[patch 24/33] PCI/MSI: Provide prepare_desc() MSI domain op

[Thomas Gleixner <tglx@linutronix.de>]

Dynamic MSI-X vector allocation post MSI-X allows to allocate vectors at a
given index or at any free index in the available table range. The latter
requires that the core code selects the index at descriptor allocation time.

This requires that the PCI/MSI-X specific setup of the MSI-X descriptor,
which is partially depending on the chosen index happens after allocation.

Implement the prepare_desc() op in the PCI/MSI-X specific msi_domain_ops
which is invoked before the core interrupt descriptor and the associated
Linux interrupt number is allocated. That callback is also provided for the
upcoming PCI/IMS implementations so the implementation specific interrupt
domain can do their domain specific initialization of the MSI descriptors.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 drivers/pci/msi/irqdomain.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -202,6 +202,14 @@ static void pci_unmask_msix(struct irq_d
 	pci_msix_unmask(irq_data_get_msi_desc(data));
 }
 
+static void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
+				  struct msi_desc *desc)
+{
+	/* Don't fiddle with preallocated MSI descriptors */
+	if (!desc->pci.mask_base)
+		msix_prepare_msi_desc(to_pci_dev(desc->dev), desc);
+}
+
 static struct msi_domain_template pci_msix_template = {
 	.chip = {
 		.name			= "PCI-MSIX",
@@ -212,6 +220,7 @@ static struct msi_domain_template pci_ms
 	},
 
 	.ops = {
+		.prepare_desc		= pci_msix_prepare_desc,
 		.set_desc		= pci_device_domain_set_desc,
 	},