PCI: j721e: Add PCIe 4x lane selection support

Add support for setting of two-bit field that allows selection of 4x lane
PCIe which was previously limited to only 2x lanes.

Link: https://lore.kernel.org/linux-pci/20231128054402.2155183-5-s-vadapalli@ti.com
Signed-off-by: Matt Ranostay <mranostay@ti.com>
Signed-off-by: Achal Verma <a-verma1@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>

Author: mranostay

drivers/pci/controller/cadence/pci-j721e.c

@@ -42,7 +42,6 @@ enum link_status {
 };
 
 #define J721E_MODE_RC			BIT(7)
-#define LANE_COUNT_MASK			BIT(8)
 #define LANE_COUNT(n)			((n) << 8)
 
 #define GENERATION_SEL_MASK		GENMASK(1, 0)
@@ -52,6 +51,7 @@ struct j721e_pcie {
 	struct clk		*refclk;
 	u32			mode;
 	u32			num_lanes;
+	u32			max_lanes;
 	void __iomem		*user_cfg_base;
 	void __iomem		*intd_cfg_base;
 	u32			linkdown_irq_regfield;
@@ -205,11 +205,15 @@ static int j721e_pcie_set_lane_count(struct j721e_pcie *pcie,
 {
 	struct device *dev = pcie->cdns_pcie->dev;
 	u32 lanes = pcie->num_lanes;
+	u32 mask = BIT(8);
 	u32 val = 0;
 	int ret;
 
+	if (pcie->max_lanes == 4)
+		mask = GENMASK(9, 8);
+
 	val = LANE_COUNT(lanes - 1);
-	ret = regmap_update_bits(syscon, offset, LANE_COUNT_MASK, val);
+	ret = regmap_update_bits(syscon, offset, mask, val);
 	if (ret)
 		dev_err(dev, "failed to set link count\n");
 
@@ -441,7 +445,9 @@ static int j721e_pcie_probe(struct platform_device *pdev)
 		dev_warn(dev, "num-lanes property not provided or invalid, setting num-lanes to 1\n");
 		num_lanes = 1;
 	}
+
 	pcie->num_lanes = num_lanes;
+	pcie->max_lanes = data->max_lanes;
 
 	if (dma_set_mask_and_coherent(dev, DMA_BIT_MASK(48)))
 		return -EINVAL;