PCI: Add pcie_get_speed_cap() to find max supported link speed

Add pcie_get_speed_cap() to find the max link speed supported by a device.
Change max_link_speed_show() to use pcie_get_speed_cap().

Signed-off-by: Tal Gilboa <talgi@mellanox.com>
[bhelgaas: return speed directly instead of error and *speed, don't export
outside drivers/pci]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 7dc5be545d18091c122b17977578173099816a36..c2ea05fbbf1d939bcda8d75e0179615ae25f4353 100644 (file)
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -158,33 +158,9 @@ static DEVICE_ATTR_RO(resource);
 static ssize_t max_link_speed_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
 {
-       struct pci_dev *pci_dev = to_pci_dev(dev);
-       u32 linkcap;
-       int err;
-       const char *speed;
-
-       err = pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &linkcap);
-       if (err)
-               return -EINVAL;
-
-       switch (linkcap & PCI_EXP_LNKCAP_SLS) {
-       case PCI_EXP_LNKCAP_SLS_16_0GB:
-               speed = "16 GT/s";
-               break;
-       case PCI_EXP_LNKCAP_SLS_8_0GB:
-               speed = "8 GT/s";
-               break;
-       case PCI_EXP_LNKCAP_SLS_5_0GB:
-               speed = "5 GT/s";
-               break;
-       case PCI_EXP_LNKCAP_SLS_2_5GB:
-               speed = "2.5 GT/s";
-               break;
-       default:
-               speed = "Unknown speed";
-       }
+       struct pci_dev *pdev = to_pci_dev(dev);
 
-       return sprintf(buf, "%s\n", speed);
+       return sprintf(buf, "%s\n", PCIE_SPEED2STR(pcie_get_speed_cap(pdev)));
 }
 static DEVICE_ATTR_RO(max_link_speed);
 

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index f6a4dd10d9b0da85a009a1cdd8b6498312573ac3..b29d3436ee9f1544ec00e4b8fd2f62a485669c94 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5146,6 +5146,50 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
 }
 EXPORT_SYMBOL(pcie_get_minimum_link);
 
+/**
+ * pcie_get_speed_cap - query for the PCI device's link speed capability
+ * @dev: PCI device to query
+ *
+ * Query the PCI device speed capability.  Return the maximum link speed
+ * supported by the device.
+ */
+enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev)
+{
+       u32 lnkcap2, lnkcap;
+
+       /*
+        * PCIe r4.0 sec 7.5.3.18 recommends using the Supported Link
+        * Speeds Vector in Link Capabilities 2 when supported, falling
+        * back to Max Link Speed in Link Capabilities otherwise.
+        */
+       pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2);
+       if (lnkcap2) { /* PCIe r3.0-compliant */
+               if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_16_0GB)
+                       return PCIE_SPEED_16_0GT;
+               else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_8_0GB)
+                       return PCIE_SPEED_8_0GT;
+               else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_5_0GB)
+                       return PCIE_SPEED_5_0GT;
+               else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_2_5GB)
+                       return PCIE_SPEED_2_5GT;
+               return PCI_SPEED_UNKNOWN;
+       }
+
+       pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap);
+       if (lnkcap) {
+               if (lnkcap & PCI_EXP_LNKCAP_SLS_16_0GB)
+                       return PCIE_SPEED_16_0GT;
+               else if (lnkcap & PCI_EXP_LNKCAP_SLS_8_0GB)
+                       return PCIE_SPEED_8_0GT;
+               else if (lnkcap & PCI_EXP_LNKCAP_SLS_5_0GB)
+                       return PCIE_SPEED_5_0GT;
+               else if (lnkcap & PCI_EXP_LNKCAP_SLS_2_5GB)
+                       return PCIE_SPEED_2_5GT;
+       }
+
+       return PCI_SPEED_UNKNOWN;
+}
+
 /**
  * pci_select_bars - Make BAR mask from the type of resource
  * @dev: the PCI device for which BAR mask is made

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fcd81911b1278486572a2845a2cdbe9829d1ad99..1186d8be60556ff212357fd20827a11825062e1c 100644 (file)
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -253,6 +253,16 @@ bool pci_bus_clip_resource(struct pci_dev *dev, int idx);
 void pci_reassigndev_resource_alignment(struct pci_dev *dev);
 void pci_disable_bridge_window(struct pci_dev *dev);
 
+/* PCIe link information */
+#define PCIE_SPEED2STR(speed) \
+       ((speed) == PCIE_SPEED_16_0GT ? "16 GT/s" : \
+        (speed) == PCIE_SPEED_8_0GT ? "8 GT/s" : \
+        (speed) == PCIE_SPEED_5_0GT ? "5 GT/s" : \
+        (speed) == PCIE_SPEED_2_5GT ? "2.5 GT/s" : \
+        "Unknown speed")
+
+enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev);
+
 /* Single Root I/O Virtualization */
 struct pci_sriov {
        int             pos;            /* Capability position */