[PATCH v3 04/10] PCI/RCEC: Add pcie_walk_rcec() to walk associated RCiEPs

[Sean V Kelley]

From: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>

When an RCEC device signals error(s) to a CPU core, the CPU core
needs to walk all the RCiEPs associated with that RCEC to check
errors. So add the function pcie_walk_rcec() to walk all RCiEPs
associated with the RCEC device.

Co-developed-by: Sean V Kelley <sean.v.kelley@xxxxxxxxx>
Signed-off-by: Sean V Kelley <sean.v.kelley@xxxxxxxxx>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
---
 drivers/pci/pci.h       |  4 +++
 drivers/pci/pcie/rcec.c | 76 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index bd25e6047b54..8bd7528d6977 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -473,9 +473,13 @@ 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_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
+		    void *userdata);
 #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_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
+				  void *userdata) {}
 #endif
 
 #ifdef CONFIG_PCI_ATS
diff --git a/drivers/pci/pcie/rcec.c b/drivers/pci/pcie/rcec.c
index 519ae086ff41..405f92fcdf7f 100644
--- a/drivers/pci/pcie/rcec.c
+++ b/drivers/pci/pcie/rcec.c
@@ -17,6 +17,82 @@
 
 #include "../pci.h"
 
+static int pcie_walk_rciep_devfn(struct pci_bus *bus, int (*cb)(struct pci_dev *, void *),
+				 void *userdata, const unsigned long bitmap)
+{
+	unsigned int devn, fn;
+	struct pci_dev *dev;
+	int retval;
+
+	for_each_set_bit(devn, &bitmap, 32) {
+		for (fn = 0; fn < 8; fn++) {
+			dev = pci_get_slot(bus, PCI_DEVFN(devn, fn));
+
+			if (!dev)
+				continue;
+
+			if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END) {
+				pci_dev_put(dev);
+				continue;
+			}
+
+			retval = cb(dev, userdata);
+			pci_dev_put(dev);
+			if (retval)
+				return retval;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * 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 provided callback on each RCiEP device found.
+ *
+ * We check the return of @cb each time. If it returns anything
+ * other than 0, we break out.
+ */
+void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
+		    void *userdata)
+{
+	u8 nextbusn, lastbusn;
+	struct pci_bus *bus;
+	unsigned int bnr;
+
+	if (!rcec->rcec_cap)
+		return;
+
+	/* Find RCiEP devices on the same bus as the RCEC */
+	if (pcie_walk_rciep_devfn(rcec->bus, cb, userdata, rcec->rcec_ext->bitmap))
+		return;
+
+	/* 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++) {
+		bus = pci_find_bus(pci_domain_nr(rcec->bus), bnr);
+		if (!bus)
+			continue;
+
+		/* Find RCiEP devices on the given bus */
+		if (pcie_walk_rciep_devfn(bus, cb, userdata, 0xffffffff))
+			return;
+	}
+}
+
 void pci_rcec_init(struct pci_dev *dev)
 {
 	u32 rcec, hdr, busn;
-- 
2.28.0