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/cpu/ti/am335x/bootblock_media.c

@@ -17,11 +17,21 @@
  * Foundation, Inc.
  */
 
+#include <boot_device.h>
 #include <cbfs.h>
 #include <console/console.h>
 #include <string.h>
 #include <symbols.h>
 
+/* FIXME: No idea how big the internal SRAM actually is. */
+static const struct mem_region_device gboot_dev =
+	MEM_REGION_DEV_INIT(_dram, CONFIG_ROM_SIZE);
+
+const struct region_device *boot_device_ro(void)
+{
+	return &gboot_dev.rdev;
+}
+
 static int dummy_open(struct cbfs_media *media)
 {
 	return 0;
@@ -35,33 +45,48 @@ static int dummy_close(struct cbfs_media *media)
 static void * on_chip_memory_map(struct cbfs_media *media, size_t offset,
 				 size_t count)
 {
-	return _dram + offset;
+	const struct region_device *boot_dev;
+	void *ptr;
+
+	boot_dev = media->context;
+
+	ptr = rdev_mmap(boot_dev, offset, count);
+
+	if (ptr == NULL)
+		return (void *)-1;
+
+	return ptr;
 }
 
 static void * dummy_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 on_chip_memory_read(struct cbfs_media *media, void *dest,
 				  size_t offset, size_t count)
 {
-	void *ptr = media->map(media, offset, count);
-	memcpy(dest, ptr, count);
-	media->unmap(media, ptr);
+	const struct region_device *boot_dev;
+
+	boot_dev = media->context;
+
+	if (rdev_readat(boot_dev, dest, offset, count) < 0)
+		return 0;
+
 	return count;
 }
 
 int init_default_cbfs_media(struct cbfs_media *media)
 {
-	struct cbfs_header *header =
-		(struct cbfs_header *)(_dram + CONFIG_CBFS_HEADER_ROM_OFFSET);
-
-	if (CBFS_HEADER_MAGIC != ntohl(header->magic)) {
-		printk(BIOS_ERR, "Invalid CBFS master header at %p\n", header);
-		return -1;
-	}
+	boot_device_init();
 
+	media->context = (void *)boot_device_ro();
 	media->open = dummy_open;
 	media->close = dummy_close;
 	media->map = on_chip_memory_map;

src/cpu/ti/am335x/nand.c

@@ -17,10 +17,16 @@
  * Foundation, Inc.
  */
 
+#include <boot_device.h>
 #include <cbfs.h>
 
+const struct region_device *boot_device_ro(void)
+{
+	return NULL;
+}
+
 int init_default_cbfs_media(struct cbfs_media *media)
 {
-        /* FIXME: add support for reading coreboot from NAND */
-	return 0;
+	/* FIXME: add support for reading coreboot from NAND */
+	return -1;
 }