Device tree and IRQ for chip on PCI

I have a chip connected on the PCI bus on an MPC512x, but if I get the IRQ property from the PCI chip, it is not set up by Linux.
The IRQ line goes directly from the chip to the MPC512x uc, so I don't know if I should create a separate node just to get the interrupt, or I should expect the pci functions to assign it an interrupt based on the PCI bus.

The description for the PCI bus is like this:
       pci: pci@80008500 {
               interrupt-map-mask = <0xf800 0x0 0x0 0x7>;
               interrupt-map = <
                               // IDSEL 0x15 - Slot PCI
                                0xa800 0x0 0x0 0x1 &ipic 0x0 0x8
                                0xa800 0x0 0x0 0x2 &ipic 0x1 0x8
                                0xa800 0x0 0x0 0x3 &ipic 0x2 0x8
                                0xa800 0x0 0x0 0x4 &ipic 0x3 0x8

                               >;
               interrupt-parent = < &ipic >;
               interrupts = <17 0x8>;
               bus-range = <0 0>;
               ranges = <0x42000000 0x0 0xa0000000 0xa0000000 0x0 0x10000000
                         0x02000000 0x0 0xb0000000 0xb0000000 0x0 0x10000000
                         0x01000000 0x0 0x00000000 0x84000000 0x0 0x01000000>;
               clock-frequency = <66000000>;
               #interrupt-cells = <1>;
               #size-cells = <2>;
               #address-cells = <3>;
               reg = <0x80008500 0x100>;
               compatible = "fsl,mpc5121-pci";
               device_type = "pci";
       };


Thanks,
Matteo