[coreboot-gerrit] Patch set updated for coreboot: libpayload: replace cbfs_media api with region_device api

Antonello Dettori (dev@dettori.io) gerrit at coreboot.org
Thu Jul 28 22:13:23 CEST 2016


Antonello Dettori (dev at dettori.io) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/15774

-gerrit

commit 66cc28aec1f98529eda522ba9fda9bd1a4e85bac
Author: Antonello Dettori <dev at dettori.io>
Date:   Thu Jul 21 15:30:46 2016 +0200

    libpayload: replace cbfs_media api with region_device api
    
    Replace all the functionality provided by the cbfs_image api with
    the more recent region_device api used throughout the rest of the
    coreboot project.
    
    Change-Id: Ia79f532a9f8701f6c586609d38f6a88bfdf116e9
    Signed-off-by: Antonello Dettori <dev at dettori.io>
---
 payloads/libpayload/arch/arm/dummy_media.c   |   5 +-
 payloads/libpayload/arch/arm64/dummy_media.c |   5 +-
 payloads/libpayload/arch/mips/dummy_media.c  |   5 +-
 payloads/libpayload/arch/x86/rom_media.c     |  85 +-----
 payloads/libpayload/drivers/video/graphics.c |   1 -
 payloads/libpayload/include/cbfs.h           |  13 +-
 payloads/libpayload/include/cbfs_core.h      |  40 +--
 payloads/libpayload/include/cbfs_ram.h       |  57 ----
 payloads/libpayload/include/mem_pool.h       |  69 +++++
 payloads/libpayload/include/region_device.h  | 248 +++++++++++++++
 payloads/libpayload/include/stddef.h         |   2 +
 payloads/libpayload/include/stdlib.h         |  19 ++
 payloads/libpayload/libc/fmap.c              |  16 +-
 payloads/libpayload/libcbfs/Makefile.inc     |   3 +-
 payloads/libpayload/libcbfs/cbfs.c           |  36 ++-
 payloads/libpayload/libcbfs/cbfs_core.c      | 114 +++----
 payloads/libpayload/libcbfs/mem_pool.c       |  48 +++
 payloads/libpayload/libcbfs/ram_media.c      | 118 --------
 payloads/libpayload/libcbfs/region_device.c  | 434 +++++++++++++++++++++++++++
 19 files changed, 938 insertions(+), 380 deletions(-)

diff --git a/payloads/libpayload/arch/arm/dummy_media.c b/payloads/libpayload/arch/arm/dummy_media.c
index c67344f..e74d4c7 100644
--- a/payloads/libpayload/arch/arm/dummy_media.c
+++ b/payloads/libpayload/arch/arm/dummy_media.c
@@ -34,10 +34,7 @@
 /* The generic cbfs code relies on the libpayload_init_default_cbfs_media
  * symbol. Therefore, provide an implementation that just throws an error. */
 
-int libpayload_init_default_cbfs_media(struct cbfs_media *media);
-
-__attribute__((weak)) int libpayload_init_default_cbfs_media(
-		struct cbfs_media *media)
+__attribute__((weak)) int libpayload_init_default_cbfs_media(void)
 {
 	return -1;
 }
diff --git a/payloads/libpayload/arch/arm64/dummy_media.c b/payloads/libpayload/arch/arm64/dummy_media.c
index c67344f..e74d4c7 100644
--- a/payloads/libpayload/arch/arm64/dummy_media.c
+++ b/payloads/libpayload/arch/arm64/dummy_media.c
@@ -34,10 +34,7 @@
 /* The generic cbfs code relies on the libpayload_init_default_cbfs_media
  * symbol. Therefore, provide an implementation that just throws an error. */
 
-int libpayload_init_default_cbfs_media(struct cbfs_media *media);
-
-__attribute__((weak)) int libpayload_init_default_cbfs_media(
-		struct cbfs_media *media)
+__attribute__((weak)) int libpayload_init_default_cbfs_media(void)
 {
 	return -1;
 }
diff --git a/payloads/libpayload/arch/mips/dummy_media.c b/payloads/libpayload/arch/mips/dummy_media.c
index 112d7fe..1732b75 100644
--- a/payloads/libpayload/arch/mips/dummy_media.c
+++ b/payloads/libpayload/arch/mips/dummy_media.c
@@ -33,10 +33,7 @@
 /* The generic cbfs code relies on the libpayload_init_default_cbfs_media
  * symbol. Therefore, provide an implementation that just throws an error. */
 
-int libpayload_init_default_cbfs_media(struct cbfs_media *media);
-
-__attribute__((weak)) int libpayload_init_default_cbfs_media(
-		struct cbfs_media *media)
+__attribute__((weak)) int libpayload_init_default_cbfs_media(void)
 {
 	return -1;
 }
diff --git a/payloads/libpayload/arch/x86/rom_media.c b/payloads/libpayload/arch/x86/rom_media.c
index 0c6f521..48c1669 100644
--- a/payloads/libpayload/arch/x86/rom_media.c
+++ b/payloads/libpayload/arch/x86/rom_media.c
@@ -26,86 +26,31 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-#define LIBPAYLOAD
 
 #include <cbfs.h>
 #include <string.h>
+#include <sysinfo.h>
 
-#ifdef LIBPAYLOAD
-# define printk(x...)
-# define init_default_cbfs_media libpayload_init_default_cbfs_media
-  extern int libpayload_init_default_cbfs_media(struct cbfs_media *media);
-#else
-# include <console/console.h>
-#endif
+static struct mem_region_device boot_dev;
 
-// Implementation of memory-mapped ROM media source on X86.
-
-static int x86_rom_open(struct cbfs_media *media) {
-	return 0;
-}
-
-static void *x86_rom_map(struct cbfs_media *media, size_t offset, size_t count) {
-	void *ptr;
-	// Some address (ex, pointer to master header) may be given in memory
-	// mapped location. To workaround that, we handle >0xf0000000 as real
-	// memory pointer.
-
-	if ((uint32_t)offset > (uint32_t)0xf0000000)
-		ptr = (void*)offset;
-	else
-		ptr = (void*)(0 - (uint32_t)media->context + offset);
-	return ptr;
+struct region_device *boot_device_ro(void)
+{
+	return &boot_dev.rdev;
 }
 
-static void *x86_rom_unmap(struct cbfs_media *media, const void *address) {
-	return NULL;
-}
-
-static size_t x86_rom_read(struct cbfs_media *media, void *dest, size_t offset,
-			   size_t count) {
-	void *ptr = x86_rom_map(media, offset, count);
-	memcpy(dest, ptr, count);
-	x86_rom_unmap(media, ptr);
-	return count;
-}
+static int init_x86rom_cbfs_media(void)
+{
+	/* The ROM is memory mapped just below 4GiB.
+	 * Form a pointer for the base. */
+	size_t romsize = lib_sysinfo.boot_media_size;
+	void *rombase = (void *)(uintptr_t)(0x100000000ULL - romsize);
 
-static int x86_rom_close(struct cbfs_media *media) {
-	return 0;
-}
+	mem_region_device_ro_init(&boot_dev, rombase, romsize);
 
