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PCI: Introduce domain_nr in pci_host_bridge

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Currently we retrieve the PCI domain number of the host bridge from the
bus sysdata (or pci_config_window if PCI_DOMAINS_GENERIC=y). Actually
we have the information at PCI host bridge probing time, and it makes
sense that we store it into pci_host_bridge. One benefit of doing so is
the requirement for supporting PCI on Hyper-V for ARM64, because the
host bridge of Hyper-V doesn't have pci_config_window, whereas ARM64 is
a PCI_DOMAINS_GENERIC=y arch, so we cannot retrieve the PCI domain
number from pci_config_window on ARM64 Hyper-V guest.

As the preparation for ARM64 Hyper-V PCI support, we introduce the
domain_nr in pci_host_bridge and a sentinel value to allow drivers to
set domain numbers properly at probing time. Currently
CONFIG_PCI_DOMAINS_GENERIC=y archs are only users of this
newly-introduced field.

Link: https://lore.kernel.org/r/20210726180657.142727-2-boqun.feng@gmail.com
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Boqun Feng 2021-07-27 02:06:50 +08:00 committed by Lorenzo Pieralisi
parent e73f0f0ee7
commit 15d82ca23c
2 changed files with 16 additions and 1 deletions
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6
drivers/pci/probe.c
View file

@ -594,6 +594,7 @@ static void pci_init_host_bridge(struct pci_host_bridge *bridge)
bridge->native_pme = 1;
bridge->native_ltr = 1;
bridge->native_dpc = 1;
bridge->domain_nr = PCI_DOMAIN_NR_NOT_SET;
device_initialize(&bridge->dev);
}
@ -898,7 +899,10 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
bus->ops = bridge->ops;
bus->number = bus->busn_res.start = bridge->busnr;
#ifdef CONFIG_PCI_DOMAINS_GENERIC
bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
if (bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET)
bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
else
bus->domain_nr = bridge->domain_nr;
#endif
b = pci_find_bus(pci_domain_nr(bus), bridge->busnr);

11
include/linux/pci.h
View file

@ -526,6 +526,16 @@ static inline int pci_channel_offline(struct pci_dev *pdev)
return (pdev->error_state != pci_channel_io_normal);
}
/*
* Currently in ACPI spec, for each PCI host bridge, PCI Segment
* Group number is limited to a 16-bit value, therefore (int)-1 is
* not a valid PCI domain number, and can be used as a sentinel
* value indicating ->domain_nr is not set by the driver (and
* CONFIG_PCI_DOMAINS_GENERIC=y archs will set it with
* pci_bus_find_domain_nr()).
*/
#define PCI_DOMAIN_NR_NOT_SET (-1)
struct pci_host_bridge {
struct device dev;
struct pci_bus *bus; /* Root bus */
@ -533,6 +543,7 @@ struct pci_host_bridge {
struct pci_ops *child_ops;
void *sysdata;
int busnr;
int domain_nr;
struct list_head windows; /* resource_entry */
struct list_head dma_ranges; /* dma ranges resource list */
u8 (*swizzle_irq)(struct pci_dev *, u8 *); /* Platform IRQ swizzler */