[U-Boot] [PATCH v2 16/18] da850_am18xxevm: Add README.da850_am18xxevm

[Tom Rini]

Add a board-specific README that documents how to write u-boot.ais to
the SPI found on this board.

Changes-series: 2
- Add

Signed-off-by: Tom Rini <trini at ti.com>
---

 board/davinci/da8xxevm/README.da850_am18xxevm |   53 +++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 board/davinci/da8xxevm/README.da850_am18xxevm

diff --git a/board/davinci/da8xxevm/README.da850_am18xxevm b/board/davinci/da8xxevm/README.da850_am18xxevm
new file mode 100644
index 0000000..382b718
--- /dev/null
+++ b/board/davinci/da8xxevm/README.da850_am18xxevm
@@ -0,0 +1,53 @@
+Summary
+=======
+The README is for the boot procedure used for the LogicPD AM1808 EVM.
+
+The board is booted in three stages. The initial bootloader which executes
+upon reset is the Rom Boot Loader(RBL) which sits in the internal ROM. The
+RBL initialises the memory and the SPI controller and reads the AIS image
+starting at block 0.  This image can contain both the SPL and U-Boot
+binaries.
+
+AIS is an image format defined by TI for the images that are to be
+loaded to memory by the RBL. The image is divided into a series of
+sections and the image's entry point is specified. Each section comes
+with meta data like the target address the section is to be copied to
+and the size of the section, which is used by the RBL to load the
+image. At the end of the image the RBL jumps to the image entry
+point.
+
+The secondary stage bootloader(spl) which is loaded by the RBL then loads
+the u-boot from a predefined location in SPI to DDR and jumps to the u-boot
+entry point.
+
+
+Compilation
+===========
+To build a SPI-bootable image, run 'make da850_am18xxevm'.  This will build
+the u-boot.ais file that needs to be written to SPI flash.
+
+
+Flashing the images to Nand
+===========================
+The AIS image can be written to SPI flash using the following commands.
+Assuming that the network is configured and enabled and the u-boot.ais file
+is tftp'able.
+
+U-Boot > sf probe 0
+U-Boot > sf erase 0 +320000
+U-Boot > tftp u-boot.ais
+U-Boot > sf write c0700000 0 $filesize
+
+
+Recovery
+========
+
+In the case of a "bricked" board, you need to use the TI tools found
+here[1] to write a UBL file and u-boot.bin.  Once the system is running
+again from these tools a good u-boot.ais may be re-written to SPI flash.
+
+
+Links
+=====
+[1]
+ http://processors.wiki.ti.com/index.php/Serial_Boot_and_Flash_Loading_Utility_for_OMAP-L137
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