[PATCH v6 06/10] PCI/RCEC: Add pcie_link_rcec() to associate RCiEPs

[Sean V Kelley <seanvk.dev@oregontracks.org>]

From: Sean V Kelley <sean.v.kelley@intel.com>

A Root Complex Event Collector provides support for
terminating error and PME messages from associated RCiEPs.

Make use of 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>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
---
 drivers/pci/pci.h              |  2 +
 drivers/pci/pcie/portdrv_pci.c |  3 ++
 drivers/pci/pcie/rcec.c        | 96 ++++++++++++++++++++++++++++++++++
 include/linux/pci.h            |  1 +
 4 files changed, 102 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 7b547fc3679a..ddb5872466fb 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -474,9 +474,11 @@ 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
diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index 4d880679b9b1..dbeb0155c2c3 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -110,6 +110,9 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
 	     (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC)))
 		return -ENODEV;
 
+	if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC)
+		pcie_link_rcec(dev);
+
 	status = pcie_port_device_register(dev);
 	if (status)
 		return status;
diff --git a/drivers/pci/pcie/rcec.c b/drivers/pci/pcie/rcec.c
index 519ae086ff41..5630480a6659 100644
--- a/drivers/pci/pcie/rcec.c
+++ b/drivers/pci/pcie/rcec.c
@@ -17,6 +17,102 @@
 
 #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_ext->bitmap;
+	unsigned int devn;
+
+	/* An RCiEP found on 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 reported via %s\n", pci_name(rcec));
+	}
+
+	return 0;
+}
+
+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_cap)
+		return;
+
+	/* Walk own bus for bitmap based association */
+	pci_walk_bus(rcec->bus, cb, rcec_data);
+
+	/* Check whether RCEC BUSN register is present */
+	if (rcec->rcec_ext->ver < PCI_RCEC_BUSN_REG_VER)
+		return;
+
+	nextbusn = rcec->rcec_ext->nextbusn;
+	lastbusn = rcec->rcec_ext->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 associating 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_cap)
+		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)
 {
 	u32 rcec, hdr, busn;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5c5c4eb642b6..ad382a9484ea 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -330,6 +330,7 @@ struct pci_dev {
 #ifdef CONFIG_PCIEPORTBUS
 	u16		rcec_cap;	/* RCEC capability offset */
 	struct rcec_ext *rcec_ext;	/* RCEC cached assoc. endpoint extended capabilities */
+	struct pci_dev  *rcec;          /* Associated RCEC device */
 #endif
 	u8		pcie_cap;	/* PCIe capability offset */
 	u8		msi_cap;	/* MSI capability offset */
-- 
2.28.0