On 09/17/2014 08:30 PM, Liviu Dudau wrote:

Add of_pci_get_domain_nr() to retrieve the PCI domain number
of a given device from DT. If the information is not present,
the function can be requested to allocate a new domain number.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---

[...]

+/**
+ * This function will try to obtain the host bridge domain number by
+ * using of_alias_get_id() call with "pci-domain" as a stem. If that
+ * fails, a local allocator will be used. The local allocator can
+ * be requested to return a new domain_nr if the information is missing
+ * from the device tree.
+ *
+ * @node: device tree node with the domain information
+ * @allocate_if_missing: if DT lacks information about the domain nr,
+ * allocate a new number.
+ *
+ * Returns the associated domain number from DT, or a new domain number
+ * if DT information is missing and @allocate_if_missing is true. If
+ * @allocate_if_missing is false then the last allocated domain number
+ * will be returned.
+ */
+int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
+{
+	int domain;
+
+	domain = atomic_read(&of_domain_nr);
+	if (domain == -1) {
+		/* first run, get max defined domain nr in device tree */
+		domain = of_get_max_pci_domain_nr();
+		/* then set the start value for allocator to be max + 1 */
+		atomic_set(&of_domain_nr, domain + 1);

atomic_read followed by atomic_set is not an atomic operation.

As I previously said, I don't like how this function is a mixture of
data retrieval and domian # allocation. I think we need 2 functions.

+	}
+	domain = of_alias_get_id(node, "pci-domain");

I still do not like using aliases here. Just put pci-domain or
linux,pci-domain into the PCI node.

I think we should assume all PCI root buses either have a domain
property or they don't and a mixture is an error. I'm not sure if that
simplifies the code or not though.

In the interest of merging, I think you should just do a simple
allocation and add the DT domain handling as a second step. You will
also need to document the DT part.

Rob