Commit 15d82ca2 authored by Boqun Feng's avatar Boqun Feng Committed by Lorenzo Pieralisi
Browse files

PCI: Introduce domain_nr in pci_host_bridge 

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: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent e73f0f0e

drivers/pci/probe.c

+5 −1
Original line number Diff line number Diff line
@@ -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

	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);

include/linux/pci.h

+11 −0
Original line number Diff line number Diff line
@@ -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 */