[PATCH 1/3] PCI: dwc: Skip allocating own MSI domain if using external MSI domain

[Simon Xue <xxm@rock-chips.com>]

From: Shawn Lin <shawn.lin@rock-chips.com>

On some platform, external MSI domain is using instead of the one
created by designware driver. For instance, if using GIC-V3-ITS
as a MSI domain, we only need set msi-map in the devicetree but
never need any bit in the designware driver to handle MSI stuff.
So skip allocating its own MSI domain for that case.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Simon Xue <xxm@rock-chips.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 10 +++++++++-
 drivers/pci/controller/dwc/pcie-designware.h      |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 8a84c005f32b..d9d93cab970a 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -235,6 +235,10 @@ int dw_pcie_allocate_domains(struct pcie_port *pp)
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	struct fwnode_handle *fwnode = of_node_to_fwnode(pci->dev->of_node);
 
+	/* Rely on the external MSI domain */
+	if (pp->msi_ext)
+		return 0;
+
 	pp->irq_domain = irq_domain_create_linear(fwnode, pp->num_vectors,
 					       &dw_pcie_msi_domain_ops, pp);
 	if (!pp->irq_domain) {
@@ -258,6 +262,9 @@ int dw_pcie_allocate_domains(struct pcie_port *pp)
 
 static void dw_pcie_free_msi(struct pcie_port *pp)
 {
+	if (pp->msi_ext)
+		return;
+
 	if (pp->msi_irq) {
 		irq_set_chained_handler(pp->msi_irq, NULL);
 		irq_set_handler_data(pp->msi_irq, NULL);
@@ -359,7 +366,8 @@ int dw_pcie_host_init(struct pcie_port *pp)
 	if (pci->link_gen < 1)
 		pci->link_gen = of_pci_get_max_link_speed(np);
 
-	if (pci_msi_enabled()) {
+	if (pci_msi_enabled() &&
+	    !pp->msi_ext) {
 		pp->has_msi_ctrl = !(pp->ops->msi_host_init ||
 				     of_property_read_bool(np, "msi-parent") ||
 				     of_property_read_bool(np, "msi-map"));
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 0207840756c4..cf3b0664302a 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -195,6 +195,7 @@ struct pcie_port {
 	u32			irq_mask[MAX_MSI_CTRLS];
 	struct pci_host_bridge  *bridge;
 	raw_spinlock_t		lock;
+	int			msi_ext;
 	DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
 };
 
-- 
2.25.1