binman: Expand documentation for entries

At present only the more complex entries are documented. It is useful to
have documentation for all entries in one place.

As a first step, add and expand the documentation to cover all entries.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/tools/binman/etype/u_boot_spl.py b/tools/binman/etype/u_boot_spl.py
index 9edd2dad03..0e99a2d2a7 100644
--- a/tools/binman/etype/u_boot_spl.py
+++ b/tools/binman/etype/u_boot_spl.py
@@ -11,6 +11,27 @@ from entry import Entry
 from blob import Entry_blob
 
 class Entry_u_boot_spl(Entry_blob):
+    """U-Boot SPL binary
+
+    Properties / Entry arguments:
+        - filename: Filename of u-boot-spl.bin (default 'spl/u-boot-spl.bin')
+
+    This is the U-Boot SPL (Secondary Program Loader) binary. This is a small
+    binary which loads before U-Boot proper, typically into on-chip SRAM. It is
+    responsible for locating, loading and jumping to U-Boot. Note that SPL is
+    not relocatable so must be loaded to the correct address in SRAM, or written
+    to run from the correct address is direct flash execution is possible (e.g.
+    on x86 devices).
+
+    SPL can access binman symbols at runtime. See:
+
+        'Access to binman entry offsets at run time (symbols)'
+
+    in the binman README for more information.
+
+    The ELF file 'spl/u-boot-spl' must also be available for this to work, since
+    binman uses that to look up symbols to write into the SPL binary.
+    """
     def __init__(self, section, etype, node):
         Entry_blob.__init__(self, section, etype, node)
         self.elf_fname = 'spl/u-boot-spl'