Commit graph

57 commits

Author SHA1 Message Date
Simon Glass
11b7cc37f1 x86: Update a stale comment about ifdtool
We use binman to build the x86 image now. Update a comment which still
refers to ifdtool.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2019-05-08 13:02:10 +08:00
Bin Meng
7bb6028768 x86: fsp: Eliminate the reset_cpu() call
In preparation for the reset driver conversion, eliminate the
reset_cpu() call in the FSP init path as it's too early for the
reset driver to work.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2018-07-20 09:33:22 +08:00
Ivan Gorinov
8199a145c4 x86: Use microcode update from device tree for all processors
Built without a ROM image with FSP (u-boot.rom), the U-Boot loader applies
the microcode update data block encoded in Device Tree to the bootstrap
processor but not passed to the other CPUs when multiprocessing is enabled.

If the bootstrap processor successfully performs a microcode update
from Device Tree, use the same data block for the other processors.

Signed-off-by: Ivan Gorinov <ivan.gorinov@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: fixed build errors on edison and qemu-x86]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
2018-07-02 09:23:28 +08:00
Tom Rini
83d290c56f SPDX: Convert all of our single license tags to Linux Kernel style
When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>
2018-05-07 09:34:12 -04:00
Bin Meng
45519924a0 x86: Rename e820entry to e820_entry
This changes 'struct e820entry' to 'struct e820_entry' to conform
with the coding style.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
2018-04-16 16:54:51 +08:00
Bin Meng
87af71c2ea x86: Use 'unsigned int' in install_e820_map() functions
This fixes the following checkpatch warning:

  warning: Prefer 'unsigned int' to bare use of 'unsigned'

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
2018-04-16 16:54:51 +08:00
Tom Rini
8e18f34c28 x86: Move commands from under arch/x86 to cmd/x86/
We only need to compile and link these files when building for full
U-Boot.  Move them to under cmd/x86/ to make sure they aren't linked in
and undiscarded due to u_boot_list_2_cmd_* being included).

Cc: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2018-01-08 16:52:22 +08:00
Bin Meng
dc80d3b230 x86: fsp: graphics: Add some notes about the graphics info hob
On some platforms (eg: Braswell), the FSP will not produce the
graphics info HOB unless you plug some cables to the display
interface (eg: HDMI) on the board. Add such notes in the FSP
video driver.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2017-10-27 15:13:47 +08:00
Bin Meng
fb2c53091f Revert "x86: fsp: Configure SPI opcode registers before SPI is locked down"
This reverts commit 1e6ebee667.

It's not appropriate to call the Intel SPI driver specific stuff in
the FSP codes. We may add a simple DTS property "intel,spi-lock-down"
and let the Intel SPI driver call these stuff instead.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
2017-10-27 15:13:47 +08:00
Bin Meng
b3fd2126dc x86: fsp: Update fsp command to show spec 1.1 header
FSP spec 1.1 adds 3 new APIs and their offsets are in the header.
Update the 'fsp hdr' command to show these new entries.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2017-09-16 14:57:44 +08:00
Bin Meng
5df91f1c82 x86: dm: video: Add a framebuffer driver that utilizes VBT
When a VBT is given to an FSP that supports graphics initialization,
the FSP will produce a graphics info HOB that contains all necessary
information for the linear frame buffer of the integrated graphics
device. This adds a DM video driver for it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2017-09-16 14:57:44 +08:00
Bin Meng
4ff333b7dd x86: fsp: Add FSP_GRAPHICS_INFO_HOB
This adds a new HOB type for graphics information introduced in FSP
spec 1.1. When graphics capability is included in FSP and enabled,
FSP produces an FSP_GRAPHICS_INFO_HOB as described in the EFI PI
specification which provides information about the graphics mode and
framebuffer.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2017-09-16 14:57:44 +08:00
Bin Meng
1e6ebee667 x86: fsp: Configure SPI opcode registers before SPI is locked down
Some Intel FSP (like Braswell) does SPI lock-down during the call
to fsp_notify(INIT_PHASE_BOOT). But before SPI lock-down is done,
it's bootloader's responsibility to configure the SPI controller's
opcode registers properly otherwise SPI controller driver doesn't
know how to communicate with the SPI flash device.

