[alsa-devel] [PATCH] ASoC: Allow codecs to override register display

[Jon Smirl]

On 7/18/08, Mark Brown <broonie at opensource.wolfsonmicro.com> wrote:
> Some codecs have unusual features in their register maps such as very
>  large registers representing arrays of coefficients. Support these
>  codecs in the register cache sysfs file by allowing them to provide a
>  function register_display() overriding the default output for register
>  contents.

My address space is sparse like Grant's. How about display_register()
returning -1 to skip the register address. The part printing the
address would need to be suppressed too.
count += sprintf(buf + count, "%2x: ", i);

Alternatively you could just make the entire codec_reg_show() overridable.

Might want to add another parameter for cached/uncached. Then we could
make a debug option to add the non-cached display.

This loop needs to be protected to not write over the sysfs limit of
PAGE_SIZE in the result. I think you will corrupt memory if PAGE_SIZE
is exceeded.

>  Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
>  ---
>   include/sound/soc.h  |    1 +
>   sound/soc/soc-core.c |   14 ++++++++++----
>   2 files changed, 11 insertions(+), 4 deletions(-)
>
>  diff --git a/include/sound/soc.h b/include/sound/soc.h
>  index 1890d87..8b1a3e7 100644
>  --- a/include/sound/soc.h
>  +++ b/include/sound/soc.h
>  @@ -410,6 +410,7 @@ struct snd_soc_codec {
>         void *control_data; /* codec control (i2c/3wire) data */
>         unsigned int (*read)(struct snd_soc_codec *, unsigned int);
>         int (*write)(struct snd_soc_codec *, unsigned int, unsigned int);
>  +       int (*display_register)(struct snd_soc_codec *, char *, unsigned int);
>         hw_write_t hw_write;
>         hw_read_t hw_read;
>         void *reg_cache;
>  diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
>  index 83f1190..49532d9 100644
>  --- a/sound/soc/soc-core.c
>  +++ b/sound/soc/soc-core.c
>  @@ -970,10 +970,16 @@ static ssize_t codec_reg_show(struct device *dev,
>                 step = codec->reg_cache_step;
>
>         count += sprintf(buf, "%s registers\n", codec->name);
>  -       for (i = 0; i < codec->reg_cache_size; i += step)
>  -               count += sprintf(buf + count, "%2x: %4x\n", i,
>  -                       codec->read(codec, i));
>  -
>  +       for (i = 0; i < codec->reg_cache_size; i += step) {
>  +               count += sprintf(buf + count, "%2x: ", i);
>  +               if (codec->display_register)
>  +                       count += codec->display_register(codec,
>  +                                                        buf + count, i);
>  +               else
>  +                       count += sprintf(buf + count, "%4x",
>  +                                        codec->read(codec, i));
>  +               count += sprintf(buf + count, "\n");
>  +       }
>         return count;
>   }
>   static DEVICE_ATTR(codec_reg, 0444, codec_reg_show, NULL);
>
> --
>  1.5.6.3
>
>


-- 
Jon Smirl
jonsmirl at gmail.com