Merge branch 'pci/err'

- Stop writing AER Capability when we don't own it (Sean V Kelley)

- Bind RCEC devices to the Port driver (Qiuxu Zhuo)

- Cache the RCEC RA Capability offset (Sean V Kelley)

- Add pci_walk_bridge() (Sean V Kelley)

- Clear AER status only when we control AER (Sean V Kelley)

- Recover from RCEC AER errors (Sean V Kelley)

- Add pcie_link_rcec() to associate RCiEPs with RCECs (Sean V Kelley)

- Recover from RCiEP AER errors (Sean V Kelley)

- Add pcie_walk_rcec() for RCEC AER handling (Sean V Kelley)

- Add pcie_walk_rcec() for RCEC PME handling (Sean V Kelley)

- Add RCEC AER error injection support (Qiuxu Zhuo)

* pci/err:
  PCI/AER: Add RCEC AER error injection support
  PCI/PME: Add pcie_walk_rcec() to RCEC PME handling
  PCI/AER: Add pcie_walk_rcec() to RCEC AER handling
  PCI/ERR: Recover from RCiEP AER errors
  PCI/ERR: Add pcie_link_rcec() to associate RCiEPs
  PCI/ERR: Recover from RCEC AER errors
  PCI/ERR: Clear AER status only when we control AER
  PCI/ERR: Add pci_walk_bridge() to pcie_do_recovery()
  PCI/ERR: Avoid negated conditional for clarity
  PCI/ERR: Use "bridge" for clarity in pcie_do_recovery()
  PCI/ERR: Simplify by computing pci_pcie_type() once
  PCI/ERR: Simplify by using pci_upstream_bridge()
  PCI/ERR: Rename reset_link() to reset_subordinates()
  PCI/ERR: Cache RCEC EA Capability offset in pci_init_capabilities()
  PCI/ERR: Bind RCEC devices to the Root Port driver
  PCI/AER: Write AER Capability only when we control it

8 files changed, 363 insertions, 68 deletions

diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index 68da9280ff11..d9697892fa3e 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -2,7 +2,7 @@
 #
 # Makefile for PCI Express features and port driver
 
-pcieportdrv-y			:= portdrv_core.o portdrv_pci.o err.o
+pcieportdrv-y			:= portdrv_core.o portdrv_pci.o err.o rcec.o
 
 obj-$(CONFIG_PCIEPORTBUS)	+= pcieportdrv.o
 
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 65dff5f3457a..77b0f2c45bc0 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -300,7 +300,8 @@ int pci_aer_raw_clear_status(struct pci_dev *dev)
 		return -EIO;
 
 	port_type = pci_pcie_type(dev);
-	if (port_type == PCI_EXP_TYPE_ROOT_PORT) {
+	if (port_type == PCI_EXP_TYPE_ROOT_PORT ||
+	    port_type == PCI_EXP_TYPE_RC_EC) {
 		pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, &status);
 		pci_write_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, status);
 	}
@@ -595,7 +596,8 @@ static umode_t aer_stats_attrs_are_visible(struct kobject *kobj,
 	if ((a == &dev_attr_aer_rootport_total_err_cor.attr ||
 	     a == &dev_attr_aer_rootport_total_err_fatal.attr ||
 	     a == &dev_attr_aer_rootport_total_err_nonfatal.attr) &&
-	    pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT)
+	    ((pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT) &&
+	     (pci_pcie_type(pdev) != PCI_EXP_TYPE_RC_EC)))
 		return 0;
 
 	return a->mode;
@@ -916,7 +918,10 @@ static bool find_source_device(struct pci_dev *parent,
 	if (result)
 		return true;
 