This introduces a Kconfig option CONFIG_FSP_LOCKDOWN_SPI for such
FSPs. When it is on, U-Boot will configure the SPI opcode registers
before the lock-down.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
2017-08-24 11:00:47 +08:00
Bin Meng
d7f7ba36b2 x86: fsp: Remove the call to set up internal uart in fsp_init()
First of all, it's inappropriate to call setup_internal_uart() in a
generic API fsp_init(), as CONFIG_INTERNAL_UART is an option that
is only available on BayTrail platform. Secondly even for BayTrail,
there is no need to call setup_internal_uart() at all, as Intel FSP
will do this for us.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
2017-06-05 08:55:22 +08:00
Bin Meng
ba65808e7d x86: fsp: Save stack address to CMOS for next S3 boot
At the end of pre-relocation phase, save the new stack address
to CMOS and use it as the stack on next S3 boot for fsp_init()
continuation function.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>
2017-05-17 17:11:46 +08:00
Bin Meng
7d0d2efef8 x86: fsp: Mark memory used by U-Boot as reserved in the E820 table for S3
U-Boot itself as well as everything that is consumed by U-Boot (like
heap, stack, dtb, etc) needs to be reserved and reported in the E820
table when S3 resume is on.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>
2017-05-17 17:11:46 +08:00
Bin Meng
b727961b07 x86: Store and display previous sleep state
Add one member in the global data to store previous sleep state,
and display the state during boot in print_cpuinfo().

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>
2017-05-17 17:11:46 +08:00
Bin Meng
1206723b6e x86: fsp: acpi: Pass different boot mode to FSP init
When ACPI S3 resume is turned on, we should pass different boot mode
to FSP init instead of default BOOT_FULL_CONFIG.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>
2017-05-17 17:11:46 +08:00
Simon Glass
76b00aca4f board_f: Drop setup_dram_config() wrapper
By making dram_init_banksize() return an error code we can drop the
wrapper. Adjust this and clean up all implementations.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
2017-04-05 16:36:51 -04:00
Simon Glass
76d1d02fd2 board_f: x86: Use checkcpu() for CPU init
At present we misuse print_cpuinfo() do so CPU init on x86. This is done
because it is the next available call after the console is enabled. But
several arches use checkcpu() instead. Despite the horrible name (which
we can fix), it seems a better choice.

Adjust the various x86 CPU implementations to move their init code into
checkcpu() and use print_cpuinfo() only for printing CPU info.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
2017-04-05 13:55:09 -04:00
Simon Glass
671549e5b0 board_f: x86: Rename x86_fsp_init() to arch_fsp_init()
While x86 is the only user and this could in principle be moved to
arch_cpu_init() there is some justification for this being a separate
call. It provides a way to handle init which is not CPU-specific, but
must happen before the CPU can be set up.

Rename the function to be more generic.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
2017-04-05 13:52:36 -04:00
Bin Meng
d9703a0725 x86: fsp: Wrap setup_internal_uart() call with CONFIG_INTERNAL_UART
For any FSP-enabled boards that want to enable debug UART support,
setup_internal_uart() will be called, but this API is only available
on BayTrail platform. Change to wrap it with CONFIG_INTERNAL_UART.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-07-12 13:46:01 +08:00
Simon Glass
e77b62e290 x86: Update microcode for secondary CPUs
Each CPU needs to have its microcode loaded. Add support for this so that
all CPUs will have the same version.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2016-03-17 10:27:25 +08:00
Bin Meng
dc5be508b0 x86: fsp: Make sure HOB list is not overwritten by U-Boot
Intel IvyBridge FSP seems to be buggy that it does not report memory
used by FSP itself as reserved in the resource descriptor HOB. The
FSP specification does not describe how resource descriptor HOBs are
generated by the FSP to describe what memory regions. It looks newer
FSPs like Queensbay and BayTrail do not have such issue. This causes
U-Boot relocation overwrites the important boot service data which is
used by FSP, and the subsequent call to fsp_notify() will fail.

To resolve this, we find out the lowest memory base address allocated
by FSP for the boot service data when walking through the HOB list in
fsp_get_usable_lowmem_top(). Check whether the memory top address is
below the FSP HOB list, and if not, use the lowest memory base address
allocated by FSP as the memory top address.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested on link (ivybridge non-FSP)
Tested-by: Simon Glass <sjg@chromium.org>
2016-02-21 13:42:52 +08:00
Stefan Roese
d521197d69 x86: baytrail: Add option to disable the internal UART to setup_early_uart()
This patch adds a parameter to the function setup_early_uart() to either
enable or disable the internal BayTrail legacy UART. Since the name
setup_early_uart() does not match its functionality any more, lets
rename it to setup_internal_uart() as well in this patch.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-01-28 13:53:30 +08:00
Tom Rini
4edde96111 Merge branch 'master' of git://git.denx.de/u-boot-x86 2016-01-14 21:51:32 -05:00
Albert ARIBAUD
ecc306639e Fix board init code to respect the C runtime environment
board_init_f_mem() alters the C runtime environment's
stack it is actually already using. This is not a valid
behaviour within a C runtime environment.

