Android documentation recommends new image format for storing DTB/DTBO
files: [1]. To support that format, two things should be done:

1. Add dt_table.h file from Android (BSD-3 relicensed version): [2].
   This header defines structures and constants that we need to work
   with that DT image format.

   Changes:
    - re-licensed from Apache to BSD-3
    - removed functions declarations
    - change the coding style to kernel (make checkpatch happy)

2. Add helper functions for Android DTB/DTBO format. In
   image-android-dt.* files you can find helper functions to work with
   Android DT image format, such us routines for:
    - printing the dump of image structure
    - getting the address and size of desired dtb/dtbo file

[1] https://source.android.com/devices/architecture/dto/partitions
[2] 
https://android.googlesource.com/platform/system/libufdt/+/58a7582180f477032cd6c74f8d9afad0038e74c3/utils/src/dt_table.h

Signed-off-by: Sam Protsenko <semen.protse...@linaro.org>
---
 common/image-android-dt.c  | 134 +++++++++++++++++++++++++++++++++++++
 include/dt_table.h         |  46 +++++++++++++
 include/image-android-dt.h |  18 +++++
 3 files changed, 198 insertions(+)
 create mode 100644 common/image-android-dt.c
 create mode 100644 include/dt_table.h
 create mode 100644 include/image-android-dt.h

