src/device/resource_allocator_common.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <device/device.h>
   4 #include <stddef.h>
   5
   6 struct pick_largest_state {
   7         struct resource *last;
   8         const struct device *result_dev;
   9         struct resource *result;
  10         int seen_last;
  11 };
  12
  13 static void pick_largest_resource(void *gp, struct device *dev,
  14                                   struct resource *resource)
  15 {
  16         struct pick_largest_state *state = gp;
  17         struct resource *last;
  18
  19         last = state->last;
  20
  21         /* Be certain to pick the successor to last. */
  22         if (resource == last) {
  23                 state->seen_last = 1;
  24                 return;
  25         }
  26         if (resource->flags & IORESOURCE_FIXED)
  27                 return; /* Skip it. */
  28         if (last && ((last->align < resource->align) ||
  29                      ((last->align == resource->align) &&
  30                       (last->size < resource->size)) ||
  31                      ((last->align == resource->align) &&
  32                       (last->size == resource->size) && (!state->seen_last)))) {
  33                 return;
  34         }
  35         if (!state->result ||
  36             (state->result->align < resource->align) ||
  37             ((state->result->align == resource->align) &&
  38              (state->result->size < resource->size))) {
  39                 state->result_dev = dev;
  40                 state->result = resource;
  41         }
  42 }
  43
  44 const struct device *largest_resource(struct bus *bus,
  45                                       struct resource **result_res,
  46                                       unsigned long type_mask,
  47                                       unsigned long type)
  48 {
  49         struct pick_largest_state state;
  50
  51         state.last = *result_res;
  52         state.result_dev = NULL;
  53         state.result = NULL;
  54         state.seen_last = 0;
  55
  56         search_bus_resources(bus, type_mask, type, pick_largest_resource,
  57                              &state);
  58
  59         *result_res = state.result;
  60         return state.result_dev;
  61 }