libpayload: New CBFS to support multiple firmware media sources.

Upgrade CBFS in libpayload to use new media-based implementation from coreboot
( http://review.coreboot.org/#/c/2182/ ).

Old CBFS functions (cbfs_find, cbfs_find_file, get_cbfs_header) are still
supported, although the recommended way is to use new CBFS API.

To migrate your existing x86 payload source:
	- Change cbfs_find to cbfs_get_file
	- Change cbfs_find_file to cbfs_get_file_content
	- Prefix every CBFS call with a CBFS_DEFAULT_MEDIA argument.

Ex, char *jpeg_data = cbfs_find_file("splash.jpg", CBFS_TYPE_BOOTSPLASH);
 => char *jpeg_data = cbfs_get_file_content(
		CBFS_DEFAULT_MEDIA, "splash.jpg", CBFS_TYPE_BOOTSPLASH);

The legacy setup_cbfs_from_{ram,flash} is also supported, although the better
equivalent is to make a new media instance:
	struct cbfs_media ram_media;
	init_cbfs_ram_media(&ram_media, start, size);
	char *data = cbfs_get_file_content(&ram_media, "myfile", my_type);

Verified by being successfully linked with filo.

Change-Id: If797bc7e3ba975d7e3be905c59424f7a93b8ce11
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/2191
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Anton Kochkov <anton.kochkov@gmail.com>

4 files changed, 420 insertions, 125 deletions

diff --git a/payloads/libpayload/libcbfs/Makefile.inc b/payloads/libpayload/libcbfs/Makefile.inc
index 50f4821732..0d3e1ec59a 100644
--- a/payloads/libpayload/libcbfs/Makefile.inc
+++ b/payloads/libpayload/libcbfs/Makefile.inc
@@ -28,4 +28,5 @@
 ##
 
 libcbfs-$(CONFIG_CBFS) += cbfs.c
+libcbfs-$(CONFIG_CBFS) += ram_media.c
 
diff --git a/payloads/libpayload/libcbfs/cbfs.c b/payloads/libpayload/libcbfs/cbfs.c
index 026b73c965..35e48dda27 100644
--- a/payloads/libpayload/libcbfs/cbfs.c
+++ b/payloads/libpayload/libcbfs/cbfs.c
@@ -2,6 +2,7 @@
  * This file is part of the libpayload project.
  *
  * Copyright (C) 2011 secunet Security Networks AG
+ * Copyright (C) 2013 Google, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -26,80 +27,221 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+#define LIBPAYLOAD
+
+#ifdef LIBPAYLOAD
+# include <libpayload-config.h>
+# ifdef CONFIG_LZMA
+#  include <lzma.h>
+#  define CBFS_CORE_WITH_LZMA
+# endif
+# define CBFS_MINI_BUILD
+#elif defined(__SMM__)
+# define CBFS_MINI_BUILD
+#else
+# define CBFS_CORE_WITH_LZMA
+# include <lib.h>
+#endif
 
-#include <endian.h>
-#include <stdio.h>
-#include <string.h>
 #include <cbfs.h>
+#include <string.h>
 
-#ifdef CONFIG_LZMA
-#define CBFS_CORE_WITH_LZMA
-#include <lzma.h>
+#ifdef LIBPAYLOAD
+# include <stdio.h>
+# define DEBUG(x...)
+# define LOG(x...) printf(x)
+# define ERROR(x...) printf(x)
+#else
+# include <console/console.h>
+# define ERROR(x...) printk(BIOS_ERR, "CBFS: " x)
+# define LOG(x...) printk(BIOS_INFO, "CBFS: " x)
+# if CONFIG_DEBUG_CBFS
+#  define DEBUG(x...) printk(BIOS_SPEW, "CBFS: " x)
+# else
+#  define DEBUG(x...)
+# endif
 #endif
 
-#define ERROR(x...) printf(x)
-#define LOG(x...)
-
-static uint32_t host_virt_to_phys(void *addr);
-static void *host_phys_to_virt(uint32_t addr);
+#if defined(CONFIG_CBFS_HEADER_ROM_OFFSET) && (CONFIG_CBFS_HEADER_ROM_OFFSET)
+# define CBFS_HEADER_ROM_ADDRESS (CONFIG_CBFS_HEADER_ROM_OFFSET)
+#else
+// Indirect address: only works on 32bit top-aligned systems.
+# define CBFS_HEADER_ROM_ADDRESS (*(uint32_t*)0xfffffffc)
+#endif
 
