Merge branch 'pci/pcie-rmw'

- Add locking for read/modify/write PCIe Capability Register accessors for
  Link Control and Root Control (Ilpo Järvinen)

- Use PCIe RMW accessors for Link Control updates in PCI core, pciehp,
  amdgpu, radeon, mlx5, ath10k, ath11k, ath12k (Ilpo Järvinen)

- Convert PCIBIOS error values in mlx5 to generic errnos (Ilpo Järvinen)

- Simplify pcie_capability_clear_and_set_word() control flow (Bjorn
  Helgaas)

* pci/pcie-rmw:
  PCI: Simplify pcie_capability_clear_and_set_word() control flow
  net/mlx5: Convert PCI error values to generic errnos
  PCI: Document the Capability accessor RMW improvements
  wifi: ath10k: Use RMW accessors for changing LNKCTL
  wifi: ath12k: Use RMW accessors for changing LNKCTL
  wifi: ath11k: Use RMW accessors for changing LNKCTL
  net/mlx5: Use RMW accessors for changing LNKCTL
  drm/radeon: Use RMW accessors for changing LNKCTL
  drm/amdgpu: Use RMW accessors for changing LNKCTL
  PCI/ASPM: Use RMW accessors for changing LNKCTL
  PCI: pciehp: Use RMW accessors for changing LNKCTL
  PCI: Make link retraining use RMW accessors for changing LNKCTL
  PCI: Add locking to RMW PCI Express Capability Register accessors

15 files changed, 151 insertions, 183 deletions

diff --git a/Documentation/PCI/pciebus-howto.rst b/Documentation/PCI/pciebus-howto.rst
index f882ff62c51f..a0027e8fb0d0 100644
--- a/Documentation/PCI/pciebus-howto.rst
+++ b/Documentation/PCI/pciebus-howto.rst
@@ -213,8 +213,12 @@ PCI Config Registers
 --------------------
 
 Each service driver runs its PCI config operations on its own
-capability structure except the PCI Express capability structure, in
-which Root Control register and Device Control register are shared
-between PME and AER. This patch assumes that all service drivers
-will be well behaved and not overwrite other service driver's
-configuration settings.
+capability structure except the PCI Express capability structure,
+that is shared between many drivers including the service drivers.
+RMW Capability accessors (pcie_capability_clear_and_set_word(),
+pcie_capability_set_word(), and pcie_capability_clear_word()) protect
+a selected set of PCI Express Capability Registers (Link Control
+Register and Root Control Register). Any change to those registers
+should be performed using RMW accessors to avoid problems due to
+concurrent updates. For the up-to-date list of protected registers,
+see pcie_capability_clear_and_set_word().
diff --git a/drivers/gpu/drm/amd/amdgpu/cik.c b/drivers/gpu/drm/amd/amdgpu/cik.c
index 5641cf05d856..e63abdf52b6c 100644
--- a/drivers/gpu/drm/amd/amdgpu/cik.c
+++ b/drivers/gpu/drm/amd/amdgpu/cik.c
@@ -1574,17 +1574,8 @@ static void cik_pcie_gen3_enable(struct amdgpu_device *adev)
 			u16 bridge_cfg2, gpu_cfg2;
 			u32 max_lw, current_lw, tmp;
 
-			pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-						  &bridge_cfg);
-			pcie_capability_read_word(adev->pdev, PCI_EXP_LNKCTL,
-						  &gpu_cfg);
-
-			tmp16 = bridge_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(root, PCI_EXP_LNKCTL, tmp16);
-
-			tmp16 = gpu_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(adev->pdev, PCI_EXP_LNKCTL,
-						   tmp16);
+			pcie_capability_set_word(root, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
+			pcie_capability_set_word(adev->pdev, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
 
 			tmp = RREG32_PCIE(ixPCIE_LC_STATUS1);
 			max_lw = (tmp & PCIE_LC_STATUS1__LC_DETECTED_LINK_WIDTH_MASK) >>
@@ -1637,21 +1628,14 @@ static void cik_pcie_gen3_enable(struct amdgpu_device *adev)
 				msleep(100);
 
