+ mcp4728_write_reg(data, ch, true);
+
+
+ /* wait for write complete, takes up to 50ms */
+ while (tries--) {
+ msleep(20);
+ ret = i2c_master_recv(data->client, inbuf, 1);
+ if (ret < 0)
+ return ret;
+ else if (ret != 1)
+ return -EIO;
+
+ if (inbuf[0] & 0x80)
+ break;
+ }
+
+ if (tries < 0) {
+ dev_err(&data->client->dev,
+ "mcp4728_store_eeprom() failed, incomplete\n");
+ return -EIO;
+ }
+ }
+
+ return len;
+}
+
+static IIO_DEVICE_ATTR(store_eeprom, S_IWUSR, NULL, mcp4728_store_eeprom, 0);
+
+
+static ssize_t mcp4728_show_scale_available(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr);
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ u8 ch = iio_attr->address;
+ int i, len = 0;
+
+ for (i = 0; i < ARRAY_SIZE(data->scale_avail[ch]); i++)
+ len += sprintf(buf + len, "%u.%06u ",
+ data->scale_avail[ch][i].integer,
+ data->scale_avail[ch][i].micro);
+
+ len += sprintf(buf + len, "\n");
+
+ return len;
+}
+
+#define SHOW_SCALE_AVAILABLE_ATTR(ch) \
+static IIO_DEVICE_ATTR(out_voltage##ch##_scale_available, S_IRUGO, \
+ mcp4728_show_scale_available, NULL, ch)
+
+SHOW_SCALE_AVAILABLE_ATTR(0);
+SHOW_SCALE_AVAILABLE_ATTR(1);
+SHOW_SCALE_AVAILABLE_ATTR(2);
+SHOW_SCALE_AVAILABLE_ATTR(3);
+
+static struct attribute *mcp4728_attributes[] = {
+ &iio_dev_attr_store_eeprom.dev_attr.attr,
+ &iio_dev_attr_out_voltage0_scale_available.dev_attr.attr,
+ &iio_dev_attr_out_voltage1_scale_available.dev_attr.attr,
+ &iio_dev_attr_out_voltage2_scale_available.dev_attr.attr,
+ &iio_dev_attr_out_voltage3_scale_available.dev_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group mcp4728_attribute_group = {
+ .attrs = mcp4728_attributes,
+};
+
+static const char * const mcp4728_powerdown_modes[] = {
+ "1kohm_to_gnd",
+ "100kohm_to_gnd",
+ "500kohm_to_gnd"
+};
+
+static int mcp4728_get_powerdown_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+
+ return data->channel_state[chan->channel].powerdown_mode;
+}
+
+static int mcp4728_set_powerdown_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan, unsigned mode)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+
+ data->channel_state[chan->channel].powerdown_mode = mode;
+
+ return 0;
+}
+
+static ssize_t mcp4728_read_powerdown(struct iio_dev *indio_dev,
+ uintptr_t private, const struct iio_chan_spec *chan, char *buf)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+
+ return sprintf(buf, "%d\n",
+ data->channel_state[chan->channel].powerdown);
+}
+
+static ssize_t mcp4728_write_powerdown(struct iio_dev *indio_dev,
+ uintptr_t private, const struct iio_chan_spec *chan,
+ const char *buf, size_t len)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ struct mcp4728_channel_state *state =
+ &data->channel_state[chan->channel];
+ bool powerdown;
+ int ret;
+
+ ret = strtobool(buf, &powerdown);
+ if (ret)
+ return ret;
+
+ state->powerdown = powerdown;
+ ret = mcp4728_write_input_reg(data, chan->channel);
+
+ if (ret < 0)
+ return ret;
+
+ return len;
+}
+
+static const struct iio_enum mcp4728_powerdown_mode_enum = {
+ .items = mcp4728_powerdown_modes,
+ .num_items = ARRAY_SIZE(mcp4728_powerdown_modes),
+ .get = mcp4728_get_powerdown_mode,
+ .set = mcp4728_set_powerdown_mode,
+};
+
+static const struct iio_chan_spec_ext_info mcp4728_ext_info[] = {
+ {
+ .name = "powerdown",
+ .read = mcp4728_read_powerdown,
+ .write = mcp4728_write_powerdown,
+ .shared = IIO_SEPARATE,
+ },
+ IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4728_powerdown_mode_enum),
+ IIO_ENUM_AVAILABLE("powerdown_mode", &mcp4728_powerdown_mode_enum),
+ { },
+};
+
+#define MCP4728_CHAN(chan) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .output = 1, \
+ .channel = chan, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_SCALE), \
+ .ext_info = mcp4728_ext_info, \
+}
+
+
+static const struct iio_chan_spec mcp4728_channels[MCP4728_NUM_CHANNELS] = {
+ MCP4728_CHAN(0),
+ MCP4728_CHAN(1),
+ MCP4728_CHAN(2),
+ MCP4728_CHAN(3),
+};
+
