commonlib/region: Turn addrspace_32bit into a more official API

We had the addrspace_32bit rdev in prog_loaders.c for a while to help
represent memory ranges as an rdev, and we've found it useful for a
couple of things that have nothing to do with program loading. This
patch moves the concept straight into commonlib/region.c so it is no
longer anchored in such a weird place, and easier to use in unit tests.
Also expand the concept to the whole address space (there's no real need
to restrict it to 32 bits in 64-bit environments) and introduce an
rdev_chain_mem() helper function to make it a bit easier to use. Replace
some direct uses of struct mem_region_device with this new API where it
seems to make sense.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: Ie4c763b77f77d227768556a9528681d771a08dca
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52533
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/src/commonlib/include/commonlib/region.h b/src/commonlib/include/commonlib/region.h
index 0080c441a5ee..764870f46c4c 100644
--- a/src/commonlib/include/commonlib/region.h
+++ b/src/commonlib/include/commonlib/region.h
@@ -164,14 +164,18 @@ static inline int rdev_chain_full(struct region_device *child,
 ssize_t rdev_relative_offset(const struct region_device *p,
 				const struct region_device *c);
 
+/* Helper functions to create an rdev that represents memory. */
+int rdev_chain_mem(struct region_device *child, const void *base, size_t size);
+int rdev_chain_mem_rw(struct region_device *child, void *base, size_t size);
+
 struct mem_region_device {
 	char *base;
 	struct region_device rdev;
 };
 
-/* Initialize at runtime a mem_region_device. This would be used when
- * the base and size are dynamic or can't be known during linking.
- * There are two variants: read-only and read-write. */
+/* Initialize at runtime a mem_region_device. Should only be used for mappings
+   that need to fit right up to the edge of the physical address space. Most use
+   cases will want to use rdev_chain_mem() instead. */
 void mem_region_device_ro_init(struct mem_region_device *mdev, void *base,
 				size_t size);
 
@@ -182,7 +186,8 @@ extern const struct region_device_ops mem_rdev_ro_ops;
 
 extern const struct region_device_ops mem_rdev_rw_ops;
 
-/* Statically initialize mem_region_device. */
+/* Statically initialize mem_region_device. Should normally only be used for
+   const globals. Most use cases will want to use rdev_chain_mem() instead. */
 #define MEM_REGION_DEV_INIT(base_, size_, ops_)				\
 	{								\
 		.base = (void *)(base_),				\