efi_loader: Add bounce buffer support

Some hardware that is supported by U-Boot can not handle DMA above 32bits.
For these systems, we need to come up with a way to expose the disk interface
in a safe way.

This patch implements EFI specific bounce buffers. For non-EFI cases, this
apparently was no issue so far, since we can just define our environment
variables conveniently.

Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index 71a3d19..9e669f5 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -27,6 +27,10 @@ struct efi_mem_list {
 /* This list contains all memory map items */
 LIST_HEAD(efi_mem);
 
+#ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
+void *efi_bounce_buffer;
+#endif
+
 /*
  * Sorts the memory list from highest address to lowest address
  *
@@ -349,5 +353,17 @@ int efi_memory_init(void)
 	efi_add_memory_map(runtime_start, runtime_pages,
 			   EFI_RUNTIME_SERVICES_CODE, false);
 
+#ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
+	/* Request a 32bit 64MB bounce buffer region */
+	uint64_t efi_bounce_buffer_addr = 0xffffffff;
+
+	if (efi_allocate_pages(1, EFI_LOADER_DATA,
+			       (64 * 1024 * 1024) >> EFI_PAGE_SHIFT,
+			       &efi_bounce_buffer_addr) != EFI_SUCCESS)
+		return -1;
+
+	efi_bounce_buffer = (void*)(uintptr_t)efi_bounce_buffer_addr;
+#endif
+
 	return 0;
 }