Merge branch 'drm-intel-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ickle...

[linux-beck.git] / drivers / pci / bus.c

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 7f0af0e9b826dafa2e64d8302c130ea87e5af00b..003170ea2e394193bdcb7af4033a98bca9d46127 100644 (file)
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -64,6 +64,77 @@ void pci_bus_remove_resources(struct pci_bus *bus)
        }
 }
 
+static bool pci_bus_resource_better(struct resource *res1, bool pos1,
+                                   struct resource *res2, bool pos2)
+{
+       /* If exactly one is positive decode, always prefer that one */
+       if (pos1 != pos2)
+               return pos1 ? true : false;
+
+       /* Prefer the one that contains the highest address */
+       if (res1->end != res2->end)
+               return (res1->end > res2->end) ? true : false;
+
+       /* Otherwise, prefer the one with highest "center of gravity" */
+       if (res1->start != res2->start)
+               return (res1->start > res2->start) ? true : false;
+
+       /* Otherwise, choose one arbitrarily (but consistently) */
+       return (res1 > res2) ? true : false;
+}
+
+static bool pci_bus_resource_positive(struct pci_bus *bus, struct resource *res)
+{
+       struct pci_bus_resource *bus_res;
+
+       /*
+        * This relies on the fact that pci_bus.resource[] refers to P2P or
+        * CardBus bridge base/limit registers, which are always positively
+        * decoded.  The pci_bus.resources list contains host bridge or
+        * subtractively decoded resources.
+        */
+       list_for_each_entry(bus_res, &bus->resources, list) {
+               if (bus_res->res == res)
+                       return (bus_res->flags & PCI_SUBTRACTIVE_DECODE) ?
+                               false : true;
+       }
+       return true;
+}
+
+/*
+ * Find the next-best bus resource after the cursor "res".  If the cursor is
+ * NULL, return the best resource.  "Best" means that we prefer positive
+ * decode regions over subtractive decode, then those at higher addresses.
+ */
+static struct resource *pci_bus_find_resource_prev(struct pci_bus *bus,
+                                                  unsigned int type,
+                                                  struct resource *res)
+{
+       bool res_pos, r_pos, prev_pos = false;
+       struct resource *r, *prev = NULL;
+       int i;
+
+       res_pos = pci_bus_resource_positive(bus, res);
+       pci_bus_for_each_resource(bus, r, i) {
+               if (!r)
+                       continue;
+
+               if ((r->flags & IORESOURCE_TYPE_BITS) != type)
+                       continue;
+
+               r_pos = pci_bus_resource_positive(bus, r);
+               if (!res || pci_bus_resource_better(res, res_pos, r, r_pos)) {
+                       if (!prev || pci_bus_resource_better(r, r_pos,
+                                                            prev, prev_pos)) {
+                               prev = r;
+                               prev_pos = r_pos;
+                       }
+               }
+       }
+
+       return prev;
+}
+
 /**
  * pci_bus_alloc_resource - allocate a resource from a parent bus
  * @bus: PCI bus
@@ -89,9 +160,10 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
                                          resource_size_t),
                void *alignf_data)
 {
-       int i, ret = -ENOMEM;
+       int ret = -ENOMEM;
        struct resource *r;
        resource_size_t max = -1;
+       unsigned int type = res->flags & IORESOURCE_TYPE_BITS;
 
        type_mask |= IORESOURCE_IO | IORESOURCE_MEM;
 
@@ -99,10 +171,9 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
        if (!(res->flags & IORESOURCE_MEM_64))
                max = PCIBIOS_MAX_MEM_32;
 
-       pci_bus_for_each_resource(bus, r, i) {
-               if (!r)
-                       continue;
-
+       /* Look for space at highest addresses first */
+       r = pci_bus_find_resource_prev(bus, type, NULL);
+       for ( ; r; r = pci_bus_find_resource_prev(bus, type, r)) {
                /* type_mask must match */
                if ((res->flags ^ r->flags) & type_mask)
                        continue;
@@ -299,6 +370,7 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
        }
        up_read(&pci_bus_sem);
 }
+EXPORT_SYMBOL_GPL(pci_walk_bus);
 
 EXPORT_SYMBOL(pci_bus_alloc_resource);
 EXPORT_SYMBOL_GPL(pci_bus_add_device);