[U-Boot] [PATCH 1/2] image: android: allow booting lz4-compressed kernels

[Eugeniu Rosca]

According to Android image format [1], kernel image resides at 1 page
offset from the boot image address. Grab the magic number from there
and allow U-Boot to handle LZ4-compressed KNL binaries instead of
hardcoding compression type to IH_COMP_NONE. Other compression types,
if needed, can be added later.

Tested on H3ULCB-KF using the image detailed in [2].

[1] Excerpt from include/android_image.h
    +-----------------+
    | boot header     | 1 page
    +-----------------+
    | kernel          | n pages
    +-----------------+
    | ramdisk         | m pages
    +-----------------+
    | second stage    | o pages
    +-----------------+

[2] => iminfo 4c000000
    ## Checking Image at 4c000000 ...
    Android image found
    kernel size:      85b9d1
    kernel address:   48080000
    ramdisk size:     54ddbc
    ramdisk addrress: 4a180000
    second size:      0
    second address:   48000800
    tags address:     48000100
    page size:        800
    os_version:       1200012a (ver: 0.9.0, level: 2018.10)
    name:
    cmdline:          buildvariant=userdebug

Signed-off-by: Eugeniu Rosca <erosca at de.adit-jv.com>
---
 common/bootm.c         |  2 +-
 common/image-android.c | 14 ++++++++++++++
 include/image.h        |  1 +
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/common/bootm.c b/common/bootm.c
index 3adbceaa38e3..bbae66df1001 100644
--- a/common/bootm.c
+++ b/common/bootm.c
@@ -154,7 +154,7 @@ static int bootm_find_os(cmd_tbl_t *cmdtp, int flag, int argc,
 #ifdef CONFIG_ANDROID_BOOT_IMAGE
 	case IMAGE_FORMAT_ANDROID:
 		images.os.type = IH_TYPE_KERNEL;
-		images.os.comp = IH_COMP_NONE;
+		images.os.comp = android_image_get_kcomp(os_hdr);
 		images.os.os = IH_OS_LINUX;
 
 		images.os.end = android_image_get_end(os_hdr);
diff --git a/common/image-android.c b/common/image-android.c
index 2f38c191e911..eec8c4decdbd 100644
--- a/common/image-android.c
+++ b/common/image-android.c
@@ -126,6 +126,20 @@ ulong android_image_get_kload(const struct andr_img_hdr *hdr)
 	return android_image_get_kernel_addr(hdr);
 }
 
+#define LZ4F_MAGIC 0x184D2204
+
+ulong android_image_get_kcomp(const struct andr_img_hdr *hdr)
+{
+	u32 *magic = (u32 *)((ulong)hdr + hdr->page_size);
+
+	switch (le32_to_cpu(*magic)) {
+	case LZ4F_MAGIC:
+		return IH_COMP_LZ4;
+	default:
+		return IH_COMP_NONE;
+	}
+}
+
 int android_image_get_ramdisk(const struct andr_img_hdr *hdr,
 			      ulong *rd_data, ulong *rd_len)
 {
diff --git a/include/image.h b/include/image.h
index 765ffecee0a7..572034afd8c3 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1312,6 +1312,7 @@ int android_image_get_second(const struct andr_img_hdr *hdr,
 			      ulong *second_data, ulong *second_len);
 ulong android_image_get_end(const struct andr_img_hdr *hdr);
 ulong android_image_get_kload(const struct andr_img_hdr *hdr);
+ulong android_image_get_kcomp(const struct andr_img_hdr *hdr);
 void android_print_contents(const struct andr_img_hdr *hdr);
 
 #endif /* CONFIG_ANDROID_BOOT_IMAGE */
-- 
2.21.0