cpuidle: irq: Add a new irq based governorandroid-hikey-linaro-4.4

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

3 files changed, 119 insertions, 0 deletions

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 8c7930b5a65f..42b2c8785025 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -25,6 +25,10 @@ config CPU_IDLE_GOV_MENU
 	bool "Menu governor (for tickless system)"
 	default y
 
+config CPU_IDLE_GOV_IRQ
+	bool "Irq governor (for tickless system)"
+	select IRQ_TIMINGS
+
 config DT_IDLE_STATES
 	bool
 
diff --git a/drivers/cpuidle/governors/Makefile b/drivers/cpuidle/governors/Makefile
index 1b512722689f..8804ee2f550c 100644
--- a/drivers/cpuidle/governors/Makefile
+++ b/drivers/cpuidle/governors/Makefile
@@ -4,3 +4,4 @@
 
 obj-$(CONFIG_CPU_IDLE_GOV_LADDER) += ladder.o
 obj-$(CONFIG_CPU_IDLE_GOV_MENU) += menu.o
+obj-$(CONFIG_CPU_IDLE_GOV_IRQ) += irq.o
diff --git a/drivers/cpuidle/governors/irq.c b/drivers/cpuidle/governors/irq.c
new file mode 100644
index 000000000000..a5a322f051b4
--- /dev/null
+++ b/drivers/cpuidle/governors/irq.c
@@ -0,0 +1,114 @@
+/*
+ * drivers/cpuidle/governors/irq.c - the irq governor
+ *
+ * Copyright (C) 2016, Linaro Ltd - Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/cpuidle.h>
+#include <linux/interrupt.h>
+#include <linux/ktime.h>
+#include <linux/pm_qos.h>
+#include <linux/sched.h>
+#include <linux/tick.h>
+
+#include "../cpuidle.h"
+
+static int irq_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
+{
+	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
+	u64 now = local_clock();
+	u64 next_irq_event = irq_timings_next_event(now);
+	s64 next_timer_event = ktime_to_us(tick_nohz_get_sleep_length());
+	s64 next_event;
+	s64 diff = S64_MAX;
+	int i, state = CPUIDLE_DRIVER_STATE_START;
+
+	/*
+	 * If there are no interrupt supposed to happen on this CPU,
+	 * then we rely on the timer expiration.
+	 *
+	 * Otherwise, irqt_get_next_prediction() returns when is
+	 * supposed to happen the next event in absolute time, so we
+	 * have to substract the current time to have the duration of
+	 * the sleep and convert it in usec.
+	 */
+	if (next_irq_event != U64_MAX) {
+
+		diff = next_irq_event - now;
+
+		/*
+		 * The event already happen, we can't fail to select a
+		 * state because the returned value is used as an
+		 * index. Return the shallowest state and let the
+		 * cpuidle code to check a need_resched() before
+		 * entering idle.
+		 */
+		if (diff < 0)
+			return CPUIDLE_DRIVER_STATE_START;
+
+		/*
+		 * Convert into microsecond, shifting by 10 (div by 1024)
+		 * is enough precise for our purpose.
+		 */
+		diff >>= 10;
+	}
+
+	next_event = min(next_timer_event, diff);
+
+	/*
+	 * Find the idle state with the lowest power while satisfying
+	 * our constraints. Never, never, default to the polling state
+	 * (x86 specific), the shallowest state's exit latency is
+	 * small enough to give fast response. The polling state must
+	 * be selected before based on deterministic information
+	 * (timer expiration or high irq rate).
+	 */
+	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
+		struct cpuidle_state *s = &drv->states[i];
+		struct cpuidle_state_usage *su = &dev->states_usage[i];
+
+		if (s->disabled || su->disable)
+			continue;
+		if (s->target_residency > next_event)
+			continue;
+		if (s->exit_latency > latency_req)
+			continue;
+
+		state = i;
+	}
+
+	return state;
+}
+
+static int irq_enable(struct cpuidle_driver *drv,
+		      struct cpuidle_device *dev)
+{
+	irq_timings_enable();
+
+	return 0;
+}
+
+static void irq_disable(struct cpuidle_driver *drv,
+			struct cpuidle_device *dev)
+{
+	irq_timings_disable();
+}
+
+static struct cpuidle_governor irq_governor = {
+	.name   = "irq",
+	.rating = 10,
+	.select = irq_select,
+	.enable = irq_enable,
+	.disable = irq_disable,
+};
+
+static int __init irq_init(void)
+{
+	return cpuidle_register_governor(&irq_governor);
+}
+
+postcore_initcall(irq_init);