On Thu, Mar 28, 2024 at 2:39 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>
> On Wed, 27 Mar 2024 22:03:20 +0000
> Lothar Rubusch <l.rubusch@xxxxxxxxx> wrote:
>
> > Add a setup function implementation to the spi module to enable spi-3wire
> > as option when specified in the device-tree.
> >
> > Signed-off-by: Lothar Rubusch <l.rubusch@xxxxxxxxx>
> > ---
> > drivers/iio/accel/adxl345.h | 2 ++
> > drivers/iio/accel/adxl345_spi.c | 12 +++++++++++-
> > 2 files changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/accel/adxl345.h b/drivers/iio/accel/adxl345.h
> > index 4ea9341d4..e6bc3591c 100644
> > --- a/drivers/iio/accel/adxl345.h
> > +++ b/drivers/iio/accel/adxl345.h
> > @@ -30,6 +30,8 @@
> > #define ADXL345_POWER_CTL_MEASURE BIT(3)
> > #define ADXL345_POWER_CTL_STANDBY 0x00
> >
> > +#define ADXL345_DATA_FORMAT_SPI_3WIRE BIT(6) /* 3-wire SPI mode */
> > +
> > #define ADXL345_DATA_FORMAT_RANGE GENMASK(1, 0) /* Set the g range */
> > #define ADXL345_DATA_FORMAT_JUSTIFY BIT(2) /* Left-justified (MSB) mode */
> > #define ADXL345_DATA_FORMAT_FULL_RES BIT(3) /* Up to 13-bits resolution */
> > diff --git a/drivers/iio/accel/adxl345_spi.c b/drivers/iio/accel/adxl345_spi.c
> > index 1c0513bd3..f145d5c1d 100644
> > --- a/drivers/iio/accel/adxl345_spi.c
> > +++ b/drivers/iio/accel/adxl345_spi.c
> > @@ -20,6 +20,16 @@ static const struct regmap_config adxl345_spi_regmap_config = {
> > .read_flag_mask = BIT(7) | BIT(6),
> > };
> >
> > +static int adxl345_spi_setup(struct device *dev, struct regmap *regmap)
> > +{
> > + struct spi_device *spi = container_of(dev, struct spi_device, dev);
> > +
> > + if (spi->mode & SPI_3WIRE)
> > + return regmap_write(regmap, ADXL345_REG_DATA_FORMAT,
> > + ADXL345_DATA_FORMAT_SPI_3WIRE);
> Your earlier patch carefully (I think) left one or two fields alone, then
> this write just comes in and changes them. In particular INT_INVERT.
>
Why do you refer here to INT_INVERT? In this code above I try to set
SPI to 3 lines. Since this is a SPI configuration, i.e. bus specific,
it happens in adxl345_spi.c. Passing this function to the bus
independent adxl345_core.c file allows to configure the bus first.
Therefore, I'm using the update function in core masking out the SPI
filag.
My reason why I try to keep INT_INVERT out is different. There is
another driver for the same part in the kernel:
./drivers/input/misc/adxl34x.c - This is a input driver, using the
interrupts of the adxl345 for the input device implementation. I
assumed, that in the iio implementation there won't be interrupt
handling for the adx345, since it is not an input device. Does this
make sense?
> If it doesn't makes sense to write it there, either write that bit
> every time here, or leave it alone every time. Not decide on whether
> to write the bit based on SPI_3WIRE or not. As far as I know they
> are unconnected features.
>
I think I did not understand. Could you please specify a bit more?
When spi-3wire is configured in the DT it has to be parsed and handled
in the bus specific part, i.e. the adxl345_spi.c Therefore I configure
SPI_3WIRE there. I don't want to place SPI specific code in the core
file.
> > + return 0;
> > +}
> > +
> > static int adxl345_spi_probe(struct spi_device *spi)
> > {
> > struct regmap *regmap;
> > @@ -33,7 +43,7 @@ static int adxl345_spi_probe(struct spi_device *spi)
> > if (IS_ERR(regmap))
> > return dev_err_probe(&spi->dev, PTR_ERR(regmap), "Error initializing regmap\n");
> >
> > - return adxl345_core_probe(&spi->dev, regmap, NULL);
> > + return adxl345_core_probe(&spi->dev, regmap, adxl345_spi_setup);
> > }
> >
> > static const struct adxl345_chip_info adxl345_spi_info = {
>