-int init_x86rom_cbfs_media(struct cbfs_media *media);
-int init_x86rom_cbfs_media(struct cbfs_media *media) {
-	// On X86, we always keep a reference of pointer to CBFS header in
-	// 0xfffffffc, and the pointer is still a memory-mapped address.
-	// Since the CBFS core always use ROM offset, we need to figure out
-	// header->romsize even before media is initialized.
-	struct cbfs_header *header = (struct cbfs_header*)
-			*(uint32_t*)(0xfffffffc);
-	if (CBFS_HEADER_MAGIC != ntohl(header->magic)) {
-#if IS_ENABLED(CONFIG_LP_ROM_SIZE)
-		printk(BIOS_ERR, "Invalid CBFS master header at %p\n", header);
-		media->context = (void*)CONFIG_LP_ROM_SIZE;
-#else
-		return -1;
-#endif
-	} else {
-		uint32_t romsize = ntohl(header->romsize);
-		media->context = (void*)romsize;
-#if IS_ENABLED(CONFIG_LP_ROM_SIZE)
-		if (CONFIG_LP_ROM_SIZE != romsize)
-			printk(BIOS_INFO, "Warning: rom size unmatch (%d/%d)\n",
-			       CONFIG_LP_ROM_SIZE, romsize);
-#endif
-	}
-	media->open = x86_rom_open;
-	media->close = x86_rom_close;
-	media->map = x86_rom_map;
-	media->unmap = x86_rom_unmap;
-	media->read = x86_rom_read;
 	return 0;
 }
 
-int init_default_cbfs_media(struct cbfs_media *media) {
-	return init_x86rom_cbfs_media(media);
+int libpayload_init_default_cbfs_media(void)
+{
+	return init_x86rom_cbfs_media();
 }
diff --git a/payloads/libpayload/drivers/video/graphics.c b/payloads/libpayload/drivers/video/graphics.c
index 943f8ed..3d93c88 100644
--- a/payloads/libpayload/drivers/video/graphics.c
+++ b/payloads/libpayload/drivers/video/graphics.c
@@ -52,7 +52,6 @@ static uint8_t *fbaddr;
 #define PIVOT_H_MASK	(PIVOT_H_LEFT|PIVOT_H_CENTER|PIVOT_H_RIGHT)
 #define PIVOT_V_MASK	(PIVOT_V_TOP|PIVOT_V_CENTER|PIVOT_V_BOTTOM)
 #define ROUNDUP(x, y)	((((x) + ((y) - 1)) / (y)) * (y))
-#define ABS(x)		((x) < 0 ? -(x) : (x))
 
 static char initialized = 0;
 
diff --git a/payloads/libpayload/include/cbfs.h b/payloads/libpayload/include/cbfs.h
index 801bdfc..12ea408 100644
--- a/payloads/libpayload/include/cbfs.h
+++ b/payloads/libpayload/include/cbfs.h
@@ -53,11 +53,11 @@ const struct cbfs_header *get_cbfs_header(void);
 struct cbfs_file *cbfs_find(const char *name);
 void *cbfs_find_file(const char *name, int type);
 
-int cbfs_execute_stage(struct cbfs_media *media, const char *name);
-void *cbfs_load_optionrom(struct cbfs_media *media, uint16_t vendor,
+int cbfs_execute_stage(struct region_device *media, const char *name);
+void *cbfs_load_optionrom(struct region_device *media, uint16_t vendor,
 			  uint16_t device);
-void *cbfs_load_payload(struct cbfs_media *media, const char *name);
-void *cbfs_load_stage(struct cbfs_media *media, const char *name);
+void *cbfs_load_payload(struct region_device *media, const char *name);
+void *cbfs_load_stage(struct region_device *media, const char *name);
 
 /* Simple buffer for streaming media. */
 struct cbfs_simple_buffer {
@@ -68,7 +68,7 @@ struct cbfs_simple_buffer {
 };
 
 void *cbfs_simple_buffer_map(struct cbfs_simple_buffer *buffer,
-			     struct cbfs_media *media,
+			     struct region_device *media,
 			     size_t offset, size_t count);
 
 void *cbfs_simple_buffer_unmap(struct cbfs_simple_buffer *buffer,
@@ -78,6 +78,7 @@ void *cbfs_simple_buffer_unmap(struct cbfs_simple_buffer *buffer,
 int run_address(void *f);
 
 /* Defined in individual arch / board implementation. */
-int init_default_cbfs_media(struct cbfs_media *media);
+int libpayload_init_default_cbfs_media(void);
+struct region_device *boot_device_ro(void);
 
 #endif
diff --git a/payloads/libpayload/include/cbfs_core.h b/payloads/libpayload/include/cbfs_core.h
index f94056d..b7234cd 100644
--- a/payloads/libpayload/include/cbfs_core.h
+++ b/payloads/libpayload/include/cbfs_core.h
@@ -50,6 +50,8 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <region_device.h>
+
 
 /** These are standard values for the known compression
     alogrithms that coreboot knows about for stages and
@@ -211,43 +213,14 @@ struct cbfs_optionrom {
 	uint32_t len;
 } __attribute__((packed));
 
-#define CBFS_MEDIA_INVALID_MAP_ADDRESS	((void*)(0xffffffff))
 #define CBFS_DEFAULT_MEDIA		((void*)(0x0))
 
-/* Media for CBFS to load files. */
-struct cbfs_media {
-
-	/* implementation dependent context, to hold resource references */
-	void *context;
-
-	/* opens media and returns 0 on success, -1 on failure */
-	int (*open)(struct cbfs_media *media);
-
-	/* returns number of bytes read from media into dest, starting from
-	 * offset for count of bytes */
-	size_t (*read)(struct cbfs_media *media, void *dest, size_t offset,
-		       size_t count);
-
-	/* returns a pointer to memory with count of bytes from media source
-	 * starting from offset, or CBFS_MEDIA_INVALID_MAP_ADDRESS on failure.
-	 * Note: mapped data can't be free unless unmap is called, even if you
-	 * do close first. */
-	void * (*map)(struct cbfs_media *media, size_t offset, size_t count);
-
-	/* returns NULL and releases the memory by address, which was allocated
-	 * by map */
-	void * (*unmap)(struct cbfs_media *media, const void *address);
-
-	/* closes media and returns 0 on success, -1 on failure. */
-	int (*close)(struct cbfs_media *media);
-};
-
 /*
  * Returns pointer to a copy of the file content or NULL on error.
  * If the file is compressed, data will be decompressed.
  * The caller owns the returned memory.
  */
-void *cbfs_get_file_content(struct cbfs_media *media, const char *name,
+void *cbfs_get_file_content(struct region_device *media, const char *name,
 			    int type, size_t *sz);
 
 /* returns decompressed size on success, 0 on failure */
@@ -255,11 +228,11 @@ int cbfs_decompress(int algo, void *src, void *dst, int len);
 
 /* 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);
+const struct cbfs_header *cbfs_get_header(struct region_device *media);
 
 /* Persistent handle to a CBFS file that has not yet been fully mapped. */
 struct cbfs_handle {
-	struct cbfs_media media;	/* copy of original media object */
+	struct region_device *media;	/* pointer to original media object */
 	u32 type;			/* CBFS file type */
 	u32 media_offset;		/* offset from beginning of media */
 	u32 attribute_offset;		/* relative offset of attributes */
@@ -269,7 +242,8 @@ struct cbfs_handle {
 
 /* Returns handle to CBFS file, or NULL on error. Does not yet map contents.
  * Caller is responsible to free() returned handle after use. */
-struct cbfs_handle *cbfs_get_handle(struct cbfs_media *media, const char *name);
+struct cbfs_handle *cbfs_get_handle(struct region_device *media,
+		const char *name);
 
