On 30/09/16 14:19, Tomas Novotny wrote:
> MCP47x6 chip supports selection of a voltage reference (VDD, VREF buffered
> or unbuffered). MCP4725 doesn't have this feature thus the setting is
> ignored and user is warned if there is an attempt to set a value other than
> zero.
>
> The setting is stored only in the volatile memory of the chip. You need to
> manually store it to the EEPROM of the chip via 'store_eeprom' sysfs entry.
>
> Signed-off-by: Tomas Novotny <tomas@xxxxxxxxxx>
> ---
> drivers/iio/dac/mcp4725.c | 45 +++++++++++++++++++++++++++++++++++++----
> include/linux/iio/dac/mcp4725.h | 1 +
> 2 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iio/dac/mcp4725.c b/drivers/iio/dac/mcp4725.c
> index cca935c..f8e54f1 100644
> --- a/drivers/iio/dac/mcp4725.c
> +++ b/drivers/iio/dac/mcp4725.c
> @@ -28,7 +28,9 @@
>
> struct mcp4725_data {
> struct i2c_client *client;
> + int id;
> u16 vref_mv;
> + unsigned vref_mode;
> u16 dac_value;
> bool powerdown;
> unsigned powerdown_mode;
> @@ -86,6 +88,7 @@ static ssize_t mcp4725_store_eeprom(struct device *dev,
> return 0;
>
> inoutbuf[0] = 0x60; /* write EEPROM */
> + inoutbuf[0] |= data->vref_mode << 3;
> inoutbuf[1] = data->dac_value >> 4;
> inoutbuf[2] = (data->dac_value & 0xf) << 4;
>
> @@ -329,8 +332,10 @@ static int mcp4725_probe(struct i2c_client *client,
> struct mcp4725_data *data;
> struct iio_dev *indio_dev;
> struct mcp4725_platform_data *platform_data = client->dev.platform_data;
> - u8 inbuf[3];
> + u8 inoutbuf[3];
> u8 pd;
> + u8 vref;
> + int ret;
> int err;
>
> if (!platform_data || !platform_data->vref_mv) {
> @@ -344,6 +349,17 @@ static int mcp4725_probe(struct i2c_client *client,
> data = iio_priv(indio_dev);
> i2c_set_clientdata(client, indio_dev);
> data->client = client;
> + data->id = id->driver_data;
> +
> + if (data->id == MCP4725 && platform_data->vref_mode > 0) {
> + dev_warn(&client->dev, "vref mode is unavailable on MCP4725, ignoring");
> + platform_data->vref_mode = 0;
> + }
> +
> + if (data->id == MCP4726 && platform_data->vref_mode > 3) {
> + dev_err(&client->dev, "vref mode is out of range");
> + return -EINVAL;
> + }
>
> indio_dev->dev.parent = &client->dev;
> indio_dev->name = id->name;
> @@ -353,17 +369,38 @@ static int mcp4725_probe(struct i2c_client *client,
> indio_dev->modes = INDIO_DIRECT_MODE;
>
> data->vref_mv = platform_data->vref_mv;
> + data->vref_mode = platform_data->vref_mode;
>
> /* read current DAC value */
> - err = i2c_master_recv(client, inbuf, 3);
> + err = i2c_master_recv(client, inoutbuf, 3);
> if (err < 0) {
> dev_err(&client->dev, "failed to read DAC value");
> return err;
> }
> - pd = (inbuf[0] >> 1) & 0x3;
> + pd = (inoutbuf[0] >> 1) & 0x3;
> data->powerdown = pd > 0 ? true : false;
> data->powerdown_mode = pd ? pd - 1 : 2; /* largest register to gnd */
> - data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4);
> + data->dac_value = (inoutbuf[1] << 4) | (inoutbuf[2] >> 4);
> + vref = inoutbuf[0] >> 3 & 0x3;
> +
> + if (data->id == MCP4726 && vref != data->vref_mode) {
> + dev_info(&client->dev,
> + "vref_mode differs (conf: %d, eeprom: %d), setting %d",
> + data->vref_mode, vref, data->vref_mode);
> +
> + inoutbuf[0] = 0x40;
> + inoutbuf[0] |= data->vref_mode << 3;
> + if (data->powerdown)
> + inoutbuf[0] |= data->powerdown << 1;
> + inoutbuf[1] = data->dac_value >> 4;
> + inoutbuf[2] = (data->dac_value & 0xf) << 4;
> +
> + ret = i2c_master_send(data->client, inoutbuf, 3);
> + if (ret < 0)
> + return ret;
> + else if (ret != 3)
> + return -EIO;
> + }
>
> return iio_device_register(indio_dev);
> }
> diff --git a/include/linux/iio/dac/mcp4725.h b/include/linux/iio/dac/mcp4725.h
> index 91530e6..370022b 100644
> --- a/include/linux/iio/dac/mcp4725.h
> +++ b/include/linux/iio/dac/mcp4725.h
> @@ -11,6 +11,7 @@
>
> struct mcp4725_platform_data {
> u16 vref_mv;
> + unsigned vref_mode;
Hmm. Should probably move the platform support over to using regulators.
This is a horible bit of legacy code.
Jonathan
> };
>
> #endif /* IIO_DAC_MCP4725_H_ */
>
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