It's been a while since I've touched U-Boot on the Raspberry Pi and
other things have been taking my time. Drop my maintainership for this
port.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
In some boards like the Raspberry Pi the initial bootloader will pass
a DT to the kernel. When using U-Boot as such kernel, the board code in
U-Boot should be able to provide U-Boot with this, already assembled
device tree blob.
This patch introduces a new config option CONFIG_OF_BOARD to use instead
of CONFIG_OF_EMBED or CONFIG_OF_SEPARATE which will initialize the DT
from a board-specific funtion instead of bundling one with U-Boot or as
a separated file. This allows boards like the Raspberry Pi to reuse the
device tree passed from the bootcode.bin and start.elf firmware
files, including the run-time selected device tree overlays.
Signed-off-by: Alex Deymo <deymo@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Convert the bcm2835 SDHCI driver over to support CONFIG_DM_MMC and move
all boards over. There is no need to keep the old code since there are no
other users.
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
The bcm283x chips provide a way for the ARM core to communicate with the
graphics processor, which is in charge of many things. This is handled by
way of a message prototcol.
At present the code for sending message (and receiving a reply) is spread
around U-Boot, primarily in the board file. This means that sending a
message from a driver requires duplicating the code.
Create a new message implementation with a function to support powering on
a subsystem as a starting point.
Signed-off-by: Simon Glass <sjg@chromium.org>
The directory structure of device tree files produced by the kernel's
'make dtbs_install' is different on ARM64, the RPi3 device tree file is
in a 'broadcom' subdirectory there.
Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Firmware provides a spin table on the raspberry pi. This table shouldn't
get overwritten by payloads, so we need to mark it as reserved.
Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
This patch removes use of U_BOOT_DEVICE in board/raspberrypi/rpi/rpi.c,
enables OF_CONTROL in the config and adjusts the rpi_*defconfig configs.
Signed-off-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
When using OF_CONTROL, the disabled value of the mini UART platdata
gets reset after board_early_init_f. So move detection and disabling
to board_init and remove board_early_init_f.
This uses the first device using the mini uart driver, as this method
works reliably with different device trees or even no device tree at all.
Signed-off-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Raspberry firmware used to pass a FDT blob at a fixed address (0x100),
but this is not true anymore. The address now depends on both the
memory size and the blob size [1].
If one wants to passthrough this FDT blob to the kernel, the most
reliable way is to save its address from the r2/x0 register in the
U-Boot entry point and expose it in a environment variable for
further processing.
This patch just does this:
- save the provided address in the global variable fw_dtb_pointer
- expose it in ${fdt_addr} if it points to a a valid FDT blob
There are many different ways to use it. One can, for example, use
the following script which will extract from the tree the command
line built by the firmware, then hand over the blob to a previously
loaded kernel:
fdt addr ${fdt_addr}
fdt get value bootargs /chosen bootargs
bootz ${kernel_addr_r} - ${fdt_addr}
Alternatively, users relying on sysboot/pxe can simply omit any FDT
statement in their extlinux.conf file, U-Boot will automagically pick
${fdt_addr} and pass it to the kernel.
[1] https://www.raspberrypi.org/forums//viewtopic.php?f=107&t=134018
Signed-off-by: Cédric Schieli <cschieli@gmail.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
On the raspberry pi, you can disable the serial port to gain dynamic frequency
scaling which can get handy at times.
However, in such a configuration the serial controller gets its rx queue filled
up with zero bytes which then happily get transmitted on to whoever calls
getc() today.
This patch adds detection logic for that case by checking whether the RX pin is
mapped to GPIO15 and disables the mini uart if it is not mapped properly.
That way we can leave the driver enabled in the tree and can determine during
runtime whether serial is usable or not, having a single binary that allows for
uart and non-uart operation.
Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Introduce virtual and physical addresses in the mapping table. This change
have no impact on existing boards because they all use idential mapping.