Split board_init_f_mem into C functions which do not alter
their own stack and always behave properly with respect to
their C runtime environment.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Acked-by: Thomas Chou <thomas@wytron.com.tw>
2016-01-13 21:05:17 -05:00
Bin Meng
59fb7fbd49 x86: fsp: Always use hex numbers in the hob command output
In the 'fsp hob' command output, decimal numbers and hexadecimal
numbers are used mixedly. Now change to always use hex numbers
to keep consistency.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:15 +08:00
Bin Meng
214feec1c5 x86: fsp: Set up init runtime buffer in update_fsp_configs()
fsp_init() runtime buffer parameter might be different across
different platforms. Move this to update_fsp_configs().

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:14 +08:00
Bin Meng
3340f2cc0b x86: fsp: Introduce CONFIG_FSP_USE_UPD Kconfig option
Not every FSP supports UPD, thus we introduce a Kconfig option
CONFIG_FSP_USE_UPD and use it to wrap these common UPD handling
codes in fsp_support.c.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:14 +08:00
Bin Meng
81f84aa6c9 x86: fsp: Rename update_fsp_upd() and change its signature
To support platform-specific configurations (might not always be
UPD on some platform), use a better name update_fsp_configs() and
accepct struct fsp_config_data as its parameter so that platform
codes can handle whatever configuration data for that FSP.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:14 +08:00
Bin Meng
cb379a34c4 x86: fsp: Rename shared_data to fsp_config_data
FSP has several config data like UPD, HDA verb table which can be
overridden or provided by bootloader. Currently in U-Boot only UPD
is handled via struct shared_data. To accommodate any platform, we
rename shared_data to fsp_config_data and move the definition from
common place fsp_support.h to platform-specific place fsp_configs.h.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:14 +08:00
Bin Meng
57ac74ff04 x86: fsp: Add boot_mode as a member of struct shared_data
Save boot_mode in struct shared_data for future refactoring.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:14 +08:00
Bin Meng
f0285fbe4e x86: fsp: Avoid cast stack_top in struct shared_data
Declare stack_top as u32 in struct shared_data and struct common_buf
so that we can avoid casting in fsp_init().

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:13 +08:00
Bin Meng
aa02446406 x86: fsp: Simplify fsp_continue()
There is no need to pass shared_data to fsp_continue() so we can
remove unnecessary codes that simplifies the function a lot.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-01-13 12:20:13 +08:00
Bin Meng
902ca5bdf3 x86: Remove legacy pci codes
Now that we have converted all x86 boards to use driver model pci,
remove these legacy pci codes.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-11-13 06:46:25 -08:00
Bin Meng
ff1e18af9d x86: fsp: Pass mrc cache to fsp_init() and save it to gd after fsp_init()
fsp_init() call has a parameter nvs_buf which is used by FSP as the
MRC cache but currently is blindly set to NULL. Retreive the MRC
cache from SPI flash and pass it to fsp_init() call. After the call,
save FSP produced MRC cache to SPI flash too.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-10-21 07:46:27 -06:00
Bin Meng
010921ae7f x86: fsp: Add a hdr sub-command to show header information
It would be helpful to have a command to show FSP header. So far
it only supports FSP header which conforms to FSP spec 1.0.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-10-21 07:46:26 -06:00
Bin Meng
62716ebb75 x86: fsp: Make hob command a sub-command to fsp
Introduce a new fsp command and make the existing hob command a
sub-command to fsp for future extension. Also move cmd_hob.c to
the dedicated fsp sub-directory in arch/x86/lib.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-10-21 07:46:26 -06:00
Bin Meng
196193a4d4 x86: fsp: Report correct number of E820 table entries
The logic to calculate the number of E820 table entries is wrong
when walking through the FSP HOB tables. Fix it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Jian Luo <jian.luo4@boschrexroth.de>
Acked-by: Simon Glass <sjg@chromium.org>
2015-09-28 21:56:27 -07:00
Bin Meng
48aa6c2614 x86: fsp: Add comments about U-Boot entering start.S twice
Add some comments in start.S for the fact that with FSP U-Boot
actually enters the code twice. Also change to use fsp_init()
and fsp_continue for accuracy.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-08-26 07:54:11 -07:00
Bin Meng
57b10f59b7 x86: fsp: Enlarge the size of malloc() pool before relocation
After fsp_init() returns, the stack has already been switched to a
place within system memory as defined by CONFIG_FSP_TEMP_RAM_ADDR.
Enlarge the size of malloc() pool before relocation since we have
plenty of memory now.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-08-26 07:54:11 -07:00
Simon Glass
ecf674b772 x86: Drop FSP error defines and use EFI instead
Now that we have an efi.h header we can use that for FSP error defines.
Drop the FSP ones.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2015-08-14 09:50:13 -06:00
Simon Glass
412400abaa x86: Split out fsp_init_phase_pci() code into a new function
This code may be useful for boards that use driver model for PCI.

