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. Mix 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 busses behind different
host bridges.
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
---
drivers/of/of_pci.c | 25 +++++++++++++++++++++++++
drivers/pci/pci.c | 9 +++++++++
include/linux/of_pci.h | 7 +++++++
include/linux/pci.h | 3 +++
4 files changed, 44 insertions(+)
diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 8481996..82d172f 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -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);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2c9ac70..d36f35f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4406,6 +4406,15 @@ static void pci_no_domains(void)
#endif
}
+#ifdef CONFIG_PCI_DOMAINS
+static atomic_t __domain_nr = ATOMIC_INIT(-1);
+
+int pci_get_new_domain_nr(void)
+{
+ return atomic_inc_return(&__domain_nr);
+}
+#endif
+
/**
* pci_ext_cfg_avail - can we access extended PCI config space?
*
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index dde3a4a..71062e9 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -15,6 +15,7 @@ struct device_node *of_pci_find_child_device(struct device_node *parent,
int of_pci_get_devfn(struct device_node *np);
int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
+int of_get_pci_domain_nr(struct device_node *node);
#else
static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
{
@@ -43,6 +44,12 @@ of_pci_parse_bus_range(struct device_node *node, struct resource *res)
{
return -EINVAL;
}
+
+static inline int
+of_get_pci_domain_nr(struct device_node *node)
+{
+ return -1;
+}
#endif
#if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index a494e5d..150da2d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1285,10 +1285,12 @@ void pci_cfg_access_unlock(struct pci_dev *dev);
*/
#ifdef CONFIG_PCI_DOMAINS
extern int pci_domains_supported;
+int pci_get_new_domain_nr(void);
#else
enum { pci_domains_supported = 0 };
static inline int pci_domain_nr(struct pci_bus *bus) { return 0; }
static inline int pci_proc_domain(struct pci_bus *bus) { return 0; }
+static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
#endif /* CONFIG_PCI_DOMAINS */
/*
@@ -1417,6 +1419,7 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
static inline int pci_domain_nr(struct pci_bus *bus) { return 0; }
static inline struct pci_dev *pci_dev_get(struct pci_dev *dev) { return NULL; }
+static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
#define dev_is_pci(d) (false)
#define dev_is_pf(d) (false)
--
2.1.0
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