Re: [PATCH 2/2] iio: dac: cio-dac: Implement and utilize register structures

William Breathitt Gray
2022-06-14T16:16:50Z

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On Tue, Jun 14, 2022 at 12:26:18PM +0100, Jonathan Cameron wrote:
> On Mon, 6 Jun 2022 10:15:18 -0400
> William Breathitt Gray <william.gray@linaro.org> wrote:
>
> > Reduce magic numbers and improve code readability by implementing and
> > utilizing named register data structures.
> >
> > Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
>
> I'm unconvinced this one really helps readability seeing
> as you are only indexing a straight forward array.
>
> Simply using u16 __iomem *
> would provide the main cleanup which is avoiding the indexing
> via * 2.
>
> Thanks,
>
> Jonathan

I agree, that is a much simpler approach and reduces the changes we need
to make to this file. I'll adjust this to u16 __iomem * in v2.

William Breathitt Gray

>
>
> > ---
> > drivers/iio/dac/cio-dac.c | 24 ++++++++++++++++--------
> > 1 file changed, 16 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/iio/dac/cio-dac.c b/drivers/iio/dac/cio-dac.c
> > index 8080984dcb03..7860450ceaf3 100644
> > --- a/drivers/iio/dac/cio-dac.c
> > +++ b/drivers/iio/dac/cio-dac.c
> > @@ -16,6 +16,7 @@
> > #include <linux/isa.h>
> > #include <linux/module.h>
> > #include <linux/moduleparam.h>
> > +#include <linux/types.h>
> >
> > #define CIO_DAC_NUM_CHAN 16
> >
> > @@ -34,14 +35,22 @@ static unsigned int num_cio_dac;
> > module_param_hw_array(base, uint, ioport, &num_cio_dac, 0);
> > MODULE_PARM_DESC(base, "Measurement Computing CIO-DAC base addresses");
> >
> > +/**
> > + * struct cio_dac_reg - device register structure
> > + * @da: D/A data
> > + */
> > +struct cio_dac_reg {
> > + u16 da[CIO_DAC_NUM_CHAN];
> > +};
> > +
> > /**
> > * struct cio_dac_iio - IIO device private data structure
> > * @chan_out_states: channels' output states
> > - * @base: base port address of the IIO device
> > + * @reg: I/O address offset for the device registers
> > */
> > struct cio_dac_iio {
> > int chan_out_states[CIO_DAC_NUM_CHAN];
> > - void __iomem *base;
> > + struct cio_dac_reg __iomem *reg;
> > };
> >
> > static int cio_dac_read_raw(struct iio_dev *indio_dev,
> > @@ -61,7 +70,6 @@ static int cio_dac_write_raw(struct iio_dev *indio_dev,
> > struct iio_chan_spec const *chan, int val, int val2, long mask)
> > {
> > struct cio_dac_iio *const priv = iio_priv(indio_dev);
> > - const unsigned int chan_addr_offset = 2 * chan->channel;
> >
> > if (mask != IIO_CHAN_INFO_RAW)
> > return -EINVAL;
> > @@ -71,7 +79,7 @@ static int cio_dac_write_raw(struct iio_dev *indio_dev,
> > return -EINVAL;
> >
> > priv->chan_out_states[chan->channel] = val;
> > - iowrite16(val, priv->base + chan_addr_offset);
> > + iowrite16(val, priv->reg->da + chan->channel);
> >
> > return 0;
> > }
> > @@ -106,8 +114,8 @@ static int cio_dac_probe(struct device *dev, unsigned int id)
> > }
> >
> > priv = iio_priv(indio_dev);
> > - priv->base = devm_ioport_map(dev, base[id], CIO_DAC_EXTENT);
> > - if (!priv->base)
> > + priv->reg = devm_ioport_map(dev, base[id], CIO_DAC_EXTENT);
> > + if (!priv->reg)
> > return -ENOMEM;
> >
> > indio_dev->info = &cio_dac_info;
> > @@ -117,8 +125,8 @@ static int cio_dac_probe(struct device *dev, unsigned int id)
> > indio_dev->name = dev_name(dev);
> >
> > /* initialize DAC outputs to 0V */
> > - for (i = 0; i < 32; i += 2)
> > - iowrite16(0, priv->base + i);
> > + for (i = 0; i < CIO_DAC_NUM_CHAN; i++)
> > + iowrite16(0, priv->reg->da + i);
> >
> > return devm_iio_device_register(dev, indio_dev);
> > }
>

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