-uint32_t romstart(void);
-uint32_t romend(void);
+#include "cbfs_core.c"
 
-#include <arch/virtual.h>
-static uint32_t host_virt_to_phys(void *addr)
+#ifndef __SMM__
+static inline int tohex4(unsigned int c)
 {
-	return virt_to_phys(addr);
+	return (c <= 9) ? (c + '0') : (c - 10 + 'a');
 }
 
-static void *host_phys_to_virt(uint32_t addr)
+static void tohex16(unsigned int val, char* dest)
 {
-	return phys_to_virt(addr);
+	dest[0] = tohex4(val>>12);
+	dest[1] = tohex4((val>>8) & 0xf);
+	dest[2] = tohex4((val>>4) & 0xf);
+	dest[3] = tohex4(val & 0xf);
 }
-#undef virt_to_phys
-#undef phys_to_virt
 
-uint32_t (*virt_to_phys)(void *) = host_virt_to_phys;
-void* (*phys_to_virt)(uint32_t) = host_phys_to_virt;
+void *cbfs_load_optionrom(struct cbfs_media *media, uint16_t vendor,
+			  uint16_t device, void *dest)
+{
+	char name[17] = "pciXXXX,XXXX.rom";
+	struct cbfs_optionrom *orom;
+	uint8_t *src;
 
+	tohex16(vendor, name+3);
+	tohex16(device, name+8);
 
-uint32_t _romstart = 0xffffffff;
-uint32_t _romend = 0;
+	orom = (struct cbfs_optionrom *)
+		cbfs_get_file_content(media, name, CBFS_TYPE_OPTIONROM);
 
-uint32_t romstart(void)
-{
-	return _romstart;
+	if (orom == NULL)
+		return NULL;
+
+	/* They might have specified a dest address. If so, we can decompress.
+	 * If not, there's not much hope of decompressing or relocating the rom.
+	 * in the common case, the expansion rom is uncompressed, we
+	 * pass 0 in for the dest, and all we have to do is find the rom and
+	 * return a pointer to it.
+	 */
+
+	/* BUG: the cbfstool is (not yet) including a cbfs_optionrom header */
+	src = (uint8_t*)orom; // + sizeof(struct cbfs_optionrom);
+
+	if (! dest)
+		return src;
+
+	if (cbfs_decompress(ntohl(orom->compression),
+			     src,
+			     dest,
+			     ntohl(orom->len)))
+		return NULL;
+
+	return dest;
 }
 
-uint32_t romend(void)
+void * cbfs_load_stage(struct cbfs_media *media, const char *name)
 {
-	return _romend;
+	struct cbfs_stage *stage = (struct cbfs_stage *)
+		cbfs_get_file_content(media, name, CBFS_TYPE_STAGE);
+	/* this is a mess. There is no ntohll. */
+	/* for now, assume compatible byte order until we solve this. */
+	uint32_t entry;
+
+	if (stage == NULL)
+		return (void *) -1;
+
+	LOG("loading stage %s @ 0x%x (%d bytes), entry @ 0x%llx\n",
+			name,
+			(uint32_t) stage->load, stage->memlen,
+			stage->entry);
+	memset((void *) (uint32_t) stage->load, 0, stage->memlen);
+
+	if (cbfs_decompress(stage->compression,
+			     ((unsigned char *) stage) +
+			     sizeof(struct cbfs_stage),
+			     (void *) (uint32_t) stage->load,
+			     stage->len))
+		return (void *) -1;
+
+	DEBUG("stage loaded.\n");
+
+	entry = stage->entry;
+	// entry = ntohll(stage->entry);
+
+	return (void *) entry;
 }
 
-#include "cbfs_core.c"
+int cbfs_execute_stage(struct cbfs_media *media, const char *name)
+{
+	struct cbfs_stage *stage = (struct cbfs_stage *)
+		cbfs_get_file_content(media, name, CBFS_TYPE_STAGE);
 
-static uint32_t ram_cbfs_offset;
+	if (stage == NULL)
+		return 1;
 
-static uint32_t ram_virt_to_phys(void *addr)
-{
-	return (uint32_t)addr - ram_cbfs_offset;
+	if (ntohl(stage->compression) != CBFS_COMPRESS_NONE) {
+		LOG("Unable to run %s:  Compressed file"
+		       "Not supported for in-place execution\n", name);
+		return 1;
+	}
+
+	/* FIXME: This isn't right */
+	LOG("run @ %p\n", (void *) ntohl((uint32_t) stage->entry));
+	return run_address((void *)(uintptr_t)ntohll(stage->entry));
 }
 
