image: add support for Android's boot image format

This patch adds support for the Android boot-image format. The header
file is from the Android project and got slightly alterted so the struct +
its defines are not generic but have something like a namespace. The
header file is from bootloader/legacy/include/boot/bootimg.h. The header
parsing has been written from scratch and I looked at
bootloader/legacy/usbloader/usbloader.c for some details.
The image contains the physical address (load address) of the kernel and
ramdisk. This address is considered only for the kernel image.
The "second image" defined in the image header is currently not
supported. I haven't found anything that is creating this.

v3 (Rob Herring):
This is based on http://patchwork.ozlabs.org/patch/126797/ with the
following changes:
- Rebased to current mainline
- Moved android image handling to separate functions in
  common/image-android.c
- s/u8/char/ in header to fix string function warnings
- Use SPDX identifiers for licenses
- Cleaned-up file source information:
  android_image.h is from file include/boot/bootimg.h in repository:
  https://android.googlesource.com/platform/bootable/bootloader/legacy
  The git commit hash is 4205b865141ff2e255fe1d3bd16de18e217ef06a
  usbloader.c would be from the same commit, but it does not appear
  to have been used for any actual code.
v4:
- s/andriod/android/
- Use a separate flag ep_found to track if the entry point has been set
rather than using a magic value.

Cc: Wolfgang Denk <wd@denx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Tom Rini <trini@ti.com>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>

common/Makefile

@@ -237,6 +237,7 @@ obj-y += console.o
 obj-$(CONFIG_CROS_EC) += cros_ec.o
 obj-y += dlmalloc.o
 obj-y += image.o
+obj-$(CONFIG_ANDROID_BOOT_IMAGE) += image-android.o
 obj-$(CONFIG_OF_LIBFDT) += image-fdt.o
 obj-$(CONFIG_FIT) += image-fit.o
 obj-$(CONFIG_FIT_SIGNATURE) += image-sig.o

common/cmd_bootm.c

@@ -222,6 +222,7 @@ static int bootm_find_os(cmd_tbl_t *cmdtp, int flag, int argc,
 			 char * const argv[])
 {
 	const void *os_hdr;
+	bool ep_found = false;
 
 	/* get kernel image header, start address and length */
 	os_hdr = boot_get_kernel(cmdtp, flag, argc, argv,
@@ -273,6 +274,18 @@ static int bootm_find_os(cmd_tbl_t *cmdtp, int flag, int argc,
 			return 1;
 		}
 		break;
+#endif
+#ifdef CONFIG_ANDROID_BOOT_IMAGE
+	case IMAGE_FORMAT_ANDROID:
+		images.os.type = IH_TYPE_KERNEL;
+		images.os.comp = IH_COMP_NONE;
+		images.os.os = IH_OS_LINUX;
+		images.ep = images.os.load;
+		ep_found = true;
+
+		images.os.end = android_image_get_end(os_hdr);
+		images.os.load = android_image_get_kload(os_hdr);
+		break;
 #endif
 	default:
 		puts("ERROR: unknown image format type!\n");
@@ -293,7 +306,7 @@ static int bootm_find_os(cmd_tbl_t *cmdtp, int flag, int argc,
 			return 1;
 		}
 #endif
-	} else {
+	} else if (!ep_found) {
 		puts("Could not find kernel entry point!\n");
 		return 1;
 	}
@@ -1001,6 +1014,14 @@ static const void *boot_get_kernel(cmd_tbl_t *cmdtp, int flag, int argc,
 		images->fit_uname_cfg = fit_uname_config;
 		images->fit_noffset_os = os_noffset;
 		break;
+#endif
+#ifdef CONFIG_ANDROID_BOOT_IMAGE
+	case IMAGE_FORMAT_ANDROID:
+		printf("## Booting Android Image at 0x%08lx ...\n", img_addr);
+		if (android_image_get_kernel((void *)img_addr, images->verify,
+					     os_data, os_len))
+			return NULL;
+		break;
 #endif
 	default:
 		printf("Wrong Image Format for %s command\n", cmdtp->name);

