powercap: idle_inject: Use higher resolution for idle injection

The resolution of the idle injection is limited to 1ms. If there is
a need for an injection of 1.2 ms, it is not possible.

The idle injection API is not yet used, so it is safe to convert the
existing API to the new time unit instead of adding more functions.

Convert to microsecond in order to use a finer grain time unit when
injecting idle cycles.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/powercap/idle_inject.c

@@ -59,14 +59,14 @@ struct idle_inject_thread {
 /**
  * struct idle_inject_device - idle injection data
  * @timer: idle injection period timer
- * @idle_duration_ms: duration of CPU idle time to inject
- * @run_duration_ms: duration of CPU run time to allow
+ * @idle_duration_us: duration of CPU idle time to inject
+ * @run_duration_us: duration of CPU run time to allow
  * @cpumask: mask of CPUs affected by idle injection
  */
 struct idle_inject_device {
 	struct hrtimer timer;
-	unsigned int idle_duration_ms;
-	unsigned int run_duration_ms;
+	unsigned int idle_duration_us;
+	unsigned int run_duration_us;
 	unsigned long int cpumask[0];
 };
 
@@ -104,16 +104,16 @@ static void idle_inject_wakeup(struct idle_inject_device *ii_dev)
  */
 static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer)
 {
-	unsigned int duration_ms;
+	unsigned int duration_us;
 	struct idle_inject_device *ii_dev =
 		container_of(timer, struct idle_inject_device, timer);
 
-	duration_ms = READ_ONCE(ii_dev->run_duration_ms);
-	duration_ms += READ_ONCE(ii_dev->idle_duration_ms);
+	duration_us = READ_ONCE(ii_dev->run_duration_us);
+	duration_us += READ_ONCE(ii_dev->idle_duration_us);
 
 	idle_inject_wakeup(ii_dev);
 
-	hrtimer_forward_now(timer, ms_to_ktime(duration_ms));
+	hrtimer_forward_now(timer, ns_to_ktime(duration_us * NSEC_PER_USEC));
 
 	return HRTIMER_RESTART;
 }
@@ -138,35 +138,35 @@ static void idle_inject_fn(unsigned int cpu)
 	 */
 	iit->should_run = 0;
 
-	play_idle(READ_ONCE(ii_dev->idle_duration_ms) * USEC_PER_MSEC);
+	play_idle(READ_ONCE(ii_dev->idle_duration_us));
 }
 
 /**
  * idle_inject_set_duration - idle and run duration update helper
- * @run_duration_ms: CPU run time to allow in milliseconds
- * @idle_duration_ms: CPU idle time to inject in milliseconds
+ * @run_duration_us: CPU run time to allow in microseconds
+ * @idle_duration_us: CPU idle time to inject in microseconds
  */
 void idle_inject_set_duration(struct idle_inject_device *ii_dev,
-			      unsigned int run_duration_ms,
-			      unsigned int idle_duration_ms)
+			      unsigned int run_duration_us,
+			      unsigned int idle_duration_us)
 {
-	if (run_duration_ms && idle_duration_ms) {
-		WRITE_ONCE(ii_dev->run_duration_ms, run_duration_ms);
-		WRITE_ONCE(ii_dev->idle_duration_ms, idle_duration_ms);
+	if (run_duration_us && idle_duration_us) {
+		WRITE_ONCE(ii_dev->run_duration_us, run_duration_us);
+		WRITE_ONCE(ii_dev->idle_duration_us, idle_duration_us);
 	}
 }
 
 /**
  * idle_inject_get_duration - idle and run duration retrieval helper
- * @run_duration_ms: memory location to store the current CPU run time
- * @idle_duration_ms: memory location to store the current CPU idle time
+ * @run_duration_us: memory location to store the current CPU run time
+ * @idle_duration_us: memory location to store the current CPU idle time
  */
 void idle_inject_get_duration(struct idle_inject_device *ii_dev,
-			      unsigned int *run_duration_ms,
-			      unsigned int *idle_duration_ms)
+			      unsigned int *run_duration_us,
+			      unsigned int *idle_duration_us)
 {
-	*run_duration_ms = READ_ONCE(ii_dev->run_duration_ms);
-	*idle_duration_ms = READ_ONCE(ii_dev->idle_duration_ms);
+	*run_duration_us = READ_ONCE(ii_dev->run_duration_us);
+	*idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
 }
 
 /**
@@ -181,10 +181,10 @@ void idle_inject_get_duration(struct idle_inject_device *ii_dev,
  */
 int idle_inject_start(struct idle_inject_device *ii_dev)
 {
-	unsigned int idle_duration_ms = READ_ONCE(ii_dev->idle_duration_ms);
-	unsigned int run_duration_ms = READ_ONCE(ii_dev->run_duration_ms);
+	unsigned int idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
+	unsigned int run_duration_us = READ_ONCE(ii_dev->run_duration_us);
 
-	if (!idle_duration_ms || !run_duration_ms)
+	if (!idle_duration_us || !run_duration_us)
 		return -EINVAL;
 
 	pr_debug("Starting injecting idle cycles on CPUs '%*pbl'\n",
@@ -193,7 +193,8 @@ int idle_inject_start(struct idle_inject_device *ii_dev)
 	idle_inject_wakeup(ii_dev);
 
 	hrtimer_start(&ii_dev->timer,
-		      ms_to_ktime(idle_duration_ms + run_duration_ms),
+		      ns_to_ktime((idle_duration_us + run_duration_us) *
+				  NSEC_PER_USEC),
 		      HRTIMER_MODE_REL);
 
 	return 0;

include/linux/idle_inject.h

@@ -20,10 +20,10 @@ int idle_inject_start(struct idle_inject_device *ii_dev);
 void idle_inject_stop(struct idle_inject_device *ii_dev);
 
 void idle_inject_set_duration(struct idle_inject_device *ii_dev,
-				 unsigned int run_duration_ms,
-				 unsigned int idle_duration_ms);
+				 unsigned int run_duration_us,
+				 unsigned int idle_duration_us);
 
 void idle_inject_get_duration(struct idle_inject_device *ii_dev,
-				 unsigned int *run_duration_ms,
-				 unsigned int *idle_duration_ms);
+				 unsigned int *run_duration_us,
+				 unsigned int *idle_duration_us);
 #endif /* __IDLE_INJECT_H__ */