6 files changed, 356 insertions, 38 deletions

diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index 8de4ed5f98..6461aa93fe 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -6,7 +6,7 @@ pcieportdrv-y			:= portdrv.o rcec.o
 
 obj-$(CONFIG_PCIEPORTBUS)	+= pcieportdrv.o
 
-obj-$(CONFIG_PCIEASPM)		+= aspm.o
+obj-y				+= aspm.o
 obj-$(CONFIG_PCIEAER)		+= aer.o err.o
 obj-$(CONFIG_PCIEAER_INJECT)	+= aer_inject.o
 obj-$(CONFIG_PCIE_PME)		+= pme.o
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 05fc30bb51..ac6293c249 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -664,11 +664,10 @@ static void pci_rootport_aer_stats_incr(struct pci_dev *pdev,
 	}
 }
 
-static void __print_tlp_header(struct pci_dev *dev,
-			       struct aer_header_log_regs *t)
+static void __print_tlp_header(struct pci_dev *dev, struct pcie_tlp_log *t)
 {
 	pci_err(dev, "  TLP Header: %08x %08x %08x %08x\n",
-		t->dw0, t->dw1, t->dw2, t->dw3);
+		t->dw[0], t->dw[1], t->dw[2], t->dw[3]);
 }
 
 static void __aer_print_error(struct pci_dev *dev,
@@ -1210,7 +1209,7 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
 {
 	int type = pci_pcie_type(dev);
 	int aer = dev->aer_cap;
-	int temp;
+	u32 aercc;
 
 	/* Must reset in this function */
 	info->status = 0;
@@ -1241,19 +1240,12 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
 			return 0;
 
 		/* Get First Error Pointer */
-		pci_read_config_dword(dev, aer + PCI_ERR_CAP, &temp);
-		info->first_error = PCI_ERR_CAP_FEP(temp);
+		pci_read_config_dword(dev, aer + PCI_ERR_CAP, &aercc);
+		info->first_error = PCI_ERR_CAP_FEP(aercc);
 
 		if (info->status & AER_LOG_TLP_MASKS) {
 			info->tlp_header_valid = 1;
-			pci_read_config_dword(dev,
-				aer + PCI_ERR_HEADER_LOG, &info->tlp.dw0);
-			pci_read_config_dword(dev,
-				aer + PCI_ERR_HEADER_LOG + 4, &info->tlp.dw1);
-			pci_read_config_dword(dev,
-				aer + PCI_ERR_HEADER_LOG + 8, &info->tlp.dw2);
-			pci_read_config_dword(dev,
-				aer + PCI_ERR_HEADER_LOG + 12, &info->tlp.dw3);
+			pcie_read_tlp_log(dev, aer + PCI_ERR_HEADER_LOG, &info->tlp);
 		}
 	}
 
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index bc0bd86695..47761c7ef2 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -24,6 +24,166 @@
 
 #include "../pci.h"
 
