diff options
Diffstat (limited to 'kernel/drivers/iio/dac/ad7303.c')
| -rw-r--r-- | kernel/drivers/iio/dac/ad7303.c | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/kernel/drivers/iio/dac/ad7303.c b/kernel/drivers/iio/dac/ad7303.c new file mode 100644 index 000000000..fa2810032 --- /dev/null +++ b/kernel/drivers/iio/dac/ad7303.c @@ -0,0 +1,303 @@ +/* + * 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 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, + .shared = IIO_SEPARATE, + }, + { }, +}; + +#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"); |