 				/* linkctl */
-				pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (bridge_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(root, PCI_EXP_LNKCTL,
-							   tmp16);
-
-				pcie_capability_read_word(adev->pdev,
-							  PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (gpu_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(adev->pdev,
-							   PCI_EXP_LNKCTL,
-							   tmp16);
+				pcie_capability_clear_and_set_word(root, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   bridge_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
+				pcie_capability_clear_and_set_word(adev->pdev, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   gpu_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
 
 				/* linkctl2 */
 				pcie_capability_read_word(root, PCI_EXP_LNKCTL2,
diff --git a/drivers/gpu/drm/amd/amdgpu/si.c b/drivers/gpu/drm/amd/amdgpu/si.c
index f64b87b11b1b..4b81f29e5fd5 100644
--- a/drivers/gpu/drm/amd/amdgpu/si.c
+++ b/drivers/gpu/drm/amd/amdgpu/si.c
@@ -2276,17 +2276,8 @@ static void si_pcie_gen3_enable(struct amdgpu_device *adev)
 			u16 bridge_cfg2, gpu_cfg2;
 			u32 max_lw, current_lw, tmp;
 
-			pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-						  &bridge_cfg);
-			pcie_capability_read_word(adev->pdev, PCI_EXP_LNKCTL,
-						  &gpu_cfg);
-
-			tmp16 = bridge_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(root, PCI_EXP_LNKCTL, tmp16);
-
-			tmp16 = gpu_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(adev->pdev, PCI_EXP_LNKCTL,
-						   tmp16);
+			pcie_capability_set_word(root, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
+			pcie_capability_set_word(adev->pdev, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
 
 			tmp = RREG32_PCIE(PCIE_LC_STATUS1);
 			max_lw = (tmp & LC_DETECTED_LINK_WIDTH_MASK) >> LC_DETECTED_LINK_WIDTH_SHIFT;
@@ -2331,21 +2322,14 @@ static void si_pcie_gen3_enable(struct amdgpu_device *adev)
 
 				mdelay(100);
 
-				pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (bridge_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(root, PCI_EXP_LNKCTL,
-							   tmp16);
-
-				pcie_capability_read_word(adev->pdev,
-							  PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (gpu_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(adev->pdev,
-							   PCI_EXP_LNKCTL,
-							   tmp16);
+				pcie_capability_clear_and_set_word(root, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   bridge_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
+				pcie_capability_clear_and_set_word(adev->pdev, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   gpu_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
 
 				pcie_capability_read_word(root, PCI_EXP_LNKCTL2,
 							  &tmp16);
diff --git a/drivers/gpu/drm/radeon/cik.c b/drivers/gpu/drm/radeon/cik.c
index 5819737c21c6..a6f3c811ceb8 100644
--- a/drivers/gpu/drm/radeon/cik.c
+++ b/drivers/gpu/drm/radeon/cik.c
@@ -9534,17 +9534,8 @@ static void cik_pcie_gen3_enable(struct radeon_device *rdev)
 			u16 bridge_cfg2, gpu_cfg2;
 			u32 max_lw, current_lw, tmp;
 
-			pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-						  &bridge_cfg);
-			pcie_capability_read_word(rdev->pdev, PCI_EXP_LNKCTL,
-						  &gpu_cfg);
-
-			tmp16 = bridge_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(root, PCI_EXP_LNKCTL, tmp16);
-
-			tmp16 = gpu_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(rdev->pdev, PCI_EXP_LNKCTL,
-						   tmp16);
+			pcie_capability_set_word(root, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
+			pcie_capability_set_word(rdev->pdev, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
 
 			tmp = RREG32_PCIE_PORT(PCIE_LC_STATUS1);
 			max_lw = (tmp & LC_DETECTED_LINK_WIDTH_MASK) >> LC_DETECTED_LINK_WIDTH_SHIFT;
@@ -9591,21 +9582,14 @@ static void cik_pcie_gen3_enable(struct radeon_device *rdev)
 				msleep(100);
 
