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Domen Puncer3747a3f2007-04-18 12:11:05 +02001Lite5200B wakeup from low-power mode (CONFIG_LITE5200B_PM)
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3
4Low-power mode as described in Lite5200B User's Manual, means that
5with support of MC68HLC908QT1 microcontroller (refered to as QT),
6everything but the SDRAM can be powered down. This brings
7maximum power saving, while one can still restore previous state
8quickly.
9
10Quick overview where U-Boot comes into the picture:
11- OS saves device states
12- OS saves wakeup handler address to physical 0x0, puts SDRAM into
13 self-refresh and signals to QT, it should power down the board
14- / board is sleeping here /
15- someone presses SW4 (connected to QT)
16- U-Boot checks PSC2_4 pin, if QT drives it down, then we woke up,
17 so get SDRAM out of self-refresh and transfer control to OS
18 wakeup handler
19- OS restores device states
20
21This was tested on Linux with USB and Ethernet in use. Adding
22support for other devices is an OS issue.