1 files changed, 66 insertions, 7 deletions

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 458133f3c020..0b625272f3ca 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1074,16 +1074,75 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
 	pnv_ioda_link_pe_by_weight(phb, pe);
 }
 
-static void pnv_ioda_setup_dev_PEs(struct pci_bus *bus)
+static struct pnv_ioda_pe *pnv_ioda_setup_npu_PE(struct pci_dev *npu_pdev)
+{
+	int pe_num, found_pe = false, rc;
+	long rid;
+	struct pnv_ioda_pe *pe;
+	struct pci_dev *gpu_pdev;
+	struct pci_dn *npu_pdn;
+	struct pci_controller *hose = pci_bus_to_host(npu_pdev->bus);
+	struct pnv_phb *phb = hose->private_data;
+
+	/*
+	 * Due to a hardware errata PE#0 on the NPU is reserved for
+	 * error handling. This means we only have three PEs remaining
+	 * which need to be assigned to four links, implying some
+	 * links must share PEs.
+	 *
+	 * To achieve this we assign PEs such that NPUs linking the
+	 * same GPU get assigned the same PE.
+	 */
+	gpu_pdev = pnv_pci_get_gpu_dev(npu_pdev);
+	for (pe_num = 0; pe_num < phb->ioda.total_pe; pe_num++) {
+		pe = &phb->ioda.pe_array[pe_num];
+		if (!pe->pdev)
+			continue;
+
+		if (pnv_pci_get_gpu_dev(pe->pdev) == gpu_pdev) {
+			/*
+			 * This device has the same peer GPU so should
+			 * be assigned the same PE as the existing
+			 * peer NPU.
+			 */
+			dev_info(&npu_pdev->dev,
+				"Associating to existing PE %d\n", pe_num);
+			pci_dev_get(npu_pdev);
+			npu_pdn = pci_get_pdn(npu_pdev);
+			rid = npu_pdev->bus->number << 8 | npu_pdn->devfn;
+			npu_pdn->pcidev = npu_pdev;
+			npu_pdn->pe_number = pe_num;
+			pe->dma_weight += pnv_ioda_dma_weight(npu_pdev);
+			phb->ioda.pe_rmap[rid] = pe->pe_number;
+
+			/* Map the PE to this link */
+			rc = opal_pci_set_pe(phb->opal_id, pe_num, rid,
+					OpalPciBusAll,
+					OPAL_COMPARE_RID_DEVICE_NUMBER,
+					OPAL_COMPARE_RID_FUNCTION_NUMBER,
+					OPAL_MAP_PE);
+			WARN_ON(rc != OPAL_SUCCESS);
+			found_pe = true;
+			break;
+		}
+	}
+
+	if (!found_pe)
+		/*
+		 * Could not find an existing PE so allocate a new
+		 * one.
+		 */
+		return pnv_ioda_setup_dev_PE(npu_pdev);
+	else
+		return pe;
+}
+
+static void pnv_ioda_setup_npu_PEs(struct pci_bus *bus)
 {
-	struct pci_bus *child;
 	struct pci_dev *pdev;
 
 	list_for_each_entry(pdev, &bus->devices, bus_list)
-		pnv_ioda_setup_dev_PE(pdev);
-
-	list_for_each_entry(child, &bus->children, node)
-		pnv_ioda_setup_dev_PEs(child);
+		pnv_ioda_setup_npu_PE(pdev);
 }
 
 static void pnv_ioda_setup_PEs(struct pci_bus *bus)
@@ -1128,7 +1187,7 @@ static void pnv_pci_ioda_setup_PEs(void)
 		 * remaining types of PHBs.
 		 */
 		if (phb->type == PNV_PHB_NPU)
-			pnv_ioda_setup_dev_PEs(hose->bus);
+			pnv_ioda_setup_npu_PEs(hose->bus);
 		else
 			pnv_ioda_setup_PEs(hose->bus);
 	}