static int powernv_add_idle_states()

in cpuidle-powernv.c [248:352]

• 65 lines of code
• 16 McCabe index (conditional complexity)

static int powernv_add_idle_states(void)
{
	int nr_idle_states = 1; /* Snooze */
	int dt_idle_states;
	u32 has_stop_states = 0;
	int i;
	u32 supported_flags = pnv_get_supported_cpuidle_states();


	/* Currently we have snooze statically defined */
	if (nr_pnv_idle_states <= 0) {
		pr_warn("cpuidle-powernv : Only Snooze is available\n");
		goto out;
	}

	/* TODO: Count only states which are eligible for cpuidle */
	dt_idle_states = nr_pnv_idle_states;

	/*
	 * Since snooze is used as first idle state, max idle states allowed is
	 * CPUIDLE_STATE_MAX -1
	 */
	if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
		pr_warn("cpuidle-powernv: discovered idle states more than allowed");
		dt_idle_states = CPUIDLE_STATE_MAX - 1;
	}

	/*
	 * If the idle states use stop instruction, probe for psscr values
	 * and psscr mask which are necessary to specify required stop level.
	 */
	has_stop_states = (pnv_idle_states[0].flags &
			   (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));

	for (i = 0; i < dt_idle_states; i++) {
		unsigned int exit_latency, target_residency;
		bool stops_timebase = false;
		struct pnv_idle_states_t *state = &pnv_idle_states[i];

		/*
		 * Skip the platform idle state whose flag isn't in
		 * the supported_cpuidle_states flag mask.
		 */
		if ((state->flags & supported_flags) != state->flags)
			continue;
		/*
		 * If an idle state has exit latency beyond
		 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
		 * in cpu-idle.
		 */
		if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
			continue;
		/*
		 * Firmware passes residency and latency values in ns.
		 * cpuidle expects it in us.
		 */
		exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
		target_residency = DIV_ROUND_UP(state->residency_ns, 1000);

		if (has_stop_states && !(state->valid))
				continue;

		if (state->flags & OPAL_PM_TIMEBASE_STOP)
			stops_timebase = true;

		if (state->flags & OPAL_PM_NAP_ENABLED) {
			/* Add NAP state */
			add_powernv_state(nr_idle_states, "Nap",
					  CPUIDLE_FLAG_NONE, nap_loop,
					  target_residency, exit_latency, 0, 0);
		} else if (has_stop_states && !stops_timebase) {
			add_powernv_state(nr_idle_states, state->name,
					  CPUIDLE_FLAG_NONE, stop_loop,
					  target_residency, exit_latency,
					  state->psscr_val,
					  state->psscr_mask);
		}

		/*
		 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
		 * within this config dependency check.
		 */
#ifdef CONFIG_TICK_ONESHOT
		else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
			 state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
			/* Add FASTSLEEP state */
			add_powernv_state(nr_idle_states, "FastSleep",
					  CPUIDLE_FLAG_TIMER_STOP,
					  fastsleep_loop,
					  target_residency, exit_latency, 0, 0);
		} else if (has_stop_states && stops_timebase) {
			add_powernv_state(nr_idle_states, state->name,
					  CPUIDLE_FLAG_TIMER_STOP, stop_loop,
					  target_residency, exit_latency,
					  state->psscr_val,
					  state->psscr_mask);
		}
#endif
		else
			continue;
		nr_idle_states++;
	}
out:
	return nr_idle_states;
}