On Thu, Feb 17, 2022 at 09:42:08AM +0100, Thomas Zimmermann wrote:
Hi
Am 16.02.22 um 18:41 schrieb Lucas De Marchi:
First the simplest ones:
- iosys_map_memset(): when abstracting system and I/O memory,
just like the memcpy() use case, memset() also has dedicated
functions to be called for using IO memory.
- iosys_map_memcpy_from(): we may need to copy data from I/O
memory, not only to.
In certain situations it's useful to be able to read or write to an
offset that is calculated by having the memory layout given by a struct
declaration. Usually we are going to read/write a u8, u16, u32 or u64.
As a pre-requisite for the implementation, add iosys_map_memcpy_from()
to be the equivalent of iosys_map_memcpy_to(), but in the other
direction. Then add 2 pairs of macros:
- iosys_map_rd() / iosys_map_wr()
- iosys_map_rd_field() / iosys_map_wr_field()
The first pair takes the C-type and offset to read/write. The second
pair uses a struct describing the layout of the mapping in order to
calculate the offset and size being read/written.
We could use readb, readw, readl, readq and the write* counterparts,
however due to alignment issues this may not work on all architectures.
If alignment needs to be checked to call the right function, it's not
possible to decide at compile-time which function to call: so just leave
the decision to the memcpy function that will do exactly that.
Finally, in order to use the above macros with a map derived from
another, add another initializer: IOSYS_MAP_INIT_OFFSET().
v2:
- Rework IOSYS_MAP_INIT_OFFSET() so it doesn't rely on aliasing rules
within the union
- Add offset to both iosys_map_rd_field() and iosys_map_wr_field() to
allow the struct itself to be at an offset from the mapping
- Add documentation to iosys_map_rd_field() with example and expected
memory layout
v3:
- Drop kernel.h include as it's not needed anymore
Cc: Sumit Semwal <sumit.sem...@linaro.org>
Cc: Christian König <christian.koe...@amd.com>
Cc: Thomas Zimmermann <tzimmerm...@suse.de>
Cc: Mauro Carvalho Chehab <mche...@kernel.org>
Cc: dri-de...@lists.freedesktop.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Lucas De Marchi <lucas.demar...@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mche...@kernel.org>
Reviewed-by: Matt Atwood <matthew.s.atw...@intel.com>
Reviewed-by: Thomas Zimmermann <tzimmerm...@suse.de>
Thanks. I applied the first 2 patches to drm-intel-next.
The rest can't be applied as there are conflicts between drm-intel-next
and drm-intel-gt-next. I should have merged the rename to
drm-intel-gt-next since the guc patches need to be applied there.
I guess the rest will have to wait some tree propagation.
Lucas De Marchi
