Hi Jonathan,
On Sat, 15 Oct 2016 15:07:00 +0100
Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On 11/10/16 14:57, Tomas Novotny wrote:
> > 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>
> A few minor bits inline. I think we should error out on invalid settings
> in the platform data. Last thing we want to do is to have to have the driver
> papering over these issues and get bitten years down the line by some refactoring
> that suddenly doesn't paper over them any more.
>
> Also, a sneaky unconnected error in a comment in here which needs to be broken
> out to it's own patch as nothing much to do with this. (good spot though!)
>
> Jonathan
> > ---
> > drivers/iio/dac/mcp4725.c | 98 ++++++++++++++++++++++++++++++++++++++---
> > include/linux/iio/dac/mcp4725.h | 2 +
> > 2 files changed, 93 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/iio/dac/mcp4725.c b/drivers/iio/dac/mcp4725.c
> > index 2b28b1f..29cf85d 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_warn(&client->dev,
> > + "ignoring unavailable external reference on MCP4725");
> Could make this an error case as something is horribly wrong if it occurs.
ok, I will scream a bit louder.
> > + pdata->use_vref = false;
> > + }
> > +
> > + if (!pdata->use_vref && pdata->vref_buffered) {
> > + dev_warn(&client->dev,
> > + "buffering is unavailable on the internal reference");
> > + pdata->vref_buffered = false;
> Likewise here. Invalid state so should really error out.
same here.
> > + }
> > +
> > + 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);
> Looks like you have a stray space in the line above.
oh, good catch.
> > + 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 +434,37 @@ 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 register to gnd */
> > + data->powerdown_mode = pd ? pd - 1 : 2; /* largest resistor to gnd */
> This fix is clearly right, but not part of the change this patch is making.
> Please break out to a separate patch.
ok, I will do.
> > 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);
> > @@ -397,6 +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..0684cf6 100644
> > --- a/include/linux/iio/dac/mcp4725.h
> > +++ b/include/linux/iio/dac/mcp4725.h
> > @@ -10,6 +10,8 @@
> > #define IIO_DAC_MCP4725_H_
> >
> Some docs on this seems wise. Maybe state the restrictions (i.e. which parts
> support which combinations).
I will write a short info here with a link to the dt documentation.
Thanks for the review,
Tomas
> > struct mcp4725_platform_data {
> > + bool use_vref;
> > + bool vref_buffered;
> > };
> >
> > #endif /* IIO_DAC_MCP4725_H_ */
> >
>
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