powerpc/pci: Assign fixed PHB number based on device-tree properties

[platform/kernel/linux-rpi.git] / arch / powerpc / kernel / pci-common.c

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index d1f91e1..c6ac4f0 100644 (file)
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -41,11 +41,18 @@
 #include <asm/ppc-pci.h>
 #include <asm/eeh.h>
 
+/* hose_spinlock protects accesses to the the phb_bitmap. */
 static DEFINE_SPINLOCK(hose_spinlock);
 LIST_HEAD(hose_list);
 
-/* XXX kill that some day ... */
-static int global_phb_number;          /* Global phb counter */
+/* For dynamic PHB numbering on get_phb_number(): max number of PHBs. */
+#define MAX_PHBS 0x10000
+
+/*
+ * For dynamic PHB numbering: used/free PHBs tracking bitmap.
+ * Accesses to this bitmap should be protected by hose_spinlock.
+ */
+static DECLARE_BITMAP(phb_bitmap, MAX_PHBS);
 
 /* ISA Memory physical address */
 resource_size_t isa_mem_base;
@@ -64,6 +71,42 @@ struct dma_map_ops *get_pci_dma_ops(void)
 }
 EXPORT_SYMBOL(get_pci_dma_ops);
 
+/*
+ * 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;
+}
+
 struct pci_controller *pcibios_alloc_controller(struct device_node *dev)
 {
        struct pci_controller *phb;
@@ -72,7 +115,7 @@ struct pci_controller *pcibios_alloc_controller(struct device_node *dev)
        if (phb == NULL)
                return NULL;
        spin_lock(&hose_spinlock);
-       phb->global_number = global_phb_number++;
+       phb->global_number = get_phb_number(dev);
        list_add_tail(&phb->list_node, &hose_list);
        spin_unlock(&hose_spinlock);
        phb->dn = dev;
@@ -94,6 +137,11 @@ EXPORT_SYMBOL_GPL(pcibios_alloc_controller);
 void pcibios_free_controller(struct pci_controller *phb)
 {
        spin_lock(&hose_spinlock);
+
+       /* Clear bit of phb_bitmap to allow reuse of this PHB number. */
+       if (phb->global_number < MAX_PHBS)
+               clear_bit(phb->global_number, phb_bitmap);
+
        list_del(&phb->list_node);
        spin_unlock(&hose_spinlock);