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

Jonathan Cameron
2022-06-14T11:17:16Z

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

> ---
> 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);
> }