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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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9d987eba8e
The current scanning code is really hard to understand because it calls the
same function in a loop where pass value is changed without any comments
explaining it:
for (pass = 0; pass < 2; pass++)
for_each_pci_bridge(dev, bus)
max = pci_scan_bridge(bus, dev, max, pass);
Unfamiliar reader cannot tell easily what is the purpose of this loop
without looking at internals of pci_scan_bridge().
In order to make this bit easier to understand, open-code the loop in
pci_scan_child_bus() and pci_hp_add_bridge() with added comments.
No functional changes intended.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
151 lines
4.2 KiB
C
151 lines
4.2 KiB
C
/*
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* Derived from "arch/powerpc/platforms/pseries/pci_dlpar.c"
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*
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* Copyright (C) 2003 Linda Xie <lxie@us.ibm.com>
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* Copyright (C) 2005 International Business Machines
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*
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* Updates, 2005, John Rose <johnrose@austin.ibm.com>
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* Updates, 2005, Linas Vepstas <linas@austin.ibm.com>
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* Updates, 2013, Gavin Shan <shangw@linux.vnet.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/pci.h>
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#include <linux/export.h>
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#include <asm/pci-bridge.h>
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#include <asm/ppc-pci.h>
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#include <asm/firmware.h>
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#include <asm/eeh.h>
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static struct pci_bus *find_bus_among_children(struct pci_bus *bus,
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struct device_node *dn)
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{
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struct pci_bus *child = NULL;
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struct pci_bus *tmp;
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if (pci_bus_to_OF_node(bus) == dn)
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return bus;
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list_for_each_entry(tmp, &bus->children, node) {
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child = find_bus_among_children(tmp, dn);
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if (child)
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break;
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}
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return child;
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}
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struct pci_bus *pci_find_bus_by_node(struct device_node *dn)
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{
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struct pci_dn *pdn = PCI_DN(dn);
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if (!pdn || !pdn->phb || !pdn->phb->bus)
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return NULL;
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return find_bus_among_children(pdn->phb->bus, dn);
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}
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EXPORT_SYMBOL_GPL(pci_find_bus_by_node);
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/**
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* pcibios_release_device - release PCI device
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* @dev: PCI device
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*
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* The function is called before releasing the indicated PCI device.
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*/
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void pcibios_release_device(struct pci_dev *dev)
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{
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struct pci_controller *phb = pci_bus_to_host(dev->bus);
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eeh_remove_device(dev);
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if (phb->controller_ops.release_device)
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phb->controller_ops.release_device(dev);
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}
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/**
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* pci_hp_remove_devices - remove all devices under this bus
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* @bus: the indicated PCI bus
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*
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* Remove all of the PCI devices under this bus both from the
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* linux pci device tree, and from the powerpc EEH address cache.
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*/
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void pci_hp_remove_devices(struct pci_bus *bus)
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{
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struct pci_dev *dev, *tmp;
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struct pci_bus *child_bus;
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/* First go down child busses */
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list_for_each_entry(child_bus, &bus->children, node)
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pci_hp_remove_devices(child_bus);
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pr_debug("PCI: Removing devices on bus %04x:%02x\n",
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pci_domain_nr(bus), bus->number);
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list_for_each_entry_safe_reverse(dev, tmp, &bus->devices, bus_list) {
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pr_debug(" Removing %s...\n", pci_name(dev));
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pci_stop_and_remove_bus_device(dev);
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}
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}
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EXPORT_SYMBOL_GPL(pci_hp_remove_devices);
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/**
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* pci_hp_add_devices - adds new pci devices to bus
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* @bus: the indicated PCI bus
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*
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* This routine will find and fixup new pci devices under
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* the indicated bus. This routine presumes that there
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* might already be some devices under this bridge, so
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* it carefully tries to add only new devices. (And that
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* is how this routine differs from other, similar pcibios
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* routines.)
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*/
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void pci_hp_add_devices(struct pci_bus *bus)
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{
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int slotno, mode, max;
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struct pci_dev *dev;
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struct pci_controller *phb;
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struct device_node *dn = pci_bus_to_OF_node(bus);
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eeh_add_device_tree_early(PCI_DN(dn));
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phb = pci_bus_to_host(bus);
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mode = PCI_PROBE_NORMAL;
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if (phb->controller_ops.probe_mode)
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mode = phb->controller_ops.probe_mode(bus);
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if (mode == PCI_PROBE_DEVTREE) {
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/* use ofdt-based probe */
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of_rescan_bus(dn, bus);
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} else if (mode == PCI_PROBE_NORMAL &&
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dn->child && PCI_DN(dn->child)) {
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/*
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* Use legacy probe. In the partial hotplug case, we
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* probably have grandchildren devices unplugged. So
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* we don't check the return value from pci_scan_slot() in
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* order for fully rescan all the way down to pick them up.
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* They can have been removed during partial hotplug.
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*/
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slotno = PCI_SLOT(PCI_DN(dn->child)->devfn);
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pci_scan_slot(bus, PCI_DEVFN(slotno, 0));
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pcibios_setup_bus_devices(bus);
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max = bus->busn_res.start;
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/*
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* Scan bridges that are already configured. We don't touch
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* them unless they are misconfigured (which will be done in
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* the second scan below).
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*/
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for_each_pci_bridge(dev, bus)
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max = pci_scan_bridge(bus, dev, max, 0);
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/* Scan bridges that need to be reconfigured */
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for_each_pci_bridge(dev, bus)
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max = pci_scan_bridge(bus, dev, max, 1);
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}
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pcibios_finish_adding_to_bus(bus);
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}
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EXPORT_SYMBOL_GPL(pci_hp_add_devices);
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