-static void *ram_phys_to_virt(uint32_t addr)
+void *cbfs_load_payload(struct cbfs_media *media, const char *name)
 {
-	return (void*)addr + ram_cbfs_offset;
+	return (struct cbfs_payload *)cbfs_get_file_content(
+			media, name, CBFS_TYPE_PAYLOAD);
 }
 
-void setup_cbfs_from_ram(void* start, uint32_t size)
-{
-	/* assumes rollover */
-	ram_cbfs_offset = (uint32_t)start + size;
-	virt_to_phys = ram_virt_to_phys;
-	phys_to_virt = ram_phys_to_virt;
+struct cbfs_file *cbfs_find(const char *name) {
+	return cbfs_get_file(CBFS_DEFAULT_MEDIA, name);
+}
+
+void *cbfs_find_file(const char *name, int type) {
+	return cbfs_get_file_content(CBFS_DEFAULT_MEDIA, name, type);
+}
+
+const struct cbfs_header *get_cbfs_header(void) {
+	return cbfs_get_header(CBFS_DEFAULT_MEDIA);
 }
 
-void setup_cbfs_from_flash(void)
+/* Simple buffer */
+
+void *cbfs_simple_buffer_map(struct cbfs_simple_buffer *buffer,
+			     struct cbfs_media *media,
+			     size_t offset, size_t count) {
+	void *address = buffer->buffer + buffer->allocated;;
+	DEBUG("simple_buffer_map(offset=%d, count=%d): "
+	      "allocated=%d, size=%d, last_allocate=%d\n",
+	    offset, count, buffer->allocated, buffer->size,
+	    buffer->last_allocate);
+	if (buffer->allocated + count >= buffer->size)
+		return CBFS_MEDIA_INVALID_MAP_ADDRESS;
+	if (media->read(media, address, offset, count) != count) {
+		ERROR("simple_buffer: fail to read %zd bytes from 0x%zx\n",
+		      count, offset);
+		return CBFS_MEDIA_INVALID_MAP_ADDRESS;
+	}
+	buffer->allocated += count;
+	buffer->last_allocate = count;
+	return address;
+}
+
+void *cbfs_simple_buffer_unmap(struct cbfs_simple_buffer *buffer,
+			       const void *address) {
+	// TODO Add simple buffer management so we can free more than last
+	// allocated one.
+	DEBUG("simple_buffer_unmap(address=0x%p): "
+	      "allocated=%d, size=%d, last_allocate=%d\n",
+	    address, buffer->allocated, buffer->size,
+	    buffer->last_allocate);
+	if ((buffer->buffer + buffer->allocated - buffer->last_allocate) ==
+	    address) {
+		buffer->allocated -= buffer->last_allocate;
+		buffer->last_allocate = 0;
+	}
+	return NULL;
+}
+
+/**
+ * run_address is passed the address of a function taking no parameters and
+ * jumps to it, returning the result.
+ * @param f the address to call as a function.
+ * @return value returned by the function.
+ */
+
+int run_address(void *f)
 {
-	virt_to_phys = host_virt_to_phys;
-	phys_to_virt = host_phys_to_virt;
+	int (*v) (void);
+	v = f;
+	return v();
 }
+
+#endif
diff --git a/payloads/libpayload/libcbfs/cbfs_core.c b/payloads/libpayload/libcbfs/cbfs_core.c
index 4bf755b0f8..4fecd40370 100644
--- a/payloads/libpayload/libcbfs/cbfs_core.c
+++ b/payloads/libpayload/libcbfs/cbfs_core.c
@@ -2,6 +2,7 @@
  * This file is part of the libpayload project.
  *
  * Copyright (C) 2011 secunet Security Networks AG
+ * Copyright (C) 2013 Google, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -27,119 +28,153 @@
  * SUCH DAMAGE.
  */
 
