x86: zimage: Allow dumping the image from outside the module

At present it is possible to dump an image within the zimage command, but
it is also useful to be able to dump it from elsewhere, for example in a
loader that has special handling for the different zimage stages.

Export this feature as a new function.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
index 708025b..3e9ee12 100644
--- a/arch/x86/lib/zimage.c
+++ b/arch/x86/lib/zimage.c
@@ -600,19 +600,12 @@
 	printf("\n");
 }
 
-int do_zboot_dump(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+void zimage_dump(struct boot_params *base_ptr)
 {
-	struct boot_params *base_ptr = state.base_ptr;
 	struct setup_header *hdr;
 	const char *version;
 	int i;
 
-	if (argc > 1)
-		base_ptr = (void *)simple_strtoul(argv[1], NULL, 16);
-	if (!base_ptr) {
-		printf("No zboot setup_base\n");
-		return CMD_RET_FAILURE;
-	}
 	printf("Setup located at %p:\n\n", base_ptr);
 	print_num64("ACPI RSDP addr", base_ptr->acpi_rsdp_addr);
 
@@ -688,6 +681,20 @@
 	print_num("Handover offset", hdr->handover_offset);
 	if (get_boot_protocol(hdr, false) >= 0x215)
 		print_num("Kernel info offset", hdr->kernel_info_offset);
+}
+
+static int do_zboot_dump(struct cmd_tbl *cmdtp, int flag, int argc,
+			 char *const argv[])
+{
+	struct boot_params *base_ptr = state.base_ptr;
+
+	if (argc > 1)
+		base_ptr = (void *)simple_strtoul(argv[1], NULL, 16);
+	if (!base_ptr) {
+		printf("No zboot setup_base\n");
+		return CMD_RET_FAILURE;
+	}
+	zimage_dump(base_ptr);
 
 	return 0;
 }