-	pci_walk_bus(parent->subordinate, find_device_iter, e_info);
+	if (pci_pcie_type(parent) == PCI_EXP_TYPE_RC_EC)
+		pcie_walk_rcec(parent, find_device_iter, e_info);
+	else
+		pci_walk_bus(parent->subordinate, find_device_iter, e_info);
 
 	if (!e_info->error_dev_num) {
 		pci_info(parent, "can't find device of ID%04x\n", e_info->id);
@@ -1034,6 +1039,7 @@ EXPORT_SYMBOL_GPL(aer_recover_queue);
  */
 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;
 
@@ -1052,8 +1058,9 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
 			&info->mask);
 		if (!(info->status & ~info->mask))
 			return 0;
-	} else if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
-	           pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
+	} else if (type == PCI_EXP_TYPE_ROOT_PORT ||
+		   type == PCI_EXP_TYPE_RC_EC ||
+		   type == PCI_EXP_TYPE_DOWNSTREAM ||
 		   info->severity == AER_NONFATAL) {
 
 		/* Link is still healthy for IO reads */
@@ -1205,6 +1212,7 @@ static int set_device_error_reporting(struct pci_dev *dev, void *data)
 	int type = pci_pcie_type(dev);
 
 	if ((type == PCI_EXP_TYPE_ROOT_PORT) ||
+	    (type == PCI_EXP_TYPE_RC_EC) ||
 	    (type == PCI_EXP_TYPE_UPSTREAM) ||
 	    (type == PCI_EXP_TYPE_DOWNSTREAM)) {
 		if (enable)
@@ -1229,9 +1237,12 @@ static void set_downstream_devices_error_reporting(struct pci_dev *dev,
 {
 	set_device_error_reporting(dev, &enable);
 
-	if (!dev->subordinate)
-		return;
-	pci_walk_bus(dev->subordinate, set_device_error_reporting, &enable);
+	if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC)
+		pcie_walk_rcec(dev, set_device_error_reporting, &enable);
+	else if (dev->subordinate)
+		pci_walk_bus(dev->subordinate, set_device_error_reporting,
+			     &enable);
+
 }
 
 /**
@@ -1329,6 +1340,11 @@ static int aer_probe(struct pcie_device *dev)
 	struct device *device = &dev->device;
 	struct pci_dev *port = dev->port;
 
+	/* Limit to Root Ports or Root Complex Event Collectors */
+	if ((pci_pcie_type(port) != PCI_EXP_TYPE_RC_EC) &&
+	    (pci_pcie_type(port) != PCI_EXP_TYPE_ROOT_PORT))
+		return -ENODEV;
+
 	rpc = devm_kzalloc(device, sizeof(struct aer_rpc), GFP_KERNEL);
 	if (!rpc)
 		return -ENOMEM;
@@ -1350,41 +1366,74 @@ static int aer_probe(struct pcie_device *dev)
 }
 
 /**
- * aer_root_reset - reset link on Root Port
- * @dev: pointer to Root Port's pci_dev data structure
+ * aer_root_reset - reset Root Port hierarchy, RCEC, or RCiEP
+ * @dev: pointer to Root Port, RCEC, or RCiEP
  *
- * Invoked by Port Bus driver when performing link reset at Root Port.
+ * Invoked by Port Bus driver when performing reset.
  */
 static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
 {
-	int aer = dev->aer_cap;
+	int type = pci_pcie_type(dev);
+	struct pci_dev *root;
+	int aer;
+	struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
 	u32 reg32;
 	int rc;
 
+	/*
+	 * Only Root Ports and RCECs have AER Root Command and Root Status
+	 * registers.  If "dev" is an RCiEP, the relevant registers are in
+	 * the RCEC.
+	 */
+	if (type == PCI_EXP_TYPE_RC_END)
+		root = dev->rcec;
+	else
+		root = dev;
+
+	/*
+	 * If the platform retained control of AER, an RCiEP may not have
+	 * an RCEC visible to us, so dev->rcec ("root") may be NULL.  In
+	 * that case, firmware is responsible for these registers.
+	 */
+	aer = root ? root->aer_cap : 0;
 
