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linux/drivers/iio/adc/ad7476.c
Lars-Peter Clausen 87c5b10fd9 iio: ad7476: Add support for the ad7091r 
Add support for the ad7091r 12 bit ADC to the ad7476 driver. Although the
ad7091r is not really related to any of the other devices supported by this
driver, luckily for us there are not so many ways (which are not totally insane)
how sampling a single channel ADC via SPI can be implemented and support for the
ad7091r can be added to the driver with just a few adjustments.

The ad7091r requires an external "conversion start" pulse to start a sample
conversion. After the conversion has finished the result can be read via SPI. We
depend on a IIO trigger to generate this signal, as a result only sampling in
buffered mode and not in manual mode is available.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
2012-09-17 22:10:00 +01:00

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/*
* AD7466/7/8 AD7476/5/7/8 (A) SPI ADC driver
*
* Copyright 2010 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/spi/spi.h>
#include <linux/regulator/consumer.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#define RES_MASK(bits) ((1 << (bits)) - 1)
struct ad7476_state;
struct ad7476_chip_info {
unsigned int int_vref_uv;
struct iio_chan_spec channel[2];
void (*reset)(struct ad7476_state *);
};
struct ad7476_state {
struct spi_device *spi;
const struct ad7476_chip_info *chip_info;
struct regulator *reg;
struct spi_transfer xfer;
struct spi_message msg;
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
* Make the buffer large enough for one 16 bit sample and one 64 bit
* aligned 64 bit timestamp.
*/
unsigned char data[ALIGN(2, sizeof(s64)) + sizeof(s64)]
____cacheline_aligned;
};
enum ad7476_supported_device_ids {
ID_AD7091R,
ID_AD7276,
ID_AD7277,
ID_AD7278,
ID_AD7466,
ID_AD7467,
ID_AD7468,
ID_AD7495,
ID_AD7940,
};
static irqreturn_t ad7476_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct ad7476_state *st = iio_priv(indio_dev);
s64 time_ns;
int b_sent;
b_sent = spi_sync(st->spi, &st->msg);
if (b_sent < 0)
goto done;
time_ns = iio_get_time_ns();
if (indio_dev->scan_timestamp)
((s64 *)st->data)[1] = time_ns;
iio_push_to_buffer(indio_dev->buffer, st->data);
done:
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
}
static void ad7091_reset(struct ad7476_state *st)
{
/* Any transfers with 8 scl cycles will reset the device */
spi_read(st->spi, st->data, 1);
}
static int ad7476_scan_direct(struct ad7476_state *st)
{
int ret;
ret = spi_sync(st->spi, &st->msg);
if (ret)
return ret;
return be16_to_cpup((__be16 *)st->data);
}
static int ad7476_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val,
int *val2,
long m)
{
int ret;
struct ad7476_state *st = iio_priv(indio_dev);
int scale_uv;
switch (m) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&indio_dev->mlock);
if (iio_buffer_enabled(indio_dev))
ret = -EBUSY;
else
ret = ad7476_scan_direct(st);
mutex_unlock(&indio_dev->mlock);
if (ret < 0)
return ret;
*val = (ret >> st->chip_info->channel[0].scan_type.shift) &
RES_MASK(st->chip_info->channel[0].scan_type.realbits);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
if (!st->chip_info->int_vref_uv) {
scale_uv = regulator_get_voltage(st->reg);
if (scale_uv < 0)
return scale_uv;
} else {
scale_uv = st->chip_info->int_vref_uv;
}
scale_uv >>= chan->scan_type.realbits;
*val = scale_uv / 1000;
*val2 = (scale_uv % 1000) * 1000;
return IIO_VAL_INT_PLUS_MICRO;
}
return -EINVAL;
}
#define _AD7476_CHAN(bits, _shift, _info_mask) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.info_mask = _info_mask | \
IIO_CHAN_INFO_SCALE_SHARED_BIT, \
.scan_type = { \
.sign = 'u', \
.realbits = (bits), \
.storagebits = 16, \
.shift = (_shift), \
.endianness = IIO_BE, \
}, \
}
#define AD7476_CHAN(bits) _AD7476_CHAN((bits), 13 - (bits), \
IIO_CHAN_INFO_RAW_SEPARATE_BIT)
#define AD7940_CHAN(bits) _AD7476_CHAN((bits), 15 - (bits), \
