On 18/10/16 18:43, Tomas Novotny wrote:
> From: Tomas Novotny <tomas@xxxxxxxxxx>
>
> MCP47x6 chip supports selection of a voltage reference (VDD, VREF buffered
> or unbuffered). MCP4725 doesn't have this feature thus the eventual setting
> is ignored and user is warned.
>
> 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>
Something odd happened and this patch wouldn't apply without some manual
intervention.
Please check the result in the testing branch of iio.git.
Thanks,
Jonathan
> ---
> drivers/iio/dac/mcp4725.c | 97 ++++++++++++++++++++++++++++++++++++++---
> include/linux/iio/dac/mcp4725.h | 11 +++++
> 2 files changed, 102 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/dac/mcp4725.c b/drivers/iio/dac/mcp4725.c
> index e481f38..83d431f 100644
> --- a/drivers/iio/dac/mcp4725.c
> +++ b/drivers/iio/dac/mcp4725.c
> @@ -27,12 +27,20 @@
>
> #define MCP4725_DRV_NAME "mcp4725"
>
> +#define MCP472X_REF_VDD 0x00
> +#define MCP472X_REF_VREF_UNBUFFERED 0x02
> +#define MCP472X_REF_VREF_BUFFERED 0x03
> +
> struct mcp4725_data {
> struct i2c_client *client;
> + int id;
> + unsigned ref_mode;
> + bool vref_buffered;
> u16 dac_value;
> bool powerdown;
> unsigned powerdown_mode;
> struct regulator *vdd_reg;
> + struct regulator *vref_reg;
> };
>
> static int mcp4725_suspend(struct device *dev)
> @@ -87,6 +95,7 @@ static ssize_t mcp4725_store_eeprom(struct device *dev,
> return 0;
>
> inoutbuf[0] = 0x60; /* write EEPROM */
> + inoutbuf[0] |= data->ref_mode << 3;
> inoutbuf[1] = data->dac_value >> 4;
> inoutbuf[2] = (data->dac_value & 0xf) << 4;
>
> @@ -279,6 +288,28 @@ static int mcp4725_set_value(struct iio_dev *indio_dev, int val)
> return 0;
> }
>
> +static int mcp4726_set_cfg(struct iio_dev *indio_dev)
> +{
> + struct mcp4725_data *data = iio_priv(indio_dev);
> + u8 outbuf[3];
> + int ret;
> +
> + outbuf[0] = 0x40;
> + outbuf[0] |= data->ref_mode << 3;
> + if (data->powerdown)
> + outbuf[0] |= data->powerdown << 1;
> + outbuf[1] = data->dac_value >> 4;
> + outbuf[2] = (data->dac_value & 0xf) << 4;
> +
> + ret = i2c_master_send(data->client, outbuf, 3);
> + if (ret < 0)
> + return ret;
> + else if (ret != 3)
> + return -EIO;
> + else
> + return 0;
> +}
> +
> static int mcp4725_read_raw(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan,
> int *val, int *val2, long mask)
> @@ -291,7 +322,11 @@ static int mcp4725_read_raw(struct iio_dev *indio_dev,
> *val = data->dac_value;
> return IIO_VAL_INT;
> case IIO_CHAN_INFO_SCALE:
> - ret = regulator_get_voltage(data->vdd_reg);
> + if (data->ref_mode == MCP472X_REF_VDD)
> + ret = regulator_get_voltage(data->vdd_reg);
> + else
> + ret = regulator_get_voltage(data->vref_reg);
> +
> if (ret < 0)
> return ret;
>
> @@ -335,8 +370,9 @@ static int mcp4725_probe(struct i2c_client *client,
> struct mcp4725_data *data;
> struct iio_dev *indio_dev;
> struct mcp4725_platform_data *pdata = dev_get_platdata(&client->dev);
> - u8 inbuf[3];
> + u8 inbuf[4];
> u8 pd;
> + u8 ref;
> int err;
>
> if (!pdata) {
> @@ -350,6 +386,26 @@ 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 && pdata->use_vref) {
> + dev_err(&client->dev,
> + "external reference is unavailable on MCP4725");
> + return -EINVAL;
> + }
> +
> + if (!pdata->use_vref && pdata->vref_buffered) {
> + dev_err(&client->dev,
> + "buffering is unavailable on the internal reference");
> + return -EINVAL;
> + }
> +
> + if (!pdata->use_vref)
> + data->ref_mode = MCP472X_REF_VDD;
> + else
> + data->ref_mode = pdata->vref_buffered ?
