Function device_find_child

freebsd/kern/subr_bus.c:2015–2037

* @brief Find a device given a unit number * * This is similar to devclass_get_devices() but only searches for * devices which have @p dev as a parent. * * @param dev the parent device to search * @param unit the unit number to search for. If the unit is -1, * return the first child of @p dev which has name * @p classname (that is, the one with the lowest unit.) * * @returns the

 *			NULL if there is no such device
 */
device_t
device_find_child(device_t dev, const char *classname, int unit)
{
	devclass_t dc;
	device_t child;

	dc = devclass_find(classname);
	if (!dc)
		return (NULL);

	if (unit != -1) {
		child = devclass_get_device(dc, unit);
		if (child && child->parent == dev)
			return (child);
	} else {
		for (unit = 0; unit < devclass_get_maxunit(dc); unit++) {
			child = devclass_get_device(dc, unit);
			if (child && child->parent == dev)
				return (child);
		}
	}
	return (NULL);
}

/**
 * @internal