| Lite5200B wakeup from low-power mode (CONFIG_LITE5200B_PM) |
| ---------------------------------------------------------- |
| |
| Low-power mode as described in Lite5200B User's Manual, means that |
| with support of MC68HLC908QT1 microcontroller (refered to as QT), |
| everything but the SDRAM can be powered down. This brings |
| maximum power saving, while one can still restore previous state |
| quickly. |
| |
| Quick overview where U-Boot comes into the picture: |
| - OS saves device states |
| - OS saves wakeup handler address to physical 0x0, puts SDRAM into |
| self-refresh and signals to QT, it should power down the board |
| - / board is sleeping here / |
| - someone presses SW4 (connected to QT) |
| - U-Boot checks PSC2_4 pin, if QT drives it down, then we woke up, |
| so get SDRAM out of self-refresh and transfer control to OS |
| wakeup handler |
| - OS restores device states |
| |
| This was tested on Linux with USB and Ethernet in use. Adding |
| support for other devices is an OS issue. |