+void pci_save_ltr_state(struct pci_dev *dev)
+{
+	int ltr;
+	struct pci_cap_saved_state *save_state;
+	u32 *cap;
+
+	if (!pci_is_pcie(dev))
+		return;
+
+	ltr = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!ltr)
+		return;
+
+	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state) {
+		pci_err(dev, "no suspend buffer for LTR; ASPM issues possible after resume\n");
+		return;
+	}
+
+	/* Some broken devices only support dword access to LTR */
+	cap = &save_state->cap.data[0];
+	pci_read_config_dword(dev, ltr + PCI_LTR_MAX_SNOOP_LAT, cap);
+}
+
+void pci_restore_ltr_state(struct pci_dev *dev)
+{
+	struct pci_cap_saved_state *save_state;
+	int ltr;
+	u32 *cap;
+
+	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
+	ltr = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state || !ltr)
+		return;
+
+	/* Some broken devices only support dword access to LTR */
+	cap = &save_state->cap.data[0];
+	pci_write_config_dword(dev, ltr + PCI_LTR_MAX_SNOOP_LAT, *cap);
+}
+
+void pci_configure_aspm_l1ss(struct pci_dev *pdev)
+{
+	int rc;
+
+	pdev->l1ss = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_L1SS);
+
+	rc = pci_add_ext_cap_save_buffer(pdev, PCI_EXT_CAP_ID_L1SS,
+					 2 * sizeof(u32));
+	if (rc)
+		pci_err(pdev, "unable to allocate ASPM L1SS save buffer (%pe)\n",
+			ERR_PTR(rc));
+}
+
+void pci_save_aspm_l1ss_state(struct pci_dev *pdev)
+{
+	struct pci_cap_saved_state *save_state;
+	u16 l1ss = pdev->l1ss;
+	u32 *cap;
+
+	/*
+	 * Save L1 substate configuration. The ASPM L0s/L1 configuration
+	 * in PCI_EXP_LNKCTL_ASPMC is saved by pci_save_pcie_state().
+	 */
+	if (!l1ss)
+		return;
+
+	save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_L1SS);
+	if (!save_state)
+		return;
+
+	cap = &save_state->cap.data[0];
+	pci_read_config_dword(pdev, l1ss + PCI_L1SS_CTL2, cap++);
+	pci_read_config_dword(pdev, l1ss + PCI_L1SS_CTL1, cap++);
+}
+
+void pci_restore_aspm_l1ss_state(struct pci_dev *pdev)
+{
+	struct pci_cap_saved_state *pl_save_state, *cl_save_state;
+	struct pci_dev *parent = pdev->bus->self;
+	u32 *cap, pl_ctl1, pl_ctl2, pl_l1_2_enable;
+	u32 cl_ctl1, cl_ctl2, cl_l1_2_enable;
+	u16 clnkctl, plnkctl;
+
+	/*
+	 * In case BIOS enabled L1.2 when resuming, we need to disable it first
+	 * on the downstream component before the upstream. So, don't attempt to
+	 * restore either until we are at the downstream component.
+	 */
+	if (pcie_downstream_port(pdev) || !parent)
+		return;
+
+	if (!pdev->l1ss || !parent->l1ss)
+		return;
+
+	cl_save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_L1SS);
+	pl_save_state = pci_find_saved_ext_cap(parent, PCI_EXT_CAP_ID_L1SS);
+	if (!cl_save_state || !pl_save_state)
+		return;
+
+	cap = &cl_save_state->cap.data[0];
+	cl_ctl2 = *cap++;
+	cl_ctl1 = *cap;
+	cap = &pl_save_state->cap.data[0];
+	pl_ctl2 = *cap++;
+	pl_ctl1 = *cap;
+
+	/* Make sure L0s/L1 are disabled before updating L1SS config */
+	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &clnkctl);
+	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &plnkctl);
+	if (FIELD_GET(PCI_EXP_LNKCTL_ASPMC, clnkctl) ||
+	    FIELD_GET(PCI_EXP_LNKCTL_ASPMC, plnkctl)) {
+		pcie_capability_write_word(pdev, PCI_EXP_LNKCTL,
+					   clnkctl & ~PCI_EXP_LNKCTL_ASPMC);
+		pcie_capability_write_word(parent, PCI_EXP_LNKCTL,
+					   plnkctl & ~PCI_EXP_LNKCTL_ASPMC);
+	}
+
+	/*
+	 * Disable L1.2 on this downstream endpoint device first, followed
+	 * by the upstream
+	 */
+	pci_clear_and_set_config_dword(pdev, pdev->l1ss + PCI_L1SS_CTL1,
+				       PCI_L1SS_CTL1_L1_2_MASK, 0);
+	pci_clear_and_set_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				       PCI_L1SS_CTL1_L1_2_MASK, 0);
+
+	/*
+	 * In addition, Common_Mode_Restore_Time and LTR_L1.2_THRESHOLD
+	 * in PCI_L1SS_CTL1 must be programmed *before* setting the L1.2
+	 * enable bits, even though they're all in PCI_L1SS_CTL1.
+	 */
+	pl_l1_2_enable = pl_ctl1 & PCI_L1SS_CTL1_L1_2_MASK;
+	pl_ctl1 &= ~PCI_L1SS_CTL1_L1_2_MASK;
+	cl_l1_2_enable = cl_ctl1 & PCI_L1SS_CTL1_L1_2_MASK;
+	cl_ctl1 &= ~PCI_L1SS_CTL1_L1_2_MASK;
+
+	/* Write back without enables first (above we cleared them in ctl1) */
+	pci_write_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, pl_ctl2);
+	pci_write_config_dword(pdev, pdev->l1ss + PCI_L1SS_CTL2, cl_ctl2);
+	pci_write_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1, pl_ctl1);
+	pci_write_config_dword(pdev, pdev->l1ss + PCI_L1SS_CTL1, cl_ctl1);
+
+	/* Then write back the enables */
+	if (pl_l1_2_enable || cl_l1_2_enable) {
+		pci_write_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				       pl_ctl1 | pl_l1_2_enable);
+		pci_write_config_dword(pdev, pdev->l1ss + PCI_L1SS_CTL1,
+				       cl_ctl1 | cl_l1_2_enable);
+	}
+
+	/* Restore L0s/L1 if they were enabled */
+	if (FIELD_GET(PCI_EXP_LNKCTL_ASPMC, clnkctl) ||
+	    FIELD_GET(PCI_EXP_LNKCTL_ASPMC, plnkctl)) {
+		pcie_capability_write_word(parent, PCI_EXP_LNKCTL, plnkctl);
+		pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, clnkctl);
+	}
+}
+
+#ifdef CONFIG_PCIEASPM
+
 #ifdef MODULE_PARAM_PREFIX
 #undef MODULE_PARAM_PREFIX
 #endif
@@ -141,16 +301,42 @@ static int policy_to_clkpm_state(struct pcie_link_state *link)
 	return 0;
 }
 
