[PATCH v6 11/12] PCI: qcom: Add Force GEN1 support

[Ansuel Smith]

From: Sham Muthayyan <smuth...@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 <smuth...@codeaurora.org>
Signed-off-by: Ansuel Smith <ansuels...@gmail.com>
Reviewed-by: Rob Herring <r...@kernel.org>
---
 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 259b627bf890..c40921589122 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 |= PCI_EXP_LNKSTA_CLS_2_5GB;
+               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