powerpc/pseries/pci: Add MSI domains

Two IRQ domains are added on top of default machine IRQ domain.

First, the top level "pSeries-PCI-MSI" domain deals with the MSI
specificities. In this domain, the HW IRQ numbers are generated by the
PCI MSI layer, they compose a unique ID for an MSI source with the PCI
device identifier and the MSI vector number.

These numbers can be quite large on a pSeries machine running under
the IBM Hypervisor and /sys/kernel/irq/ and /proc/interrupts will
require small fixes to show them correctly.

Second domain is the in-the-middle "pSeries-MSI" domain which acts as
a proxy between the PCI MSI subsystem and the machine IRQ subsystem.
It usually allocate the MSI vector numbers but, on pSeries machines,
this is done by the RTAS FW and RTAS returns IRQ numbers in the IRQ
number space of the machine. This is why the in-the-middle "pSeries-MSI"
domain has the same HW IRQ numbers as its parent domain.

Only the XIVE (P9/P10) parent domain is supported for now. We still
need to add support for IRQ domain hierarchy under XICS.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210701132750.1475580-6-clg@kaod.org

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index 1f051a786fb3..d9280262588b 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h
@@ -85,6 +85,7 @@ struct pci_host_bridge;
 int pseries_root_bridge_prepare(struct pci_host_bridge *bridge);
 
 extern struct pci_controller_ops pseries_pci_controller_ops;
+int pseries_msi_allocate_domains(struct pci_controller *phb);
 
 unsigned long pseries_memory_block_size(void);