12-22-2009 06:14 AM
I try to use GPIO & external interrupts. I do not see in the cat /proc/interrupts. I do see the interrupts in dts file for GPIO but not for external interrupt
Please can you let me know how to get them?
12-22-2009 07:10 AM
Make sure the driver is compiled into the kernel.
In the kernel menu config, set
Device Drivers -> GPIO Support -> Xilinx GPIO support
12-22-2009 07:11 AM
The GPIO driver does not support interrupts at this time so you wouldn't see them in proc/interrupts.
The device tree file would have them if you put them into the EDK system as it's a reflection of the EDK system (system.mhs).
12-22-2009 07:45 AM
Thanks. What about the external interrupt signal directly connected to the interrupt controller. How do I access/see on the linux.?
12-22-2009 07:47 AM
You would need to hook into the interrrupt system like done in drivers.
You might be able to do some kind of user mode driver as I think they can use interrupts. I don't know much about what kind of performance to expect there, but I would expect it to be slow.
12-22-2009 07:59 AM
Whether or not a device uses interrupts is essentially opaque to the user application that uses the driver. For example,
a read on the device could either return the most recently read value which was read by the driver at the last interrupt, or, it could just go and read from the device on the spot. A select could poll in user space for a change in value, or poll in the kernel for a change in value, or put the process to sleep until the next device interrupt. The ways to implement the driver are very numerous (off the top of my head, I don't know what choices this particular driver did make. The application could be written the same regardless of whether the driver uses interrupts or not.
To re-architect the driver to use interrupts rather than polling won't be a 10 minue job, so I'd really only seriously consider it if you are planning on using GPIO as some sort of input data bus and have some throughput needs to achieve.
You can read up on some of this drivers usage details here:http://xilinx.wikidot.com/osl-gpio-driver
12-22-2009 08:06 AM
Thanks for your responses. This is actually the continuation of the touch screen issue. I need to use interrupt for pen_irq. I can use it thro GPIO or directly connect to the interrupt contoller.
I have been using stand alone system for long time. Now, I am switching all my systems to linux based. I have many devices(pcores) which use interrupt.