[PATCH v2 10/10] PCIe: qcom: add Force GEN1 support

[Ansuel Smith <ansuelsmth@gmail.com>]

From: Sham Muthayyan <smuthayy@codeaurora.org>

Add Force GEN1 support needed in some ipq806x board
that needs to limit some pcie line to gen1 for some
hardware limitation.
This is set by the max-link-speed dts entry and needed
by some soc based on ipq806x. (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 8047ac7dc8c7..2212e9498b91 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
@@ -199,6 +202,7 @@ struct qcom_pcie {
 	struct phy *phy;
 	struct gpio_desc *reset;
 	const struct qcom_pcie_ops *ops;
+	bool force_gen1;
 };
 
 #define to_qcom_pcie(x)		dev_get_drvdata((x)->dev)
@@ -441,6 +445,11 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 
 	/* wait for clock acquisition */
 	usleep_range(1000, 1500);
+	if (pcie->force_gen1) {
+		writel_relaxed((readl_relaxed(
+		  pcie->pci->dbi_base + PCIE20_LNK_CONTROL2_LINK_STATUS2) | 1),
+		  pcie->pci->dbi_base + PCIE20_LNK_CONTROL2_LINK_STATUS2);
+	}
 
 
 	/* Set the Max TLP size to 2K, instead of using default of 4K */
@@ -1440,6 +1449,10 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 		goto err_pm_runtime_put;
 	}
 
+	ret = of_pci_get_max_link_speed(pdev->dev.of_node);
+	if (ret == 1)
+		pcie->force_gen1 = true;
+
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "parf");
 	pcie->parf = devm_ioremap_resource(dev, res);
 	if (IS_ERR(pcie->parf)) {
-- 
2.25.1