PCI: Add pcie_get_width_cap() to find max supported link width

Add pcie_get_width_cap() to find the max link width supported by a device.
Change max_link_width_show() to use pcie_get_width_cap().

Signed-off-by: Tal Gilboa <talgi@mellanox.com>
[bhelgaas: return width directly instead of error and *width, 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 c2ea05f..63d0952 100644 (file)
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -167,15 +167,9 @@ static DEVICE_ATTR_RO(max_link_speed);
 static ssize_t max_link_width_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
 {
-       struct pci_dev *pci_dev = to_pci_dev(dev);
-       u32 linkcap;
-       int err;
-
-       err = pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &linkcap);
-       if (err)
-               return -EINVAL;
+       struct pci_dev *pdev = to_pci_dev(dev);
 
-       return sprintf(buf, "%u\n", (linkcap & PCI_EXP_LNKCAP_MLW) >> 4);
+       return sprintf(buf, "%u\n", pcie_get_width_cap(pdev));
 }
 static DEVICE_ATTR_RO(max_link_width);
 

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b29d343..43075be 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5191,6 +5191,24 @@ enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev)
 }
 
 /**
+ * pcie_get_width_cap - query for the PCI device's link width capability
+ * @dev: PCI device to query
+ *
+ * Query the PCI device width capability.  Return the maximum link width
+ * supported by the device.
+ */
+enum pcie_link_width pcie_get_width_cap(struct pci_dev *dev)
+{
+       u32 lnkcap;
+
+       pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap);
+       if (lnkcap)
+               return (lnkcap & PCI_EXP_LNKCAP_MLW) >> 4;
+
+       return PCIE_LNK_WIDTH_UNKNOWN;
+}
+
+/**
  * pci_select_bars - Make BAR mask from the type of resource
  * @dev: the PCI device for which BAR mask is made
  * @flags: resource type mask to be selected

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 1186d8b..66738f1 100644 (file)
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -262,6 +262,7 @@ void pci_disable_bridge_window(struct pci_dev *dev);
         "Unknown speed")
 
 enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev);
+enum pcie_link_width pcie_get_width_cap(struct pci_dev *dev);
 
 /* Single Root I/O Virtualization */
 struct pci_sriov {