-	/* Disable Root's interrupt in response to error messages */
-	pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, &reg32);
-	reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
-	pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
+	if ((host->native_aer || pcie_ports_native) && aer) {
+		/* Disable Root's interrupt in response to error messages */
+		pci_read_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, &reg32);
+		reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
+		pci_write_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, reg32);
+	}
 
-	rc = pci_bus_error_reset(dev);
-	pci_info(dev, "Root Port link has been reset\n");
+	if (type == PCI_EXP_TYPE_RC_EC || type == PCI_EXP_TYPE_RC_END) {
+		if (pcie_has_flr(dev)) {
+			rc = pcie_flr(dev);
+			pci_info(dev, "has been reset (%d)\n", rc);
+		} else {
+			pci_info(dev, "not reset (no FLR support)\n");
+			rc = -ENOTTY;
+		}
+	} else {
+		rc = pci_bus_error_reset(dev);
+		pci_info(dev, "Root Port link has been reset (%d)\n", rc);
+	}
 
-	/* Clear Root Error Status */
-	pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, &reg32);
-	pci_write_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, reg32);
+	if ((host->native_aer || pcie_ports_native) && aer) {
+		/* Clear Root Error Status */
+		pci_read_config_dword(root, aer + PCI_ERR_ROOT_STATUS, &reg32);
+		pci_write_config_dword(root, aer + PCI_ERR_ROOT_STATUS, reg32);
 
-	/* Enable Root Port's interrupt in response to error messages */
-	pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, &reg32);
-	reg32 |= ROOT_PORT_INTR_ON_MESG_MASK;
-	pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
+		/* Enable Root Port's interrupt in response to error messages */
+		pci_read_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, &reg32);
+		reg32 |= ROOT_PORT_INTR_ON_MESG_MASK;
+		pci_write_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, reg32);
+	}
 
 	return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
 }
 
 static struct pcie_port_service_driver aerdriver = {
 	.name		= "aer",
-	.port_type	= PCI_EXP_TYPE_ROOT_PORT,
+	.port_type	= PCIE_ANY_PORT,
 	.service	= PCIE_PORT_SERVICE_AER,
 
 	.probe		= aer_probe,
diff --git a/drivers/pci/pcie/aer_inject.c b/drivers/pci/pcie/aer_inject.c
index c2cbf425afc5..767f8859b99b 100644
--- a/drivers/pci/pcie/aer_inject.c
+++ b/drivers/pci/pcie/aer_inject.c
@@ -333,8 +333,11 @@ static int aer_inject(struct aer_error_inj *einj)
 	if (!dev)
 		return -ENODEV;
 	rpdev = pcie_find_root_port(dev);
+	/* If Root Port not found, try to find an RCEC */
+	if (!rpdev)
+		rpdev = dev->rcec;
 	if (!rpdev) {
-		pci_err(dev, "Root port not found\n");
+		pci_err(dev, "Neither Root Port nor RCEC found\n");
 		ret = -ENODEV;
 		goto out_put;
 	}
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index c543f419d8f9..510f31f0ef6d 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -146,38 +146,71 @@ out:
 	return 0;
 }
 
+/**
+ * pci_walk_bridge - walk bridges potentially AER affected
+ * @bridge:	bridge which may be a Port, an RCEC, or an RCiEP
+ * @cb:		callback to be called for each device found
+ * @userdata:	arbitrary pointer to be passed to callback
+ *
+ * If the device provided is a bridge, walk the subordinate bus, including
+ * any bridged devices on buses under this bus.  Call the provided callback
+ * on each device found.
+ *
+ * If the device provided has no subordinate bus, e.g., an RCEC or RCiEP,
+ * call the callback on the device itself.
+ */
+static void pci_walk_bridge(struct pci_dev *bridge,
+			    int (*cb)(struct pci_dev *, void *),
+			    void *userdata)
+{
+	if (bridge->subordinate)
+		pci_walk_bus(bridge->subordinate, cb, userdata);
+	else
+		cb(bridge, userdata);
+}
+
 pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
-			pci_channel_state_t state,
-			pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
+		pci_channel_state_t state,
+		pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev))
 {
+	int type = pci_pcie_type(dev);
+	struct pci_dev *bridge;
 	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
-	struct pci_bus *bus;
+	struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
 
