linux-kernel - Re: [PATCH 2/3] iio: dac: ad3552r: add support for ad3541r and ad3551r

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Date: Fri, 10 May 2024 10:42:49 -0500
From: David Lechner <dlechner@...libre.com>
To: Angelo Dureghello <adureghello@...libre.com>
Cc: jic23@...nel.org, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	nuno.sa@...log.com, lars@...afoo.de, Michael.Hennerich@...log.com, 
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] iio: dac: ad3552r: add support for ad3541r and ad3551r

On Fri, May 10, 2024 at 9:19 AM Angelo Dureghello
<adureghello@...libre.com> wrote:
>
> From: Angelo Dureghello <adureghello@...libre.com>
>
> Add support for single-output dac variants.
>
> Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> ---
>  drivers/iio/dac/ad3552r.c | 39 +++++++++++++++++++++++++++++----------
>  1 file changed, 29 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iio/dac/ad3552r.c b/drivers/iio/dac/ad3552r.c
> index a492e8f2fc0f..0dd6f995c3e2 100644
> --- a/drivers/iio/dac/ad3552r.c
> +++ b/drivers/iio/dac/ad3552r.c
> @@ -140,7 +140,9 @@ enum ad3552r_ch_vref_select {
>  };
>
>  enum ad3542r_id {
> +       AD3541R_ID = 0x400b,
>         AD3542R_ID = 0x4009,
> +       AD3551R_ID = 0x400a,
>         AD3552R_ID = 0x4008,
>  };
>
> @@ -745,7 +747,8 @@ static void ad3552r_calc_gain_and_offset(struct ad3552r_desc *dac, s32 ch)
>         } else {
>                 /* Normal range */
>                 idx = dac->ch_data[ch].range;
> -               if (dac->chip_id == AD3542R_ID) {
> +               if (dac->chip_id == AD3541R_ID ||
> +                   dac->chip_id == AD3542R_ID) {
>                         v_min = ad3542r_ch_ranges[idx][0];
>                         v_max = ad3542r_ch_ranges[idx][1];
>                 } else {
> @@ -780,7 +783,7 @@ static int ad3552r_find_range(u16 id, s32 *vals)
>         int i, len;
>         const s32 (*ranges)[2];
>
> -       if (id == AD3542R_ID) {
> +       if (id == AD3541R_ID || id == AD3542R_ID) {
>                 len = ARRAY_SIZE(ad3542r_ch_ranges);
>                 ranges = ad3542r_ch_ranges;
>         } else {
> @@ -955,9 +958,10 @@ static int ad3552r_configure_device(struct ad3552r_desc *dac)
>                         dev_err(dev, "mandatory reg property missing\n");
>                         goto put_child;
>                 }
> -               if (ch >= AD3552R_NUM_CH) {
> -                       dev_err(dev, "reg must be less than %d\n",
> -                               AD3552R_NUM_CH);
> +               if (ch >= AD3552R_NUM_CH ||
> +                       (dac->chip_id == AD3541R_ID && ch) ||
> +                       (dac->chip_id == AD3551R_ID && ch)) {
> +                       dev_err(dev, "channel %d is not supported\n", ch);
>                         err = -EINVAL;
>                         goto put_child;
>                 }
> @@ -987,9 +991,10 @@ static int ad3552r_configure_device(struct ad3552r_desc *dac)
>                                 goto put_child;
>
>                         dac->ch_data[ch].range = val;
> -               } else if (dac->chip_id == AD3542R_ID) {
> +               } else if (dac->chip_id == AD3541R_ID ||
> +                          dac->chip_id == AD3542R_ID) {
>                         dev_err(dev,
> -                               "adi,output-range-microvolt is required for ad3542r\n");
> +                               "adi,output-range-microvolt is required for ad354xr\n");
>                         err = -EINVAL;
>                         goto put_child;
>                 } else {
> @@ -1088,10 +1093,20 @@ static int ad3552r_probe(struct spi_device *spi)
>                 return err;
>
>         /* Config triggered buffer device */
> -       if (dac->chip_id == AD3552R_ID)
> -               indio_dev->name = "ad3552r";
> -       else
> +       switch (dac->chip_id) {
> +       case AD3541R_ID:
> +               indio_dev->name = "ad3541r";
> +               break;
> +       case AD3542R_ID:
>                 indio_dev->name = "ad3542r";
> +               break;
> +       case AD3551R_ID:
> +               indio_dev->name = "ad3551r";
> +               break;
> +       case AD3552R_ID:
> +               indio_dev->name = "ad3552r";
> +               break;
> +       }
>         indio_dev->dev.parent = &spi->dev;
>         indio_dev->info = &ad3552r_iio_info;
>         indio_dev->num_channels = dac->num_ch;
> @@ -1110,14 +1125,18 @@ static int ad3552r_probe(struct spi_device *spi)
>  }
>
>  static const struct spi_device_id ad3552r_id[] = {
> +       { "ad3541r", AD3541R_ID },
>         { "ad3542r", AD3542R_ID },
> +       { "ad3551r", AD3551R_ID },
>         { "ad3552r", AD3552R_ID },
>         { }
>  };
>  MODULE_DEVICE_TABLE(spi, ad3552r_id);
>
>  static const struct of_device_id ad3552r_of_match[] = {
> +       { .compatible = "adi,ad3541r"},
>         { .compatible = "adi,ad3542r"},
> +       { .compatible = "adi,ad3551r"},
>         { .compatible = "adi,ad3552r"},
>         { }
>  };
> --
> 2.45.0.rc1
>
>

It looks like it is time for a chip_info struct here instead of the if
and switch statements to get chip-specific data. Most other IIO
drivers have this already and it is the preferred way to look up this
kind of information in the IIO subsystem. I prefer the drivers that
don't put all of the info structs in an array (that way the code is
less verbose). So I would suggest looking at e.g. adc/aspeed_adc,
starting with aspeed_adc_matches, to see what I mean and how to
implement it. (So one patch to add the info structs and a second patch
to add the single channel chips)