 				/* linkctl */
-				pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (bridge_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(root, PCI_EXP_LNKCTL,
-							   tmp16);
-
-				pcie_capability_read_word(rdev->pdev,
-							  PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (gpu_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(rdev->pdev,
-							   PCI_EXP_LNKCTL,
-							   tmp16);
+				pcie_capability_clear_and_set_word(root, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   bridge_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
+				pcie_capability_clear_and_set_word(rdev->pdev, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   gpu_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
 
 				/* linkctl2 */
 				pcie_capability_read_word(root, PCI_EXP_LNKCTL2,
diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index 8d5e4b25609d..a91012447b56 100644
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -7131,17 +7131,8 @@ static void si_pcie_gen3_enable(struct radeon_device *rdev)
 			u16 bridge_cfg2, gpu_cfg2;
 			u32 max_lw, current_lw, tmp;
 
-			pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-						  &bridge_cfg);
-			pcie_capability_read_word(rdev->pdev, PCI_EXP_LNKCTL,
-						  &gpu_cfg);
-
-			tmp16 = bridge_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(root, PCI_EXP_LNKCTL, tmp16);
-
-			tmp16 = gpu_cfg | PCI_EXP_LNKCTL_HAWD;
-			pcie_capability_write_word(rdev->pdev, PCI_EXP_LNKCTL,
-						   tmp16);
+			pcie_capability_set_word(root, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
+			pcie_capability_set_word(rdev->pdev, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_HAWD);
 
 			tmp = RREG32_PCIE(PCIE_LC_STATUS1);
 			max_lw = (tmp & LC_DETECTED_LINK_WIDTH_MASK) >> LC_DETECTED_LINK_WIDTH_SHIFT;
@@ -7188,22 +7179,14 @@ static void si_pcie_gen3_enable(struct radeon_device *rdev)
 				msleep(100);
 
 				/* linkctl */
-				pcie_capability_read_word(root, PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (bridge_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(root,
-							   PCI_EXP_LNKCTL,
-							   tmp16);
-
-				pcie_capability_read_word(rdev->pdev,
-							  PCI_EXP_LNKCTL,
-							  &tmp16);
-				tmp16 &= ~PCI_EXP_LNKCTL_HAWD;
-				tmp16 |= (gpu_cfg & PCI_EXP_LNKCTL_HAWD);
-				pcie_capability_write_word(rdev->pdev,
-							   PCI_EXP_LNKCTL,
-							   tmp16);
+				pcie_capability_clear_and_set_word(root, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   bridge_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
+				pcie_capability_clear_and_set_word(rdev->pdev, PCI_EXP_LNKCTL,
+								   PCI_EXP_LNKCTL_HAWD,
+								   gpu_cfg &
+								   PCI_EXP_LNKCTL_HAWD);
 
 				/* linkctl2 */
 				pcie_capability_read_word(root, PCI_EXP_LNKCTL2,
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c b/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
index 4804990b7f22..85a2dfbb5c46 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
@@ -311,7 +311,7 @@ static int mlx5_check_dev_ids(struct mlx5_core_dev *dev, u16 dev_id)
 	list_for_each_entry(sdev, &bridge_bus->devices, bus_list) {
 		err = pci_read_config_word(sdev, PCI_DEVICE_ID, &sdev_id);
 		if (err)
-			return err;
+			return pcibios_err_to_errno(err);
 		if (sdev_id != dev_id) {
 			mlx5_core_warn(dev, "unrecognized dev_id (0x%x)\n", sdev_id);
 			return -EPERM;
@@ -371,7 +371,7 @@ static int mlx5_pci_link_toggle(struct mlx5_core_dev *dev)
 