 	/*
-	 * Error recovery runs on all subordinates of the first downstream port.
-	 * If the downstream port detected the error, it is cleared at the end.
+	 * If the error was detected by a Root Port, Downstream Port, RCEC,
+	 * or RCiEP, recovery runs on the device itself.  For Ports, that
+	 * also includes any subordinate devices.
+	 *
+	 * If it was detected by another device (Endpoint, etc), recovery
+	 * runs on the device and anything else under the same Port, i.e.,
+	 * everything under "bridge".
 	 */
-	if (!(pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
-	      pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM))
-		dev = dev->bus->self;
-	bus = dev->subordinate;
-
-	pci_dbg(dev, "broadcast error_detected message\n");
+	if (type == PCI_EXP_TYPE_ROOT_PORT ||
+	    type == PCI_EXP_TYPE_DOWNSTREAM ||
+	    type == PCI_EXP_TYPE_RC_EC ||
+	    type == PCI_EXP_TYPE_RC_END)
+		bridge = dev;
+	else
+		bridge = pci_upstream_bridge(dev);
+
+	pci_dbg(bridge, "broadcast error_detected message\n");
 	if (state == pci_channel_io_frozen) {
-		pci_walk_bus(bus, report_frozen_detected, &status);
-		status = reset_link(dev);
+		pci_walk_bridge(bridge, report_frozen_detected, &status);
+		status = reset_subordinates(bridge);
 		if (status != PCI_ERS_RESULT_RECOVERED) {
-			pci_warn(dev, "link reset failed\n");
+			pci_warn(bridge, "subordinate device reset failed\n");
 			goto failed;
 		}
 	} else {
-		pci_walk_bus(bus, report_normal_detected, &status);
+		pci_walk_bridge(bridge, report_normal_detected, &status);
 	}
 
 	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
 		status = PCI_ERS_RESULT_RECOVERED;
-		pci_dbg(dev, "broadcast mmio_enabled message\n");
-		pci_walk_bus(bus, report_mmio_enabled, &status);
+		pci_dbg(bridge, "broadcast mmio_enabled message\n");
+		pci_walk_bridge(bridge, report_mmio_enabled, &status);
 	}
 
 	if (status == PCI_ERS_RESULT_NEED_RESET) {
@@ -187,27 +220,35 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 		 * drivers' slot_reset callbacks?
 		 */
 		status = PCI_ERS_RESULT_RECOVERED;
-		pci_dbg(dev, "broadcast slot_reset message\n");
-		pci_walk_bus(bus, report_slot_reset, &status);
+		pci_dbg(bridge, "broadcast slot_reset message\n");
+		pci_walk_bridge(bridge, report_slot_reset, &status);
 	}
 
 	if (status != PCI_ERS_RESULT_RECOVERED)
 		goto failed;
 
-	pci_dbg(dev, "broadcast resume message\n");
-	pci_walk_bus(bus, report_resume, &status);
+	pci_dbg(bridge, "broadcast resume message\n");
+	pci_walk_bridge(bridge, report_resume, &status);
 
-	if (pcie_aer_is_native(dev))
-		pcie_clear_device_status(dev);
-	pci_aer_clear_nonfatal_status(dev);
-	pci_info(dev, "device recovery successful\n");
+	/*
+	 * If we have native control of AER, clear error status in the Root
+	 * Port or Downstream Port that signaled the error.  If the
+	 * platform retained control of AER, it is responsible for clearing
+	 * this status.  In that case, the signaling device may not even be
+	 * visible to the OS.
+	 */
+	if (host->native_aer || pcie_ports_native) {
+		pcie_clear_device_status(bridge);
+		pci_aer_clear_nonfatal_status(bridge);
+	}
+	pci_info(bridge, "device recovery successful\n");
 	return status;
 
 failed:
-	pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
+	pci_uevent_ers(bridge, PCI_ERS_RESULT_DISCONNECT);
 
