There are several users of the hwconfig APIs (8xxx DDR) before we have
the environment properly setup. This causes issues because of the
numerous ways the environment might be accessed because of the
non-volatile memory it might be stored in. Additionally the access
might be so early that memory isn't even properly setup for us.
Towards resolving these issues we provide versions of all the hwconfig
APIs that can be passed in a buffer to parse and leave it to the caller
to determine how to allocate and populate the buffer.
We use the _f naming convention for these new APIs even though they are
perfectly useable after relocation and the environment being ready.
We also now warn if the non-f APIs are called before the environment is
ready to allow users to address the issues.
Finally, we convert the 8xxx DDR code to utilize the new APIs to
hopefully address the issue once and for all. We have the 8xxx DDR code
create a buffer on the stack and populate it via getenv_f().
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Wolfgang Denk <wd@denx.de>
This patch implements simple hwconfig infrastructure: an
interface for software knobs to control a hardware.
This is very simple implementation, i.e. it is implemented
via `hwconfig' environment variable. Later we could write
some "hwconfig <enable|disable|list>" commands, ncurses
interface for Award BIOS-like interface, and frame-buffer
interface for AMI GUI[1] BIOS-like interface with mouse
support[2].
Current implementation details/limitations:
1. Doesn't support options dependencies and mutual exclusion.
We can implement this by integrating apt-get[3] into the
u-boot. But I didn't bother yet.
2. Since we don't implement hwconfig command, i.e. we're working
with the environement directly, there is no way to tell that
toggling a particular option will need a reboot to take
an effect. So, for now it's advised to always reboot the
target after modifying hwconfig variable.
3. We support hwconfig options with arguments. For example,
set hwconfig dr_usb:mode=peripheral,phy_type=ulpi
That means:
- dr_usb - enable Dual-Role USB controller;
- dr_usb:mode=peripheral - USB in Function mode;
- dr_usb:phy_type=ulpi - USB should work with ULPI PHYs;
The purpose of this simple implementation is to define some
internal API and then we can continue improving user experience
by adding more mature interface, like hwconfig command with
bells and whistles. Or not adding, if we feel that current
interface fits its needs.
[1] http://en.wikipedia.org/wiki/American_Megatrends
[2] Regarding ncurses and GUI with mouse support -- I'm just
kidding.
[3] The comment regarding apt-get is also a joke, meaning that
dependency tracking could be non-trivial. For example, for
enabling HW feature X we may need to disable Y, and turn Z
into reduced mode (like RMII-only interface for ethernet,
no MII).
It's quite trivial to implement simple cases though.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Kim Phillips <kim.phillips@freescale.com>