common/image-android.c

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2011 Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <image.h>
+#include <android_image.h>
+
+static char andr_tmp_str[ANDR_BOOT_ARGS_SIZE + 1];
+
+int android_image_get_kernel(const struct andr_img_hdr *hdr, int verify,
+			     ulong *os_data, ulong *os_len)
+{
+	/*
+	 * Not all Android tools use the id field for signing the image with
+	 * sha1 (or anything) so we don't check it. It is not obvious that the
+	 * string is null terminated so we take care of this.
+	 */
+	strncpy(andr_tmp_str, hdr->name, ANDR_BOOT_NAME_SIZE);
+	andr_tmp_str[ANDR_BOOT_NAME_SIZE] = '\0';
+	if (strlen(andr_tmp_str))
+		printf("Android's image name: %s\n", andr_tmp_str);
+
+	printf("Kernel load addr 0x%08x size %u KiB\n",
+	       hdr->kernel_addr, DIV_ROUND_UP(hdr->kernel_size, 1024));
+	strncpy(andr_tmp_str, hdr->cmdline, ANDR_BOOT_ARGS_SIZE);
+	andr_tmp_str[ANDR_BOOT_ARGS_SIZE] = '\0';
+	if (strlen(andr_tmp_str)) {
+		printf("Kernel command line: %s\n", andr_tmp_str);
+		setenv("bootargs", andr_tmp_str);
+	}
+	if (hdr->ramdisk_size)
+		printf("RAM disk load addr 0x%08x size %u KiB\n",
+		       hdr->ramdisk_addr,
+		       DIV_ROUND_UP(hdr->ramdisk_size, 1024));
+
+	if (os_data) {
+		*os_data = (ulong)hdr;
+		*os_data += hdr->page_size;
+	}
+	if (os_len)
+		*os_len = hdr->kernel_size;
+	return 0;
+}
+
+int android_image_check_header(const struct andr_img_hdr *hdr)
+{
+	return memcmp(ANDR_BOOT_MAGIC, hdr->magic, ANDR_BOOT_MAGIC_SIZE);
+}
+
+ulong android_image_get_end(const struct andr_img_hdr *hdr)
+{
+	u32 size = 0;
+	/*
+	 * The header takes a full page, the remaining components are aligned
+	 * on page boundary
+	 */
+	size += hdr->page_size;
+	size += ALIGN(hdr->kernel_size, hdr->page_size);
+	size += ALIGN(hdr->ramdisk_size, hdr->page_size);
+	size += ALIGN(hdr->second_size, hdr->page_size);
+
+	return size;
+}
+
+ulong android_image_get_kload(const struct andr_img_hdr *hdr)
+{
+	return hdr->kernel_addr;
+}
+
+int android_image_get_ramdisk(const struct andr_img_hdr *hdr,
+			      ulong *rd_data, ulong *rd_len)
+{
+	if (!hdr->ramdisk_size)
+		return -1;
+	*rd_data = (unsigned long)hdr;
+	*rd_data += hdr->page_size;
+	*rd_data += ALIGN(hdr->kernel_size, hdr->page_size);
+
+	*rd_len = hdr->ramdisk_size;
+	return 0;
+}

common/image.c

@@ -659,10 +659,12 @@ int genimg_get_format(const void *img_addr)
 	if (image_check_magic(hdr))
 		format = IMAGE_FORMAT_LEGACY;
 #if defined(CONFIG_FIT) || defined(CONFIG_OF_LIBFDT)
-	else {
-		if (fdt_check_header(img_addr) == 0)
-			format = IMAGE_FORMAT_FIT;
-	}
+	else if (fdt_check_header(img_addr) == 0)
+		format = IMAGE_FORMAT_FIT;
+#endif
+#ifdef CONFIG_ANDROID_BOOT_IMAGE
+	else if (android_image_check_header(img_addr) == 0)
+		format = IMAGE_FORMAT_ANDROID;
 #endif
 
 	return format;
@@ -932,7 +934,15 @@ int boot_get_ramdisk(int argc, char * const argv[], bootm_headers_t *images,
 				(ulong)images->legacy_hdr_os);
 
 		image_multi_getimg(images->legacy_hdr_os, 1, &rd_data, &rd_len);
-	} else {
+	}
+#ifdef CONFIG_ANDROID_BOOT_IMAGE
+	else if ((genimg_get_format(images) == IMAGE_FORMAT_ANDROID) &&
+		 (!android_image_get_ramdisk((void *)images->os.start,
+		 &rd_data, &rd_len))) {
+		/* empty */
+	}
+#endif
+	else {
 		/*
 		 * no initrd image
 		 */

