1 files changed, 49 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index cab05f31223f..c419554d0b4b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -10,6 +10,8 @@
 #include <linux/kernel.h>
 #include <linux/delay.h>
 #include <linux/init.h>
+#include <linux/of.h>
+#include <linux/of_pci.h>
 #include <linux/pci.h>
 #include <linux/pm.h>
 #include <linux/slab.h>
@@ -4439,6 +4441,53 @@ int pci_get_new_domain_nr(void)
 {
         return atomic_inc_return(&__domain_nr);
 }
+
+#ifdef CONFIG_PCI_DOMAINS_GENERIC
+void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
+{
+        static int use_dt_domains = -1;
+        int domain = of_get_pci_domain_nr(parent->of_node);
+
+        /*
+         * Check DT domain and use_dt_domains values.
+         *
+         * If DT domain property is valid (domain >= 0) and
+         * use_dt_domains != 0, the DT assignment is valid since this means
+         * we have not previously allocated a domain number by using
+         * pci_get_new_domain_nr(); we should also update use_dt_domains to
+         * 1, to indicate that we have just assigned a domain number from
+         * DT.
+         *
+         * If DT domain property value is not valid (ie domain < 0), and we
+         * have not previously assigned a domain number from DT
+         * (use_dt_domains != 1) we should assign a domain number by
+         * using the:
+         *
+         * pci_get_new_domain_nr()
+         *
+         * API and update the use_dt_domains value to keep track of method we
+         * are using to assign domain numbers (use_dt_domains = 0).
+         *
+         * All other combinations imply we have a platform that is trying
+         * to mix domain numbers obtained from DT and pci_get_new_domain_nr(),
+         * which is a recipe for domain mishandling and it is prevented by
+         * invalidating the domain value (domain = -1) and printing a
+         * corresponding error.
+         */
+        if (domain >= 0 && use_dt_domains) {
+                use_dt_domains = 1;
+        } else if (domain < 0 && use_dt_domains != 1) {
+                use_dt_domains = 0;
+                domain = pci_get_new_domain_nr();
+        } else {
+                dev_err(parent, "Node %s has inconsistent \"linux,pci-domain\" property in DT\n",
+                        parent->of_node->full_name);
+                domain = -1;
+        }
+
+        bus->domain_nr = domain;
+}
+#endif
 #endif
 
 /**