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>

1 files changed, 2 insertions, 26 deletions

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 7dc5be5..c2ea05f 100644
--- 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);