Signed-off-by: York Sun <york.sun@nxp.com>
Now that rpi_*defconfig and Kconfig (rather than the config header file)
provide the identity of the build, we don't need to separate config
headers and board directories for each RPi variant. Set CONFIG_SYS_BOARD
and CONFIG_SYS_CONFIG_NAME so that we can get rid of the duplication. This
requires a tiny number of extra ifdefs in the config header.
The only disadvantage of this approach is that the $board/$board_name
environment variables aren't as descriptive as they used to be. This isn't
really an issue because those only exist to allow scripts to create DTB
filenames at runtime. However, the RPi board code already sets $fdtfile to
something more accurate based on FW-reported board ID anyway.
While at it, unify some Kconfig select options, and add a MAINTAINERS
entry for bcm283x too.
Partially-suggested-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
On all Pis so far, the VC FW provides a short stub to set up the ARM CPU
before entering the kernel (a/k/a U-Boot for us). This feature is not
currently supported by the VC FW when booting in 64-bit mode. However,
this feature will likely appear in the near future, and this U-Boot port
assumes that such a feature is in place. Without that feature, or a
temporary workaround described below, U-Boot will not boot.
Once the VC FW does provide the ARM stub, u-boot.bin built for rpi_3 can
be used drectly as kernel7.img, in the same way as any other RPi port. The
following config.txt is required:
# Fix mini UART input frequency, and setup/enable up the UART.
# Without this option, U-Boot will not boot, even if you don't care
# about the serial console. This option will always be required for
# all RPi3 use-cases, unless the PL011 UART is used, which is not
# yet supported by rpi_3* builds of U-Boot.
enable_uart=1
# Boot in AArch64 (64-bit) mode.
# It is possible that a future VC FW will remove the need for this
# option, instead auto-setting 32-/64-bit mode based on the "kernel"
# filename present on the SD card.
arm_control=0x200
Prior to the VC FW providing the ARM boot stub, you can use the following
steps to build an equivalent stub into the U-Boot binary:
git clone https://github.com/swarren/rpi-3-aarch64-demo.git \
../rpi-3-aarch64-demo
(cd ../rpi-3-aarch64-demo && ./build.sh)
Build U-Boot for rpi_3 in the usual way
cat ../rpi-3-aarch64-demo/armstub64.bin u-boot.bin > u-boot.bin.stubbed
Use u-boot.bin.stubbed as kernel7.img on the Pi SD card.
In this case, the following additional entries are required in config.txt:
# Tell the FW to load the kernel image at address 0, the reset vector.
kernel_old=1
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
The Raspberry Pi 3 contains a BCM2837 SoC. The BCM2837 is a BCM2836 with
the CPU complex swapped out for a quad-core ARMv8. This can operate in 32-
or 64-bit mode. 32-bit mode is the current default selected by the
VideoCore firmware on the Raspberry Pi 3. This patch adds a 32-bit port of
U-Boot for the Raspberry Pi 3.
>From U-Boot's perspective, the only delta between the RPi 2 and RPi 3 is a
change in usage of the SoC UARTs. On all previous Pis, the PL011 was the
only UART in use. The Raspberry Pi 3 adds a Bluetooth module which uses a
UART to connect to the SoC. By default, the PL011 is used for this purpose
since it has larger FIFOs than the other "mini" UART. However, this can
be configured via the VideoCore firmware's config.txt file. This patch
hard-codes use of the mini UART in the RPi 3 port. If your system uses the
PL011 UART for the console even on the RPi 3, please use the RPi 2 U-Boot
port instead. A future change might determine which UART to use at
run-time, thus allowing the RPi 2 and RPi 3 (32-bit) ports to be squashed
together.
The mini UART has some limitations. One externally visible issue in the
BCM2837 integration is that the UART divides the SoC's "core clock" to
generate the baud rate. The core clock is typically variable, and under
control of the VideoCore firmware for thermal management reasons. If the
VC FW does modify the core clock rate, UART communication will be
corrupted since the baud rate will vary from the expected value. This was
not an issue for the PL011 UART, since it is fed by a fixed 3MHz clock. To
work around this, the VideoCore firmware can be told not to modify the SoC
core clock. However, the only way this can happen and be thermally safe is
to limit the core clock to a low/minimum frequency. This leaves
performance on the table for use-cases that don't care about a UART
console. Consequently, use of the mini UART console must be explicitly
requested by entering the following line into config.txt:
enable_uart=1
A recent version of the VC firmware is required to ensure that the mini
UART is fully and correctly initialized by the VC FW; at least
firmware.git 046effa13ebc "firmware: arm_loader: emmc clock depends on
core clock See: https://github.com/raspberrypi/firmware/issues/572".
