On creation of irq_desc and irq_data.

Hi, I am reading through mini2440 code. I am going through the init_irq (http://lxr.free-electrons.com/source/arch/arm/mach-s3c24xx/mach-mini2440.c#L...) code. In it (http://lxr.free-electrons.com/source/arch/arm/mach-s3c24xx/irq.c#L446) there is irq_domain_add_legacy(..) which references irq_desc and irq_data. I am not sure where these descriptors are created? In the irq_domain_add_legacy there is a lookup for irq_data from the number. Could someone tell where these descriptors are created? Thanks.