcp3001 && device_index != mcp3201 && device_index != mcp3301) {
ret = spi_sync(adc->spi, &adc->msg);
if (ret < 0)
return ret;
} else {
ret = spi_read(adc->spi, &adc->rx_buf, sizeof(adc->rx_buf));
if (ret < 0)
return ret;
}
switch (device_index) {
case mcp3001:
*val = (adc->rx_buf[0] << 5 | adc->rx_buf[1] >> 3);
return 0;
case mcp3002:
case mcp3004:
case mcp3008:
*val = (adc->rx_buf[0] << 2 | adc->rx_buf[1] >> 6);
return 0;
case mcp3201:
*val = (adc->rx_buf[0] << 7 | adc->rx_buf[1] >> 1);
return 0;
case mcp3202:
case mcp3204:
case mcp3208:
*val = (adc->rx_buf[0] << 4 | adc->rx_buf[1] >> 4);
return 0;
case mcp3301:
*val = sign_extend32((adc->rx_buf[0] & 0x1f) << 8
| adc->rx_buf[1], 12);
return 0;
default:
return -EINVAL;
}
}
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;
int device_index = 0;
mutex_lock(&adc->lock);
device_index = spi_get_device_id(adc->spi)->driver_data;
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = mcp320x_adc_conversion(adc, channel->address,
channel->differential, device_index, val);
if (ret < 0)
goto out;
ret = IIO_VAL_INT;
break;
case IIO_CHAN_INFO_SCALE:
ret = regulator_get_voltage(adc->reg);
if (ret < 0)
goto out;
/* convert regulator output voltage to mV */
*val = ret / 1000;
*val2 = adc->chip_info->resolution;
ret = IIO_VAL_FRACTIONAL_LOG2;
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(chan1, chan2) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (chan1), \
.channel2 = (chan2), \
.address = (chan1), \
.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 mcp3201_channels[] = {
MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),
};
static const struct iio_chan_spec mcp3202_channels[] = {
MCP320X_VOLTAGE_CHANNEL(0),
MCP320X_VOLTAGE_CHANNEL(1),
MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),
MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),
};
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, 1),
MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),
MCP320X_VOLTAGE_CHANNEL_DIFF(2, 3),
MCP320X_VOLTAGE_CHANNEL_DIFF(3, 2),
};
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, 1),
MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),
MCP320X_VOLTAGE_CHANNEL_DIFF(2, 3),
MCP320X_VOLTAGE_CHANNEL_DIFF(3, 2),
MCP320X_VOLTAGE_CHANNEL_DIFF(4, 5),
MCP320X_VOLTAGE_CHANNEL_DIFF(5, 4),
MCP320X_VOLTAGE_CHANNEL_DIFF(6, 7),
MCP320X_VOLTAGE_CHANNEL_DIFF(7, 6),
};
static const struct iio_info mcp320x_info = {
.read_raw = mcp320x_read_raw,
.driver_module = THIS_MODULE,
};
static const struct mcp320x_chip_info mcp320x_chip_infos[] = {
[mcp3001] = {
.channels = mcp3201_channels,
.num_channels = ARRAY_SIZE(mcp3201_channels),
.resolution = 10
},
[mcp3002] = {
.channels = mcp3202_channels,
.num_channels = ARRAY_SIZE(mcp3202_channels),
.resolution = 10
},
[mcp3004] = {
.channels = mcp3204_channels,
.num_channels = ARRAY_SIZE(mcp3204_channels),
.resolution = 10
},
[mcp3008] = {
.channels = mcp3208_channels,
.num_channels = ARRAY_SIZE(mcp3208_channels),
.resolution = 10
},
[mcp3201] = {
.channels = mcp3201_channels,
.num_channels = ARRAY_SIZE(mcp3201_channels),
.resolution = 12
},
[mcp3202] = {
.channels = mcp3202_channels,
.num_channels = ARRAY_SIZE(mcp3202_channels),
.resolution = 12
},
[mcp3204] = {
.channels = mcp3204_channels,
.num_channels = ARRAY_SIZE(mcp3204_channels),
.resolution = 12
},
[mcp3208] = {
.channels = mcp3208_channels,
