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| -rw-r--r-- | doc/README.hwconfig | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/doc/README.hwconfig b/doc/README.hwconfig new file mode 100644 index 0000000..cf54965 --- /dev/null +++ b/doc/README.hwconfig @@ -0,0 +1,50 @@ +To enable this feature just define CONFIG_HWCONFIG in your board +config file. + +This implements a simple hwconfig infrastructure: an +interface for software knobs to control hardware. + +This a is very simple implementation, i.e. it is implemented +via the `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 Das + U-Boot. But I haven't bothered yet. + +2. Since we don't implement a 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 + effect. So, for now it's advised to always reboot the + target after modifying the hwconfig variable. + +3. We support hwconfig options with arguments. For example, + + set hwconfig "dr_usb:mode=peripheral,phy_type=ulpi" + + This selects three hwconfig options: + 1. dr_usb - enable Dual-Role USB controller; + 2. dr_usb_mode:peripheral - USB in Function mode; + 3. dr_usb_phy_type:ulpi - USB should work with ULPI PHYs. + +The purpose of this simple implementation is to refine the +internal API and then we can continue improving the user +experience by adding more mature interfaces, like a hwconfig +command with bells and whistles. Or not adding, if we feel +that the current interface fits people's 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. |