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.
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
drivers/pci/probe.c | 6 +++++-
include/linux/pci.h | 11 +++++++++++
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 79177ac37880..60c50d4f156f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -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);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 540b377ca8f6..01aa201e1df0 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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 */
--
2.32.0