-/* The CBFS core requires a couple of #defines or functions to adapt it to the target environment:
+/* The CBFS core requires a couple of #defines or functions to adapt it to the
+ * target environment:
  *
  * CBFS_CORE_WITH_LZMA (must be #define)
  *      if defined, ulzma() must exist for decompression of data streams
  *
- * phys_to_virt(x), virt_to_phys(x)
- *      translate physical addresses to virtual and vice versa
- *      can be idempotent if no mapping is necessary.
+ * CBFS_HEADER_ROM_ADDRESS
+ *	ROM address (offset) of CBFS header. Underlying CBFS media may interpret
+ *	it in other way so we call this "address".
  *
  * ERROR(x...)
  *      print an error message x (in printf format)
  *
  * LOG(x...)
- *      print a debug message x (in printf format)
+ *      print a message x (in printf format)
  *
- * romstart()
- *      returns the start address of the ROM image, or 0xffffffff if ROM is
- *      top-aligned. This is a physical address.
+ * DEBUG(x...)
+ *      print a debug message x (in printf format)
  *
- * romend()
- *      returns the highest address of the ROM image + 1, for use if
- *      romstart() == 0xffffffff. This is a physical address.
  */
 
-#include <cbfs_core.h>
+#include <cbfs.h>
+#include <string.h>
 
-
-/* returns pointer to master header or 0xffffffff if not found */
-struct cbfs_header *get_cbfs_header(void)
+/* returns a pointer to CBFS master header, or CBFS_HEADER_INVALID_ADDRESS
+ *  on failure */
+const struct cbfs_header *cbfs_get_header(struct cbfs_media *media)
 {
-	struct cbfs_header *header;
-
-	/* find header */
-	if (romstart() == 0xffffffff) {
-		header = (struct cbfs_header*)phys_to_virt(*(uint32_t*)phys_to_virt(romend() + CBFS_HEADPTR_ADDR));
-	} else {
-		// FIXME: where's the master header on ARM (our current bottom-aligned platform)?
-		header = NULL;
+	const struct cbfs_header *header;
+	struct cbfs_media default_media;
+
+	if (media == CBFS_DEFAULT_MEDIA) {
+		media = &default_media;
+		if (init_default_cbfs_media(media) != 0) {
+			ERROR("Failed to initializee default media.\n");
+			return NULL;
+		}
+	}
+
+	media->open(media);
+	DEBUG("CBFS_HEADER_ROM_ADDRESS: 0x%x/0x%x\n", CBFS_HEADER_ROM_ADDRESS,
+	      CONFIG_ROM_SIZE);
+	header = media->map(media, CBFS_HEADER_ROM_ADDRESS, sizeof(*header));
+	media->close(media);
+
+	if (header == CBFS_MEDIA_INVALID_MAP_ADDRESS) {
+		ERROR("Failed to load CBFS header from 0x%x\n",
+		      CBFS_HEADER_ROM_ADDRESS);
+		return CBFS_HEADER_INVALID_ADDRESS;
 	}
+
 	if (CBFS_HEADER_MAGIC != ntohl(header->magic)) {
-		ERROR("Could not find valid CBFS master header at %p: %x vs %x.\n", header, CBFS_HEADER_MAGIC, ntohl(header->magic));
+		ERROR("Could not find valid CBFS master header at %x: "
+		      "%x vs %x.\n", CBFS_HEADER_ROM_ADDRESS, CBFS_HEADER_MAGIC,
+		      ntohl(header->magic));
 		if (header->magic == 0xffffffff) {
 			ERROR("Maybe ROM is not mapped properly?\n");
 		}
-		return (void*)0xffffffff;
+		return CBFS_HEADER_INVALID_ADDRESS;
 	}
 	return header;
 }
 