+static void pci_update_aspm_saved_state(struct pci_dev *dev)
+{
+	struct pci_cap_saved_state *save_state;
+	u16 *cap, lnkctl, aspm_ctl;
+
+	save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
+	if (!save_state)
+		return;
+
+	pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &lnkctl);
+
+	/*
+	 * Update ASPM and CLKREQ bits of LNKCTL in save_state. We only
+	 * write PCI_EXP_LNKCTL_CCC during enumeration, so it shouldn't
+	 * change after being captured in save_state.
+	 */
+	aspm_ctl = lnkctl & (PCI_EXP_LNKCTL_ASPMC | PCI_EXP_LNKCTL_CLKREQ_EN);
+	lnkctl &= ~(PCI_EXP_LNKCTL_ASPMC | PCI_EXP_LNKCTL_CLKREQ_EN);
+
+	/* Depends on pci_save_pcie_state(): cap[1] is LNKCTL */
+	cap = (u16 *)&save_state->cap.data[0];
+	cap[1] = lnkctl | aspm_ctl;
+}
+
 static void pcie_set_clkpm_nocheck(struct pcie_link_state *link, int enable)
 {
 	struct pci_dev *child;
 	struct pci_bus *linkbus = link->pdev->subordinate;
 	u32 val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
 
-	list_for_each_entry(child, &linkbus->devices, bus_list)
+	list_for_each_entry(child, &linkbus->devices, bus_list) {
 		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
 						   PCI_EXP_LNKCTL_CLKREQ_EN,
 						   val);
+		pci_update_aspm_saved_state(child);
+	}
 	link->clkpm_enabled = !!enable;
 }
 
@@ -769,6 +955,12 @@ static void pcie_config_aspm_link(struct pcie_link_state *link, u32 state)
 		pcie_config_aspm_dev(parent, upstream);
 
 	link->aspm_enabled = state;
+
+	/* Update latest ASPM configuration in saved context */
+	pci_save_aspm_l1ss_state(link->downstream);
+	pci_update_aspm_saved_state(link->downstream);
+	pci_save_aspm_l1ss_state(parent);
+	pci_update_aspm_saved_state(parent);
 }
 
 static void pcie_config_aspm_path(struct pcie_link_state *link)
@@ -938,6 +1130,78 @@ out:
 	up_read(&pci_bus_sem);
 }
 
