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

Uwe Kleine-König (The Capable Hub)
2026-04-17T13:11:27Z

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@baylibre.com>
---
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