[Intel-gfx] [PATCH 2/2] iosys-map: Add per-word write

[Lucas De Marchi]

On Fri, Jun 17, 2022 at 01:52:04AM -0700, Lucas De Marchi wrote:
>Like was done for read, provide the equivalent for write. Even if
>current users are not in the hot path, this should future-proof it.
>
>v2:
>  - Remove default from _Generic() - callers wanting to write more
>    than u64 should use iosys_map_memcpy_to()
>  - Add WRITE_ONCE() cases dereferencing the pointer when using system
>    memory

Thomas, do you have any additional concern on this patch regarding your
previous review?

thanks
Lucas De Marchi

>
>Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
>Reviewed-by: Reviewed-by: Christian König <christian.koenig at amd.com> # v1
>---
> include/linux/iosys-map.h | 42 ++++++++++++++++++++++++++++++---------
> 1 file changed, 33 insertions(+), 9 deletions(-)
>
>diff --git a/include/linux/iosys-map.h b/include/linux/iosys-map.h
>index f59dd00ed202..580e14cd360c 100644
>--- a/include/linux/iosys-map.h
>+++ b/include/linux/iosys-map.h
>@@ -337,9 +337,13 @@ static inline void iosys_map_memset(struct iosys_map *dst, size_t offset,
> #ifdef CONFIG_64BIT
> #define __iosys_map_rd_io_u64_case(val_, vaddr_iomem_)				\
> 	u64: val_ = readq(vaddr_iomem_)
>+#define __iosys_map_wr_io_u64_case(val_, vaddr_iomem_)			\
>+	u64: writeq(val_, vaddr_iomem_)
> #else
> #define __iosys_map_rd_io_u64_case(val_, vaddr_iomem_)				\
> 	u64: memcpy_fromio(&(val_), vaddr_iomem__, sizeof(u64))
>+#define __iosys_map_wr_io_u64_case(val_, vaddr_iomem_)			\
>+	u64: memcpy_toio(vaddr_iomem_, &(val_), sizeof(u64))
> #endif
>
> #define __iosys_map_rd_io(val__, vaddr_iomem__, type__) _Generic(val__,		\
>@@ -354,6 +358,19 @@ static inline void iosys_map_memset(struct iosys_map *dst, size_t offset,
> 	val__ = READ_ONCE(*((type__ *)vaddr__));				\
> })
>
>+#define __iosys_map_wr_io(val__, vaddr_iomem__, type__) _Generic(val__,		\
>+	u8: writeb(val__, vaddr_iomem__),					\
>+	u16: writew(val__, vaddr_iomem__),					\
>+	u32: writel(val__, vaddr_iomem__),					\
>+	__iosys_map_wr_io_u64_case(val__, vaddr_iomem__))
>+
>+#define __iosys_map_wr_sys(val__, vaddr__, type__) ({				\
>+	compiletime_assert(sizeof(type__) <= sizeof(u64),			\
>+			   "Unsupported access size for __iosys_map_wr_sys()"); \
>+	WRITE_ONCE(*((type__ *)vaddr__), val__);				\
>+})
>+
>+
> /**
>  * iosys_map_rd - Read a C-type value from the iosys_map
>  *
>@@ -386,12 +403,17 @@ static inline void iosys_map_memset(struct iosys_map *dst, size_t offset,
>  * @type__:	Type of the value being written
>  * @val__:	Value to write
>  *
>- * Write a C-type value to the iosys_map, handling possible un-aligned accesses
>- * to the mapping.
>+ * Write a C type value (u8, u16, u32 and u64) to the iosys_map. For other types
>+ * or if pointer may be unaligned (and problematic for the architecture
>+ * supported), use iosys_map_memcpy_to()
>  */
>-#define iosys_map_wr(map__, offset__, type__, val__) ({			\
>-	type__ val = (val__);						\
>-	iosys_map_memcpy_to(map__, offset__, &val, sizeof(val));	\
>+#define iosys_map_wr(map__, offset__, type__, val__) ({				\
>+	type__ val = (val__);							\
>+	if ((map__)->is_iomem) {						\
>+		__iosys_map_wr_io(val, (map__)->vaddr_iomem + (offset__), type__);\
>+	} else {								\
>+		__iosys_map_wr_sys(val, (map__)->vaddr + (offset__), type__);	\
>+	}									\
> })
>
> /**
>@@ -472,10 +494,12 @@ static inline void iosys_map_memset(struct iosys_map *dst, size_t offset,
>  * @field__:		Member of the struct to read
>  * @val__:		Value to write
>  *
>- * Write a value to the iosys_map considering its layout is described by a C struct
>- * starting at @struct_offset__. The field offset and size is calculated and the
>- * @val__ is written handling possible un-aligned memory accesses. Refer to
>- * iosys_map_rd_field() for expected usage and memory layout.
>+ * Write a value to the iosys_map considering its layout is described by a C
>+ * struct starting at @struct_offset__. The field offset and size is calculated
>+ * and the @val__ is written. If the field access would incur in un-aligned
>+ * access, then either iosys_map_memcpy_to() needs to be used or the
>+ * architecture must support it. Refer to iosys_map_rd_field() for expected
>+ * usage and memory layout.
>  */
> #define iosys_map_wr_field(map__, struct_offset__, struct_type__, field__, val__) ({	\
> 	struct_type__ *s;								\
>-- 
>2.36.1
>