+static int mcp4728_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ struct mcp4728_channel_state *state =
+ &data->channel_state[chan->channel];
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ *val = data->channel_state[chan->channel].dac_value;
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ *val = (state->gain + 1) * MCP4728_INT_VREF_MV;
+ *val2 = MCP4728_RESOLUTION;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ }
+ return -EINVAL;
+}
+
+static int mcp4728_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ struct mcp4728_channel_state *state =
+ &data->channel_state[chan->channel];
+ struct mcp4728_scale *scale_avail =
+ data->scale_avail[chan->channel];
+
+ int ret, gain;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ state->dac_value = val;
+ ret = mcp4728_write_input_reg(data, chan->channel);
+ break;
+ case IIO_CHAN_INFO_SCALE:
+ ret = -EINVAL;
+
+ for (gain = 0; gain < 2; ++gain) {
+ if (val == scale_avail[gain].integer &&
+ val2 == scale_avail[gain].micro) {
+
+ state->gain = gain;
+ ret = mcp4728_write_input_reg(data,
+ chan->channel);
+ }
+ }
+
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
+static const struct iio_info mcp4728_info = {
+ .read_raw = mcp4728_read_raw,
+ .write_raw = mcp4728_write_raw,
+ .attrs = &mcp4728_attribute_group,
+ .driver_module = THIS_MODULE,
+};
+
+static int mcp4728_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct mcp4728_data *data;
+ struct iio_dev *indio_dev;
+ u8 inbuf[24];
+ u8 *reg;
+ u8 pd;
+ int err;
+ int i, gain;
+ u64 scale_uv;
+
+ indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+ if (indio_dev == NULL)
+ return -ENOMEM;
+ data = iio_priv(indio_dev);
+ i2c_set_clientdata(client, indio_dev);
+ data->client = client;
+
+ indio_dev->dev.parent = &client->dev;
+ indio_dev->info = &mcp4728_info;
+ return err;
+ }
+
+ for (i = 0; i < MCP4728_NUM_CHANNELS; ++i) {
+ reg = &inbuf[6*i];
+ pd = (reg[1] >> 5) & 0x3;
+ data->channel_state[i].powerdown = pd > 0 ? true : false;
+
+ /* set to 500kohm_to_gnd if channel is now powered down */
+ data->channel_state[i].powerdown_mode = pd ? pd-1 : 2;
+ data->channel_state[i].dac_value = ((reg[1] & 0x0f) << 8) |
+ (reg[2]);
+ data->channel_state[i].gain = (reg[1] >> 4) & 0x01;
+
+ /* Use internal reference */
+ data->channel_state[i].vref = 1;
+
+ /* Populate available ADC input ranges */
+ for (gain = 0; gain < 2; gain++) {
+ /*
+ [gain=0] = Gain Setting 1, vref x 1
+ [gain=1] = Gain Setting 2, vref x 2
+
+ The scale is calculated by doing:
+ Vref >> (realbits - gain)
+ which multiplies by two on the second component
+ of the array.
+ */
+ scale_uv = ((u64) MCP4728_INT_VREF_MV * 100000) >>
+ (MCP4728_RESOLUTION - gain);
+ data->scale_avail[i][gain].micro =
+ do_div(scale_uv, 100000) * 10;
+ data->scale_avail[i][gain].integer = scale_uv;
+ }
+ }
+
+ return iio_device_register(indio_dev);
+}
+
+static int mcp4728_remove(struct i2c_client *client)
+{
+ iio_device_unregister(i2c_get_clientdata(client));
+ return 0;
+}
+
+static const struct i2c_device_id mcp4728_id[] = {
+ { "mcp4728", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, mcp4728_id);
+
+static struct i2c_driver mcp4728_driver = {
+ .driver = {
+ .name = MCP4728_DRV_NAME,
+ .pm = MCP4728_PM_OPS,
+ },
+ .probe = mcp4728_probe,
+ .remove = mcp4728_remove,
+ .id_table = mcp4728_id,
+};
+module_i2c_driver(mcp4728_driver);
+
+MODULE_AUTHOR("Evgeny Boger <boger@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("MCP4728 quad 12-bit DAC");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/iio/dac/mcp4728.h b/include/linux/iio/dac/mcp4728.h
new file mode 100644
index 0000000..14adb0c
--- /dev/null
+++ b/include/linux/iio/dac/mcp4728.h
@@ -0,0 +1,16 @@
+/*
+ * MCP4728 DAC driver
+ *
+ * Copyright (C) 2016 Evgeny Boger <boger@xxxxxxxxxxxxxx>
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef IIO_DAC_MCP4728_H_
+#define IIO_DAC_MCP4728_H_
+
+struct mcp4728_platform_data {
+ u16 vref_mv;
+};
+
+#endif /* IIO_DAC_MCP4728_H_ */
