region: add rdev_chain_full()

Instead of open coding an offset of 0 and querying the size of a
region device provide a rdev_chain_full() helper function that
does that for the caller. For the existing users that match this pattern
convert them to using rdev_chain_full().

Change-Id: Ie316790a8a5b16a7f7e22f86f58bd2e633c19450
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36683
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/commonlib/include/commonlib/cbfs.h

@@ -32,14 +32,13 @@ int cbfs_locate(struct cbfsf *fh, const struct region_device *cbfs,
 static inline void cbfs_file_data(struct region_device *data,
 					const struct cbfsf *file)
 {
-	rdev_chain(data, &file->data, 0, region_device_sz(&file->data));
+	rdev_chain_full(data, &file->data);
 }
 
 static inline void cbfs_file_metadata(struct region_device *metadata,
 					const struct cbfsf *file)
 {
-	rdev_chain(metadata, &file->metadata, 0,
-			region_device_sz(&file->metadata));
+	rdev_chain_full(metadata, &file->metadata);
 }
 
 /*

src/commonlib/include/commonlib/region.h

@@ -73,7 +73,6 @@ ssize_t rdev_eraseat(const struct region_device *rd, size_t offset,
 int rdev_chain(struct region_device *child, const struct region_device *parent,
 		size_t offset, size_t size);
 
-
 /* A region_device operations. */
 struct region_device_ops {
 	void *(*mmap)(const struct region_device *, size_t, size_t);
@@ -145,6 +144,13 @@ static inline void *rdev_mmap_full(const struct region_device *rd)
 	return rdev_mmap(rd, 0, region_device_sz(rd));
 }
 
+static inline int rdev_chain_full(struct region_device *child,
+				const struct region_device *parent)
+{
+	/* Chain full size of parent. */
+	return rdev_chain(child, parent, 0, region_device_sz(parent));
+}
+
 /*
  * Compute relative offset of the child (c) w.r.t. the parent (p). Returns < 0
  * when child is not within the parent's region.

src/lib/fmap.c

@@ -49,8 +49,7 @@ static int find_fmap_directory(struct region_device *fmrd)
 
 		cache = car_get_var_ptr(&fmap_cache);
 		if (region_device_sz(&cache->rdev))
-			return rdev_chain(fmrd, &cache->rdev, 0,
-					  region_device_sz(&cache->rdev));
+			return rdev_chain_full(fmrd, &cache->rdev);
 	}
 
 	boot_device_init();

src/lib/region_file.c

@@ -208,7 +208,7 @@ int region_file_init(struct region_file *f, const struct region_device *p)
 	f->slot = RF_FATAL;
 
 	/* Keep parent around for accessing data later. */
-	if (rdev_chain(&f->rdev, p, 0, region_device_sz(p)))
+	if (rdev_chain_full(&f->rdev, p))
 		return -1;
 
 	if (rdev_readat(p, &mb, 0, sizeof(mb)) < 0) {