-// by must be power-of-two
-#define CBFS_ALIGN(val, by) (typeof(val))((uint32_t)(val + by - 1) & (uint32_t)~(by - 1))
-#define CBFS_ALIGN_UP(val, by) CBFS_ALIGN(val + 1, by)
-
 /* public API starts here*/
-struct cbfs_file *cbfs_find(const char *name)
+struct cbfs_file *cbfs_get_file(struct cbfs_media *media, const char *name)
 {
-	struct cbfs_header *header = get_cbfs_header();
-	if (header == (void*)0xffffffff) return NULL;
-
-	LOG("Searching for %s\n", name);
-
-	void *data, *dataend, *origdata;
-	/* find first entry */
-	if (romstart() == 0xffffffff) {
-		data = (void*)phys_to_virt(romend()) - ntohl(header->romsize) + ntohl(header->offset);
-		dataend = (void*)phys_to_virt(romend());
-	} else {
-		data = (void*)phys_to_virt(romstart()) + ntohl(header->offset);
-		dataend = (void*)phys_to_virt(romstart()) + ntohl(header->romsize);
-	}
-	dataend -= ntohl(header->bootblocksize);
-
-	int align = ntohl(header->align);
-
-	origdata = data;
-	while ((data < (dataend - 1)) && (data >= origdata)) {
-		struct cbfs_file *file = data;
-		if (memcmp(CBFS_FILE_MAGIC, file->magic, strlen(CBFS_FILE_MAGIC)) != 0) {
-			// no file header found. corruption?
-			// proceed in aligned steps to resynchronize
-			LOG("ERROR: No file header found at %p, attempting to recover by searching for header\n", data);
-			data = phys_to_virt(CBFS_ALIGN_UP(virt_to_phys(data), align));
-			continue;
-		}
-		LOG("Check %s\n", CBFS_NAME(file));
-		if (strcmp(CBFS_NAME(file), name) == 0) {
-			return file;
-		}
-		void *olddata = data;
-		data = phys_to_virt(CBFS_ALIGN(virt_to_phys(data) + ntohl(file->len) + ntohl(file->offset), align));
-		if (olddata > data) {
-			LOG("Something is wrong here. File chain moved from %p to %p\n", olddata, data);
+	const char *file_name;
+	uint32_t offset, align, romsize, name_len;
+	const struct cbfs_header *header;
+	struct cbfs_file file, *file_ptr;
+	struct cbfs_media default_media;
+
+	if (media == CBFS_DEFAULT_MEDIA) {
+		media = &default_media;
+		if (init_default_cbfs_media(media) != 0) {
+			ERROR("Failed to initializee default media.\n");
 			return NULL;
 		}
 	}
-	return NULL;
-}
-
-void *cbfs_get_file(const char *name)
-{
-	struct cbfs_file *file = cbfs_find(name);
 
-	if (file == NULL) {
-		ERROR("Could not find file '%s'.\n", name);
+	if (CBFS_HEADER_INVALID_ADDRESS == (header = cbfs_get_header(media)))
 		return NULL;
-	}
 
-	return (void*)CBFS_SUBHEADER(file);
+	// Logical offset (for source media) of first file.
+	offset = ntohl(header->offset);
+	align = ntohl(header->align);
+	romsize = ntohl(header->romsize);
+
+	// TODO header->romsize seems broken now on ARM. Remove this when it's
+	// fixed.
+#if defined(CONFIG_ARCH_ARMV7) && CONFIG_ARCH_ARMV7
+	romsize = CONFIG_ROM_SIZE;
+#endif
+	DEBUG("offset: 0x%x, align: %d, romsize: %d\n", offset, align, romsize);
+
+	LOG("Looking for '%s' starting from 0x%x.\n", name, offset);
+	media->open(media);
+	while (offset < romsize &&
+	       media->read(media, &file, offset, sizeof(file)) == sizeof(file)) {
+		if (memcmp(CBFS_FILE_MAGIC, file.magic,
+			   sizeof(file.magic)) != 0) {
+			uint32_t new_align = align;
+			if (offset % align)
+				new_align += align - (offset % align);
+			ERROR("ERROR: No file header found at 0x%xx - "
+			      "try next aligned address: 0x%x.\n", offset,
+			      offset + new_align);
+			offset += new_align;
+			continue;
+		}
+		name_len = ntohl(file.offset) - sizeof(file);
+		DEBUG(" - load entry 0x%x file name (%d bytes)...\n", offset,
+		      name_len);
+
+		// load file name (arbitrary length).
+		file_name = (const char*)media->map(
+				media, offset + sizeof(file), name_len);
+		if (file_name == CBFS_MEDIA_INVALID_MAP_ADDRESS) {
+			ERROR("ERROR: Failed to get filename: 0x%x.\n", offset);
+		} else if (strcmp(file_name, name) == 0) {
+			int file_offset = ntohl(file.offset),
+			    file_len = ntohl(file.len);
+			LOG("Found file (offset=0x%x, len=%d).\n",
+			    offset + file_offset, file_len);
+			media->unmap(media, file_name);
+			file_ptr = media->map(media, offset,
+					      file_offset + file_len);
+			media->close(media);
+			return file_ptr;
+		} else {
+			LOG(" (unmatched file @0x%x: %s)\n", offset, file_name);
+			media->unmap(media, file_name);
+		}
+
+		// Move to next file.
+		offset += ntohl(file.len) + ntohl(file.offset);
+		if (offset % align)
+			offset += align - (offset % align);
+	}
+	media->close(media);
+	ERROR("ERROR: Not found.\n");
+	return NULL;
 }
 
