sh_eth: add generic wake-on-lan support via magic packet
Add generic functionality to support Wake-on-LAN using MagicPacket which are supported by at least a few versions of sh_eth. Only add functionality for WoL, no specific sh_eth versions are marked to support WoL yet. WoL is enabled in the suspend callback by setting MagicPacket detection and disabling all interrupts expect MagicPacket. In the resume path the driver needs to reset the hardware to rearm the WoL logic, this prevents the driver from simply restoring the registers and to take advantage of that sh_eth was not suspended to reduce resume time. To reset the hardware the driver closes and reopens the device just like it would do in a normal suspend/resume scenario without WoL enabled, but it both closes and opens the device in the resume callback since the device needs to be open for WoL to work. One quirk needed for WoL is that the module clock needs to be prevented from being switched off by Runtime PM. To keep the clock alive the suspend callback need to call clk_enable() directly to increase the usage count of the clock. Then when Runtime PM decreases the clock usage count it won't reach 0 and be switched off. Signed-off-by: NNiklas Söderlund <niklas.soderlund+renesas@ragnatech.se> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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