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List:       linux-arm-kernel
Subject:    GPIO IRQ
From:       Rafael_Rodríguez_Velilla <rrv66 () tid ! es>
Date:       2003-10-29 17:57:55
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    I have a FPGA that has a pair of buffers for sending data. I also 
have two outputs from the FPGA that go into a pair of GPIOs in my PXA255.
I would want to use those signals to announce when each buffer is 
available for writing from the PXA.
I have a task that polls the GPIOs to check when it can start writting, 
but I'd want to do it with IRQs.
   Is there some facility in the ARM kernel to put a task to sleep till 
certain GPIO goes up? (it should enable the IRQ only if some task is 
listening to it, wake up those tasks that are waiting for the IRQ and 
disable the IRQ till some other task is waiting for the IRQ to be awaken).

   If not, any hint on how to implement it?

   Should I do it from the driver? (The user-space application writes 
into a buffer of the driver, then the driver, as a result of the IRQ 
writes the buffer into the FPGA blocking any other write to the buffer 
of the driver from the user-space until it has finished writing it into 
the fpga).

   Thank you.


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