 	err = pci_read_config_word(dev->pdev, PCI_DEVICE_ID, &dev_id);
 	if (err)
-		return err;
+		return pcibios_err_to_errno(err);
 	err = mlx5_check_dev_ids(dev, dev_id);
 	if (err)
 		return err;
@@ -384,18 +384,13 @@ static int mlx5_pci_link_toggle(struct mlx5_core_dev *dev)
 		pci_cfg_access_lock(sdev);
 	}
 	/* PCI link toggle */
-	err = pci_read_config_word(bridge, cap + PCI_EXP_LNKCTL, &reg16);
-	if (err)
-		return err;
-	reg16 |= PCI_EXP_LNKCTL_LD;
-	err = pci_write_config_word(bridge, cap + PCI_EXP_LNKCTL, reg16);
+	err = pcie_capability_set_word(bridge, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_LD);
 	if (err)
-		return err;
+		return pcibios_err_to_errno(err);
 	msleep(500);
-	reg16 &= ~PCI_EXP_LNKCTL_LD;
-	err = pci_write_config_word(bridge, cap + PCI_EXP_LNKCTL, reg16);
+	err = pcie_capability_clear_word(bridge, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_LD);
 	if (err)
-		return err;
+		return pcibios_err_to_errno(err);
 
 	/* Check link */
 	if (!bridge->link_active_reporting) {
@@ -408,7 +403,7 @@ static int mlx5_pci_link_toggle(struct mlx5_core_dev *dev)
 	do {
 		err = pci_read_config_word(bridge, cap + PCI_EXP_LNKSTA, &reg16);
 		if (err)
-			return err;
+			return pcibios_err_to_errno(err);
 		if (reg16 & PCI_EXP_LNKSTA_DLLLA)
 			break;
 		msleep(20);
@@ -426,7 +421,7 @@ static int mlx5_pci_link_toggle(struct mlx5_core_dev *dev)
 	do {
 		err = pci_read_config_word(dev->pdev, PCI_DEVICE_ID, &reg16);
 		if (err)
-			return err;
+			return pcibios_err_to_errno(err);
 		if (reg16 == dev_id)
 			break;
 		msleep(20);
diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c
index a7f44f6335fb..9275a672f90c 100644
--- a/drivers/net/wireless/ath/ath10k/pci.c
+++ b/drivers/net/wireless/ath/ath10k/pci.c
@@ -1963,8 +1963,9 @@ static int ath10k_pci_hif_start(struct ath10k *ar)
 	ath10k_pci_irq_enable(ar);
 	ath10k_pci_rx_post(ar);
 
-	pcie_capability_write_word(ar_pci->pdev, PCI_EXP_LNKCTL,
-				   ar_pci->link_ctl);
+	pcie_capability_clear_and_set_word(ar_pci->pdev, PCI_EXP_LNKCTL,
+					   PCI_EXP_LNKCTL_ASPMC,
+					   ar_pci->link_ctl & PCI_EXP_LNKCTL_ASPMC);
 
 	return 0;
 }
@@ -2821,8 +2822,8 @@ static int ath10k_pci_hif_power_up(struct ath10k *ar,
 
 	pcie_capability_read_word(ar_pci->pdev, PCI_EXP_LNKCTL,
 				  &ar_pci->link_ctl);
-	pcie_capability_write_word(ar_pci->pdev, PCI_EXP_LNKCTL,
-				   ar_pci->link_ctl & ~PCI_EXP_LNKCTL_ASPMC);
+	pcie_capability_clear_word(ar_pci->pdev, PCI_EXP_LNKCTL,
+				   PCI_EXP_LNKCTL_ASPMC);
 
 	/*
 	 * Bring the target up cleanly.
diff --git a/drivers/net/wireless/ath/ath11k/pci.c b/drivers/net/wireless/ath/ath11k/pci.c
index 79e2cbe82638..ec40adc1cb23 100644
--- a/drivers/net/wireless/ath/ath11k/pci.c
+++ b/drivers/net/wireless/ath/ath11k/pci.c
@@ -581,8 +581,8 @@ static void ath11k_pci_aspm_disable(struct ath11k_pci *ab_pci)
 		   u16_get_bits(ab_pci->link_ctl, PCI_EXP_LNKCTL_ASPM_L1));
 