+void pci_bridge_reconfigure_ltr(struct pci_dev *pdev)
+{
+	struct pci_dev *bridge;
+	u32 ctl;
+
+	bridge = pci_upstream_bridge(pdev);
+	if (bridge && bridge->ltr_path) {
+		pcie_capability_read_dword(bridge, PCI_EXP_DEVCTL2, &ctl);
+		if (!(ctl & PCI_EXP_DEVCTL2_LTR_EN)) {
+			pci_dbg(bridge, "re-enabling LTR\n");
+			pcie_capability_set_word(bridge, PCI_EXP_DEVCTL2,
+						 PCI_EXP_DEVCTL2_LTR_EN);
+		}
+	}
+}
+
+void pci_configure_ltr(struct pci_dev *pdev)
+{
+	struct pci_host_bridge *host = pci_find_host_bridge(pdev->bus);
+	struct pci_dev *bridge;
+	u32 cap, ctl;
+
+	if (!pci_is_pcie(pdev))
+		return;
+
+	pcie_capability_read_dword(pdev, PCI_EXP_DEVCAP2, &cap);
+	if (!(cap & PCI_EXP_DEVCAP2_LTR))
+		return;
+
+	pcie_capability_read_dword(pdev, PCI_EXP_DEVCTL2, &ctl);
+	if (ctl & PCI_EXP_DEVCTL2_LTR_EN) {
+		if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT) {
+			pdev->ltr_path = 1;
+			return;
+		}
+
+		bridge = pci_upstream_bridge(pdev);
+		if (bridge && bridge->ltr_path)
+			pdev->ltr_path = 1;
+
+		return;
+	}
+
+	if (!host->native_ltr)
+		return;
+
+	/*
+	 * Software must not enable LTR in an Endpoint unless the Root
+	 * Complex and all intermediate Switches indicate support for LTR.
+	 * PCIe r4.0, sec 6.18.
+	 */
+	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT) {
+		pcie_capability_set_word(pdev, PCI_EXP_DEVCTL2,
+					 PCI_EXP_DEVCTL2_LTR_EN);
+		pdev->ltr_path = 1;
+		return;
+	}
+
+	/*
+	 * If we're configuring a hot-added device, LTR was likely
+	 * disabled in the upstream bridge, so re-enable it before enabling
+	 * it in the new device.
+	 */
+	bridge = pci_upstream_bridge(pdev);
+	if (bridge && bridge->ltr_path) {
+		pci_bridge_reconfigure_ltr(pdev);
+		pcie_capability_set_word(pdev, PCI_EXP_DEVCTL2,
+					 PCI_EXP_DEVCTL2_LTR_EN);
+		pdev->ltr_path = 1;
+	}
+}
+
 /* Recheck latencies and update aspm_capable for links under the root */
 static void pcie_update_aspm_capable(struct pcie_link_state *root)
 {
@@ -1447,3 +1711,5 @@ bool pcie_aspm_support_enabled(void)
 {
 	return aspm_support_enabled;
 }
+
+#endif /* CONFIG_PCIEASPM */
diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index e5d7c12854..a668820696 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -190,7 +190,8 @@ out:
 static void dpc_process_rp_pio_error(struct pci_dev *pdev)
 {
 	u16 cap = pdev->dpc_cap, dpc_status, first_error;
-	u32 status, mask, sev, syserr, exc, dw0, dw1, dw2, dw3, log, prefix;
+	u32 status, mask, sev, syserr, exc, log, prefix;
+	struct pcie_tlp_log tlp_log;
 	int i;
 
 	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_STATUS, &status);
@@ -216,16 +217,9 @@ static void dpc_process_rp_pio_error(struct pci_dev *pdev)
 
 	if (pdev->dpc_rp_log_size < 4)
 		goto clear_status;
-	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG,
-			      &dw0);
-	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG + 4,
-			      &dw1);
-	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG + 8,
-			      &dw2);
-	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG + 12,
-			      &dw3);
+	pcie_read_tlp_log(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG, &tlp_log);
 	pci_err(pdev, "TLP Header: %#010x %#010x %#010x %#010x\n",
-		dw0, dw1, dw2, dw3);
+		tlp_log.dw[0], tlp_log.dw[1], tlp_log.dw[2], tlp_log.dw[3]);
 
 	if (pdev->dpc_rp_log_size < 5)
 		goto clear_status;
@@ -303,10 +297,70 @@ void dpc_process_error(struct pci_dev *pdev)
 	}
 }
 