include/android_image.h

@@ -0,0 +1,69 @@
+/*
+ * This is from the Android Project,
+ * Repository: https://android.googlesource.com/platform/bootable/bootloader/legacy
+ * File: include/boot/bootimg.h
+ * Commit: 4205b865141ff2e255fe1d3bd16de18e217ef06a
+ *
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#ifndef _ANDROID_IMAGE_H_
+#define _ANDROID_IMAGE_H_
+
+#define ANDR_BOOT_MAGIC "ANDROID!"
+#define ANDR_BOOT_MAGIC_SIZE 8
+#define ANDR_BOOT_NAME_SIZE 16
+#define ANDR_BOOT_ARGS_SIZE 512
+
+struct andr_img_hdr {
+	char magic[ANDR_BOOT_MAGIC_SIZE];
+
+	u32 kernel_size;	/* size in bytes */
+	u32 kernel_addr;	/* physical load addr */
+
+	u32 ramdisk_size;	/* size in bytes */
+	u32 ramdisk_addr;	/* physical load addr */
+
+	u32 second_size;	/* size in bytes */
+	u32 second_addr;	/* physical load addr */
+
+	u32 tags_addr;		/* physical addr for kernel tags */
+	u32 page_size;		/* flash page size we assume */
+	u32 unused[2];		/* future expansion: should be 0 */
+
+	char name[ANDR_BOOT_NAME_SIZE]; /* asciiz product name */
+
+	char cmdline[ANDR_BOOT_ARGS_SIZE];
+
+	u32 id[8]; /* timestamp / checksum / sha1 / etc */
+};
+
+/*
+ * +-----------------+
+ * | boot header     | 1 page
+ * +-----------------+
+ * | kernel          | n pages
+ * +-----------------+
+ * | ramdisk         | m pages
+ * +-----------------+
+ * | second stage    | o pages
+ * +-----------------+
+ *
+ * n = (kernel_size + page_size - 1) / page_size
+ * m = (ramdisk_size + page_size - 1) / page_size
+ * o = (second_size + page_size - 1) / page_size
+ *
+ * 0. all entities are page_size aligned in flash
+ * 1. kernel and ramdisk are required (size != 0)
+ * 2. second is optional (second_size == 0 -> no second)
+ * 3. load each element (kernel, ramdisk, second) at
+ *    the specified physical address (kernel_addr, etc)
+ * 4. prepare tags at tag_addr.  kernel_args[] is
+ *    appended to the kernel commandline in the tags.
+ * 5. r0 = 0, r1 = MACHINE_TYPE, r2 = tags_addr
+ * 6. if second_size != 0: jump to second_addr
+ *    else: jump to kernel_addr
+ */
+#endif

include/image.h

@@ -412,6 +412,7 @@ enum fit_load_op {
 #define IMAGE_FORMAT_INVALID	0x00
 #define IMAGE_FORMAT_LEGACY	0x01	/* legacy image_header based format */
 #define IMAGE_FORMAT_FIT	0x02	/* new, libfdt based format */
+#define IMAGE_FORMAT_ANDROID	0x03	/* Android boot image */
 
 int genimg_get_format(const void *img_addr);
 int genimg_has_config(bootm_headers_t *images);
@@ -1030,4 +1031,16 @@ static inline int fit_image_check_target_arch(const void *fdt, int node)
 #endif /* CONFIG_FIT_VERBOSE */
 #endif /* CONFIG_FIT */
 
+#if defined(CONFIG_ANDROID_BOOT_IMAGE)
+struct andr_img_hdr;
+int android_image_check_header(const struct andr_img_hdr *hdr);
+int android_image_get_kernel(const struct andr_img_hdr *hdr, int verify,
+			     ulong *os_data, ulong *os_len);
+int android_image_get_ramdisk(const struct andr_img_hdr *hdr,
+			      ulong *rd_data, ulong *rd_len);
+ulong android_image_get_end(const struct andr_img_hdr *hdr);
+ulong android_image_get_kload(const struct andr_img_hdr *hdr);
+
+#endif /* CONFIG_ANDROID_BOOT_IMAGE */
+
 #endif	/* __IMAGE_H__ */