coreboot: introduce boot_device

The boot_device is a region_device that represents the
device from which coreboot retrieves and boots its stages.
The existing cbfs implementations use the boot_device as
the intermediary for accessing the CBFS region. Also,
there's currently only support for a read-only view of
the boot_device. i.e. one cannot write to the boot_device
using this view. However, a writable boot_device could
be added in the future.

Change-Id: Ic0da796ab161b8025c90631be3423ba6473ad31c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/10216
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/arch/x86/lib/Makefile.inc

@@ -6,6 +6,7 @@ romstage-y += memset.c
 romstage-y += memcpy.c
 romstage-y += memmove.c
 romstage-y += rom_media.c
+romstage-y += mmap_boot.c
 
 endif # CONFIG_ARCH_ROMSTAGE_X86_32
 
@@ -22,6 +23,7 @@ ramstage-y += memcpy.c
 ramstage-y += memmove.c
 ramstage-y += ebda.c
 ramstage-y += rom_media.c
+ramstage-y += mmap_boot.c
 ramstage-$(CONFIG_COOP_MULTITASKING) += thread.c
 ramstage-$(CONFIG_COOP_MULTITASKING) += thread_switch.S
 ramstage-$(CONFIG_COLLECT_TIMESTAMPS) += timestamp.c
@@ -32,6 +34,7 @@ smm-y += memset.c
 smm-y += memcpy.c
 smm-y += memmove.c
 smm-y += rom_media.c
+smm-y += mmap_boot.c
 
 rmodules_x86_32-y += memset.c
 rmodules_x86_32-y += memcpy.c

src/arch/x86/lib/mmap_boot.c

@@ -0,0 +1,31 @@
+/*
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc.
+ */
+
+#include <boot_device.h>
+
+/* The ROM is memory mapped just below 4GiB. Form a pointer for the base. */
+#define rom_base ((void *)(uintptr_t)(-(int32_t)CONFIG_ROM_SIZE))
+
+static const struct mem_region_device boot_dev =
+	MEM_REGION_DEV_INIT(rom_base, CONFIG_ROM_SIZE);
+
+const struct region_device *boot_device_ro(void)
+{
+	return &boot_dev.rdev;
+}

src/arch/x86/lib/rom_media.c

@@ -17,6 +17,8 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc.
  */
+
+#include <boot_device.h>
 #include <cbfs.h>
 #include <string.h>
 
@@ -36,14 +38,19 @@ static int x86_rom_open(struct cbfs_media *media) {
 
 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.
+	const struct region_device *boot_dev;
 
+	boot_dev = media->context;
+
+	/* Extremely large offsets are considered relative to end of region. */
 	if ((uint32_t)offset > (uint32_t)0xf0000000)
-		ptr = (void*)offset;
-	else
-		ptr = (void*)(0 - (uint32_t)media->context + offset);
+		offset += region_device_sz(boot_dev);
+
+	ptr = rdev_mmap(boot_dev, offset, count);
+
+	if (ptr == NULL)
+		return (void *)-1;
+
 	return ptr;
 }
 
@@ -53,7 +60,13 @@ static void *x86_rom_unmap(struct cbfs_media *media, const void *address) {
 
 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);
+	void *ptr;
+
+	ptr = x86_rom_map(media, offset, count);
+
+	if (ptr == (void *)-1)
+		return 0;
+
 	memcpy(dest, ptr, count);
 	x86_rom_unmap(media, ptr);
 	return count;
@@ -63,30 +76,14 @@ static int x86_rom_close(struct cbfs_media *media) {
 	return 0;
 }
 
-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 defined(CONFIG_ROM_SIZE)
-		printk(BIOS_ERR, "Invalid CBFS master header at %p\n", header);
-		media->context = (void*)CONFIG_ROM_SIZE;
-#else
+static int init_x86rom_cbfs_media(struct cbfs_media *media) {
+	boot_device_init();
+
+	media->context = (void *)boot_device_ro();
+
+	if (media->context == NULL)
 		return -1;
-#endif
-	} else {
-		uint32_t romsize = ntohl(header->romsize);
-		media->context = (void*)romsize;
-#if defined(CONFIG_ROM_SIZE)
-		if (CONFIG_ROM_SIZE != romsize)
-			printk(BIOS_INFO, "Warning: rom size unmatch (%d/%d)\n",
-			       CONFIG_ROM_SIZE, romsize);
-#endif
-	}
+
 	media->open = x86_rom_open;
 	media->close = x86_rom_close;
 	media->map = x86_rom_map;