 	/* disable L0s and L1 */
-	pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-				   ab_pci->link_ctl & ~PCI_EXP_LNKCTL_ASPMC);
+	pcie_capability_clear_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+				   PCI_EXP_LNKCTL_ASPMC);
 
 	set_bit(ATH11K_PCI_ASPM_RESTORE, &ab_pci->flags);
 }
@@ -590,8 +590,10 @@ static void ath11k_pci_aspm_disable(struct ath11k_pci *ab_pci)
 static void ath11k_pci_aspm_restore(struct ath11k_pci *ab_pci)
 {
 	if (test_and_clear_bit(ATH11K_PCI_ASPM_RESTORE, &ab_pci->flags))
-		pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-					   ab_pci->link_ctl);
+		pcie_capability_clear_and_set_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_ASPMC,
+						   ab_pci->link_ctl &
+						   PCI_EXP_LNKCTL_ASPMC);
 }
 
 static int ath11k_pci_power_up(struct ath11k_base *ab)
diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c
index 5990a55801f0..e4f08a066ca1 100644
--- a/drivers/net/wireless/ath/ath12k/pci.c
+++ b/drivers/net/wireless/ath/ath12k/pci.c
@@ -794,8 +794,8 @@ static void ath12k_pci_aspm_disable(struct ath12k_pci *ab_pci)
 		   u16_get_bits(ab_pci->link_ctl, PCI_EXP_LNKCTL_ASPM_L1));
 
 	/* disable L0s and L1 */
-	pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-				   ab_pci->link_ctl & ~PCI_EXP_LNKCTL_ASPMC);
+	pcie_capability_clear_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+				   PCI_EXP_LNKCTL_ASPMC);
 
 	set_bit(ATH12K_PCI_ASPM_RESTORE, &ab_pci->flags);
 }
@@ -803,8 +803,10 @@ static void ath12k_pci_aspm_disable(struct ath12k_pci *ab_pci)
 static void ath12k_pci_aspm_restore(struct ath12k_pci *ab_pci)
 {
 	if (test_and_clear_bit(ATH12K_PCI_ASPM_RESTORE, &ab_pci->flags))
-		pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-					   ab_pci->link_ctl);
+		pcie_capability_clear_and_set_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_ASPMC,
+						   ab_pci->link_ctl &
+						   PCI_EXP_LNKCTL_ASPMC);
 }
 
 static void ath12k_pci_kill_tasklets(struct ath12k_base *ab)
diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 3c230ca3de58..6554a2e89d36 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -497,22 +497,35 @@ int pcie_capability_write_dword(struct pci_dev *dev, int pos, u32 val)
 }
 EXPORT_SYMBOL(pcie_capability_write_dword);
 
-int pcie_capability_clear_and_set_word(struct pci_dev *dev, int pos,
-				       u16 clear, u16 set)
+int pcie_capability_clear_and_set_word_unlocked(struct pci_dev *dev, int pos,
+						u16 clear, u16 set)
 {
 	int ret;
 	u16 val;
 
 	ret = pcie_capability_read_word(dev, pos, &val);
-	if (!ret) {
-		val &= ~clear;
-		val |= set;
-		ret = pcie_capability_write_word(dev, pos, val);
-	}
+	if (ret)
+		return ret;
+
+	val &= ~clear;
+	val |= set;
+	return pcie_capability_write_word(dev, pos, val);
+}
+EXPORT_SYMBOL(pcie_capability_clear_and_set_word_unlocked);
+
+int pcie_capability_clear_and_set_word_locked(struct pci_dev *dev, int pos,
+					      u16 clear, u16 set)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&dev->pcie_cap_lock, flags);
+	ret = pcie_capability_clear_and_set_word_unlocked(dev, pos, clear, set);
+	spin_unlock_irqrestore(&dev->pcie_cap_lock, flags);
 
 	return ret;
 }
-EXPORT_SYMBOL(pcie_capability_clear_and_set_word);
+EXPORT_SYMBOL(pcie_capability_clear_and_set_word_locked);
 
 int pcie_capability_clear_and_set_dword(struct pci_dev *dev, int pos,
 					u32 clear, u32 set)
@@ -521,13 +534,12 @@ int pcie_capability_clear_and_set_dword(struct pci_dev *dev, int pos,
 	u32 val;
 
 	ret = pcie_capability_read_dword(dev, pos, &val);
-	if (!ret) {
-		val &= ~clear;
-		val |= set;
-		ret = pcie_capability_write_dword(dev, pos, val);
-	}
+	if (ret)
+		return ret;
 
