PCI: designware: Keep viewport fixed for IO transaction if num_viewport > 2

Most of the platforms have 3 or more viewports.  For such platforms, We do
not need to share viewports between IO and CFG.  Assign viewport 2 to IO
transactions in such cases.
Tested-by: Dong Bo <dongbo4@huawei.com>
Signed-off-by: Pratyush Anand <pratyush.anand@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/pci/designware-pcie.txt

@@ -17,6 +17,8 @@ Required properties:
 - num-lanes: number of lanes to use
 
 Optional properties:
+- num-viewport: number of view ports configured in hardware.  If a platform
+  does not specify it, the driver assumes 2.
 - num-lanes: number of lanes to use (this property should be specified unless
   the link is brought already up in BIOS)
 - reset-gpio: gpio pin number of power good signal
@@ -44,4 +46,5 @@ Example configuration:
 		interrupts = <25>, <24>;
 		#interrupt-cells = <1>;
 		num-lanes = <1>;
+		num-viewport = <3>;
 	};

drivers/pci/host/pcie-designware.c

@@ -61,6 +61,7 @@
 #define PCIE_ATU_VIEWPORT		0x900
 #define PCIE_ATU_REGION_INBOUND		(0x1 << 31)
 #define PCIE_ATU_REGION_OUTBOUND	(0x0 << 31)
+#define PCIE_ATU_REGION_INDEX2		(0x2 << 0)
 #define PCIE_ATU_REGION_INDEX1		(0x1 << 0)
 #define PCIE_ATU_REGION_INDEX0		(0x0 << 0)
 #define PCIE_ATU_CR1			0x904
@@ -616,6 +617,10 @@ int dw_pcie_host_init(struct pcie_port *pp)
 	if (ret)
 		pp->lanes = 0;
 
+	ret = of_property_read_u32(np, "num-viewport", &pp->num_viewport);
+	if (ret)
+		pp->num_viewport = 2;
+
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
 		if (!pp->ops->msi_host_init) {
 			pp->irq_domain = irq_domain_add_linear(pp->dev->of_node,
@@ -707,6 +712,7 @@ static int dw_pcie_rd_other_conf(struct pcie_port *pp, struct pci_bus *bus,
 				  type, cpu_addr,
 				  busdev, cfg_size);
 	ret = dw_pcie_cfg_read(va_cfg_base + where, size, val);
+	if (pp->num_viewport <= 2)
 		dw_pcie_prog_outbound_atu(pp, PCIE_ATU_REGION_INDEX0,
 					  PCIE_ATU_TYPE_IO, pp->io_base,
 					  pp->io_bus_addr, pp->io_size);
@@ -744,6 +750,7 @@ static int dw_pcie_wr_other_conf(struct pcie_port *pp, struct pci_bus *bus,
 				  type, cpu_addr,
 				  busdev, cfg_size);
 	ret = dw_pcie_cfg_write(va_cfg_base + where, size, val);
+	if (pp->num_viewport <= 2)
 		dw_pcie_prog_outbound_atu(pp, PCIE_ATU_REGION_INDEX0,
 					  PCIE_ATU_TYPE_IO, pp->io_base,
 					  pp->io_bus_addr, pp->io_size);
@@ -882,10 +889,15 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
 	 * uses its own address translation component rather than ATU, so
 	 * we should not program the ATU here.
 	 */
-	if (!pp->ops->rd_other_conf)
+	if (!pp->ops->rd_other_conf) {
 		dw_pcie_prog_outbound_atu(pp, PCIE_ATU_REGION_INDEX1,
 					  PCIE_ATU_TYPE_MEM, pp->mem_base,
 					  pp->mem_bus_addr, pp->mem_size);
+		if (pp->num_viewport > 2)
+			dw_pcie_prog_outbound_atu(pp, PCIE_ATU_REGION_INDEX2,
+						  PCIE_ATU_TYPE_IO, pp->io_base,
+						  pp->io_bus_addr, pp->io_size);
+	}
 
 	dw_pcie_wr_own_conf(pp, PCI_BASE_ADDRESS_0, 4, 0);
 

drivers/pci/host/pcie-designware.h

@@ -44,6 +44,7 @@ struct pcie_port {
 	struct resource		*busn;
 	int			irq;
 	u32			lanes;
+	u32			num_viewport;
 	struct pcie_host_ops	*ops;
 	int			msi_irq;
 	struct irq_domain	*irq_domain;