ARM: Add device tree support to the ARM platform

To allow newer ARM platforms to use kexec, pass device tree
information to the kernel during boot.

By default the dtb is found from /proc/device-tree. A user can specify
a dtb file or use legacy ATAGs

Signed-off-by: Matthew Leach <matthew.leach@arm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 78 insertions, 9 deletions

diff --git a/kexec/arch/arm/kexec-zImage-arm.c b/kexec/arch/arm/kexec-zImage-arm.c
index 88a6c29..46cedbf 100644
--- a/kexec/arch/arm/kexec-zImage-arm.c
+++ b/kexec/arch/arm/kexec-zImage-arm.c
@@ -13,13 +13,18 @@
 #include <unistd.h>
 #include <getopt.h>
 #include <unistd.h>
+#include <libfdt.h>
 #include <arch/options.h>
 #include "../../kexec.h"
 #include "../../kexec-syscall.h"
+#include "kexec-arm.h"
+#include "../../fs2dt.h"
 #include "crashdump-arm.h"
 
 #define BOOT_PARAMS_SIZE 1536
 
+off_t initrd_base = 0, initrd_size = 0;
+
 struct tag_header {
 	uint32_t size;
 	uint32_t tag;
@@ -96,6 +101,8 @@ void zImage_arm_usage(void)
 		"     --append=STRING       Set the kernel command line to STRING.\n"
 		"     --initrd=FILE         Use FILE as the kernel's initial ramdisk.\n"
 		"     --ramdisk=FILE        Use FILE as the kernel's initial ramdisk.\n"
+		"     --dtb=FILE            Use FILE as the fdt blob.\n"
+		"     --atags               Use ATAGs instead of device-tree.\n"
 		);
 }
 
@@ -219,9 +226,13 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 	off_t command_line_len;
 	const char *ramdisk;
 	char *ramdisk_buf;
-	off_t ramdisk_length;
-	off_t ramdisk_offset;
 	int opt;
+	int use_atags;
+	char *dtb_buf;
+	off_t dtb_length;
+	char *dtb_file;
+	off_t dtb_offset;
+
 	/* See options.h -- add any more there, too. */
 	static const struct option options[] = {
 		KEXEC_ARCH_OPTIONS
@@ -229,6 +240,8 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 		{ "append",		1, 0, OPT_APPEND },
 		{ "initrd",		1, 0, OPT_RAMDISK },
 		{ "ramdisk",		1, 0, OPT_RAMDISK },
+		{ "dtb",		1, 0, OPT_DTB },
+		{ "atags",		0, 0, OPT_ATAGS },
 		{ 0, 			0, 0, 0 },
 	};
 	static const char short_options[] = KEXEC_ARCH_OPT_STR "a:r:";
@@ -240,7 +253,9 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 	command_line_len = 0;
 	ramdisk = 0;
 	ramdisk_buf = 0;
-	ramdisk_length = 0;
+	initrd_size = 0;
+	use_atags = 0;
+	dtb_file = NULL;
 	while((opt = getopt_long(argc, argv, short_options, options, 0)) != -1) {
 		switch(opt) {
 		default:
@@ -257,15 +272,28 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 		case OPT_RAMDISK:
 			ramdisk = optarg;
 			break;
+		case OPT_DTB:
+			dtb_file = optarg;
+			break;
+		case OPT_ATAGS:
+			use_atags = 1;
+			break;
 		}
 	}
+
+	if (use_atags && dtb_file) {
+		fprintf(stderr, "You can only use ATAGs if you don't specify a "
+		        "dtb file.\n");
+		return -1;
+	}
+
 	if (command_line) {
 		command_line_len = strlen(command_line) + 1;
 		if (command_line_len > COMMAND_LINE_SIZE)
 			command_line_len = COMMAND_LINE_SIZE;
 	}
 	if (ramdisk) {
-		ramdisk_buf = slurp_file(ramdisk, &ramdisk_length);
+		ramdisk_buf = slurp_file(ramdisk, &initrd_size);
 	}
 
 	/*
@@ -315,12 +343,53 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 	/* assume the maximum kernel compression ratio is 4,
 	 * and just to be safe, place ramdisk after that
 	 */
-	ramdisk_offset = base + len * 4;
+	initrd_base = base + len * 4;
 
-	if (atag_arm_load(info, base + atag_offset,
-			 command_line, command_line_len,
-			 ramdisk_buf, ramdisk_length, ramdisk_offset) == -1)
-		return -1;
+	if (use_atags) {
+		/*
+		 * use ATAGs from /proc/atags
+		 */
+		if (atag_arm_load(info, base + atag_offset,
+		                  command_line, command_line_len,
+		                  ramdisk_buf, initrd_size, initrd_base) == -1)
+			return -1;
+	} else {
+		/*
+		 * Read a user-specified DTB file.
+		 */
+		if (dtb_file) {
+			dtb_buf = slurp_file(dtb_file, &dtb_length);
+		} else {
+			/*
+			 * Extract the DTB from /proc/device-tree.
+			 */
+			create_flatten_tree(&dtb_buf, &dtb_length, command_line);
+		}
+
+		if (fdt_check_header(dtb_buf) != 0) {
+			fprintf(stderr, "Invalid FDT buffer.\n");
+			return -1;
+		}
+
+		if (base + atag_offset + dtb_length > base + offset) {
+			fprintf(stderr, "DTB too large!\n");
+			return -1;
+		}
+
+		if (ramdisk) {
+			add_segment(info, ramdisk_buf, initrd_size,
+			            initrd_base, initrd_size);
+		}
+
+		/* Stick the dtb at the end of the initrd and page
+		 * align it.
+		 */
+		dtb_offset = initrd_base + initrd_size + getpagesize();
+		dtb_offset &= ~(getpagesize() - 1);
+
+		add_segment(info, dtb_buf, dtb_length,
+		            dtb_offset, dtb_length);
+	}
 
 	add_segment(info, buf, len, base + offset, len);