Function cf_get_method

freebsd/kern/kern_cpu.c:454–563

* Used by the cpufreq core, this function will populate *level with the current * frequency as either determined by a cached value sc->curr_level, or in the * case the lower level driver has set the CPUFREQ_FLAG_UNCACHED flag, it will * obtain the frequency from the driver itself. */

 * obtain the frequency from the driver itself.
 */
static int
cf_get_method(device_t dev, struct cf_level *level)
{
	struct cpufreq_softc *sc;
	struct cf_level *levels;
	struct cf_setting *curr_set;
	struct pcpu *pc;
	int bdiff, count, diff, error, i, type;
	uint64_t rate;

	sc = device_get_softc(dev);
	error = 0;
	levels = NULL;

	/*
	 * If we already know the current frequency, and the driver didn't ask
	 * for uncached usage, we're done.
	 */
	CF_MTX_LOCK(&sc->lock);
	curr_set = &sc->curr_level.total_set;
	error = CPUFREQ_DRV_TYPE(sc->cf_drv_dev, &type);
	if (error == 0 && (type & CPUFREQ_FLAG_UNCACHED)) {
		struct cf_setting set;

		/*
		 * If the driver wants to always report back the real frequency,
		 * first try the driver and if that fails, fall back to
		 * estimating.
		 */
		if (CPUFREQ_DRV_GET(sc->cf_drv_dev, &set) == 0) {
			sc->curr_level.total_set = set;
			CF_DEBUG("get returning immediate freq %d\n",
			    curr_set->freq);
			goto out;
		}
	} else if (curr_set->freq != CPUFREQ_VAL_UNKNOWN) {
		CF_DEBUG("get returning known freq %d\n", curr_set->freq);
		error = 0;
		goto out;
	}
	CF_MTX_UNLOCK(&sc->lock);

	/*
	 * We need to figure out the current level.  Loop through every
	 * driver, getting the current setting.  Then, attempt to get a best
	 * match of settings against each level.
	 */
	count = CF_MAX_LEVELS;
	levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
	if (levels == NULL)
		return (ENOMEM);
	error = CPUFREQ_LEVELS(sc->dev, levels, &count);
	if (error) {
		if (error == E2BIG)
			printf("cpufreq: need to increase CF_MAX_LEVELS\n");
		free(levels, M_TEMP);
		return (error);
	}