Add memory test feature for mpc85xx POST.

The memory test is performed after DDR initialization when U-boot stills runs
in flash and cache. On recent mpc85xx platforms, the total memory can be more
than 2GB. To cover whole memory, it needs be mapped 2GB at a time using a
sliding TLB window. After the testing, DDR is remapped with up to 2GB memory
from the lowest address as normal.

If memory test fails, DDR DIMM SPD and DDR controller registers are dumped for
further debugging.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/doc/README.fsl-ddr b/doc/README.fsl-ddr
index e108a0d50c..1657ef6170 100644
--- a/doc/README.fsl-ddr
+++ b/doc/README.fsl-ddr
@@ -78,6 +78,20 @@ If the DDR controller supports address hashing, it can be enabled by hwconfig.
 Syntax is:
 hwconfig=fsl_ddr:addr_hash=true
 
+
+Memory testing options for mpc85xx
+==================================
+1. Memory test can be done once U-boot prompt comes up using mtest, or
+2. Memory test can be done with Power-On-Self-Test function, activated at
+   compile time.
+
+   In order to enable the POST memory test, CONFIG_POST needs to be
+   defined in board configuraiton header file. By default, POST memory test
+   performs a fast test. A slow test can be enabled by changing the flag at
+   compiling time. To test memory bigger than 2GB, 36BIT support is needed.
+   Memory is tested within a 2GB window. TLBs are used to map the virtual 2GB
+   window to physical address so that all physical memory can be tested.
+
 Combination of hwconfig
 =======================
 Hwconfig can be combined with multiple parameters, for example, on a supported