.num_channels = ARRAY_SIZE(mcp3208_channels),
.resolution = 12
},
[mcp3301] = {
.channels = mcp3201_channels,
.num_channels = ARRAY_SIZE(mcp3201_channels),
.resolution = 13
},
};
static int mcp320x_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct mcp320x *adc;
const struct mcp320x_chip_info *chip_info;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
if (!indio_dev)
return -ENOMEM;
adc = iio_priv(indio_dev);
adc->spi = spi;
indio_dev->dev.parent = &spi->dev;
indio_dev->dev.of_node = spi->dev.of_node;
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &mcp320x_info;
spi_set_drvdata(spi, indio_dev);
chip_info = &mcp320x_chip_infos[spi_get_device_id(spi)->driver_data];
indio_dev->channels = chip_info->channels;
indio_dev->num_channels = chip_info->num_channels;
adc->chip_info = chip_info;
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 = devm_regulator_get(&spi->dev, "vref");
if (IS_ERR(adc->reg))
return PTR_ERR(adc->reg);
ret = regulator_enable(adc->reg);
if (ret < 0)
return ret;
mutex_init(&adc->lock);
ret = iio_device_register(indio_dev);
if (ret < 0)
goto reg_disable;
return 0;
reg_disable:
regulator_disable(adc->reg);
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);
return 0;
}
#if defined(CONFIG_OF)
static const struct of_device_id mcp320x_dt_ids[] = {
/* NOTE: The use of compatibles with no vendor prefix is deprecated. */
{
.compatible = "mcp3001",
.data = &mcp320x_chip_infos[mcp3001],
}, {
.compatible = "mcp3002",
.data = &mcp320x_chip_infos[mcp3002],
}, {
.compatible = "mcp3004",
.data = &mcp320x_chip_infos[mcp3004],
}, {
.compatible = "mcp3008",
.data = &mcp320x_chip_infos[mcp3008],
}, {
.compatible = "mcp3201",
.data = &mcp320x_chip_infos[mcp3201],
}, {
.compatible = "mcp3202",
.data = &mcp320x_chip_infos[mcp3202],
}, {
.compatible = "mcp3204",
.data = &mcp320x_chip_infos[mcp3204],
}, {
.compatible = "mcp3208",
.data = &mcp320x_chip_infos[mcp3208],
}, {
.compatible = "mcp3301",
.data = &mcp320x_chip_infos[mcp3301],
}, {
.compatible = "microchip,mcp3001",
.data = &mcp320x_chip_infos[mcp3001],
}, {
.compatible = "microchip,mcp3002",
.data = &mcp320x_chip_infos[mcp3002],
}, {
.compatible = "microchip,mcp3004",
.data = &mcp320x_chip_infos[mcp3004],
}, {
.compatible = "microchip,mcp3008",
.data = &mcp320x_chip_infos[mcp3008],
}, {
.compatible = "microchip,mcp3201",
.data = &mcp320x_chip_infos[mcp3201],
}, {
.compatible = "microchip,mcp3202",
.data = &mcp320x_chip_infos[mcp3202],
}, {
.compatible = "microchip,mcp3204",
.data = &mcp320x_chip_infos[mcp3204],
}, {
.compatible = "microchip,mcp3208",
.data = &mcp320x_chip_infos[mcp3208],
}, {
.compatible = "microchip,mcp3301",
.data = &mcp320x_chip_infos[mcp3301],
}, {
}
};
MODULE_DEVICE_TABLE(of, mcp320x_dt_ids);
#endif
static const struct spi_device_id mcp320x_id[] = {
{ "mcp3001", mcp3001 },
{ "mcp3002", mcp3002 },
{ "mcp3004", mcp3004 },
{ "mcp3008", mcp3008 },
{ "mcp3201", mcp3201 },
{ "mcp3202", mcp3202 },
{ "mcp3204", mcp3204 },
{ "mcp3208", mcp3208 },
{ "mcp3301", mcp3301 },
{ }
};
MODULE_DEVICE_TABLE(spi, mcp320x_id);
static struct spi_driver mcp320x_driver = {
.driver = {
.name = "mcp320x",
.of_match_table = of_match_ptr(mcp320x_dt_ids),
},
.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 MCP3x01/02/04/08");
MODULE_LICENSE("GPL v2");
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