GPIOs

[Mitch Bradley]

I hope we can find some better way to distinguish between the different 
board flavors in early startup code.  The current technique, involving 
an EC command (whose response latency cannot be guaranteed) with the 
answer cached in CMOS RAM (which cannot be accessed quickly due to the 
power-glitch prevention circuitry) has caused me a great deal of grief 
to make it work reliably, and still takes too long.

I was looking forward to deleting that code when we deprecate the A-test 
boards.  Now it appears that the problem will come back in spades, since 
it's unlikely that we will be able to deprecate B2.

John Watlington wrote:
>
> I'm proposing a new GPIO map for XO-1.5 B3 and beyond.
>
> The changes are:
> - Moved the control signals for the internal and external SD ports
>  and the WLAN around to match new port assignment.
>
> - The power control for the internal SD port (MSD_PWROFF) is provided
>  through a separate GPIO2 (instead of the faulty default output, 
> SDIO2PWOFF).
>  As there is an external pullup on this signal, there is no need to
>  enable the (default off) internal pullup.    GPIO2 has been tested
>  by Via to remain powered and glitch-free in states S0/S3.
>
> - For B2 prototypes, I am proposing the use of GPIO2 as an ECO'd power
> control signal for the WLAN.
>
> - The DCONIRQ line has been moved (again).  On B2, the interrupt
>  input chosen is synchronized by the RTC clock, preventing reliable
>  detection of DCON interrupts (which are one video line in duration).
>  This time, it is connected to GPIO12, which is only powered in S0
>  but can generate SCI/SMI interrupts and is not "owned" by ACPI.
>
> - The EC/CPU interrupt will also be routed to another pin capable
>  of generating SCI/SMI interrupts that is not "owned" by ACPI at the
>  request of pgf.   It is routed to GPIO11, which is only powered in S0.
>  This pin will be diode isolated from the other interrupt input (powered
>  in S3.)   Unfortunately, I can't find another interrupt input not 
> owned by
>  ACPI that is powered in S3.
>
> - The HDD_LED# signal (yet to be supported) has been moved to GPO4
>   to free up GPIO11.
>
> Cheers,
> wad