 /* Given a cbfs_handle and an attribute tag, return a mapping for the first
  * instance of the attribute or NULL if none found. */
diff --git a/payloads/libpayload/include/cbfs_ram.h b/payloads/libpayload/include/cbfs_ram.h
deleted file mode 100644
index 72839fe..0000000
--- a/payloads/libpayload/include/cbfs_ram.h
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * This file is part of the libpayload project.
- *
- * Copyright (C) 2013 Google, Inc.
- *
- * This file is dual-licensed. You can choose between:
- *   - The GNU GPL, version 2, as published by the Free Software Foundation
- *   - The revised BSD license (without advertising clause)
- *
- * ---------------------------------------------------------------------------
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- * ---------------------------------------------------------------------------
- * 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.
- * ---------------------------------------------------------------------------
- */
-
-#ifndef _CBFS_RAM_H_
-#define _CBFS_RAM_H_
-
-#include <stdint.h>
-
-struct cbfs_media;
-
-/* The following functions return 0 for success. None-zero on error. */
-int init_cbfs_ram_media(struct cbfs_media *media, void *start, size_t size);
-int setup_cbfs_from_ram(void *start, uint32_t size);
-int setup_cbfs_from_flash(void);
-
-#endif  /* _CBFS_RAM_H_ */
diff --git a/payloads/libpayload/include/mem_pool.h b/payloads/libpayload/include/mem_pool.h
new file mode 100644
index 0000000..c21fa0e
--- /dev/null
+++ b/payloads/libpayload/include/mem_pool.h
@@ -0,0 +1,69 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _MEM_POOL_H_
+#define _MEM_POOL_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+/*
+ * The memory pool allows one to allocate memory from a fixed size buffer
+ * that also allows freeing semantics for reuse. However, the current
+ * limitation is that the most recent allocation is the only one that
+ * can be freed. If one tries to free any allocation that isn't the
+ * most recently allocated it will result in a leak within the memory pool.
+ *
+ * The memory returned by allocations are at least 8 byte aligned. Note
+ * that this requires the backing buffer to start on at least an 8 byte
+ * alignment.
+ */
+
+struct mem_pool {
+	uint8_t *buf;
+	size_t size;
+	uint8_t *last_alloc;
+	size_t free_offset;
+};
+
+#define MEM_POOL_INIT(buf_, size_)	\
+	{				\
+		.buf = (buf_),		\
+		.size = (size_),	\
+		.last_alloc = NULL,	\
+		.free_offset = 0,	\
+	}
+
+static inline void mem_pool_reset(struct mem_pool *mp)
+{
+	mp->last_alloc = NULL;
+	mp->free_offset = 0;
+}
+
+/* Initialize a memory pool. */
+static inline void mem_pool_init(struct mem_pool *mp, void *buf, size_t sz)
+{
+	mp->buf = buf;
+	mp->size = sz;
+	mem_pool_reset(mp);
+}
+
+/* Allocate requested size from the memory pool. NULL returned on error. */
+void *mem_pool_alloc(struct mem_pool *mp, size_t sz);
+
+/* Free allocation from memory pool. */
+void mem_pool_free(struct mem_pool *mp, void *alloc);
+
+#endif /* _MEM_POOL_H_ */
diff --git a/payloads/libpayload/include/region_device.h b/payloads/libpayload/include/region_device.h
new file mode 100644
index 0000000..8926ecf
--- /dev/null
+++ b/payloads/libpayload/include/region_device.h
@@ -0,0 +1,248 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _REGION_H_
+#define _REGION_H_
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <mem_pool.h>
+
+/*
+ * Region support.
+ *
+ * Regions are intended to abstract away the access mechanisms for blocks of
+ * data. This could be SPI, eMMC, or a memory region as the backing store.
+ * They are accessed through a region_device.  Subregions can be made by
+ * chaining together multiple region_devices.
+ */
+
+struct region_device;
+
+/*
+ * Returns NULL on error otherwise a buffer is returned with the conents of
+ * the requested data at offset of size.
+ */
+void *rdev_mmap(const struct region_device *rd, size_t offset, size_t size);
+
+/* Unmap a previously mapped area. Returns 0 on success, < 0 on error. */
+int rdev_munmap(const struct region_device *rd, void *mapping);
+
+/*
+ * Returns < 0 on error otherwise returns size of data read at provided
+ * offset filling in the buffer passed.
+ */
+ssize_t rdev_readat(const struct region_device *rd, void *b, size_t offset,
+			size_t size);
+
+/*
+ * Returns < 0 on error otherwise returns size of data wrote at provided
+ * offset from the buffer passed.
+ */
+ssize_t rdev_writeat(const struct region_device *rd, void *b, size_t offset,
+			size_t size);
+
+/*
+ * Returns < 0 on error otherwise returns size of data erased.
+ * If eraseat ops is not defined it returns size which indicates
+ * that operation was successful.
+ */
+ssize_t rdev_eraseat(const struct region_device *rd, size_t offset,
+			size_t size);
+
+/****************************************
+ *  Implementation of a region device   *
+ ****************************************/
+
+/*
+ * Create a child region of the parent provided the sub-region is within
+ * the parent's region. Returns < 0 on error otherwise 0 on success. Note
+ * that the child device only calls through the parent's operations.
+ */
+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);
+	int (*munmap)(const struct region_device *, void *);
+	ssize_t (*readat)(const struct region_device *, void *, size_t, size_t);
+	ssize_t (*writeat)(const struct region_device *, void *, size_t,
+		size_t);
+	ssize_t (*eraseat)(const struct region_device *, size_t, size_t);
+};
+
+struct region {
+	size_t offset;
+	size_t size;
+};
+
+struct region_device {
+	const struct region_device *root;
+	const struct region_device_ops *ops;
+	struct region region;
+};
+
+#define REGION_DEV_INIT(ops_, offset_, size_)		\
+	{						\
+		.root = NULL,				\
+		.ops = (ops_),				\
+		.region = {				\
+			.offset = (offset_),		\
+			.size = (size_),		\
+		},					\
+	}
+
+/* Helper to dynamically initialize region device. */
+void region_device_init(struct region_device *rdev,
+			const struct region_device_ops *ops, size_t offset,
+			size_t size);
+
+static inline size_t region_offset(const struct region *r)
+{
+	return r->offset;
+}
+
+static inline size_t region_sz(const struct region *r)
+{
+	return r->size;
+}
+
+static inline const struct region *region_device_region(
+					const struct region_device *rdev)
+{
+	return &rdev->region;
+}
+
+static inline size_t region_device_sz(const struct region_device *rdev)
+{
+	return region_sz(region_device_region(rdev));
+}
+
+static inline size_t region_device_offset(const struct region_device *rdev)
+{
+	return region_offset(region_device_region(rdev));
+}
+
+/* Memory map entire region device. Same semantics as rdev_mmap() above. */
+static inline void *rdev_mmap_full(const struct region_device *rd)
+{
+	return rdev_mmap(rd, 0, region_device_sz(rd));
+}
+
+/*
+ * Compute relative offset of the child (c) w.r.t. the parent (p). Returns < 0
+ * when child is not within the parent's region.
+ */
+ssize_t rdev_relative_offset(const struct region_device *p,
+				const struct region_device *c);
+
+struct mem_region_device {
+	char *base;
+	struct region_device rdev;
+};
+
+/* Inititalize 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. */
+void mem_region_device_ro_init(struct mem_region_device *mdev, void *base,
+				size_t size);
+
+void mem_region_device_rw_init(struct mem_region_device *mdev, void *base,
+				size_t size);
+
+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. */
+#define MEM_REGION_DEV_INIT(base_, size_, ops_)				\
+	{								\
+		.base = (void *)(base_),				\
+		.rdev = REGION_DEV_INIT((ops_), 0, (size_)),		\
+	}
+
+#define MEM_REGION_DEV_RO_INIT(base_, size_)				\
+		MEM_REGION_DEV_INIT(base_, size_, &mem_rdev_ro_ops)	\
+
+#define MEM_REGION_DEV_RW_INIT(base_, size_)				\
+		MEM_REGION_DEV_INIT(base_, size_, &mem_rdev_rw_ops)	\
+
+struct mmap_helper_region_device {
+	struct mem_pool pool;
+	struct region_device rdev;
+};
+
+#define MMAP_HELPER_REGION_INIT(ops_, offset_, size_)			\
+	{								\
+		.rdev = REGION_DEV_INIT((ops_), (offset_), (size_)),	\
+	}
+
+void mmap_helper_device_init(struct mmap_helper_region_device *mdev,
+				void *cache, size_t cache_size);
+
+void *mmap_helper_rdev_mmap(const struct region_device *, size_t, size_t);
+int mmap_helper_rdev_munmap(const struct region_device *, void *);
+
+/* A translated region device provides the ability to publish a region device
+ * in one address space and use an access mechanism within another address
+ * space. The sub region is the window within the 1st address space and
+ * the request is modified prior to accessing the second address space
+ * provided by access_dev. */
+struct xlate_region_device {
+	const struct region_device *access_dev;
+	struct region sub_region;
+	struct region_device rdev;
+};
+
+extern const struct region_device_ops xlate_rdev_ro_ops;
+
+extern const struct region_device_ops xlate_rdev_rw_ops;
+
+#define XLATE_REGION_DEV_INIT(access_dev_, sub_offset_, sub_size_,	\
+		parent_sz_, ops_)					\
+	{								\
+		.access_dev = access_dev_,				\
+		.sub_region = {						\
+			.offset = (sub_offset_),			\
+			.size = (sub_size_),				\
+		},							\
+		.rdev = REGION_DEV_INIT((ops_), 0,  (parent_sz_)),	\
+	}
+
+#define XLATE_REGION_DEV_RO_INIT(access_dev_, sub_offset_, sub_size_,	\
+		parent_sz_)						\
+		XLATE_REGION_DEV_INIT(access_dev_, sub_offset_,		\
+			sub_size_, parent_sz_, &xlate_rdev_ro_ops),	\
+
+#define XLATE_REGION_DEV_RW_INIT(access_dev_, sub_offset_, sub_size_,	\
+		parent_sz_)						\
+		XLATE_REGION_DEV_INIT(access_dev_, sub_offset_,		\
+			sub_size_, parent_sz_, &xlate_rdev_rw_ops),	\
+
+/* Helper to dynamically initialize xlate region device. */
+void xlate_region_device_ro_init(struct xlate_region_device *xdev,
+			      const struct region_device *access_dev,
+			      size_t sub_offset, size_t sub_size,
+			      size_t parent_size);
+
+void xlate_region_device_rw_init(struct xlate_region_device *xdev,
+			      const struct region_device *access_dev,
+			      size_t sub_offset, size_t sub_size,
+			      size_t parent_size);
+
+#endif /* _REGION_H_ */
diff --git a/payloads/libpayload/include/stddef.h b/payloads/libpayload/include/stddef.h
index fe455b8..a35bd68 100644
--- a/payloads/libpayload/include/stddef.h
+++ b/payloads/libpayload/include/stddef.h
@@ -20,6 +20,8 @@ typedef __SIZE_TYPE__ ssize_t;
 	offsetof(struct structure, member) == offset, \
 	"`struct " #structure "` offset for `" #member "` is not " #offset)
 