Note: It would be better to have driver model automatically call this
function somehow. However for now it is probably safer to have it under
board control.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2015-08-14 03:24:21 -06:00
Bin Meng
da60fb7934 x86: fsp: Do not assert VPD_IMAGE_REV when DEBUG
When using different release version of Intel FSP, the VPD_IMAGE_REV
is different (ie: BayTrail Gold 3 is 0x0303 while Gold 4 is 0x0304).
Remove the asserting of this so that U-Boot does not hang in a debug
build.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-08-14 03:24:21 -06:00
Simon Glass
8b097916fa x86: Add some missing global_data declarations in files that use gd
Some files use global_data but don't declare it. Fix this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2015-08-05 08:42:41 -06:00
Bin Meng
1ed6648be0 x86: Reserve PCIe ECAM address range in the E820 table
We should mark PCIe ECAM address range in the E820 table as reserved
otherwise kernel will not attempt to use ECAM.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-07-28 10:36:25 -06:00
Bin Meng
aefaff8ed8 x86: fsp: Move FspInitEntry call to board_init_f()
The call to FspInitEntry is done in arch/x86/lib/fsp/fsp_car.S so far.
It worked pretty well but looks not that good. Apart from doing too
much work than just enabling CAR, it cannot read the configuration
data from device tree at that time. Now we want to move it a little
bit later as part of init_sequence_f[] being called by board_init_f().
This way it looks and works better in the U-Boot initialization path.

Due to FSP's design, after calling FspInitEntry it will not return to
its caller, instead it jumps to a continuation function which is given
by bootloader with a new stack in system memory. The original stack in
the CAR is gone, but its content is perserved by FSP and described by
a bootloader temporary memory HOB. Technically we can recover anything
we had before in the previous stack, but that is way too complicated.
To make life much easier, in the FSP continuation routine we just
simply call fsp_init_done() and jump back to car_init_ret() to redo
the whole board_init_f() initialization, but this time with a non-zero
HOB list pointer saved in U-Boot's global data so that we can bypass
the FspInitEntry for the second time.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Andrew Bradford <andrew.bradford@kodakalaris.com>
Tested-by: Simon Glass <sjg@chromium.org>
2015-07-14 18:03:15 -06:00
Bin Meng
002610f620 x86: fsp: Load GDT before calling FspInitEntry
Currently the FSP execution environment GDT is setup by U-Boot in
arch/x86/cpu/start16.S, which works pretty well. But if we try to
move the FspInitEntry call a little bit later to better fit into
U-Boot's initialization sequence, FSP will fail to bring up the AP
due to #GP fault as AP's GDT is duplicated from BSP whose GDT is
now moved into CAR, and unfortunately FSP calls AP initialization
after it disables the CAR. So basically the BSP's GDT still refers
to the one in the CAR, whose content is no longer available, so
when AP starts up and loads its segment register, it blows up.

To resolve this, we load GDT before calling into FspInitEntry.
The GDT is the same one used in arch/x86/cpu/start16.S, which is
in the ROM and exists forever.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Andrew Bradford <andrew.bradford@kodakalaris.com>
Tested-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
2015-07-14 18:03:15 -06:00
Andrew Bradford
1dc03c2639 x86: fsp_support: Correct high mem comment typo
High mem starts at 4 GiB.

Signed-off-by: Andrew Bradford <andrew.bradford@kodakalaris.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
2015-06-04 02:39:39 -06:00