[PATCH v6 4/5] powerpc/powernv/pci: Hook up the writes to PCI_SECONDARY_BUS register

[Sergey Miroshnichenko <s.miroshnichenko@yadro.com>]

Writing a new value to the PCI_SECONDARY_BUS register of the bridge means
that its children will become addressable on another address (new B in BDF)
or even un-addressable if the secondary bus is set to zero.

On PowerNV, device PEs are heavily BDF-dependent, so they must be updated
on every such change of its address.

Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
---
 arch/powerpc/platforms/powernv/pci.c | 118 ++++++++++++++++++++++++++-
 1 file changed, 116 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index a5b04410c8b4..e9b4ed0f97a3 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -717,13 +717,127 @@ int pnv_pci_cfg_read(struct pci_dn *pdn,
 				    where, size, val);
 }
 
+static void invalidate_children_pes(struct pci_dn *pdn)
+{
+	struct pnv_phb *phb = pdn->phb->private_data;
+	struct pci_dn *child;
+	bool found_pe = false;
+	int pe_num;
+	int pe_bus;
+
+	list_for_each_entry(child, &pdn->child_list, list) {
+		struct pnv_ioda_pe *pe = (child->pe_number != IODA_INVALID_PE) ?
+			&phb->ioda.pe_array[child->pe_number] :
+			NULL;
+
+		if (!child->busno)
+			continue;
+
+		if ((child->class_code >> 8) == PCI_CLASS_BRIDGE_PCI)
+			invalidate_children_pes(child);
+
+		if (pe) {
+			u8 rid_bus = (pe->rid >> 8) & 0xff;
+
+			if (rid_bus) {
+				pe_num = child->pe_number;
+				pe_bus = rid_bus;
+				found_pe = true;
+			}
+
+			pe->rid &= 0xff;
+		}
+
+		child->busno = 0;
+	}
+
+	if (found_pe) {
+		u16 rid = pe_bus << 8;
+
+		opal_pci_set_pe(phb->opal_id, pe_num, rid, 7, 0, 0, OPAL_UNMAP_PE);
+	}
+}
+
+static u8 pre_hook_new_sec_bus(struct pci_dn *pdn, u8 new_secondary_bus)
+{
+	u32 old_secondary_bus = 0;
+
+	if ((pdn->class_code >> 8) != PCI_CLASS_BRIDGE_PCI)
+		return 0;
+
+	pnv_pci_cfg_read(pdn, PCI_SECONDARY_BUS, 1, &old_secondary_bus);
+	old_secondary_bus &= 0xff;
+
+	if (old_secondary_bus != new_secondary_bus)
+		invalidate_children_pes(pdn);
+
+	return old_secondary_bus;
+}
+
+static void update_children_pes(struct pci_dn *pdn, u8 new_secondary_bus)
+{
+	struct pnv_phb *phb = pdn->phb->private_data;
+	struct pci_dn *child;
+	bool found_pe = false;
+	int pe_num;
+
+	if (!new_secondary_bus)
+		return;
+
+	list_for_each_entry(child, &pdn->child_list, list) {
+		struct pnv_ioda_pe *pe = (child->pe_number != IODA_INVALID_PE) ?
+			&phb->ioda.pe_array[child->pe_number] :
+			NULL;
+
+		if (child->busno)
+			continue;
+
+		child->busno = new_secondary_bus;
+
+		if (pe) {
+			pe->rid |= (child->busno << 8);
+			pe_num = child->pe_number;
+			found_pe = true;
+		}
+	}
+
+	if (found_pe) {
+		u16 rid = new_secondary_bus << 8;
+
+		opal_pci_set_pe(phb->opal_id, pe_num, rid, 7, 0, 0, OPAL_MAP_PE);
+	}
+}
+
+static void post_hook_new_sec_bus(struct pci_dn *pdn, u8 new_secondary_bus)
+{
+	if ((pdn->class_code >> 8) != PCI_CLASS_BRIDGE_PCI)
+		return;
+
+	update_children_pes(pdn, new_secondary_bus);
+}
+
 int pnv_pci_cfg_write(struct pci_dn *pdn,
 		      int where, int size, u32 val)
 {
 	struct pnv_phb *phb = pdn->phb->private_data;
+	u8 old_secondary_bus = 0, new_secondary_bus = 0;
+	int rc;
+
+	if (where == PCI_SECONDARY_BUS) {
+		new_secondary_bus = val & 0xff;
+		old_secondary_bus = pre_hook_new_sec_bus(pdn, new_secondary_bus);
+	} else if (where == PCI_PRIMARY_BUS && size > 1) {
+		new_secondary_bus = (val >> 8) & 0xff;
+		old_secondary_bus = pre_hook_new_sec_bus(pdn, new_secondary_bus);
+	}
 
-	return pnv_pci_cfg_write_raw(phb->opal_id, pdn->busno, pdn->devfn,
-				     where, size, val);
+	rc = pnv_pci_cfg_write_raw(phb->opal_id, pdn->busno, pdn->devfn,
+				   where, size, val);
+
+	if (new_secondary_bus && old_secondary_bus != new_secondary_bus)
+		post_hook_new_sec_bus(pdn, new_secondary_bus);
+
+	return rc;
 }
 
 #if CONFIG_EEH
-- 
2.21.0