+#define __unused __attribute__((unused))
+
 /* Standard units. */
 #define KiB (1<<10)
 #define MiB (1<<20)
diff --git a/payloads/libpayload/include/stdlib.h b/payloads/libpayload/include/stdlib.h
index 689bf01..cf9156f 100644
--- a/payloads/libpayload/include/stdlib.h
+++ b/payloads/libpayload/include/stdlib.h
@@ -41,6 +41,25 @@
 #define ALIGN_DOWN(x,a)         ((x) & ~((typeof(x))(a)-1UL))
 #define IS_ALIGNED(x,a)         (((x) & ((typeof(x))(a)-1UL)) == 0)
 
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define ABS(a) (((a) < 0) ? (-(a)) : (a))
+#define CEIL_DIV(a, b)  (((a) + (b) - 1) / (b))
+#define IS_POWER_OF_2(x)  (((x) & ((x) - 1)) == 0)
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ * @param ptr:    the pointer to the member.
+ * @param type:   the type of the container struct this is embedded in.
+ * @param member: the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member) ({			\
+	const __typeof__(((type *)0)->member) * __mptr = (ptr);	\
+	(type *)((char *)__mptr - offsetof(type, member)); })
+
 /**
  * @defgroup malloc Memory allocation functions
  * @{
diff --git a/payloads/libpayload/libc/fmap.c b/payloads/libpayload/libc/fmap.c
index af9902e..cf0c57c 100644
--- a/payloads/libpayload/libc/fmap.c
+++ b/payloads/libpayload/libc/fmap.c
@@ -41,15 +41,13 @@ int fmap_region_by_name(const uint32_t fmap_offset, const char * const name,
 
 	struct fmap *fmap;
 	struct fmap fmap_head;
-	struct cbfs_media default_media;
-	struct cbfs_media *media = &default_media;
+	struct region_device default_media;
+	struct region_device *media = &default_media;
 
-	if (init_default_cbfs_media(media) != 0)
-		return -1;
-
-	media->open(media);
+	libpayload_init_default_cbfs_media();
+	media = boot_device_ro();
 
-	if (!media->read(media, &fmap_head, fmap_offset, sizeof(fmap_head)))
+	if (rdev_readat(media, &fmap_head, fmap_offset, sizeof(fmap_head)) < 0)
 		return -1;
 
 	if (memcmp(fmap_head.signature, FMAP_SIGNATURE, sizeof(fmap_head.signature))) {
@@ -63,11 +61,9 @@ int fmap_region_by_name(const uint32_t fmap_offset, const char * const name,
 	if (!fmap)
 		return -1;
 
-	if (!media->read(media, fmap, fmap_offset, fmap_size))
+	if (rdev_readat(media, fmap, fmap_offset, fmap_size) < 0)
 		goto err;
 
-	media->close(media);
-
 	for (i = 0; i < fmap->nareas; i++) {
 		if (strcmp((const char *)fmap->areas[i].name, name) != 0)
 			continue;
diff --git a/payloads/libpayload/libcbfs/Makefile.inc b/payloads/libpayload/libcbfs/Makefile.inc
index 133b215..4a3ce1e 100644
--- a/payloads/libpayload/libcbfs/Makefile.inc
+++ b/payloads/libpayload/libcbfs/Makefile.inc
@@ -28,4 +28,5 @@
 ##
 
 libcbfs-$(CONFIG_LP_CBFS) += cbfs.c
-libcbfs-$(CONFIG_LP_CBFS) += ram_media.c
+libcbfs-$(CONFIG_LP_CBFS) += region_device.c
+libcbfs-$(CONFIG_LP_CBFS) += mem_pool.c
diff --git a/payloads/libpayload/libcbfs/cbfs.c b/payloads/libpayload/libcbfs/cbfs.c
index 38b1ff8..3751b95 100644
--- a/payloads/libpayload/libcbfs/cbfs.c
+++ b/payloads/libpayload/libcbfs/cbfs.c
@@ -83,7 +83,7 @@ static void tohex16(unsigned int val, char* dest)
 	dest[3] = tohex4(val & 0xf);
 }
 
