PM: EM: Add a flag indicating units of power values in Energy Model

There are different platforms and devices which might use different scale
for the power values. Kernel sub-systems might need to check if all
Energy Model (EM) devices are using the same scale. Address that issue and
store the information inside EM for each device. Thanks to that they can
be easily compared and proper action triggered.

Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 23 insertions, 1 deletions

diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index c1ff7fa030ab..efe2a595988e 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -52,6 +52,17 @@ static int em_debug_cpus_show(struct seq_file *s, void *unused)
 }
 DEFINE_SHOW_ATTRIBUTE(em_debug_cpus);
 
+static int em_debug_units_show(struct seq_file *s, void *unused)
+{
+	struct em_perf_domain *pd = s->private;
+	char *units = pd->milliwatts ? "milliWatts" : "bogoWatts";
+
+	seq_printf(s, "%s\n", units);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(em_debug_units);
+
 static void em_debug_create_pd(struct device *dev)
 {
 	struct dentry *d;
@@ -64,6 +75,8 @@ static void em_debug_create_pd(struct device *dev)
 		debugfs_create_file("cpus", 0444, d, dev->em_pd->cpus,
 				    &em_debug_cpus_fops);
 
+	debugfs_create_file("units", 0444, d, dev->em_pd, &em_debug_units_fops);
+
 	/* Create a sub-directory for each performance state */
 	for (i = 0; i < dev->em_pd->nr_perf_states; i++)
 		em_debug_create_ps(&dev->em_pd->table[i], d);
@@ -250,17 +263,24 @@ EXPORT_SYMBOL_GPL(em_cpu_get);
  * @cpus	: Pointer to cpumask_t, which in case of a CPU device is
  *		obligatory. It can be taken from i.e. 'policy->cpus'. For other
  *		type of devices this should be set to NULL.
+ * @milliwatts	: Flag indicating that the power values are in milliWatts or
+ *		in some other scale. It must be set properly.
  *
  * Create Energy Model tables for a performance domain using the callbacks
  * defined in cb.
  *
+ * The @milliwatts is important to set with correct value. Some kernel
+ * sub-systems might rely on this flag and check if all devices in the EM are
+ * using the same scale.
+ *
  * If multiple clients register the same performance domain, all but the first
  * registration will be ignored.
  *
  * Return 0 on success
  */
 int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
-				struct em_data_callback *cb, cpumask_t *cpus)
+				struct em_data_callback *cb, cpumask_t *cpus,
+				bool milliwatts)
 {
 	unsigned long cap, prev_cap = 0;
 	int cpu, ret;
@@ -313,6 +333,8 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
 	if (ret)
 		goto unlock;
 
+	dev->em_pd->milliwatts = milliwatts;
+
 	em_debug_create_pd(dev);
 	dev_info(dev, "EM: created perf domain\n");