From 20ce0c247b2500cb7060cb115274ba71abda2626 Mon Sep 17 00:00:00 2001 From: Krishna Kumar Date: Mon, 1 Jul 2024 13:15:07 +0530 Subject: powerpc/pci: Hotplug driver bridge support There is an issue with the hotplug operation when it's done on the bridge/switch slot. The bridge-port and devices behind the bridge, which become offline by hot-unplug operation, don't get hot-plugged/enabled by doing hot-plug operation on that slot. Only the first port of the bridge gets enabled and the remaining port/devices remain unplugged. The hot plug/unplug operation is done by the hotplug driver (drivers/pci/ hotplug/pnv_php.c). This behavior is due to missing code for the switch/bridge. The existing driver depends on pci_hp_add_devices() function for device enablement. This function calls pci_scan_slot() on only one device-node/port of the bridge, not on all the siblings' device-node/port. The missing code needs to be added which will find all the sibling device-nodes/bridge-ports and will run explicit pci_scan_slot() on those. A new function has been added for this purpose which is invoked from pci_hp_add_devices(). This new function traverse_siblings_and_scan_slot() gets all the sibling bridge-ports by traversal and explicitly invokes pci_scan_slot() on them. Tested-by: Shawn Anastasio Signed-off-by: Krishna Kumar [mpe: Move the code into pci-hotplug.c] Signed-off-by: Michael Ellerman Link: https://msgid.link/20240701074513.94873-3-krishnak@linux.ibm.com --- arch/powerpc/kernel/pci-hotplug.c | 35 ++++++++++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c index 0fe251c6ac2c..9ea74973d78d 100644 --- a/arch/powerpc/kernel/pci-hotplug.c +++ b/arch/powerpc/kernel/pci-hotplug.c @@ -93,6 +93,36 @@ void pci_hp_remove_devices(struct pci_bus *bus) } EXPORT_SYMBOL_GPL(pci_hp_remove_devices); +static void traverse_siblings_and_scan_slot(struct device_node *start, struct pci_bus *bus) +{ + struct device_node *dn; + int slotno; + + u32 class = 0; + + if (!of_property_read_u32(start->child, "class-code", &class)) { + /* Call of pci_scan_slot for non-bridge/EP case */ + if (!((class >> 8) == PCI_CLASS_BRIDGE_PCI)) { + slotno = PCI_SLOT(PCI_DN(start->child)->devfn); + pci_scan_slot(bus, PCI_DEVFN(slotno, 0)); + return; + } + } + + /* Iterate all siblings */ + for_each_child_of_node(start, dn) { + class = 0; + + if (!of_property_read_u32(start->child, "class-code", &class)) { + /* Call of pci_scan_slot on each sibling-nodes/bridge-ports */ + if ((class >> 8) == PCI_CLASS_BRIDGE_PCI) { + slotno = PCI_SLOT(PCI_DN(dn)->devfn); + pci_scan_slot(bus, PCI_DEVFN(slotno, 0)); + } + } + } +} + /** * pci_hp_add_devices - adds new pci devices to bus * @bus: the indicated PCI bus @@ -106,7 +136,7 @@ EXPORT_SYMBOL_GPL(pci_hp_remove_devices); */ void pci_hp_add_devices(struct pci_bus *bus) { - int slotno, mode, max; + int mode, max; struct pci_dev *dev; struct pci_controller *phb; struct device_node *dn = pci_bus_to_OF_node(bus); @@ -129,8 +159,7 @@ void pci_hp_add_devices(struct pci_bus *bus) * order for fully rescan all the way down to pick them up. * They can have been removed during partial hotplug. */ - slotno = PCI_SLOT(PCI_DN(dn->child)->devfn); - pci_scan_slot(bus, PCI_DEVFN(slotno, 0)); + traverse_siblings_and_scan_slot(dn, bus); max = bus->busn_res.start; /* * Scan bridges that are already configured. We don't touch -- cgit v1.2.3