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
This allows U-Boot to known the name of the board.
The existing rpi_2_defconfig can operate correctly on the Raspberry Pi 3
in 32-bit mode /if/ you have configured the firmware to use the PL011 UART
as the console UART (the default is the mini UART). This requires two
things:
a) config.txt should contain dtoverlay=pi3-miniuart-bt
b) You should run the following to tell the VC FW to process DT when
booting, and copy u-boot.bin.img (rather than u-boot.bin) to the SD card
as the kernel image:
path/to/kernel/scripts/mkknlimg --dtok u-boot.bin u-boot.bin.img
This works as of firmware.git commit 046effa13ebc "firmware: arm_loader:
emmc clock depends on core clock See:
https://github.com/raspberrypi/firmware/issues/572".
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
To simplify support for new SoCs, just use a constant filename
for the unknown case. In practice this case shouldn't be hit anyway, so
the filename isn't relevant, and certainly doesn't need to differentiate
between SoCs. If a user has an as-yet-unknown board, they can override
this value in the environment anyway.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Currently, CONFIG_BCM2835 is defined for all BCM283x builds and _BCM2836
is defined when building for that SoC. That means there isn't a single
define that means "exactly BCM2835". This will complicate future patches
where BCM2835-vs-anything-else needs to be determined simply.
Modify the code to define one or the other of CONFIG_BCM2835/BCM2836 so
future patches are simpler.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
For Raspberry Pi, we had the input clock rate to the pl011 fixed in
the rpi.c file, but it may be changed by firmware due to user changes
to config.txt. Since the firmware always sets up the uart (default
115200 output unless the user changes it), we can just skip our own
uart init to simplify the boot process and more reliably get serial
output.
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Tom Rini <trini@konsulko.com>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Gets propagated into the device tree and then into /proc/cpuinfo where
users often expect it.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Stephen Warren <swarren@wwwdotorg.org>
Let's set "ethaddr" when we get the ethernet address too, so that
fdt_fixup_ethernet() sets the address in the device tree and the Linux
driver can pick it up.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
The P5 header was not present on "Model B" any board prior to Revision 2.0,
there's no need for a separate device tree.
Also, it looks like "rev2" is incorrectly used to only cover the 512MiB
memory models; there also were 256MiB 2.0 boards.
I don't have all of the boards to check this, I'm following this table:
http://elinux.org/RPi_HardwareHistory#Board_Revision_History
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
This source has been blessed by Dom Cobley at the RPi Foundation, so seems
like the best source to refer to. It's a superset of and consistent with
the other sources.
Cc: Lubomir Rintel <lkundrak@v3.sk>
Cc: Eric Anholt <eric@anholt.net>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
The RPi has two different schemes for encoding board revision values.
When adding RPi 2 support, I thought that the conflicting type field
values were to be interpreted based on bcm2835-vs-bcm2836. In fact, the
scheme bit determines the encoding. The RPi Zero uses the bcm2835 yet
uses the new encoding scheme. Fix the code to cater for this correctly.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
There are two numbering schemes for the RPi revision values; old and new
scheme. The values within each scheme overlap. Hence, it doesn't make
sense to have absolute/global names for the revision IDs. Get rid of the
names and just use the raw revision/type values to set up the array of
per-revision data.
This change makes most sense when coupled with the next change. However,
it's split out so that the mechanical cut/paste is separate from the
logic changes for easier review and problem bisection.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Add CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG support and enable it to set
'board_rev' and 'board_name' envs.
'board_rev' can be used in scripts to determine what board we are running on
and 'board_name' for pretty printing.
