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of/pci: Add pci_get_new_domain_nr() and of_get_pci_domain_nr()

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Add pci_get_new_domain_nr() to allocate a new domain number and
of_get_pci_domain_nr() to retrieve the PCI domain number of a given device
from DT.  Host bridge drivers or architecture-specific code can choose to
implement their PCI domain number policy using these two functions.

Using of_get_pci_domain_nr() guarantees a stable PCI domain number on every
boot provided that all host bridge controllers are assigned a number in the
device tree using "linux,pci-domain" property.  Mixing use of
pci_get_new_domain_nr() and of_get_pci_domain_nr() is not recommended as it
can lead to potentially conflicting domain numbers being assigned to root
buses behind different host bridges.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Grant Likely <grant.likely@linaro.org>
CC: Rob Herring <robh+dt@kernel.org>
CC: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Liviu Dudau 2014-09-29 15:29:27 +01:00 • committed by Bjorn Helgaas
parent 670ba0c888
commit 41e5c0f81d
4 changed files with 44 additions and 0 deletions
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25
drivers/of/of_pci.c
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@ -89,6 +89,31 @@ int of_pci_parse_bus_range(struct device_node *node, struct resource *res)
}
EXPORT_SYMBOL_GPL(of_pci_parse_bus_range);
/**
* This function will try to obtain the host bridge domain number by
* finding a property called "linux,pci-domain" of the given device node.
*
* @node: device tree node with the domain information
*
* Returns the associated domain number from DT in the range [0-0xffff], or
* a negative value if the required property is not found.
*/
int of_get_pci_domain_nr(struct device_node *node)
{
const __be32 *value;
int len;
u16 domain;
value = of_get_property(node, "linux,pci-domain", &len);
if (!value || len < sizeof(*value))
return -EINVAL;
domain = (u16)be32_to_cpup(value);
return domain;
}
EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
#ifdef CONFIG_PCI_MSI
static LIST_HEAD(of_pci_msi_chip_list);