PCI: dwc: Add a 'num_lanes' field to struct dw_pcie

Add a 'num_lanes' field to allow drivers to provide a the number of lanes
if not in DT or using a custom DT property. A driver can provide a
non-zero value which is used if the DT doesn't have a 'num-lanes'
property.

Link: https://lore.kernel.org/r/20200821035420.380495-24-robh@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/controller/dwc/pcie-designware.c

@@ -546,9 +546,7 @@ static u8 dw_pcie_iatu_unroll_enabled(struct dw_pcie *pci)
 
 void dw_pcie_setup(struct dw_pcie *pci)
 {
-	int ret;
 	u32 val;
-	u32 lanes;
 	struct device *dev = pci->dev;
 	struct device_node *np = dev->of_node;
 
@@ -562,16 +560,16 @@ void dw_pcie_setup(struct dw_pcie *pci)
 		"enabled" : "disabled");
 
 
-	ret = of_property_read_u32(np, "num-lanes", &lanes);
-	if (ret) {
-		dev_dbg(pci->dev, "property num-lanes isn't found\n");
+	of_property_read_u32(np, "num-lanes", &pci->num_lanes);
+	if (!pci->num_lanes) {
+		dev_dbg(pci->dev, "Using h/w default number of lanes\n");
 		return;
 	}
 
 	/* Set the number of lanes */
 	val = dw_pcie_readl_dbi(pci, PCIE_PORT_LINK_CONTROL);
 	val &= ~PORT_LINK_MODE_MASK;
-	switch (lanes) {
+	switch (pci->num_lanes) {
 	case 1:
 		val |= PORT_LINK_MODE_1_LANES;
 		break;
@@ -585,7 +583,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
 		val |= PORT_LINK_MODE_8_LANES;
 		break;
 	default:
-		dev_err(pci->dev, "num-lanes %u: invalid value\n", lanes);
+		dev_err(pci->dev, "num-lanes %u: invalid value\n", pci->num_lanes);
 		return;
 	}
 	dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, val);
@@ -593,7 +591,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
 	/* Set link width speed control register */
 	val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
 	val &= ~PORT_LOGIC_LINK_WIDTH_MASK;
-	switch (lanes) {
+	switch (pci->num_lanes) {
 	case 1:
 		val |= PORT_LOGIC_LINK_WIDTH_1_LANES;
 		break;

drivers/pci/controller/dwc/pcie-designware.h

@@ -246,6 +246,7 @@ struct dw_pcie {
 	struct dw_pcie_ep	ep;
 	const struct dw_pcie_ops *ops;
 	unsigned int		version;
+	int			num_lanes;
 };
 
 #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)