IIO_CHAN_INFO_RAW_SEPARATE_BIT)
#define AD7091R_CHAN(bits) _AD7476_CHAN((bits), 16 - (bits), 0)
static const struct ad7476_chip_info ad7476_chip_info_tbl[] = {
[ID_AD7091R] = {
.channel[0] = AD7091R_CHAN(12),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
.reset = ad7091_reset,
},
[ID_AD7276] = {
.channel[0] = AD7940_CHAN(12),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
},
[ID_AD7277] = {
.channel[0] = AD7940_CHAN(10),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
},
[ID_AD7278] = {
.channel[0] = AD7940_CHAN(8),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
},
[ID_AD7466] = {
.channel[0] = AD7476_CHAN(12),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
},
[ID_AD7467] = {
.channel[0] = AD7476_CHAN(10),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
},
[ID_AD7468] = {
.channel[0] = AD7476_CHAN(8),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
},
[ID_AD7495] = {
.channel[0] = AD7476_CHAN(12),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
.int_vref_uv = 2500000,
},
[ID_AD7940] = {
.channel[0] = AD7940_CHAN(14),
.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
},
};
static const struct iio_info ad7476_info = {
.driver_module = THIS_MODULE,
.read_raw = &ad7476_read_raw,
};
static int __devinit ad7476_probe(struct spi_device *spi)
{
struct ad7476_state *st;
struct iio_dev *indio_dev;
int ret;
indio_dev = iio_device_alloc(sizeof(*st));
if (indio_dev == NULL) {
ret = -ENOMEM;
goto error_ret;
}
st = iio_priv(indio_dev);
st->chip_info =
&ad7476_chip_info_tbl[spi_get_device_id(spi)->driver_data];
st->reg = regulator_get(&spi->dev, "vcc");
if (IS_ERR(st->reg)) {
ret = PTR_ERR(st->reg);
goto error_free_dev;
}
ret = regulator_enable(st->reg);
if (ret)
goto error_put_reg;
spi_set_drvdata(spi, indio_dev);
st->spi = spi;
/* Establish that the iio_dev is a child of the spi device */
indio_dev->dev.parent = &spi->dev;
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = st->chip_info->channel;
indio_dev->num_channels = 2;
indio_dev->info = &ad7476_info;
/* Setup default message */
st->xfer.rx_buf = &st->data;
st->xfer.len = st->chip_info->channel[0].scan_type.storagebits / 8;
spi_message_init(&st->msg);
spi_message_add_tail(&st->xfer, &st->msg);
ret = iio_triggered_buffer_setup(indio_dev, NULL,
&ad7476_trigger_handler, NULL);
if (ret)
goto error_disable_reg;
if (st->chip_info->reset)
st->chip_info->reset(st);
ret = iio_device_register(indio_dev);
if (ret)
goto error_ring_unregister;
return 0;
error_ring_unregister:
iio_triggered_buffer_cleanup(indio_dev);
error_disable_reg:
regulator_disable(st->reg);
error_put_reg:
regulator_put(st->reg);
error_free_dev:
iio_device_free(indio_dev);
error_ret:
return ret;
}
static int __devexit ad7476_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct ad7476_state *st = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
iio_triggered_buffer_cleanup(indio_dev);
regulator_disable(st->reg);
regulator_put(st->reg);
iio_device_free(indio_dev);
return 0;
}
static const struct spi_device_id ad7476_id[] = {
{"ad7091r", ID_AD7091R},
{"ad7273", ID_AD7277},
{"ad7274", ID_AD7276},
{"ad7276", ID_AD7276},
{"ad7277", ID_AD7277},
{"ad7278", ID_AD7278},
{"ad7466", ID_AD7466},
{"ad7467", ID_AD7467},
{"ad7468", ID_AD7468},
{"ad7475", ID_AD7466},
{"ad7476", ID_AD7466},
{"ad7476a", ID_AD7466},
{"ad7477", ID_AD7467},
{"ad7477a", ID_AD7467},
{"ad7478", ID_AD7468},
{"ad7478a", ID_AD7468},
{"ad7495", ID_AD7495},
{"ad7910", ID_AD7467},
{"ad7920", ID_AD7466},
{"ad7940", ID_AD7940},
{}
};
MODULE_DEVICE_TABLE(spi, ad7476_id);
static struct spi_driver ad7476_driver = {
.driver = {
.name = "ad7476",
.owner = THIS_MODULE,
},
.probe = ad7476_probe,
.remove = __devexit_p(ad7476_remove),
.id_table = ad7476_id,
};
module_spi_driver(ad7476_driver);
MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("Analog Devices AD7476 and similar 1-channel ADCs");
MODULE_LICENSE("GPL v2");
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