Function nexus_alloc_resource

freebsd/arm64/arm64/nexus.c:217–273

* Allocate a resource on behalf of child. NB: child is usually going to be a * child of one of our descendants, not a direct child of nexus0. * (Exceptions include footbridge.) */

 * (Exceptions include footbridge.)
 */
static struct resource *
nexus_alloc_resource(device_t bus, device_t child, int type, int *rid,
    rman_res_t start, rman_res_t end, rman_res_t count, u_int flags)
{
	struct nexus_device *ndev = DEVTONX(child);
	struct resource *rv;
	struct resource_list_entry *rle;
	struct rman *rm;
	int needactivate = flags & RF_ACTIVE;

	/*
	 * If this is an allocation of the "default" range for a given
	 * RID, and we know what the resources for this device are
	 * (ie. they aren't maintained by a child bus), then work out
	 * the start/end values.
	 */
	if (RMAN_IS_DEFAULT_RANGE(start, end) && (count == 1)) {
		if (device_get_parent(child) != bus || ndev == NULL)
			return(NULL);
		rle = resource_list_find(&ndev->nx_resources, type, *rid);
		if (rle == NULL)
			return(NULL);
		start = rle->start;
		end = rle->end;
		count = rle->count;
	}

	switch (type) {
	case SYS_RES_IRQ:
		rm = &irq_rman;
		break;

	case SYS_RES_MEMORY:
	case SYS_RES_IOPORT:
		rm = &mem_rman;
		break;

	default:
		return (NULL);
	}

	rv = rman_reserve_resource(rm, start, end, count, flags, child);
	if (rv == NULL)
		return (NULL);

	rman_set_rid(rv, *rid);
	rman_set_bushandle(rv, rman_get_start(rv));

	if (needactivate) {
		if (bus_activate_resource(child, type, *rid, rv)) {
			rman_release_resource(rv);
			return (NULL);
		}
	}

	return (rv);
}