irqchip/gic-v3-its: Add support for device tree msi-map and msi-mask

Some platform devices create child devices dynamically and require the
parent device's msi-map to map device IDs to actual sideband information.

A typical use case is using ITS as a PCIe Endpoint Controller(EPC)'s
doorbell function, where PCI hosts send TLP memory writes to the EP
controller. The EP controller converts these writes to AXI transactions
and appends platform-specific sideband information.

EPC's DTS will provide such information by msi-map and msi-mask. A
simplified dts as

pcie-ep@10000000 {
	...
	msi-map = <0 &its 0xc 8>;
                          ^^^ 0xc is implement defined sideband information,
			      which append to AXI write transaction.
	           ^ 0 is function index.

	msi-mask = <0x7>
}

Check msi-map if msi-parent missed to keep compatility with existing systems.

Signed-off-by: Frank Li <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

0 files changed, 0 insertions, 0 deletions