Signed-off-by: Guillaume GARDET <guillaume.gardet@free.fr>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Seen this one in the wild. Is labelled "Raspberry Pi Model A+ V1.1,
(C) Raspberry Pi 2014". A standard A+ board, much like the one with
version 0x12, didn't notice any differencies.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Now that we have a new header file for cache-aligned allocation, we should
move the stack-based allocation macro there also.
Signed-off-by: Simon Glass <sjg@chromium.org>
The mailbox buffer is required to be at least 16 bytes aligned, but for
cache invalidation and/or flush it needs to be cacheline aligned.
Use ALLOC_CACHE_ALIGN_BUFFER for all mailbox buffer allocations.
Signed-off-by: Alexander Stein <alexanders83@web.de>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
BCM2835 (used on Raspberry Pi) and BCM2836 (used on Raspberry Pi 2)
are similar enough. One of the biggest differences is the ARM
processor. It is reasonable to collect the source files into a
single place, arch/arm/mach-bcm283x/.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Apparently the firmware's board rev response includes both the board
revision and some other data even on the RPi1. In particular, the
"warranty bit" is bit 24. We need to mask that out when looking up the
board ID.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
USB doesn't seem to work yet; the controller detects the on-board Hub/
Ethernet device but can't read the descriptors from it. I haven't
investigated yet.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
We now have api functions that can support compiling simplefb code as its own
module. Since this code is not part of the display functionality, extract it
to its own file.
Raspberry Pi is updated to accommodate the changes.
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Bo Shen <voice.shen@atmel.com>
Tested-by: Josh Wu <josh.wu@atmel.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Create a fake model table entry with default values, so we can error
check the board rev value once when querying it from the firmware, rather
than error-checking for invalid board rev values every time the model
table is used.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Add a board rev entry for the new model A+, and augment the board
rev error handling code to be a bit more verbose.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Model A and CM RPis don't have an on-board USB Ethernet device. Hence,
there's no point setting $usbethaddr based on the device fuses. Use the
model detection code to gate this. Note that the fuses are actually
programmed even on those devices though.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Adjust the configuration to use the driver model version of the pl01x
serial driver. Add the required platform data.
Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
The U-Boot port runs on a variety of RPi models, not just the B. So,
rename the port to something slightly more generic.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Detect the board revision early during boot, and print the decoded
model name.
Eventually, this information can be used for tasks such as:
- Allowing/preventing USB device mode; some models have a USB device on-
board so only host mode makes sense. Others connect the SoC directly
to the USB connector, so device-mode might make sense.
- The on-board USB hub/Ethernet requires different GPIOs to enable it,
although luckily the default appears to be fine so far.
- The compute module contains an on-board eMMC device, so we could store
the environment there. Other models use an SD card and so don't support
saving the environment (unless we store it in a file on the FAT boot
partition...)
Set $fdtfile based on this information. At present, the mainline Linux
kernel doesn't contain a separate DTB for most models, but I hope that
will change soon.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
This function can fail if the device tree runs out of space. Rather than
silently booting with an incomplete device tree, allow the failure to be
detected.
Unfortunately this involves changing a lot of places in the code. I have
not changed behvaiour to return an error where one is not currently
returned, to avoid unexpected breakage.
Eventually it would be nice to allow boards to register functions to be
called to update the device tree. This would avoid all the many functions
to do this. However it's not clear yet if this should be done using driver
model or with a linker list. This work is left for later.
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Anatolij Gustschin <agust@denx.de>
This commit introduces a Kconfig symbol for each ARM CPU:
CPU_ARM720T, CPU_ARM920T, CPU_ARM926EJS, CPU_ARM946ES, CPU_ARM1136,
CPU_ARM1176, CPU_V7, CPU_PXA, CPU_SA1100.
Also, it adds the CPU feature Kconfig symbol HAS_VBAR which is selected
for CPU_ARM1176 and CPU_V7.
For each target, the corresponding CPU is selected and the definition of
SYS_CPU in the corresponding Kconfig file is removed.
