npu2-opencapi: Train OpenCAPI links and setup devices

Scan the OpenCAPI links under the NPU, and for each link, reset the card,
set up a device, train the link and register a PHB.

Implement the necessary operations for the OpenCAPI PHB type.

For bringup, test and debug purposes, we allow an NVRAM setting,
"opencapi-link-training" that can be set to either disable link training
completely or to use the prbs31 test pattern.

To disable link training:

    nvram -p ibm,skiboot --update-config opencapi-link-training=none

To use prbs31:

    nvram -p ibm,skiboot --update-config opencapi-link-training=prbs31

Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

core/pci.c

@@ -1549,7 +1549,8 @@ static void pci_add_one_device_node(struct phb *phb,
 	pd->dn = np = dt_new(parent_node, name);
 
 	/* XXX FIXME: make proper "compatible" properties */
-	if (pci_has_cap(pd, PCI_CFG_CAP_ID_EXP, false)) {
+	if (pci_has_cap(pd, PCI_CFG_CAP_ID_EXP, false) ||
+		phb->phb_type == phb_type_npu_v2_opencapi) {
 		snprintf(compat, MAX_NAME, "pciex%x,%x",
 			 vdid & 0xffff, vdid >> 16);
 		dt_add_property_cells(np, "ibm,pci-config-space-type", 1);