[PATCH v1 1/6] sdio: Add syntactic sugar to store a pointer in sdio_driver_id

[Ulf Hansson]

On Fri, 17 Apr 2026 at 15:11, Uwe Kleine-König (The Capable Hub)
<u.kleine-koenig at baylibre.com> wrote:
>
> On all current Linux architectures sizeof(long) == sizeof(void *) and
> this is used a lot through the kernel. For example it enables the usual
> practice to store pointers in sdio_driver_id's .driver_data member.
>
> This works fine, but involves casting and thus isn't type-safe.
> Additionally with the CHERI architecture extension there are machines
> with sizeof(void *) > sizeof(long) for with the traditional approach of
> storing a pointer in .driver_data doesn't work.
>
> By replacing the plain unsigned long .driver_data by an anonymous union,
> most of the casting can be dropped and it yields a working solution for
> CHERI.
>
> All users of struct sdio_driver_id are initialized in a way that is
> compatible with the new definition, so no adaptions are needed there.
>
> Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig at baylibre.com>

Acked-by: Ulf Hansson <ulf.hansson at linaro.org>

Feel free to take this via whatever tree makes best sense!

Kind regards
Uffe

> ---
>  include/linux/mod_devicetable.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 5b1725fe9707..0eb5d196f5b5 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -414,7 +414,10 @@ struct sdio_device_id {
>         __u8    class;                  /* Standard interface or SDIO_ANY_ID */
>         __u16   vendor;                 /* Vendor or SDIO_ANY_ID */
>         __u16   device;                 /* Device ID or SDIO_ANY_ID */
> -       kernel_ulong_t driver_data;     /* Data private to the driver */
> +       union {                         /* Data private to the driver */
> +               kernel_ulong_t driver_data;
> +               const void *driver_data_ptr;
> +       };
>  };
>
>  /* SSB core, see drivers/ssb/ */
> --
> 2.47.3
>