+/*
+ * This function should run under locking protection, specifically
+ * hose_spinlock.
+ */
+static int get_phb_number(struct device_node *dn)
+{
+ int ret, phb_id = -1;
+ u64 prop;
+
+ /*
+ * Try fixed PHB numbering first, by checking archs and reading
+ * the respective device-tree properties. Firstly, try powernv by
+ * reading "ibm,opal-phbid", only present in OPAL environment.
+ */
+ ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop);
+ if (ret)
+ ret = of_property_read_u32_index(dn, "reg", 1, (u32 *)&prop);
+
+ if (!ret)
+ phb_id = (int)(prop & (MAX_PHBS - 1));
+
+ /* We need to be sure to not use the same PHB number twice. */
+ if ((phb_id >= 0) && !test_and_set_bit(phb_id, phb_bitmap))
+ return phb_id;
+
+ /*
+ * If not pseries nor powernv, or if fixed PHB numbering tried to add
+ * the same PHB number twice, then fallback to dynamic PHB numbering.
+ */
+ phb_id = find_first_zero_bit(phb_bitmap, MAX_PHBS);
+ BUG_ON(phb_id >= MAX_PHBS);
+ set_bit(phb_id, phb_bitmap);
+
+ return phb_id;
+}
+