da850: Add instructions to copy AIS image to NAND

Add instructions to write an AIS image to NAND
by using the u-boot nand tools.

Signed-off-by: Axel Haslam <ahaslam@baylibre.com>

board/davinci/da8xxevm/README.da850

@@ -47,6 +47,47 @@ U-Boot > sf erase 0 +320000
 U-Boot > tftp u-boot.ais
 U-Boot > sf write c0700000 0 $filesize
 
+Flashing the images to NAND
+===========================
+The AIS image can be written to NAND using the u-boot "nand" commands.
+
+Example:
+
+OMAPL138_LCDK requires the AIS image to be written to the second block of
+the NAND flash.
+
+From the "nand info" command we see that the second block would start at
+offset 0x20000:
+
+  U-Boot > nand info
+      sector size      128 KiB (0x20000)
+      Page size       2048 b
+
+From the tftp command we see that we need to copy 0x74908 bytes from
+memory address 0xc0700000 (0x75000 if we align a page of 2048):
+
+  U-Boot > tftp u-boot.ais
+      Load address: 0xc0700000
+      Bytes transferred = 477448 (74908 hex)
+
+The commands to write the image from memory to NAND would be:
+
+  U-Boot > nand erase 0x20000 0x75000
+  U-Boot > nand write 0xc0700000 0x20000 0x75000
+
+Alternatively, MTD partitions may be defined. Using "mtdparts" to
+conveniently have a bootloader partition starting at the second block
+(offset 0x20000):
+
+  setenv mtdids nand0=davinci_nand.0
+  setenv mtdparts mtdparts=davinci_nand.0:128k(bootenv),2m(bootloader)
+
+In this case the commands would be simplified to:
+
+  U-Boot > tftp u-boot.ais
+  U-Boot > nand erase.part bootloader
+  U-Boot > nand write 0xc0700000 bootloader
+
 Flashing the images to MMC
 ==========================
 If the boot pins are set to boot from mmc, the RBL will try to load the