> + MCP472X_REF_VREF_BUFFERED :
> + MCP472X_REF_VREF_UNBUFFERED;
>
> data->vdd_reg = devm_regulator_get(&client->dev, "vdd");
> if (IS_ERR(data->vdd_reg))
> @@ -359,6 +415,18 @@ static int mcp4725_probe(struct i2c_client *client,
> if (err)
> return err;
>
> + if (pdata->use_vref) {
> + data->vref_reg = devm_regulator_get(&client->dev, "vref");
> + if (IS_ERR(data->vref_reg)) {
> + err = PTR_ERR(data->vdd_reg);
> + goto err_disable_vdd_reg;
> + }
> +
> + err = regulator_enable(data->vref_reg);
> + if (err)
> + goto err_disable_vdd_reg;
> + }
> +
> indio_dev->dev.parent = &client->dev;
> indio_dev->name = id->name;
> indio_dev->info = &mcp4725_info;
> @@ -366,23 +434,38 @@ static int mcp4725_probe(struct i2c_client *client,
> indio_dev->num_channels = 1;
> indio_dev->modes = INDIO_DIRECT_MODE;
>
> - /* read current DAC value */
> - err = i2c_master_recv(client, inbuf, 3);
> + /* read current DAC value and settings */
> + err = i2c_master_recv(client, inbuf, data->id == MCP4725 ? 3 : 4);
> if (err < 0) {
> dev_err(&client->dev, "failed to read DAC value");
> - goto err_disable_vdd_reg;
> + goto err_disable_vref_reg;
> }
> pd = (inbuf[0] >> 1) & 0x3;
> data->powerdown = pd > 0 ? true : false;
> data->powerdown_mode = pd ? pd - 1 : 2; /* largest resistor to gnd */
> data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4);
> + if (data->id == MCP4726)
> + ref = (inbuf[3] >> 3) & 0x3;
> +
> + if (data->id == MCP4726 && ref != data->ref_mode) {
> + dev_info(&client->dev,
> + "voltage reference mode differs (conf: %u, eeprom: %u), setting %u",
> + data->ref_mode, ref, data->ref_mode);
> + err = mcp4726_set_cfg(indio_dev);
> + if (err < 0)
> + goto err_disable_vref_reg;
> + }
>
> err = iio_device_register(indio_dev);
> if (err)
> - goto err_disable_vdd_reg;
> + goto err_disable_vref_reg;
>
> return 0;
>
> +err_disable_vref_reg:
> + if (data->vref_reg)
> + regulator_disable(data->vref_reg);
> +
> err_disable_vdd_reg:
> regulator_disable(data->vdd_reg);
>
> @@ -396,6 +479,8 @@ static int mcp4725_remove(struct i2c_client *client)
>
> iio_device_unregister(indio_dev);
>
> + if (data->vref_reg)
> + regulator_disable(data->vref_reg);
> regulator_disable(data->vdd_reg);
>
> return 0;
> diff --git a/include/linux/iio/dac/mcp4725.h b/include/linux/iio/dac/mcp4725.h
> index 7c062e8..628b2cf 100644
> --- a/include/linux/iio/dac/mcp4725.h
> +++ b/include/linux/iio/dac/mcp4725.h
> @@ -9,7 +9,18 @@
> #ifndef IIO_DAC_MCP4725_H_
> #define IIO_DAC_MCP4725_H_
>
> +/**
> + * struct mcp4725_platform_data - MCP4725/6 DAC specific data.
> + * @use_vref: Whether an external reference voltage on Vref pin should be used.
> + * Additional vref-supply must be specified when used.
> + * @vref_buffered: Controls buffering of the external reference voltage.
> + *
> + * Vref related settings are available only on MCP4756. See
> + * Documentation/devicetree/bindings/iio/dac/mcp4725.txt for more information.
> + */
> struct mcp4725_platform_data {
> + bool use_vref;
> + bool vref_buffered;
> };
>
> #endif /* IIO_DAC_MCP4725_H_ */
>
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