diff --git a/common/image-android-dt.c b/common/image-android-dt.c
new file mode 100644
index 0000000000..f218db06bb
--- /dev/null
+++ b/common/image-android-dt.c
@@ -0,0 +1,134 @@
+/*
+ * (C) Copyright 2018 Linaro Ltd.
+ * Sam Protsenko <semen.protse...@linaro.org>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+#include <image-android-dt.h>
+#include <common.h>
+#include <linux/libfdt_env.h>
+#include <linux/libfdt.h>
+
+/**
+ * Check if image header is correct.
+ *
+ * @param hdr Address to image header
+ * @return true if header is correct or false if header is incorrect
+ */
+bool android_dt_check_header(const struct dt_table_header *hdr)
+{
+       return fdt32_to_cpu(hdr->magic) == DT_TABLE_MAGIC;
+}
+
+/**
+ * Get the address of FDT (dtb or dtbo) in memory by its index in image.
+ *
+ * @param hdr Address to image header
+ * @param index Index of desired FDT in image (starting from 0)
+ * @param[out] addr If not null, will contain address to specified FDT
+ * @param[out] size If not NULL, will contain size of specified FDT
+ *
+ * @return true on success or false on error
+ */
+bool android_dt_get_fdt_by_index(const struct dt_table_header *hdr,
+                                u32 index, ulong *addr, u32 *size)
+{
+       const struct dt_table_entry *e;
+       u32 entry_count = fdt32_to_cpu(hdr->dt_entry_count);
+       u32 entries_offset = fdt32_to_cpu(hdr->dt_entries_offset);
+       u32 entry_size = fdt32_to_cpu(hdr->dt_entry_size);
+       u32 dt_offset, dt_size;
+
+       if (index > entry_count) {
+               printf("Error: index > dt_entry_count (%u > %u)\n", index,
+                      entry_count);
+               return false;
+       }
+
+       e = (const struct dt_table_entry *)((ulong)hdr + entries_offset
+                       + index * entry_size);
+       dt_offset = fdt32_to_cpu(e->dt_offset);
+       dt_size = fdt32_to_cpu(e->dt_size);
+
+       if (addr)
+               *addr = ((ulong)hdr + dt_offset);
+       if (size)
+               *size = dt_size;
+
+       return true;
+}
+
+#if !defined(CONFIG_SPL_BUILD)
+static void android_dt_print_fdt_info(const struct fdt_header *fdt)
+{
+       u32 fdt_size;
+       int root_node_off;
+       const char *compatible = NULL;
+
+       fdt_size = fdt_totalsize(fdt);
+       root_node_off = fdt_path_offset(fdt, "/");
+       if (root_node_off < 0) {
+               printf("Error: Root node not found\n");
+       } else {
+               compatible = fdt_getprop(fdt, root_node_off, "compatible",
+                                        NULL);
+       }
+
+       printf("           (FDT)size = %d\n", fdt_size);
+       printf("     (FDT)compatible = %s\n",
+              compatible ? compatible : "(unknown)");
+}
+
+/**
+ * Print information about DT image structure.
+ *
+ * @param hdr Address to image header
+ */
+void android_dt_print_contents(const struct dt_table_header *hdr)
+{
+       u32 i;
+       u32 entry_count = fdt32_to_cpu(hdr->dt_entry_count);
+       u32 entries_offset = fdt32_to_cpu(hdr->dt_entries_offset);
+       u32 entry_size = fdt32_to_cpu(hdr->dt_entry_size);
+
+       /* Print image header info */
+       printf("dt_table_header:\n");
+       printf("               magic = %08x\n", fdt32_to_cpu(hdr->magic));
+       printf("          total_size = %d\n", fdt32_to_cpu(hdr->total_size));
+       printf("         header_size = %d\n", fdt32_to_cpu(hdr->header_size));
+       printf("       dt_entry_size = %d\n", entry_size);
+       printf("      dt_entry_count = %d\n", entry_count);
+       printf("   dt_entries_offset = %d\n", entries_offset);
+       printf("           page_size = %d\n", fdt32_to_cpu(hdr->page_size));
+       printf("         reserved[0] = %08x\n", fdt32_to_cpu(hdr->reserved[0]));
+
+       /* Print image entries info */
+       for (i = 0; i < entry_count; ++i) {
+               const struct dt_table_entry *e;
+               const struct fdt_header *fdt;
+               u32 dt_offset, dt_size;
+               u32 j;
+
+               e = (const struct dt_table_entry *)((ulong)hdr + entries_offset
+                               + i * entry_size);
+               dt_offset = fdt32_to_cpu(e->dt_offset);
+               dt_size = fdt32_to_cpu(e->dt_size);
+
+               printf("dt_table_entry[%d]:\n", i);
+               printf("             dt_size = %d\n", dt_size);
+               printf("           dt_offset = %d\n", dt_offset);
+               printf("                  id = %08x\n", fdt32_to_cpu(e->id));
+               printf("                 rev = %08x\n", fdt32_to_cpu(e->rev));
+
+               for (j = 0; j < 4; ++j) {
+                       printf("           custom[%d] = %08x\n", j,
+                              fdt32_to_cpu(e->custom[j]));
+               }
+
+               /* Print FDT info for this entry */
+               fdt = (const struct fdt_header *)((ulong)hdr + dt_offset);
+               android_dt_print_fdt_info(fdt);
+       }
+}
+#endif
diff --git a/include/dt_table.h b/include/dt_table.h
new file mode 100644
index 0000000000..19cbbeab2a
--- /dev/null
+++ b/include/dt_table.h
@@ -0,0 +1,46 @@
+/*
+ * This is from the Android Project,
+ * Repository: https://android.googlesource.com/platform/system/libufdt
+ * File: utils/src/dt_table.h
+ * Commit: 58a7582180f477032cd6c74f8d9afad0038e74c3
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef DT_TABLE_H
+#define DT_TABLE_H
+
+#include <linux/types.h>
+
+#define DT_TABLE_MAGIC                 0xd7b7ab1e
+#define DT_TABLE_DEFAULT_PAGE_SIZE     2048
+
+struct dt_table_header {
+       u32 magic;              /* DT_TABLE_MAGIC */
+       u32 total_size;         /* includes dt_table_header + all dt_table_entry
+                                * and all dtb/dtbo
+                                */
+       u32 header_size;        /* sizeof(dt_table_header) */
+
+       u32 dt_entry_size;      /* sizeof(dt_table_entry) */
+       u32 dt_entry_count;     /* number of dt_table_entry */
+       u32 dt_entries_offset;  /* offset to the first dt_table_entry
+                                * from head of dt_table_header.
+                                * The value will be equal to header_size if
+                                * no padding is appended
+                                */
+       u32 page_size;          /* flash page size we assume */
+       u32 reserved[1];        /* must be zero */
+};
+
+struct dt_table_entry {
+       u32 dt_size;
+       u32 dt_offset;          /* offset from head of dt_table_header */
+
+       u32 id;                 /* optional, must be zero if unused */
+       u32 rev;                /* optional, must be zero if unused */
+       u32 custom[4];          /* optional, must be zero if unused */
+};
+
+#endif
diff --git a/include/image-android-dt.h b/include/image-android-dt.h
new file mode 100644
index 0000000000..f9b5ff3f13
--- /dev/null
+++ b/include/image-android-dt.h
@@ -0,0 +1,18 @@
+/*
+ * (C) Copyright 2018 Linaro Ltd.
+ * Sam Protsenko <semen.protse...@linaro.org>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+#ifndef IMAGE_ANDROID_DT_H
+#define IMAGE_ANDROID_DT_H
+
+#include <dt_table.h>
+
+bool android_dt_check_header(const struct dt_table_header *hdr);
+void android_dt_print_contents(const struct dt_table_header *hdr);
+bool android_dt_get_fdt_by_index(const struct dt_table_header *hdr,
+                                u32 index, ulong *addr, u32 *size);
+
+#endif /* IMAGE_ANDROID_DT_H */
-- 
2.17.0

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