-void *cbfs_load_optionrom(struct cbfs_media *media, uint16_t vendor,
+void *cbfs_load_optionrom(struct region_device *media, uint16_t vendor,
 			  uint16_t device)
 {
 	char name[17] = "pciXXXX,XXXX.rom";
@@ -94,7 +94,7 @@ void *cbfs_load_optionrom(struct cbfs_media *media, uint16_t vendor,
 	return cbfs_get_file_content(media, name, CBFS_TYPE_OPTIONROM, NULL);
 }
 
-void * cbfs_load_stage(struct cbfs_media *media, const char *name)
+void *cbfs_load_stage(struct region_device *media, const char *name)
 {
 	struct cbfs_stage *stage = (struct cbfs_stage *)
 		cbfs_get_file_content(media, name, CBFS_TYPE_STAGE, NULL);
@@ -131,7 +131,8 @@ void * cbfs_load_stage(struct cbfs_media *media, const char *name)
 	return (void *) entry;
 }
 
-int cbfs_execute_stage(struct cbfs_media *media, const char *name)
+
+int cbfs_execute_stage(struct region_device *media, const char *name)
 {
 	struct cbfs_stage *stage = (struct cbfs_stage *)
 		cbfs_get_file_content(media, name, CBFS_TYPE_STAGE, NULL);
@@ -152,23 +153,23 @@ int cbfs_execute_stage(struct cbfs_media *media, const char *name)
 	return result;
 }
 
-void *cbfs_load_payload(struct cbfs_media *media, const char *name)
+void *cbfs_load_payload(struct region_device *media, const char *name)
 {
 	return (struct cbfs_payload *)cbfs_get_file_content(
 		media, name, CBFS_TYPE_PAYLOAD, NULL);
 }
 
-struct cbfs_file *cbfs_find(const char *name) {
+struct cbfs_file *cbfs_find(const char *name)
+{
 	struct cbfs_handle *handle = cbfs_get_handle(CBFS_DEFAULT_MEDIA, name);
-	struct cbfs_media *m = &handle->media;
 	void *ret;
 
 	if (!handle)
 		return NULL;
 
-	ret = m->map(m, handle->media_offset,
+	ret = rdev_mmap(handle->media, handle->media_offset,
 		     handle->content_offset + handle->content_size);
-	if (ret == CBFS_MEDIA_INVALID_MAP_ADDRESS) {
+	if (ret == NULL) {
 		free(handle);
 		return NULL;
 	}
@@ -177,30 +178,32 @@ struct cbfs_file *cbfs_find(const char *name) {
 	return ret;
 }
 
-void *cbfs_find_file(const char *name, int type) {
+void *cbfs_find_file(const char *name, int type)
+{
 	return cbfs_get_file_content(CBFS_DEFAULT_MEDIA, name, type, NULL);
 }
 
-const struct cbfs_header *get_cbfs_header(void) {
+const struct cbfs_header *get_cbfs_header(void)
+{
 	return cbfs_get_header(CBFS_DEFAULT_MEDIA);
 }
 
 /* Simple buffer */
 
 void *cbfs_simple_buffer_map(struct cbfs_simple_buffer *buffer,
-			     struct cbfs_media *media,
-			     size_t offset, size_t count) {
+		struct region_device *media, size_t offset, size_t count)
+{
 	void *address = buffer->buffer + buffer->allocated;;
 	DEBUG("simple_buffer_map(offset=%zu, count=%zu): "
 	      "allocated=%zu, size=%zu, last_allocate=%zu\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) {
+		return NULL;
+	if (rdev_readat(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;
+		return NULL;
 	}
 	buffer->allocated += count;
 	buffer->last_allocate = count;
@@ -208,7 +211,8 @@ void *cbfs_simple_buffer_map(struct cbfs_simple_buffer *buffer,
 }
 
 void *cbfs_simple_buffer_unmap(struct cbfs_simple_buffer *buffer,
-			       const void *address) {
+		const void *address)
+{
 	// TODO Add simple buffer management so we can free more than last
 	// allocated one.
 	DEBUG("simple_buffer_unmap(address=0x%p): "
diff --git a/payloads/libpayload/libcbfs/cbfs_core.c b/payloads/libpayload/libcbfs/cbfs_core.c
index 7e660ce..ccca2af 100644
--- a/payloads/libpayload/libcbfs/cbfs_core.c
+++ b/payloads/libpayload/libcbfs/cbfs_core.c
@@ -54,32 +54,29 @@
 
 /* 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)
+const struct cbfs_header *cbfs_get_header(struct region_device *media)
 {
 	int32_t rel_offset;
 	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 initialize default media.\n");
-			return CBFS_HEADER_INVALID_ADDRESS;
-		}
+		libpayload_init_default_cbfs_media();
+		media = boot_device_ro();
 	}
-	media->open(media);
 
-	if (!media->read(media, &rel_offset, (size_t)(0 - sizeof(int32_t)),
-			 sizeof(int32_t))) {
-		ERROR("Could not read CBFS master header offset!\n");
-		return CBFS_HEADER_INVALID_ADDRESS;
-	}
-	header = media->map(media, (size_t)rel_offset, sizeof(*header));
+	/* Find the CBFS master header pointer/offset at 0xfffffffc.
+	 * There is no return value check since the offset can be negative. */
+	rdev_readat(media, &rel_offset,
+			lib_sysinfo.boot_media_size - sizeof(int32_t),
+			sizeof(int32_t));
+
+	rel_offset += lib_sysinfo.boot_media_size;
+
+	header = rdev_mmap(media, rel_offset, sizeof(*header));
 	DEBUG("CBFS header at %#zx (-%#zx from end of image).\n",
 		(size_t)rel_offset, (size_t)-rel_offset);
-	media->close(media);
 
-	if (header == CBFS_MEDIA_INVALID_MAP_ADDRESS) {
+	if (header == NULL) {
 		ERROR("Failed to load CBFS header from %#zx(-%#zx)\n",
 			(size_t)rel_offset, (size_t)-rel_offset);
 		return CBFS_HEADER_INVALID_ADDRESS;
@@ -99,7 +96,7 @@ const struct cbfs_header *cbfs_get_header(struct cbfs_media *media)
 }
 
 static int get_cbfs_range(uint32_t *offset, uint32_t *cbfs_end,
-			  struct cbfs_media *media)
+			  struct region_device *media)
 {
 	const struct cbfs_header *header;
 
@@ -115,17 +112,17 @@ static int get_cbfs_range(uint32_t *offset, uint32_t *cbfs_end,
 	header = cbfs_get_header(media);
 	if (header == CBFS_HEADER_INVALID_ADDRESS)
 		return -1;
-	// Logical offset (for source media) of first file.
+	/* Logical offset (for source media) of first file. */
 	*offset = ntohl(header->offset);
 	*cbfs_end = ntohl(header->romsize);
 #if IS_ENABLED(CONFIG_LP_ARCH_X86)
-	// resolve actual length of ROM used for CBFS components
-	// the bootblock size was not taken into account
+	/*resolve actual length of ROM used for CBFS components
+	 * the bootblock size was not taken into account. */
 	*cbfs_end -= ntohl(header->bootblocksize);
 
