--- /dev/null
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff