[PATCH 11/18] PCI: Export pcie_get_width() using the code from sysfs PCI link width show function

[Dave Jiang <dave.jiang@xxxxxxxxx>]

Move the logic in current_link_width_show() to a common function and export
that functiuon as pcie_get_width() to allow other drivers to to retrieve
the current negotiated link width.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
 drivers/pci/pci-sysfs.c |    9 +--------
 drivers/pci/pci.c       |   20 ++++++++++++++++++++
 include/linux/pci.h     |    1 +
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 0217bb5ca8fa..139096c39380 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -215,15 +215,8 @@ static ssize_t current_link_width_show(struct device *dev,
 				       struct device_attribute *attr, char *buf)
 {
 	struct pci_dev *pci_dev = to_pci_dev(dev);
-	u16 linkstat;
-	int err;
 
-	err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
-	if (err)
-		return -EINVAL;
-
-	return sysfs_emit(buf, "%u\n",
-		(linkstat & PCI_EXP_LNKSTA_NLW) >> PCI_EXP_LNKSTA_NLW_SHIFT);
+	return sysfs_emit(buf, "%u\n", pcie_get_width(pci_dev));
 }
 static DEVICE_ATTR_RO(current_link_width);
 
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d0131b5623b1..0858fa2f1c2d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6235,6 +6235,26 @@ enum pci_bus_speed pcie_get_speed(struct pci_dev *dev)
 }
 EXPORT_SYMBOL(pcie_get_speed);
 
+/**
+ * pcie_get_width - query for the PCI device's current link width
+ * @dev: PCI device to query
+ *
+ * Query the PCI device current negoiated width.
+ */
+
+enum pcie_link_width pcie_get_width(struct pci_dev *dev)
+{
+	u16 linkstat;
+	int err;
+
+	err = pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &linkstat);
+	if (err)
+		return PCIE_LNK_WIDTH_UNKNOWN;
+
+	return FIELD_GET(PCI_EXP_LNKSTA_NLW, linkstat);
+}
+EXPORT_SYMBOL(pcie_get_width);
+
 /**
  * pcie_bandwidth_capable - calculate a PCI device's link bandwidth capability
  * @dev: PCI device
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 6a065986ff8f..21eca09a98e2 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -305,6 +305,7 @@ enum pci_bus_speed {
 
 enum pci_bus_speed pcie_get_speed(struct pci_dev *dev);
 enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev);
+enum pcie_link_width pcie_get_width(struct pci_dev *dev);
 enum pcie_link_width pcie_get_width_cap(struct pci_dev *dev);
 
 struct pci_vpd {