-	// fine tune the length to handle alignment positioning.
-	// using (bootblock size) % align, to derive the
-	// number of bytes the bootblock is off from the alignment size.
+	/* fine tune the length to handle alignment positioning.
+	 * using (bootblock size) % align, to derive the
+	 * number of bytes the bootblock is off from the alignment size. */
 	if ((ntohl(header->bootblocksize) % CBFS_ALIGNMENT))
 		*cbfs_end -= (CBFS_ALIGNMENT -
 			(ntohl(header->bootblocksize) % CBFS_ALIGNMENT));
@@ -135,10 +132,11 @@ static int get_cbfs_range(uint32_t *offset, uint32_t *cbfs_end,
 	return 0;
 }
 
-/* public API starts here*/
-struct cbfs_handle *cbfs_get_handle(struct cbfs_media *media, const char *name)
+/* Public API starts here. */
+struct cbfs_handle *cbfs_get_handle(struct region_device *media,
+		const char *name)
 {
-	const char *vardata;
+	char *vardata;
 	uint32_t offset, cbfs_end, vardata_len;
 	struct cbfs_file file;
 	struct cbfs_handle *handle = malloc(sizeof(*handle));
@@ -147,33 +145,34 @@ struct cbfs_handle *cbfs_get_handle(struct cbfs_media *media, const char *name)
 		return NULL;
 
 	if (get_cbfs_range(&offset, &cbfs_end, media)) {
-		ERROR("Failed to find cbfs range\n");
+		ERROR("Failed to find cbfs range.\n");
 		return NULL;
 	}
 
 	if (media == CBFS_DEFAULT_MEDIA) {
-		media = &handle->media;
-		if (init_default_cbfs_media(media) != 0) {
-			ERROR("Failed to initialize default media.\n");
-			return NULL;
-		}
+		libpayload_init_default_cbfs_media();
+		media = boot_device_ro();
+		handle->media = media;
 	} else {
-		memcpy(&handle->media, media, sizeof(*media));
+		handle->media = malloc(sizeof(*media));
+		if (!handle->media)
+			return NULL;
+		memcpy(handle->media, media, sizeof(*media));
 	}
 
 	DEBUG("CBFS location: 0x%x~0x%x\n", offset, cbfs_end);
 	DEBUG("Looking for '%s' starting from 0x%x.\n", name, offset);
 
-	media->open(media);
 	while (offset < cbfs_end &&
-	       media->read(media, &file, offset, sizeof(file)) == sizeof(file)) {
+		rdev_readat(media, &file, offset, sizeof(file)) ==
+		sizeof(file)) {
 		if (memcmp(CBFS_FILE_MAGIC, file.magic,
 			   sizeof(file.magic)) != 0) {
 			uint32_t new_align = CBFS_ALIGNMENT;
 			if (offset % CBFS_ALIGNMENT)
 				new_align += CBFS_ALIGNMENT -
 					(offset % CBFS_ALIGNMENT);
-			ERROR("ERROR: No file header found at 0x%xx - "
+			ERROR("ERROR: No file header found at 0x%x - "
 			      "try next aligned address: 0x%x.\n", offset,
 			      offset + new_align);
 			offset += new_align;
@@ -184,17 +183,16 @@ struct cbfs_handle *cbfs_get_handle(struct cbfs_media *media, const char *name)
 			offset, vardata_len);
 
 		// load file name (arbitrary length).
-		vardata = (const char*)media->map(
-				media, offset + sizeof(file), vardata_len);
-		if (vardata == CBFS_MEDIA_INVALID_MAP_ADDRESS) {
+		vardata = rdev_mmap(media, offset + sizeof(file),
+			       vardata_len);
+		if (vardata == NULL) {
 			ERROR("ERROR: Failed to get filename: 0x%x.\n", offset);
 		} else if (strcmp(vardata, name) == 0) {
 			int file_offset = ntohl(file.offset),
 			    file_len = ntohl(file.len);
 			DEBUG("Found file (offset=0x%x, len=%d).\n",
 			    offset + file_offset, file_len);
-			media->unmap(media, vardata);
-			media->close(media);
+			rdev_munmap(media, vardata);
 			handle->type = ntohl(file.type);
 			handle->media_offset = offset;
 			handle->content_offset = file_offset;
@@ -205,7 +203,7 @@ struct cbfs_handle *cbfs_get_handle(struct cbfs_media *media, const char *name)
 		} else {
 			DEBUG(" (unmatched file @0x%x: %s)\n", offset,
 			      vardata);
-			media->unmap(media, vardata);
+			rdev_munmap(media, vardata);
 		}
 
 		// Move to next file.
@@ -213,14 +211,13 @@ struct cbfs_handle *cbfs_get_handle(struct cbfs_media *media, const char *name)
 		if (offset % CBFS_ALIGNMENT)
 			offset += CBFS_ALIGNMENT - (offset % CBFS_ALIGNMENT);
 	}
-	media->close(media);
 	LOG("WARNING: '%s' not found.\n", name);
 	return NULL;
 }
 
 void *cbfs_get_contents(struct cbfs_handle *handle, size_t *size, size_t limit)
 {
-	struct cbfs_media *m = &handle->media;
+	struct region_device *m = handle->media;
 	size_t on_media_size = handle->content_size;
 	int algo = CBFS_COMPRESS_NONE;
 	void *ret = NULL;
@@ -231,6 +228,7 @@ void *cbfs_get_contents(struct cbfs_handle *handle, size_t *size, size_t limit)
 
 	struct cbfs_file_attr_compression *comp =
 		cbfs_get_attr(handle, CBFS_FILE_ATTR_TAG_COMPRESSION);
+
 	if (comp) {
 		algo = ntohl(comp->compression);
 		DEBUG("File '%s' is compressed (alg=%d)\n", name, algo);
@@ -247,22 +245,29 @@ void *cbfs_get_contents(struct cbfs_handle *handle, size_t *size, size_t limit)
 		}
 	}
 
-	void *data = m->map(m, handle->media_offset + handle->content_offset,
+	void *data = rdev_mmap(m, handle->media_offset + handle->content_offset,
 			    on_media_size);
-	if (data == CBFS_MEDIA_INVALID_MAP_ADDRESS)
+	if (data == NULL)
 		return NULL;
 
+	/* Used to avoid running out of heap memory from malloc. */
+	if (algo == CBFS_COMPRESS_NONE)
+		return data;
+
 	ret = malloc(*size);
+	if (!ret)
+		return NULL;
+
 	if (ret != NULL && !cbfs_decompress(algo, data, ret, *size)) {
 		free(ret);
 		ret = NULL;
 	}
 
-	m->unmap(m, data);
+	rdev_munmap(m, data);
 	return ret;
 }
 
-void *cbfs_get_file_content(struct cbfs_media *media, const char *name,
+void *cbfs_get_file_content(struct region_device *media, const char *name,
 			    int type, size_t *sz)
 {
 	void *ret = NULL;
@@ -283,7 +288,7 @@ void *cbfs_get_file_content(struct cbfs_media *media, const char *name,
 
 void *cbfs_get_attr(struct cbfs_handle *handle, uint32_t tag)
 {
-	struct cbfs_media *m = &handle->media;
+	struct region_device *m = handle->media;
 	uint32_t offset = handle->media_offset + handle->attribute_offset;
 	uint32_t end = handle->media_offset + handle->content_offset;
 	struct cbfs_file_attribute attr;
@@ -294,26 +299,23 @@ void *cbfs_get_attr(struct cbfs_handle *handle, uint32_t tag)
 	if (handle->attribute_offset <= sizeof(struct cbfs_file))
 		return NULL;
 
