Doubt in interrupt sharing

Hi,

Does the interrupt number (ie: the first argument in request_irq api function of driver programming) maps to the pin number allocated for the interrupt in that processor? If so do one interrupt number maps to only one pin in the processor or one pin number can be mapped to multiple interrupt numbers or one interrupt number can be mapped to multiple pin numbers?

int request_irq( unsigned int irq,irq_handler_t handler,unsigned long irq_flags,const char * devname,void *dev_id);

Please reply!

Hi,

Look at:Interrupts and Interrupt Handling

This chapter looks at how interrupts are handled by the Linux kernel. Whilst the kernel has generic mechanisms and interfaces for handling interrupts, most of the interrupt handling details are architecture specific.

Linux uses a lot of different pieces of hardware to perform many different tasks. The video device drives the monitor, the IDE device drives the disks and so on. You could drive these devices synchronously, that is you could send a request for some operation (say writing a block of memory out to disk) and then wait for the operation to complete. That method, although it would work, is very inefficient and the operating system would spend a lot of time ``busy doing nothing'' as it waited for each operation to complete. A better, more efficient, way is to make the request and then do other, more useful work and later be interrupted by the device when it has finished the request. With this scheme, there may be many outstanding requests to the devices in the system all happening at the same time.

This article form LDP is older but still useful information to lead to understanding interrupts.

EDIT: Be sure to look at: http://www.tldp.org/LDP/tlk/dd/drivers.html
Hope this helps.
Have fun & enjoy!