x86: ivybridge: Implement SDRAM init
Implement SDRAM init using the Memory Reference Code (mrc.bin) provided in
the board directory and the SDRAM SPD information in the device tree. This
also needs the Intel Management Engine (me.bin) to work. Binary blobs
everywhere: so far we have MRC, ME and microcode.
SDRAM init works by setting up various parameters and calling the MRC. This
in turn does some sort of magic to work out how much memory there is and
the timing parameters to use. It also sets up the DRAM controllers. When
the MRC returns, we use the information it provides to map out the
available memory in U-Boot.
U-Boot normally moves itself to the top of RAM. On x86 the RAM is not
generally contiguous, and anyway some RAM may be above 4GB which doesn't
work in 32-bit mode. So we relocate to the top of the largest block of
RAM we can find below 4GB. Memory above 4GB is accessible with special
functions (see physmem).
It would be possible to build U-Boot in 64-bit mode but this wouldn't
necessarily provide any more memory, since the largest block is often below
4GB. Anyway U-Boot doesn't need huge amounts of memory - even a very large
ramdisk seldom exceeds 100-200MB. U-Boot has support for booting 64-bit
kernels directly so this does not pose a limitation in that area. Also there
are probably parts of U-Boot that will not work correctly in 64-bit mode.
The MRC is one.
There is some work remaining in this area. Since memory init is very slow
(over 500ms) it is possible to save the parameters in SPI flash to speed it
up next time. Suspend/resume support is not fully implemented, or at least
it is not efficient.
With this patch, link boots to a prompt.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f27d731..43c22ff 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -50,6 +50,17 @@
int
default 36
+config HPET_ADDRESS
+ hex
+ default 0xfed00000 if !HPET_ADDRESS_OVERRIDE
+
+config SMM_TSEG
+ bool
+ default n
+
+config SMM_TSEG_SIZE
+ hex
+
config ROM_SIZE
hex
default 0x800000
@@ -63,6 +74,15 @@
SPI flash format. You will need to supply the me.bin file in
your board directory.
+config X86_RAMTEST
+ bool "Perform a simple RAM test after SDRAM initialisation"
+ help
+ If there is something wrong with SDRAM then the platform will
+ often crash within U-Boot or the kernel. This option enables a
+ very simple RAM test that quickly checks whether the SDRAM seems
+ to work correctly. It is not exhaustive but can save time by
+ detecting obvious failures.
+
source "arch/x86/cpu/ivybridge/Kconfig"
source "board/chromebook-x86/coreboot/Kconfig"