 	/* TODO: Should kernel panic here? */
-	pci_info(dev, "device recovery failed\n");
+	pci_info(bridge, "device recovery failed\n");
 
 	return status;
 }
diff --git a/drivers/pci/pcie/pme.c b/drivers/pci/pcie/pme.c
index 6a32970bb731..3fc08488d65f 100644
--- a/drivers/pci/pcie/pme.c
+++ b/drivers/pci/pcie/pme.c
@@ -310,7 +310,10 @@ static int pcie_pme_can_wakeup(struct pci_dev *dev, void *ign)
 static void pcie_pme_mark_devices(struct pci_dev *port)
 {
 	pcie_pme_can_wakeup(port, NULL);
-	if (port->subordinate)
+
+	if (pci_pcie_type(port) == PCI_EXP_TYPE_RC_EC)
+		pcie_walk_rcec(port, pcie_pme_can_wakeup, NULL);
+	else if (port->subordinate)
 		pci_walk_bus(port->subordinate, pcie_pme_can_wakeup, NULL);
 }
 
@@ -320,10 +323,16 @@ static void pcie_pme_mark_devices(struct pci_dev *port)
  */
 static int pcie_pme_probe(struct pcie_device *srv)
 {
-	struct pci_dev *port;
+	struct pci_dev *port = srv->port;
 	struct pcie_pme_service_data *data;
+	int type = pci_pcie_type(port);
 	int ret;
 
+	/* Limit to Root Ports or Root Complex Event Collectors */
+	if (type != PCI_EXP_TYPE_RC_EC &&
+	    type != PCI_EXP_TYPE_ROOT_PORT)
+		return -ENODEV;
+
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
@@ -333,7 +342,6 @@ static int pcie_pme_probe(struct pcie_device *srv)
 	data->srv = srv;
 	set_service_data(srv, data);
 
-	port = srv->port;
 	pcie_pme_interrupt_enable(port, false);
 	pcie_clear_root_pme_status(port);
 
@@ -445,7 +453,7 @@ static void pcie_pme_remove(struct pcie_device *srv)
 
 static struct pcie_port_service_driver pcie_pme_driver = {
 	.name		= "pcie_pme",
-	.port_type	= PCI_EXP_TYPE_ROOT_PORT,
+	.port_type	= PCIE_ANY_PORT,
 	.service	= PCIE_PORT_SERVICE_PME,
 
 	.probe		= pcie_pme_probe,
diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index 50a9522ab07d..e1fed6649c41 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -233,12 +233,9 @@ static int get_port_device_capability(struct pci_dev *dev)
 	}
 #endif
 
-	/*
-	 * Root ports are capable of generating PME too.  Root Complex
-	 * Event Collectors can also generate PMEs, but we don't handle
-	 * those yet.
-	 */
-	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT &&
+	/* Root Ports and Root Complex Event Collectors may generate PMEs */
+	if ((pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
+	     pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC) &&
 	    (pcie_ports_native || host->native_pme)) {
 		services |= PCIE_PORT_SERVICE_PME;
 
diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index 3a3ce40ae1ab..0b250bc5f405 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -101,14 +101,19 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = {
 static int pcie_portdrv_probe(struct pci_dev *dev,
 					const struct pci_device_id *id)
 {
+	int type = pci_pcie_type(dev);
 	int status;
 
 	if (!pci_is_pcie(dev) ||
-	    ((pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT) &&
-	     (pci_pcie_type(dev) != PCI_EXP_TYPE_UPSTREAM) &&
-	     (pci_pcie_type(dev) != PCI_EXP_TYPE_DOWNSTREAM)))
+	    ((type != PCI_EXP_TYPE_ROOT_PORT) &&
+	     (type != PCI_EXP_TYPE_UPSTREAM) &&
+	     (type != PCI_EXP_TYPE_DOWNSTREAM) &&
+	     (type != PCI_EXP_TYPE_RC_EC)))
 		return -ENODEV;
 
