On Tue, 30 Apr 2002 Russell King - ARM Linux wrote :
>On Tue, Apr 30, 2002 at 02:27:18PM -0000, ashok mp wrote:
> > So does that mean that i cant route all the pcmcia
> > signals to one GPIO pin.
>
>Well, there are around 16 possible states of
>BVD1/BVD2/CD/RDYINT
>each of them mean something completely different. You can't
>encode
>these 16 states onto one GPIO signal.
Cant i have a register implemented in CPLD, in which each
bit will correspomd to BVD1/BVD2/CD/RDYINT and have trigger to a
single GPIO pin, when ever any signail state
changes.
>
> > For the code , the IRQ number for the ready signal is being
> > assigned to the irq feild of the socket_cap_t structure and
>no
> > interrupt is being register for this signal.
>
>Correct - the IRQ is claimed by the device driver itself, not
>the
>PCMCIA code.
>
> > One for the ready signal
> > and one which i can register for an interrupt.(which will
> > be a multiplexed out put of card detect , bvd,...)
>
>If you're thinking about multiplexing BVD1/BVD2, presumably you
>have some spare GPIOs for use as outputs to drive this
>multiplexing.
>If that's the case, why bother with the multiplexing at all.
>
>It's normal for each of the card detect and BVD lines to be
>routed
>to a GPIO input with IRQ edge detection turned on. If you
>start
>multiplexing stuff, you'll cause transitions on the GPIO, which
>will cause IRQs. This doesn't sound like a very sensible
>approach
>to me.
>
>Is there some reason why you can't use 2 GPIO lines and ignore
>the
>BVD lines, or use 4 GPIO lines and be done with it?
>
I dont have spare GPIO pins, thats the reason i want this stuff to
be done with minimal GPIO pins.
Sorry for using the wrong term multiplexing, i ment all
the status bits (BVD/RD etc) will be available in one register and
any state change will set a single GPIO pin( as mentoned
earlier).
For the code , it seems that i need atleast 2 GPIO pin,
One for the irq_info_req() for device driver.
And one i will register for interrupt.( This is the 1 GPIO pin iam
talking about).
Does this sound sane?
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