-	m->open(m);
 	while (offset + sizeof(attr) <= end) {
-		if (m->read(m, &attr, offset, sizeof(attr)) != sizeof(attr)) {
+		if (rdev_readat(m, &attr, offset, sizeof(attr)) !=
+				sizeof(attr)) {
 			ERROR("Failed to read attribute header %#x\n", offset);
-			m->close(m);
 			return NULL;
 		}
 		if (ntohl(attr.tag) != tag) {
 			offset += ntohl(attr.len);
 			continue;
 		}
-		ret = m->map(m, offset, ntohl(attr.len));
-		if (ret == CBFS_MEDIA_INVALID_MAP_ADDRESS) {
+		ret = rdev_mmap(m, offset, ntohl(attr.len));
+		if (ret == NULL) {
 			ERROR("Failed to map attribute at %#x\n", offset);
-			m->close(m);
 			return NULL;
 		}
 		return ret;
 	}
-	m->close(m);
 
 	return NULL;
 }
diff --git a/payloads/libpayload/libcbfs/mem_pool.c b/payloads/libpayload/libcbfs/mem_pool.c
new file mode 100644
index 0000000..c1d3961
--- /dev/null
+++ b/payloads/libpayload/libcbfs/mem_pool.c
@@ -0,0 +1,48 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <mem_pool.h>
+
+void *mem_pool_alloc(struct mem_pool *mp, size_t sz)
+{
+	void *p;
+
+	/* Make all allocations be at least 8 byte aligned. */
+	sz = ALIGN_UP(sz, 8);
+
+	/* Determine if any space available. */
+	if ((mp->size - mp->free_offset) < sz)
+		return NULL;
+
+	p = &mp->buf[mp->free_offset];
+
+	mp->free_offset += sz;
+	mp->last_alloc = p;
+
+	return p;
+}
+
+void mem_pool_free(struct mem_pool *mp, void *p)
+{
+	/* Determine if p was the most recent allocation. */
+	if (p == NULL || mp->last_alloc != p)
+		return;
+
+	mp->free_offset = mp->last_alloc - mp->buf;
+	/* No way to track allocation before this one. */
+	mp->last_alloc = NULL;
+}
diff --git a/payloads/libpayload/libcbfs/ram_media.c b/payloads/libpayload/libcbfs/ram_media.c
deleted file mode 100644
index d5469f6..0000000
--- a/payloads/libpayload/libcbfs/ram_media.c
+++ /dev/null
@@ -1,118 +0,0 @@
-/*
- * 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 <cbfs_ram.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;
-	/* assume addressing from top of image in this case */
-	if (offset > 0xf0000000) {
-		offset = m->size + offset;
-	}
-	if (offset + count > m->size) {
-		printf("ERROR: ram_map: request out of range (0x%zx+0x%zx)\n",
-		       offset, count);
-		return CBFS_MEDIA_INVALID_MAP_ADDRESS;
-	}
-	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);
-	if (ptr == CBFS_MEDIA_INVALID_MAP_ADDRESS)
-		return 0;
-	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) {
-	// 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 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 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;
-}
diff --git a/payloads/libpayload/libcbfs/region_device.c b/payloads/libpayload/libcbfs/region_device.c
new file mode 100644
index 0000000..f87075a
--- /dev/null
+++ b/payloads/libpayload/libcbfs/region_device.c
@@ -0,0 +1,434 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <region_device.h>
+
+static inline size_t region_end(const struct region *r)
+{
+	return region_sz(r) + region_offset(r);
+}
+
+static int is_subregion(const struct region *p, const struct region *c)
+{
+	if (region_offset(c) < region_offset(p))
+		return 0;
+
+	if (region_sz(c) > region_sz(p))
+		return 0;
+
+	if (region_end(c) > region_end(p))
+		return 0;
+
+	return 1;
+}
+
+static int normalize_and_ok(const struct region *outer, struct region *inner)
+{
+	inner->offset += region_offset(outer);
+	return is_subregion(outer, inner);
+}
+
+static const struct region_device *rdev_root(const struct region_device *rdev)
+{
+	if (rdev->root == NULL)
+		return rdev;
+	return rdev->root;
+}
+
+ssize_t rdev_relative_offset(const struct region_device *p,
+				const struct region_device *c)
+{
+	if (rdev_root(p) != rdev_root(c))
+		return -1;
+
+	if (!is_subregion(&p->region, &c->region))
+		return -1;
+
+	return region_device_offset(c) - region_device_offset(p);
+}
+
+void *rdev_mmap(const struct region_device *rd, size_t offset, size_t size)
+{
+	const struct region_device *rdev;
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+
+	if (!normalize_and_ok(&rd->region, &req))
+		return NULL;
+
+	rdev = rdev_root(rd);
+
+	return rdev->ops->mmap(rdev, req.offset, req.size);
+}
+
+int rdev_munmap(const struct region_device *rd, void *mapping)
+{
+	const struct region_device *rdev;
+
+	rdev = rdev_root(rd);
+
+	return rdev->ops->munmap(rdev, mapping);
+}
+
+ssize_t rdev_readat(const struct region_device *rd, void *b, size_t offset,
+			size_t size)
+{
+	const struct region_device *rdev;
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+
+	if (!normalize_and_ok(&rd->region, &req))
+		return -1;
+
+	rdev = rdev_root(rd);
+
+	return rdev->ops->readat(rdev, b, req.offset, req.size);
+}
+
+ssize_t rdev_writeat(const struct region_device *rd, void *b, size_t offset,
+			size_t size)
+{
+	const struct region_device *rdev;
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+
+	if (!normalize_and_ok(&rd->region, &req))
+		return -1;
+
+	rdev = rdev_root(rd);
+
+	if (rdev->ops->writeat == NULL)
+		return -1;
+
+	return rdev->ops->writeat(rdev, b, req.offset, req.size);
+}
+
+ssize_t rdev_eraseat(const struct region_device *rd, size_t offset,
+			size_t size)
+{
+	const struct region_device *rdev;
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+
+	if (!normalize_and_ok(&rd->region, &req))
+		return -1;
+
+	rdev = rdev_root(rd);
+
+	/* If the eraseat ptr is NULL we assume that the erase
+	 * function was completed successfully. */
+	if (rdev->ops->eraseat == NULL)
+		return size;
+
+	return rdev->ops->eraseat(rdev, req.offset, req.size);
+}
+
+int rdev_chain(struct region_device *child, const struct region_device *parent,
+		size_t offset, size_t size)
+{
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+
+	if (!normalize_and_ok(&parent->region, &req))
+		return -1;
+
+	/* Keep track of root region device. Note the offsets are relative
+	 * to the root device. */
+	child->root = rdev_root(parent);
+	child->ops = NULL;
+	child->region.offset = req.offset;
+	child->region.size = req.size;
+
+	return 0;
+}
+
+static void mem_region_device_init(struct mem_region_device *mdev,
+		const struct region_device_ops *ops, void *base, size_t size)
+{
+	memset(mdev, 0, sizeof(*mdev));
+	mdev->base = base;
+	mdev->rdev.ops = ops;
+	mdev->rdev.region.size = size;
+}
+
