how the interrupt handler(ISR) knows the source of interrupt ?

["Mansha Linux" <mansha.linux@xxxxxxxxx>]

hi all,

 

When the external hardware device  raise the interrupt the corresponding ISR will be executed.

but how this ISR will come to know about the source of interrupt. i mean the ISR will identify with respect to device id ..but when this device id is passed to the ISR  and as well as IRQ number?

--
regards,
Mansha