cbfs: new API and better program loading

A new CBFS API is introduced to allow making CBFS access
easier for providing multiple CBFS sources. That is achieved
by decoupling the cbfs source from a CBFS file. A CBFS
source is described by a descriptor. It contains the necessary
properties for walking a CBFS to locate a file. The CBFS
file is then decoupled from the CBFS descriptor in that it's
no longer needed to access the contents of the file.

All of this is accomplished using the regions infrastructure
by repsenting CBFS sources and files as region_devices. Because
region_devices can be chained together forming subregions this
allows one to decouple a CBFS source from a file. This also allows
one to provide CBFS files that came from other sources for
payload and/or stage loading.

The program loading takes advantage of those very properties
by allowing multiple sources for locating a program. Because of
this we can reduce the overhead of loading programs because
it's all done in the common code paths. Only locating the
program is per source.

Change-Id: I339b84fce95f03d1dbb63a0f54a26be5eb07f7c8
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9134
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/arch/riscv/rom_media.c b/src/arch/riscv/rom_media.c
index f18030c..dd57849 100644
--- a/src/arch/riscv/rom_media.c
+++ b/src/arch/riscv/rom_media.c
@@ -18,76 +18,13 @@
  * Foundation, Inc.
  */
 #include <boot_device.h>
-#include <cbfs.h>
-#include <console/console.h>
-#include <string.h>
 
 /* This assumes that the CBFS resides at 0x0, which is true for the default
  * configuration. */
-static const struct mem_region_device gboot_dev =
+static const struct mem_region_device boot_dev =
 	MEM_REGION_DEV_INIT(NULL, CONFIG_ROM_SIZE);
 
 const struct region_device *boot_device_ro(void)
 {
-	return &gboot_dev.rdev;
-}
-
-static int rom_media_open(struct cbfs_media *media) {
-	return 0;
-}
-
-static void *rom_media_map(struct cbfs_media *media, size_t offset, size_t count) {
-	const struct region_device *boot_dev;
-	void *ptr;
-
-	printk(BIOS_INFO, "%s: media %p, offset %lx, size %ld.\n", __func__, media, offset, count);
-	boot_dev = media->context;
-
-	ptr = rdev_mmap(boot_dev, offset, count);
-
-	if (ptr == NULL)
-		return (void *)-1;
-
-	return ptr;
-}
-
-static void *rom_media_unmap(struct cbfs_media *media, const void *address) {
-	const struct region_device *boot_dev;
-
-	boot_dev = media->context;
-
-	rdev_munmap(boot_dev, (void *)address);
-
-	return NULL;
-}
-
-static size_t rom_media_read(struct cbfs_media *media, void *dest, size_t offset,
-			   size_t count) {
-	const struct region_device *boot_dev;
-
-	boot_dev = media->context;
-
-	if (rdev_readat(boot_dev, dest, offset, count) < 0)
-		return 0;
-
-	return count;
-}
-
-static int rom_media_close(struct cbfs_media *media) {
-	return 0;
-}
-
-static int init_rom_media_cbfs(struct cbfs_media *media) {
-	boot_device_init();
-	media->context = (void *)boot_device_ro();
-	media->open = rom_media_open;
-	media->close = rom_media_close;
-	media->map = rom_media_map;
-	media->unmap = rom_media_unmap;
-	media->read = rom_media_read;
-	return 0;
-}
-
-int init_default_cbfs_media(struct cbfs_media *media) {
-	return init_rom_media_cbfs(media);
+	return &boot_dev.rdev;
 }