+void mem_region_device_ro_init(struct mem_region_device *mdev, void *base,
+				size_t size)
+{
+	return mem_region_device_init(mdev, &mem_rdev_ro_ops, base, size);
+}
+
+void mem_region_device_rw_init(struct mem_region_device *mdev, void *base,
+		size_t size)
+{
+	return mem_region_device_init(mdev, &mem_rdev_rw_ops, base, size);
+}
+
+void region_device_init(struct region_device *rdev,
+			const struct region_device_ops *ops, size_t offset,
+			size_t size)
+{
+	memset(rdev, 0, sizeof(*rdev));
+	rdev->root = NULL;
+	rdev->ops = ops;
+	rdev->region.offset = offset;
+	rdev->region.size = size;
+}
+
+static void xlate_region_device_init(struct xlate_region_device *xdev,
+			const struct region_device_ops *ops,
+			const struct region_device *access_dev,
+			size_t sub_offset, size_t sub_size,
+			size_t parent_size)
+{
+	memset(xdev, 0, sizeof(*xdev));
+	xdev->access_dev = access_dev;
+	xdev->sub_region.offset = sub_offset;
+	xdev->sub_region.size = sub_size;
+	region_device_init(&xdev->rdev, ops, 0, parent_size);
+}
+
+void xlate_region_device_ro_init(struct xlate_region_device *xdev,
+			      const struct region_device *access_dev,
+			      size_t sub_offset, size_t sub_size,
+			      size_t parent_size)
+{
+	xlate_region_device_init(xdev, &xlate_rdev_ro_ops, access_dev,
+			sub_offset, sub_size, parent_size);
+}
+
+void xlate_region_device_rw_init(struct xlate_region_device *xdev,
+			      const struct region_device *access_dev,
+			      size_t sub_offset, size_t sub_size,
+			      size_t parent_size)
+{
+	xlate_region_device_init(xdev, &xlate_rdev_rw_ops, access_dev,
+			sub_offset, sub_size, parent_size);
+}
+
+static void *mdev_mmap(const struct region_device *rd, size_t offset,
+			size_t size __unused)
+{
+	const struct mem_region_device *mdev;
+
+	mdev = container_of(rd, __typeof__(*mdev), rdev);
+
+	return &mdev->base[offset];
+}
+
+static int mdev_munmap(const struct region_device *rd __unused,
+			void *mapping __unused)
+{
+	return 0;
+}
+
+static ssize_t mdev_readat(const struct region_device *rd, void *b,
+				size_t offset, size_t size)
+{
+	const struct mem_region_device *mdev;
+
+	mdev = container_of(rd, __typeof__(*mdev), rdev);
+
+	memcpy(b, &mdev->base[offset], size);
+
+	return size;
+}
+
+static ssize_t mdev_writeat(const struct region_device *rd, void *b,
+				size_t offset, size_t size)
+{
+	const struct mem_region_device *mdev;
+
+	mdev = container_of(rd, __typeof__(*mdev), rdev);
+
+	memcpy(&mdev->base[offset], b, size);
+
+	return size;
+}
+
+static ssize_t mdev_eraseat(const struct region_device *rd, size_t offset,
+				size_t size)
+{
+	const struct mem_region_device *mdev;
+
+	mdev = container_of(rd, __typeof__(*mdev), rdev);
+
+	memset(&mdev->base[offset], 0, size);
+
+	return size;
+}
+
+const struct region_device_ops mem_rdev_ro_ops = {
+	.mmap = mdev_mmap,
+	.munmap = mdev_munmap,
+	.readat = mdev_readat,
+};
+
+const struct region_device_ops mem_rdev_rw_ops = {
+	.mmap = mdev_mmap,
+	.munmap = mdev_munmap,
+	.readat = mdev_readat,
+	.writeat = mdev_writeat,
+	.eraseat = mdev_eraseat,
+};
+
+void mmap_helper_device_init(struct mmap_helper_region_device *mdev,
+				void *cache, size_t cache_size)
+{
+	mem_pool_init(&mdev->pool, cache, cache_size);
+}
+
+void *mmap_helper_rdev_mmap(const struct region_device *rd, size_t offset,
+				size_t size)
+{
+	struct mmap_helper_region_device *mdev;
+	void *mapping;
+
+	mdev = container_of((void *)rd, __typeof__(*mdev), rdev);
+
+	mapping = mem_pool_alloc(&mdev->pool, size);
+
+	if (mapping == NULL)
+		return NULL;
+
+	if (rd->ops->readat(rd, mapping, offset, size) != size) {
+		mem_pool_free(&mdev->pool, mapping);
+		return NULL;
+	}
+
+	return mapping;
+}
+
+int mmap_helper_rdev_munmap(const struct region_device *rd, void *mapping)
+{
+	struct mmap_helper_region_device *mdev;
+
+	mdev = container_of((void *)rd, __typeof__(*mdev), rdev);
+
+	mem_pool_free(&mdev->pool, mapping);
+
+	return 0;
+}
+
+static void *xlate_mmap(const struct region_device *rd, size_t offset,
+			size_t size)
+{
+	const struct xlate_region_device *xldev;
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+
+	xldev = container_of(rd, __typeof__(*xldev), rdev);
+
+	if (!is_subregion(&xldev->sub_region, &req))
+		return NULL;
+
+	offset -= region_offset(&xldev->sub_region);
+
+	return rdev_mmap(xldev->access_dev, offset, size);
+}
+
+static int xlate_munmap(const struct region_device *rd, void *mapping)
+{
+	const struct xlate_region_device *xldev;
+
+	xldev = container_of(rd, __typeof__(*xldev), rdev);
+
+	return rdev_munmap(xldev->access_dev, mapping);
+}
+
+static ssize_t xlate_readat(const struct region_device *rd, void *b,
+				size_t offset, size_t size)
+{
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+	const struct xlate_region_device *xldev;
+
+	xldev = container_of(rd, __typeof__(*xldev), rdev);
+
+	if (!is_subregion(&xldev->sub_region, &req))
+		return -1;
+
+	offset -= region_offset(&xldev->sub_region);
+
+	return rdev_readat(xldev->access_dev, b, offset, size);
+}
+
+static ssize_t xlate_writeat(const struct region_device *rd, void *b,
+				size_t offset, size_t size)
+{
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+	const struct xlate_region_device *xldev;
+
+	xldev = container_of(rd, __typeof__(*xldev), rdev);
+
+	if (!is_subregion(&xldev->sub_region, &req))
+		return -1;
+
+	offset -= region_offset(&xldev->sub_region);
+
+	return rdev_writeat(xldev->access_dev, b, offset, size);
+}
+
+static ssize_t xlate_eraseat(const struct region_device *rd,
+				size_t offset, size_t size)
+{
+	struct region req = {
+		.offset = offset,
+		.size = size,
+	};
+	const struct xlate_region_device *xldev;
+
+	xldev = container_of(rd, __typeof__(*xldev), rdev);
+
+	if (!is_subregion(&xldev->sub_region, &req))
+		return -1;
+
+	offset -= region_offset(&xldev->sub_region);
+
+	return rdev_eraseat(xldev->access_dev, offset, size);
+}
+
+const struct region_device_ops xlate_rdev_ro_ops = {
+	.mmap = xlate_mmap,
+	.munmap = xlate_munmap,
+	.readat = xlate_readat,
+};
+
+const struct region_device_ops xlate_rdev_rw_ops = {
+	.mmap = xlate_mmap,
+	.munmap = xlate_munmap,
+	.readat = xlate_readat,
+	.writeat = xlate_writeat,
+	.eraseat = xlate_eraseat,
+};



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