-	return ret;
+	val &= ~clear;
+	val |= set;
+	return pcie_capability_write_dword(dev, pos, val);
 }
 EXPORT_SYMBOL(pcie_capability_clear_and_set_dword);
 
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 8711325605f0..fd713abdfb9f 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -332,17 +332,11 @@ int pciehp_check_link_status(struct controller *ctrl)
 static int __pciehp_link_set(struct controller *ctrl, bool enable)
 {
 	struct pci_dev *pdev = ctrl_dev(ctrl);
-	u16 lnk_ctrl;
 
-	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &lnk_ctrl);
+	pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
+					   PCI_EXP_LNKCTL_LD,
+					   enable ? 0 : PCI_EXP_LNKCTL_LD);
 
-	if (enable)
-		lnk_ctrl &= ~PCI_EXP_LNKCTL_LD;
-	else
-		lnk_ctrl |= PCI_EXP_LNKCTL_LD;
-
-	pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, lnk_ctrl);
-	ctrl_dbg(ctrl, "%s: lnk_ctrl = %x\n", __func__, lnk_ctrl);
 	return 0;
 }
 
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 60230da957e0..f7315b13bb82 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4927,7 +4927,6 @@ static int pcie_wait_for_link_status(struct pci_dev *pdev,
 int pcie_retrain_link(struct pci_dev *pdev, bool use_lt)
 {
 	int rc;
-	u16 lnkctl;
 
 	/*
 	 * Ensure the updated LNKCTL parameters are used during link
@@ -4939,17 +4938,14 @@ int pcie_retrain_link(struct pci_dev *pdev, bool use_lt)
 	if (rc)
 		return rc;
 
-	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &lnkctl);
-	lnkctl |= PCI_EXP_LNKCTL_RL;
-	pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, lnkctl);
+	pcie_capability_set_word(pdev, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_RL);
 	if (pdev->clear_retrain_link) {
 		/*
 		 * Due to an erratum in some devices the Retrain Link bit
 		 * needs to be cleared again manually to allow the link
 		 * training to succeed.
 		 */
-		lnkctl &= ~PCI_EXP_LNKCTL_RL;
-		pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, lnkctl);
+		pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_RL);
 	}
 
 	return pcie_wait_for_link_status(pdev, use_lt, !use_lt);
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 3dafba0b5f41..1bf630059264 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -199,7 +199,7 @@ static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
 {
 	int same_clock = 1;
-	u16 reg16, parent_reg, child_reg[8];
+	u16 reg16, ccc, parent_old_ccc, child_old_ccc[8];
 	struct pci_dev *child, *parent = link->pdev;
 	struct pci_bus *linkbus = parent->subordinate;
 	/*
@@ -221,6 +221,7 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
 
 	/* Port might be already in common clock mode */
 	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
+	parent_old_ccc = reg16 & PCI_EXP_LNKCTL_CCC;
 	if (same_clock && (reg16 & PCI_EXP_LNKCTL_CCC)) {
 		bool consistent = true;
 
@@ -237,34 +238,29 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
 		pci_info(parent, "ASPM: current common clock configuration is inconsistent, reconfiguring\n");
 	}
 
+	ccc = same_clock ? PCI_EXP_LNKCTL_CCC : 0;
 	/* Configure downstream component, all functions */
 	list_for_each_entry(child, &linkbus->devices, bus_list) {
 		pcie_capability_read_word(child, PCI_EXP_LNKCTL, &reg16);
-		child_reg[PCI_FUNC(child->devfn)] = reg16;
-		if (same_clock)
-			reg16 |= PCI_EXP_LNKCTL_CCC;
-		else
-			reg16 &= ~PCI_EXP_LNKCTL_CCC;
-		pcie_capability_write_word(child, PCI_EXP_LNKCTL, reg16);
+		child_old_ccc[PCI_FUNC(child->devfn)] = reg16 & PCI_EXP_LNKCTL_CCC;
+		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_CCC, ccc);
 	}
 
