Function cpufreq_expand_set

freebsd/kern/kern_cpu.c:784–838

* Expand a group of relative settings, creating derived levels from them. */

 * Expand a group of relative settings, creating derived levels from them.
 */
static int
cpufreq_expand_set(struct cpufreq_softc *sc, struct cf_setting_array *set_arr)
{
	struct cf_level *fill, *search;
	struct cf_setting *set;
	int i;

	CF_MTX_ASSERT(&sc->lock);

	/*
	 * Walk the set of all existing levels in reverse.  This is so we
	 * create derived states from the lowest absolute settings first
	 * and discard duplicates created from higher absolute settings.
	 * For instance, a level of 50 Mhz derived from 100 Mhz + 50% is
	 * preferable to 200 Mhz + 25% because absolute settings are more
	 * efficient since they often change the voltage as well.
	 */
	TAILQ_FOREACH_REVERSE(search, &sc->all_levels, cf_level_lst, link) {
		/* Add each setting to the level, duplicating if necessary. */
		for (i = 0; i < set_arr->count; i++) {
			set = &set_arr->sets[i];

			/*
			 * If this setting is less than 100%, split the level
			 * into two and add this setting to the new level.
			 */
			fill = search;
			if (set->freq < 10000) {
				fill = cpufreq_dup_set(sc, search, set);

				/*
				 * The new level was a duplicate of an existing
				 * level or its absolute setting is too high
				 * so we freed it.  For example, we discard a
				 * derived level of 1000 MHz/25% if a level
				 * of 500 MHz/100% already exists.
				 */
				if (fill == NULL)
					break;
			}

			/* Add this setting to the existing or new level. */
			KASSERT(fill->rel_count < MAX_SETTINGS,
			    ("cpufreq: too many relative drivers (%d)",
			    MAX_SETTINGS));
			fill->rel_set[fill->rel_count] = *set;
			fill->rel_count++;
			CF_DEBUG(
			"expand set added rel setting %d%% to %d level\n",
			    set->freq / 100, fill->total_set.freq);
		}
	}

	return (0);
}

static struct cf_level *
cpufreq_dup_set(struct cpufreq_softc *sc, struct cf_level *dup,