[PATCH v4 10/10] PCI: qcom: Add Force GEN1 support

[Ansuel Smith <ansuelsmth@gmail.com>]

From: Sham Muthayyan <smuthayy@codeaurora.org>

Add Force GEN1 support needed in some ipq8064 board that needs to limit
some PCIe line to gen1 for some hardware limitation. This is set by the
max-link-speed binding and needed by some soc based on ipq8064. (for
example Netgear R7800 router)

Signed-off-by: Sham Muthayyan <smuthayy@codeaurora.org>
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index ab6f1bdd24c3..f6190c954e92 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -27,6 +27,7 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 #define PCIE20_PARF_SYS_CTRL			0x00
@@ -99,6 +100,8 @@
 #define PCIE20_v3_PARF_SLV_ADDR_SPACE_SIZE	0x358
 #define SLV_ADDR_SPACE_SZ			0x10000000
 
+#define PCIE20_LNK_CONTROL2_LINK_STATUS2	0xa0
+
 #define DEVICE_TYPE_RC				0x4
 
 #define QCOM_PCIE_2_1_0_MAX_SUPPLY	3
@@ -195,6 +198,7 @@ struct qcom_pcie {
 	struct phy *phy;
 	struct gpio_desc *reset;
 	const struct qcom_pcie_ops *ops;
+	int gen;
 };
 
 #define to_qcom_pcie(x)		dev_get_drvdata((x)->dev)
@@ -395,6 +399,11 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 	/* wait for clock acquisition */
 	usleep_range(1000, 1500);
 
+	if (pcie->gen == 1) {
+		val = readl(pci->dbi_base + PCIE20_LNK_CONTROL2_LINK_STATUS2);
+		val |= 1;
+		writel(val, pci->dbi_base + PCIE20_LNK_CONTROL2_LINK_STATUS2);
+	}
 
 	/* Set the Max TLP size to 2K, instead of using default of 4K */
 	writel(CFG_REMOTE_RD_REQ_BRIDGE_SIZE_2K,
@@ -1397,6 +1406,10 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 		goto err_pm_runtime_put;
 	}
 
+	pcie->gen = of_pci_get_max_link_speed(pdev->dev.of_node);
+	if (pcie->gen < 0)
+		pcie->gen = 2;
+
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "parf");
 	pcie->parf = devm_ioremap_resource(dev, res);
 	if (IS_ERR(pcie->parf)) {
-- 
2.25.1