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- 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.
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