+static void pci_clear_surpdn_errors(struct pci_dev *pdev)
+{
+	if (pdev->dpc_rp_extensions)
+		pci_write_config_dword(pdev, pdev->dpc_cap +
+				       PCI_EXP_DPC_RP_PIO_STATUS, ~0);
+
+	/*
+	 * In practice, Surprise Down errors have been observed to also set
+	 * error bits in the Status Register as well as the Fatal Error
+	 * Detected bit in the Device Status Register.
+	 */
+	pci_write_config_word(pdev, PCI_STATUS, 0xffff);
+
+	pcie_capability_write_word(pdev, PCI_EXP_DEVSTA, PCI_EXP_DEVSTA_FED);
+}
+
+static void dpc_handle_surprise_removal(struct pci_dev *pdev)
+{
+	if (!pcie_wait_for_link(pdev, false)) {
+		pci_info(pdev, "Data Link Layer Link Active not cleared in 1000 msec\n");
+		goto out;
+	}
+
+	if (pdev->dpc_rp_extensions && dpc_wait_rp_inactive(pdev))
+		goto out;
+
+	pci_aer_raw_clear_status(pdev);
+	pci_clear_surpdn_errors(pdev);
+
+	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_STATUS,
+			      PCI_EXP_DPC_STATUS_TRIGGER);
+
+out:
+	clear_bit(PCI_DPC_RECOVERED, &pdev->priv_flags);
+	wake_up_all(&dpc_completed_waitqueue);
+}
+
+static bool dpc_is_surprise_removal(struct pci_dev *pdev)
+{
+	u16 status;
+
+	if (!pdev->is_hotplug_bridge)
+		return false;
+
+	if (pci_read_config_word(pdev, pdev->aer_cap + PCI_ERR_UNCOR_STATUS,
+				 &status))
+		return false;
+
+	return status & PCI_ERR_UNC_SURPDN;
+}
+
 static irqreturn_t dpc_handler(int irq, void *context)
 {
 	struct pci_dev *pdev = context;
 
+	/*
+	 * According to PCIe r6.0 sec 6.7.6, errors are an expected side effect
+	 * of async removal and should be ignored by software.
+	 */
+	if (dpc_is_surprise_removal(pdev)) {
+		dpc_handle_surprise_removal(pdev);
+		return IRQ_HANDLED;
+	}
+
 	dpc_process_error(pdev);
 
 	/* We configure DPC so it only triggers on ERR_FATAL */
diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
index 5f4914d313..e86298dbbc 100644
--- a/drivers/pci/pcie/edr.c
+++ b/drivers/pci/pcie/edr.c
@@ -32,10 +32,10 @@ static int acpi_enable_dpc(struct pci_dev *pdev)
 	int status = 0;
 
 	/*
-	 * Behavior when calling unsupported _DSM functions is undefined,
-	 * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
+	 * Per PCI Firmware r3.3, sec 4.6.12, EDR_PORT_DPC_ENABLE_DSM is
+	 * optional. Return success if it's not implemented.
 	 */
-	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
+	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 6,
 			    1ULL << EDR_PORT_DPC_ENABLE_DSM))
 		return 0;
 
@@ -46,12 +46,7 @@ static int acpi_enable_dpc(struct pci_dev *pdev)
 	argv4.package.count = 1;
 	argv4.package.elements = &req;
 
-	/*
-	 * Per Downstream Port Containment Related Enhancements ECN to PCI
-	 * Firmware Specification r3.2, sec 4.6.12, EDR_PORT_DPC_ENABLE_DSM is
-	 * optional.  Return success if it's not implemented.
-	 */
-	obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
+	obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 6,
 				EDR_PORT_DPC_ENABLE_DSM, &argv4);
 	if (!obj)
 		return 0;
@@ -85,8 +80,9 @@ static struct pci_dev *acpi_dpc_port_get(struct pci_dev *pdev)
 	u16 port;
 
 	/*
-	 * Behavior when calling unsupported _DSM functions is undefined,
-	 * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
+	 * If EDR_PORT_LOCATE_DSM is not implemented under the target of
+	 * EDR, the target is the port that experienced the containment
+	 * event (PCI Firmware r3.3, sec 4.6.13).
 	 */
 	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
 			    1ULL << EDR_PORT_LOCATE_DSM))
@@ -104,6 +100,16 @@ static struct pci_dev *acpi_dpc_port_get(struct pci_dev *pdev)
 	}
 
 	/*
+	 * Bit 31 represents the success/failure of the operation. If bit
+	 * 31 is set, the operation failed.
+	 */
+	if (obj->integer.value & BIT(31)) {
+		ACPI_FREE(obj);
+		pci_err(pdev, "Locate Port _DSM failed\n");
+		return NULL;
+	}
+
+	/*
 	 * Firmware returns DPC port BDF details in following format:
 	 *	15:8 = bus
 	 *	 7:3 = device
diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index 1f3803bde7..12c89ea031 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -96,7 +96,7 @@ struct pcie_port_service_driver {
 int pcie_port_service_register(struct pcie_port_service_driver *new);
 void pcie_port_service_unregister(struct pcie_port_service_driver *new);
 
-extern struct bus_type pcie_port_bus_type;
+extern const struct bus_type pcie_port_bus_type;
 
 struct pci_dev;