+	if (type == PCI_EXP_TYPE_RC_EC)
+		pcie_link_rcec(dev);
+
 	status = pcie_port_device_register(dev);
 	if (status)
 		return status;
@@ -195,6 +200,8 @@ static const struct pci_device_id port_pci_ids[] = {
 	{ PCI_DEVICE_CLASS(((PCI_CLASS_BRIDGE_PCI << 8) | 0x00), ~0) },
 	/* subtractive decode PCI-to-PCI bridge, class type is 060401h */
 	{ PCI_DEVICE_CLASS(((PCI_CLASS_BRIDGE_PCI << 8) | 0x01), ~0) },
+	/* handle any Root Complex Event Collector */
+	{ PCI_DEVICE_CLASS(((PCI_CLASS_SYSTEM_RCEC << 8) | 0x00), ~0) },
 	{ },
 };
 
diff --git a/drivers/pci/pcie/rcec.c b/drivers/pci/pcie/rcec.c
new file mode 100644
index 000000000000..2c5c552994e4
--- /dev/null
+++ b/drivers/pci/pcie/rcec.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Root Complex Event Collector Support
+ *
+ * Authors:
+ *  Sean V Kelley <sean.v.kelley@intel.com>
+ *  Qiuxu Zhuo <qiuxu.zhuo@intel.com>
+ *
+ * Copyright (C) 2020 Intel Corp.
+ */
+
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/pci_regs.h>
+
+#include "../pci.h"
+
+struct walk_rcec_data {
+	struct pci_dev *rcec;
+	int (*user_callback)(struct pci_dev *dev, void *data);
+	void *user_data;
+};
+
+static bool rcec_assoc_rciep(struct pci_dev *rcec, struct pci_dev *rciep)
+{
+	unsigned long bitmap = rcec->rcec_ea->bitmap;
+	unsigned int devn;
+
+	/* An RCiEP found on a different bus in range */
+	if (rcec->bus->number != rciep->bus->number)
+		return true;
+
+	/* Same bus, so check bitmap */
+	for_each_set_bit(devn, &bitmap, 32)
+		if (devn == rciep->devfn)
+			return true;
+
+	return false;
+}
+
+static int link_rcec_helper(struct pci_dev *dev, void *data)
+{
+	struct walk_rcec_data *rcec_data = data;
+	struct pci_dev *rcec = rcec_data->rcec;
+
+	if ((pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) &&
+	    rcec_assoc_rciep(rcec, dev)) {
+		dev->rcec = rcec;
+		pci_dbg(dev, "PME & error events signaled via %s\n",
+			pci_name(rcec));
+	}
+
+	return 0;
+}
+
+static int walk_rcec_helper(struct pci_dev *dev, void *data)
+{
+	struct walk_rcec_data *rcec_data = data;
+	struct pci_dev *rcec = rcec_data->rcec;
+
+	if ((pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) &&
+	    rcec_assoc_rciep(rcec, dev))
+		rcec_data->user_callback(dev, rcec_data->user_data);
+
+	return 0;
+}
+
+static void walk_rcec(int (*cb)(struct pci_dev *dev, void *data),
+		      void *userdata)
+{
+	struct walk_rcec_data *rcec_data = userdata;
+	struct pci_dev *rcec = rcec_data->rcec;
+	u8 nextbusn, lastbusn;
+	struct pci_bus *bus;
+	unsigned int bnr;
+
+	if (!rcec->rcec_ea)
+		return;
+
+	/* Walk own bus for bitmap based association */
+	pci_walk_bus(rcec->bus, cb, rcec_data);
+
+	nextbusn = rcec->rcec_ea->nextbusn;
