some additional comments
On Sat, 1 Oct 2016, Jonathan Cameron wrote:
> 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;
parenthesis would be good to make the expression above more clear
> > +
> > + 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);
use %u, these are unsigned variables
> > +
> > + 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_ */
> >
>
--
Peter Meerwald-Stadler
+43-664-2444418 (mobile)
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