PCI: qcom: Support pci speed set for ipq806x

Some SoC based on ipq8064/5 needs to be limited to pci GEN1 speed due to
some hardware limitations. Add support for speed setting defined by the
max-link-speed binding. If not defined the max speed is set to GEN2 by
default.

Link: https://lore.kernel.org/r/20200615210608.21469-12-ansuelsmth@gmail.com
Signed-off-by: Sham Muthayyan <smuthayy@codeaurora.org>
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Stanimir Varbanov <svarbanov@mm-sol.com>

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 6f37ab9..17498e6 100644 (file)
--- 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)) {