-void *cbfs_find_file(const char *name, int type)
+void *cbfs_get_file_content(struct cbfs_media *media, const char *name, int type)
 {
-	struct cbfs_file *file = cbfs_find(name);
+	struct cbfs_file *file = cbfs_get_file(media, name);
 
 	if (file == NULL) {
 		ERROR("Could not find file '%s'.\n", name);
@@ -147,7 +182,8 @@ void *cbfs_find_file(const char *name, int type)
 	}
 
 	if (ntohl(file->type) != type) {
-		ERROR("File '%s' is of type %x, but we requested %x.\n", name, ntohl(file->type), type);
+		ERROR("File '%s' is of type %x, but we requested %x.\n", name,
+		      ntohl(file->type), type);
 		return NULL;
 	}
 
@@ -168,7 +204,9 @@ int cbfs_decompress(int algo, void *src, void *dst, int len)
 			return -1;
 #endif
 		default:
-			ERROR("tried to decompress %d bytes with algorithm #%x, but that algorithm id is unsupported.\n", len, algo);
+			ERROR("tried to decompress %d bytes with algorithm #%x,"
+			      "but that algorithm id is unsupported.\n", len,
+			      algo);
 			return -1;
 	}
 }
diff --git a/payloads/libpayload/libcbfs/ram_media.c b/payloads/libpayload/libcbfs/ram_media.c
new file mode 100644
index 0000000000..87b5292b63
--- /dev/null
+++ b/payloads/libpayload/libcbfs/ram_media.c
@@ -0,0 +1,114 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * Copyright (C) 2013 Google, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#include <cbfs.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+// Implementation of a media source based on given memory buffer.
+struct ram_media {
+	char *start;
+	size_t size;
+};
+
+static int ram_open(struct cbfs_media *media) {
+	return 0;
+}
+
+static void *ram_map(struct cbfs_media *media, size_t offset, size_t count) {
+	struct ram_media *m = (struct ram_media*)media->context;
+	if (offset + count >= m->size) {
+		printf("ERROR: ram_map: request out of range (0x%x+0x%x)\n",
+		       offset, count);
+		return NULL;
+	}
+	return (void*)(m->start + offset);
+}
+
+static void *ram_unmap(struct cbfs_media *media, const void *address) {
+	return NULL;
+}
+
+static size_t ram_read(struct cbfs_media *media, void *dest, size_t offset,
+			   size_t count) {
+	void *ptr = ram_map(media, offset, count);
+	memcpy(dest, ptr, count);
+	ram_unmap(media, ptr);
+	return count;
+}
+
+static int ram_close(struct cbfs_media *media) {
+	return 0;
+}
+
+int init_cbfs_ram_media(struct cbfs_media *media, void *start, size_t size);
+int init_cbfs_ram_media(struct cbfs_media *media, void *start, size_t size) {
+	// TODO Find a way to release unused media. Maybe adding media->destroy.
+	struct ram_media *m = (struct ram_media*)malloc(sizeof(*m));
+	m->start = start;
+	m->size = size;
+	media->context = (void*)m;
+	media->open = ram_open;
+	media->close = ram_close;
+	media->map = ram_map;
+	media->unmap = ram_unmap;
+	media->read = ram_read;
+	return 0;
+}
+
+// Legacy setup_cbfs_from_*.
+static int is_default_cbfs_media_initialized;
+static struct cbfs_media default_cbfs_media;
+
+int setup_cbfs_from_ram(void *start, uint32_t size);
+int setup_cbfs_from_ram(void *start, uint32_t size) {
+	int result = init_cbfs_ram_media(&default_cbfs_media, start, size);
+	if (result == 0)
+		is_default_cbfs_media_initialized = 1;
+	return result;
+}
+
+extern int libpayload_init_default_cbfs_media(struct cbfs_media *media);
+int setup_cbfs_from_flash(void);
+int setup_cbfs_from_flash(void) {
+	int result = libpayload_init_default_cbfs_media(&default_cbfs_media);
+	if (result == 0)
+	    is_default_cbfs_media_initialized = 1;
+	return result;
+}
+
+int init_default_cbfs_media(struct cbfs_media *media) {
+	int result = 0;
+	if (is_default_cbfs_media_initialized != 1) {
+		result = setup_cbfs_from_flash();
+	}
+	if (result == 0)
+		memcpy(media, &default_cbfs_media, sizeof(*media));
+	return result;
+}