Also, it removes redundant "string" type in some Kconfig files.
Signed-off-by: Georges Savoundararadj <savoundg@gmail.com>
Acked-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
The built-in SMSC 95xx chip doesn't know its own MAC address. Instead,
we must query it from the VC firmware; it's probably encoded in fuses
on the BCM2835.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Convert the BCM2835 GPIO driver to use driver model, and switch over
Raspberry Pi to use this, since it is the only board.
Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Now the types of CONFIG_SYS_{ARCH, CPU, SOC, VENDOR, BOARD, CONFIG_NAME}
are specified in arch/Kconfig.
We can delete the ones in arch and board Kconfig files.
This commit can be easily reproduced by the following command:
find . -name Kconfig -a ! -path ./arch/Kconfig | xargs sed -i -e '
/config[[:space:]]SYS_\(ARCH\|CPU\|SOC\|\VENDOR\|BOARD\|CONFIG_NAME\)/ {
N
s/\n[[:space:]]*string//
}
'
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
We have switched to Kconfig and the boards.cfg file is going to
be removed. We have to retrieve the board status and maintainers
information from it.
The MAINTAINERS format as in Linux Kernel would be nice
because we can crib the scripts/get_maintainer.pl script.
After some discussion, we chose to put a MAINTAINERS file under each
board directory, not the top-level one because we want to collect
relevant information for a board into a single place.
TODO:
Modify get_maintainer.pl to scan multiple MAINTAINERS files.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Suggested-by: Tom Rini <trini@ti.com>
Acked-by: Simon Glass <sjg@chromium.org>
This commit adds:
- arch/${ARCH}/Kconfig
provide a menu to select target boards
- board/${VENDOR}/${BOARD}/Kconfig or board/${BOARD}/Kconfig
set CONFIG macros to the appropriate values for each board
- configs/${TARGET_BOARD}_defconfig
default setting of each board
(This commit was automatically generated by a conversion script
based on boards.cfg)
In Linux Kernel, defconfig files are located under
arch/${ARCH}/configs/ directory.
It works in Linux Kernel since ARCH is always given from the
command line for cross compile.
But in U-Boot, ARCH is not given from the command line.
Which means we cannot know ARCH until the board configuration is done.
That is why all the "*_defconfig" files should be gathered into a
single directory ./configs/.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
Send RPC commands to the VideoCore to turn on the SDHCI and USB modules.
For SDHCI this isn't needed in practice, since the firmware already
turned on the power in order to load U-Boot. However, it's best to be
explicit. For USB, this is necessary, since the module isn't powered
otherwise. This will allow the kernel USB driver to work.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Add a DT simple-framebuffer node to DT when booting the Linux kernel.
This will allow the kernel to inherit the framebuffer configuration from
U-Boot, and display a graphical boot console, and even run a full SW-
rendered X server.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Simon Glass <sjg@chromium.org>
Enable the SD controller driver for the Raspberry Pi. Enable a number
of useful MMC, partition, and filesystem-related commands. Set up the
environment to provide standard locations for loading a kernel, DTB,
etc. Provide a boot command that loads and executes boot.scr.uimg from
the SD card; this is written considering future extensibilty to USB
storage.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
The firmware running on the bcm2835 SoC's VideoCore CPU determines how
much of the system RAM is available for use by the ARM CPU. Previously,
U-Boot assumed that only 128MB was available, since this was the
smallest value configured by any public firmware. However, we can now
query the actual value at run-time from the firmware using the mbox
property protocol.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
The Raspberry Pi model B uses the BCM2835 SoC, has 256MB of RAM,
contains an SMSC 9512 USB LAN/Hub chip, and various IO connectors.
For more details, see http://www.raspberrypi.org/.
Various portions (cache enable, MACH_TYPE setup, RAM size limit, stack
relocation to top of RAM) extracted from work by:
Oleksandr Tymoshenko <gonzo@bluezbox.com>.
GPIO driver enablement by Vikram Narayanan <vikram186@gmail.com>.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Tom Rini <trini@ti.com>
