+ while (bus->parent)
+ bus = bus->parent;
+
+ return bus;
+}
+
+static struct dca_domain *dca_allocate_domain(struct pci_bus *rc)
+{
+ struct dca_domain *domain;
+
+ domain = kzalloc(sizeof(*domain), GFP_NOWAIT);
+ if (!domain)
+ return NULL;
+
+ INIT_LIST_HEAD(&domain->dca_providers);
+ domain->pci_rc = rc;
+
+ return domain;
+}
+
+static void dca_free_domain(struct dca_domain *domain)
+{
+ list_del(&domain->node);
+ kfree(domain);
+}
+
+static struct dca_domain *dca_find_domain(struct pci_bus *rc)
+{
+ struct dca_domain *domain;
+
+ list_for_each_entry(domain, &dca_domains, node)
+ if (domain->pci_rc == rc)
+ return domain;
+
+ return NULL;
+}
+
+static struct dca_domain *dca_get_domain(struct device *dev)
+{
+ struct pci_bus *rc;
+ struct dca_domain *domain;
+
+ rc = dca_pci_rc_from_dev(dev);
+ domain = dca_find_domain(rc);
+
+ if (!domain) {
+ domain = dca_allocate_domain(rc);
+ if (domain)
+ list_add(&domain->node, &dca_domains);
+ }
+
+ return domain;
+}
+
+static struct dca_provider *dca_find_provider_by_dev(struct device *dev)
+{
+ struct dca_provider *dca;
+ struct pci_bus *rc;
+ struct dca_domain *domain;
+
+ if (dev) {
+ rc = dca_pci_rc_from_dev(dev);
+ domain = dca_find_domain(rc);
+ if (!domain)
+ return NULL;
+ } else {
+ if (!list_empty(&dca_domains))
+ domain = list_first_entry(&dca_domains,
+ struct dca_domain,
+ node);
+ else
+ return NULL;