PCI/ERR: Add pcie_link_rcec() to associate RCiEPs

A Root Complex Event Collector terminates error and PME messages from
associated RCiEPs.

Use the RCEC Endpoint Association Extended Capability to identify
associated RCiEPs. Link the associated RCiEPs as the RCECs are enumerated.

Co-developed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Link: https://lore.kernel.org/r/20201121001036.8560-12-sean.v.kelley@intel.com
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> # non-native/no RCEC
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/pci/pci.h

@@ -472,9 +472,11 @@ static inline void pci_dpc_init(struct pci_dev *pdev) {}
 #ifdef CONFIG_PCIEPORTBUS
 void pci_rcec_init(struct pci_dev *dev);
 void pci_rcec_exit(struct pci_dev *dev);
+void pcie_link_rcec(struct pci_dev *rcec);
 #else
 static inline void pci_rcec_init(struct pci_dev *dev) {}
 static inline void pci_rcec_exit(struct pci_dev *dev) {}
+static inline void pcie_link_rcec(struct pci_dev *rcec) {}
 #endif
 
 #ifdef CONFIG_PCI_ATS

drivers/pci/pcie/portdrv_pci.c

@@ -111,6 +111,9 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
 	     (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;

drivers/pci/pcie/rcec.c

@@ -15,6 +15,100 @@
 
 #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 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);
+}
+
 void pci_rcec_init(struct pci_dev *dev)
 {
 	struct rcec_ea *rcec_ea;

include/linux/pci.h

@@ -330,6 +330,7 @@ struct pci_dev {
 #endif
 #ifdef CONFIG_PCIEPORTBUS
 	struct rcec_ea	*rcec_ea;	/* RCEC cached endpoint association */
+	struct pci_dev  *rcec;          /* Associated RCEC device */
 #endif
 	u8		pcie_cap;	/* PCIe capability offset */
 	u8		msi_cap;	/* MSI capability offset */