 	/* Configure upstream component */
-	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
-	parent_reg = reg16;
-	if (same_clock)
-		reg16 |= PCI_EXP_LNKCTL_CCC;
-	else
-		reg16 &= ~PCI_EXP_LNKCTL_CCC;
-	pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
+	pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
+					   PCI_EXP_LNKCTL_CCC, ccc);
 
 	if (pcie_retrain_link(link->pdev, true)) {
 
 		/* Training failed. Restore common clock configurations */
 		pci_err(parent, "ASPM: Could not configure common clock\n");
 		list_for_each_entry(child, &linkbus->devices, bus_list)
-			pcie_capability_write_word(child, PCI_EXP_LNKCTL,
-					   child_reg[PCI_FUNC(child->devfn)]);
-		pcie_capability_write_word(parent, PCI_EXP_LNKCTL, parent_reg);
+			pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
+							   PCI_EXP_LNKCTL_CCC,
+							   child_old_ccc[PCI_FUNC(child->devfn)]);
+		pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_CCC, parent_old_ccc);
 	}
 }
 
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8bac3ce02609..f1587fb0ba71 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2324,6 +2324,7 @@ struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
 		.end = -1,
 	};
 
+	spin_lock_init(&dev->pcie_cap_lock);
 #ifdef CONFIG_PCI_MSI
 	raw_spin_lock_init(&dev->msi_lock);
 #endif
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c69a2cc1f412..7ee498cd1f37 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -467,6 +467,7 @@ struct pci_dev {
 	pci_dev_flags_t dev_flags;
 	atomic_t	enable_cnt;	/* pci_enable_device has been called */
 
+	spinlock_t	pcie_cap_lock;		/* Protects RMW ops in capability accessors */
 	u32		saved_config_space[16]; /* Config space saved at suspend time */
 	struct hlist_head saved_cap_space;
 	int		rom_attr_enabled;	/* Display of ROM attribute enabled? */
@@ -1217,11 +1218,40 @@ int pcie_capability_read_word(struct pci_dev *dev, int pos, u16 *val);
 int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val);
 int pcie_capability_write_word(struct pci_dev *dev, int pos, u16 val);
 int pcie_capability_write_dword(struct pci_dev *dev, int pos, u32 val);
-int pcie_capability_clear_and_set_word(struct pci_dev *dev, int pos,
-				       u16 clear, u16 set);
+int pcie_capability_clear_and_set_word_unlocked(struct pci_dev *dev, int pos,
+						u16 clear, u16 set);
+int pcie_capability_clear_and_set_word_locked(struct pci_dev *dev, int pos,
+					      u16 clear, u16 set);
 int pcie_capability_clear_and_set_dword(struct pci_dev *dev, int pos,
 					u32 clear, u32 set);
 
+/**
+ * pcie_capability_clear_and_set_word - RMW accessor for PCI Express Capability Registers
+ * @dev:	PCI device structure of the PCI Express device
+ * @pos:	PCI Express Capability Register
+ * @clear:	Clear bitmask
+ * @set:	Set bitmask
+ *
+ * Perform a Read-Modify-Write (RMW) operation using @clear and @set
+ * bitmasks on PCI Express Capability Register at @pos. Certain PCI Express
+ * Capability Registers are accessed concurrently in RMW fashion, hence
+ * require locking which is handled transparently to the caller.
+ */
+static inline int pcie_capability_clear_and_set_word(struct pci_dev *dev,
+						     int pos,
+						     u16 clear, u16 set)
+{
+	switch (pos) {
+	case PCI_EXP_LNKCTL:
+	case PCI_EXP_RTCTL:
+		return pcie_capability_clear_and_set_word_locked(dev, pos,
+								 clear, set);
+	default:
+		return pcie_capability_clear_and_set_word_unlocked(dev, pos,
+								   clear, set);
+	}
+}
+
 static inline int pcie_capability_set_word(struct pci_dev *dev, int pos,
 					   u16 set)
 {