+	lastbusn = rcec->rcec_ea->lastbusn;
+
+	/* All RCiEP devices are on the same bus as the RCEC */
+	if (nextbusn == 0xff && lastbusn == 0x00)
+		return;
+
+	for (bnr = nextbusn; bnr <= lastbusn; bnr++) {
+		/* No association indicated (PCIe 5.0-1, 7.9.10.3) */
+		if (bnr == rcec->bus->number)
+			continue;
+
+		bus = pci_find_bus(pci_domain_nr(rcec->bus), bnr);
+		if (!bus)
+			continue;
+
+		/* Find RCiEP devices on the given bus ranges */
+		pci_walk_bus(bus, cb, rcec_data);
+	}
+}
+
+/**
+ * pcie_link_rcec - Link RCiEP devices associated with RCEC.
+ * @rcec: RCEC whose RCiEP devices should be linked.
+ *
+ * Link the given RCEC to each RCiEP device found.
+ */
+void pcie_link_rcec(struct pci_dev *rcec)
+{
+	struct walk_rcec_data rcec_data;
+
+	if (!rcec->rcec_ea)
+		return;
+
+	rcec_data.rcec = rcec;
+	rcec_data.user_callback = NULL;
+	rcec_data.user_data = NULL;
+
+	walk_rcec(link_rcec_helper, &rcec_data);
+}
+
+/**
+ * pcie_walk_rcec - Walk RCiEP devices associating with RCEC and call callback.
+ * @rcec:	RCEC whose RCiEP devices should be walked
+ * @cb:		Callback to be called for each RCiEP device found
+ * @userdata:	Arbitrary pointer to be passed to callback
+ *
+ * Walk the given RCEC. Call the callback on each RCiEP found.
+ *
+ * If @cb returns anything other than 0, break out.
+ */
+void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
+		    void *userdata)
+{
+	struct walk_rcec_data rcec_data;
+
+	if (!rcec->rcec_ea)
+		return;
+
+	rcec_data.rcec = rcec;
+	rcec_data.user_callback = cb;
+	rcec_data.user_data = userdata;
+
+	walk_rcec(walk_rcec_helper, &rcec_data);
+}
+
+void pci_rcec_init(struct pci_dev *dev)
+{
+	struct rcec_ea *rcec_ea;
+	u32 rcec, hdr, busn;
+	u8 ver;
+
+	/* Only for Root Complex Event Collectors */
+	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC)
+		return;
+
+	rcec = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_RCEC);
+	if (!rcec)
+		return;
+
+	rcec_ea = kzalloc(sizeof(*rcec_ea), GFP_KERNEL);
+	if (!rcec_ea)
+		return;
+
+	pci_read_config_dword(dev, rcec + PCI_RCEC_RCIEP_BITMAP,
+			      &rcec_ea->bitmap);
+
+	/* Check whether RCEC BUSN register is present */
+	pci_read_config_dword(dev, rcec, &hdr);
+	ver = PCI_EXT_CAP_VER(hdr);
+	if (ver >= PCI_RCEC_BUSN_REG_VER) {
+		pci_read_config_dword(dev, rcec + PCI_RCEC_BUSN, &busn);
+		rcec_ea->nextbusn = PCI_RCEC_BUSN_NEXT(busn);
+		rcec_ea->lastbusn = PCI_RCEC_BUSN_LAST(busn);
+	} else {
+		/* Avoid later ver check by setting nextbusn */
+		rcec_ea->nextbusn = 0xff;
+		rcec_ea->lastbusn = 0x00;
+	}
+
+	dev->rcec_ea = rcec_ea;
+}
+
+void pci_rcec_exit(struct pci_dev *dev)
+{
+	kfree(dev->rcec_ea);
+	dev->rcec_ea = NULL;
+}