swh:1:snp:c3bf2749e3476071fa748f67b0ffa2fdc5fe49d9
Tip revision: 5e01dc7b26d9f24f39abace5da98ccbd6a5ceb52 authored by Linus Torvalds on 03 November 2013, 23:41:51 UTC
Linux 3.12
Linux 3.12
Tip revision: 5e01dc7
ad7303.c
/*
* AD7303 Digital to analog converters driver
*
* Copyright 2013 Analog Devices Inc.
*
* Licensed under the GPL-2.
*/
#include <linux/err.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/regulator/consumer.h>
#include <linux/of.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/platform_data/ad7303.h>
#define AD7303_CFG_EXTERNAL_VREF BIT(15)
#define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
#define AD7303_CFG_ADDR_OFFSET 10
#define AD7303_CMD_UPDATE_DAC (0x3 << 8)
/**
* struct ad7303_state - driver instance specific data
* @spi: the device for this driver instance
* @config: cached config register value
* @dac_cache: current DAC raw value (chip does not support readback)
* @data: spi transfer buffer
*/
struct ad7303_state {
struct spi_device *spi;
uint16_t config;
uint8_t dac_cache[2];
struct regulator *vdd_reg;
struct regulator *vref_reg;
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
*/
__be16 data ____cacheline_aligned;
};
static int ad7303_write(struct ad7303_state *st, unsigned int chan,
uint8_t val)
{
st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |
(chan << AD7303_CFG_ADDR_OFFSET) |
st->config | val);
return spi_write(st->spi, &st->data, sizeof(st->data));
}
static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,
uintptr_t private, const struct iio_chan_spec *chan, char *buf)
{
struct ad7303_state *st = iio_priv(indio_dev);
return sprintf(buf, "%d\n", (bool)(st->config &
AD7303_CFG_POWER_DOWN(chan->channel)));
}
static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
size_t len)
{
struct ad7303_state *st = iio_priv(indio_dev);
bool pwr_down;
int ret;
ret = strtobool(buf, &pwr_down);
if (ret)
return ret;
mutex_lock(&indio_dev->mlock);
if (pwr_down)
st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
else
st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);
/* There is no noop cmd which allows us to only update the powerdown
* mode, so just write one of the DAC channels again */
ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);
mutex_unlock(&indio_dev->mlock);
return ret ? ret : len;
}
static int ad7303_get_vref(struct ad7303_state *st,
struct iio_chan_spec const *chan)
{
int ret;
if (st->config & AD7303_CFG_EXTERNAL_VREF)
return regulator_get_voltage(st->vref_reg);
ret = regulator_get_voltage(st->vdd_reg);
if (ret < 0)
return ret;
return ret / 2;
}
static int ad7303_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val, int *val2, long info)
{
struct ad7303_state *st = iio_priv(indio_dev);
int vref_uv;
switch (info) {
case IIO_CHAN_INFO_RAW:
*val = st->dac_cache[chan->channel];
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
vref_uv = ad7303_get_vref(st, chan);
if (vref_uv < 0)
return vref_uv;
*val = 2 * vref_uv / 1000;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
default:
break;
}
return -EINVAL;
}
static int ad7303_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int val, int val2, long mask)
{
struct ad7303_state *st = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
if (val >= (1 << chan->scan_type.realbits) || val < 0)
return -EINVAL;
mutex_lock(&indio_dev->mlock);
ret = ad7303_write(st, chan->address, val);
if (ret == 0)
st->dac_cache[chan->channel] = val;
mutex_unlock(&indio_dev->mlock);
break;
default:
ret = -EINVAL;
}
return ret;
}
static const struct iio_info ad7303_info = {
.read_raw = ad7303_read_raw,
.write_raw = ad7303_write_raw,
.driver_module = THIS_MODULE,
};
static const struct iio_chan_spec_ext_info ad7303_ext_info[] = {
{
.name = "powerdown",
.read = ad7303_read_dac_powerdown,
.write = ad7303_write_dac_powerdown,
},
{ },
};
#define AD7303_CHANNEL(chan) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.output = 1, \
.channel = (chan), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.address = (chan), \
.scan_type = { \
.sign = 'u', \
.realbits = '8', \
.storagebits = '8', \
.shift = '0', \
}, \
.ext_info = ad7303_ext_info, \
}
static const struct iio_chan_spec ad7303_channels[] = {
AD7303_CHANNEL(0),
AD7303_CHANNEL(1),
};
static int ad7303_probe(struct spi_device *spi)
{
const struct spi_device_id *id = spi_get_device_id(spi);
struct iio_dev *indio_dev;
struct ad7303_state *st;
bool ext_ref;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
if (indio_dev == NULL)
return -ENOMEM;
st = iio_priv(indio_dev);
spi_set_drvdata(spi, indio_dev);
st->spi = spi;
st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
if (IS_ERR(st->vdd_reg))
return PTR_ERR(st->vdd_reg);
ret = regulator_enable(st->vdd_reg);
if (ret)
return ret;
if (spi->dev.of_node) {
ext_ref = of_property_read_bool(spi->dev.of_node,
"REF-supply");
} else {
struct ad7303_platform_data *pdata = spi->dev.platform_data;
if (pdata && pdata->use_external_ref)
ext_ref = true;
else
ext_ref = false;
}
if (ext_ref) {
st->vref_reg = devm_regulator_get(&spi->dev, "REF");
if (IS_ERR(st->vref_reg)) {
ret = PTR_ERR(st->vref_reg);
goto err_disable_vdd_reg;
}
ret = regulator_enable(st->vref_reg);
if (ret)
goto err_disable_vdd_reg;
st->config |= AD7303_CFG_EXTERNAL_VREF;
}
indio_dev->dev.parent = &spi->dev;
indio_dev->name = id->name;
indio_dev->info = &ad7303_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = ad7303_channels;
indio_dev->num_channels = ARRAY_SIZE(ad7303_channels);
ret = iio_device_register(indio_dev);
if (ret)
goto err_disable_vref_reg;
return 0;
err_disable_vref_reg:
if (st->vref_reg)
regulator_disable(st->vref_reg);
err_disable_vdd_reg:
regulator_disable(st->vdd_reg);
return ret;
}
static int ad7303_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct ad7303_state *st = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
if (st->vref_reg)
regulator_disable(st->vref_reg);
regulator_disable(st->vdd_reg);
return 0;
}
static const struct spi_device_id ad7303_spi_ids[] = {
{ "ad7303", 0 },
{}
};
MODULE_DEVICE_TABLE(spi, ad7303_spi_ids);
static struct spi_driver ad7303_driver = {
.driver = {
.name = "ad7303",
.owner = THIS_MODULE,
},
.probe = ad7303_probe,
.remove = ad7303_remove,
.id_table = ad7303_spi_ids,
};
module_spi_driver(ad7303_driver);
MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Analog Devices AD7303 DAC driver");
MODULE_LICENSE("GPL v2");