Hi Jonathan, Peter,
On Sat, 1 Oct 2016 13:48:38 +0200 (CEST), Peter Meerwald-Stadler
<pmeerw@xxxxxxxxxx> wrote:
>
> 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
ok.
> > > +
> > > + 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
Yes, you are right.
> > > +
> > > + 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.
ok, I will do.
Thanks for the review,
Tomas
> > Jonathan
> > > };
> > >
> > > #endif /* IIO_DAC_MCP4725_H_ */
> > >
> >
>
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