2 files changed, 54 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 13f3d936472..5320364582c 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -465,3 +465,52 @@ void drm_pci_exit(struct drm_driver *driver, struct pci_driver *pdriver)
         DRM_INFO("Module unloaded\n");
 }
 EXPORT_SYMBOL(drm_pci_exit);
+
+int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *mask)
+{
+        struct pci_dev *root;
+        int pos;
+        u32 lnkcap, lnkcap2;
+
+        *mask = 0;
+        if (!dev->pdev)
+                return -EINVAL;
+
+        if (!pci_is_pcie(dev->pdev))
+                return -EINVAL;
+
+        root = dev->pdev->bus->self;
+
+        pos = pci_pcie_cap(root);
+        if (!pos)
+                return -EINVAL;
+
+        /* we've been informed via and serverworks don't make the cut */
+        if (root->vendor == PCI_VENDOR_ID_VIA ||
+            root->vendor == PCI_VENDOR_ID_SERVERWORKS)
+                return -EINVAL;
+
+        pci_read_config_dword(root, pos + PCI_EXP_LNKCAP, &lnkcap);
+        pci_read_config_dword(root, pos + PCI_EXP_LNKCAP2, &lnkcap2);
+
+        lnkcap &= PCI_EXP_LNKCAP_SLS;
+        lnkcap2 &= 0xfe;
+
+        if (lnkcap2) { /* PCIE GEN 3.0 */
+                if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_2_5GB)
+                        *mask |= DRM_PCIE_SPEED_25;
+                if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_5_0GB)
+                        *mask |= DRM_PCIE_SPEED_50;
+                if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_8_0GB)
+                        *mask |= DRM_PCIE_SPEED_80;
+        } else {
+                if (lnkcap & 1)
+                        *mask |= DRM_PCIE_SPEED_25;
+                if (lnkcap & 2)
+                        *mask |= DRM_PCIE_SPEED_50;
+        }
+
+        DRM_INFO("probing gen 2 caps for device %x:%x = %x/%x\n", root->vendor, root->device, lnkcap, lnkcap2);
+        return 0;
+}
+EXPORT_SYMBOL(drm_pcie_get_speed_cap_mask);
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 31ad880ca2e..e4e3be3b946 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1761,6 +1761,11 @@ extern int drm_get_pci_dev(struct pci_dev *pdev,
                            const struct pci_device_id *ent,
                            struct drm_driver *driver);
 
+#define DRM_PCIE_SPEED_25 1
+#define DRM_PCIE_SPEED_50 2
+#define DRM_PCIE_SPEED_80 4
+
+extern int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *speed_mask);
 
 /* platform section */
 extern int drm_platform_init(struct drm_driver *driver, struct platform_device *platform_device);