[PATCH v3 1/2] PM / devfreq: Add governor feature flag

From: Chanwoo Choi <cw00.choi@samsung.com>
To: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-tegra@vger.kernel.org
Cc: digetx@gmail.com, leonard.crestez@nxp.com, lukasz.luba@arm.com,
	enric.balletbo@collabora.com, hl@rock-chips.com,
	thierry.reding@gmail.com, jonathanh@nvidia.com,
	abel.vesa@nxp.com, k.konieczny@samsung.com,
	b.zolnierkie@samsung.com, cw00.choi@samsung.com,
	chanwoo@kernel.org, myungjoo.ham@samsung.com,
	kyungmin.park@samsung.com
Subject: [PATCH v3 1/2] PM / devfreq: Add governor feature flag
Date: Wed,  7 Oct 2020 14:07:02 +0900	[thread overview]
Message-ID: <20201007050703.20759-2-cw00.choi@samsung.com> (raw)
In-Reply-To: <20201007050703.20759-1-cw00.choi@samsung.com>

The devfreq governor is able to have the specific flag as follows
in order to implement the specific feature. For example, devfreq allows
user to change the governors on runtime via sysfs interface.
But, if devfreq device uses 'passive' governor, don't allow user to change
the governor. For this case, define the DEVFREQ_GOV_FLAT_IMMUTABLE
and set it to flag of passive governor.

[Definition for governor flag]
- DEVFREQ_GOV_FLAG_IMMUTABLE
  : If immutable flag is set, governor is never changeable to other governors.
- DEVFREQ_GOV_FLAG_IRQ_DRIVEN
  : Devfreq core won't schedule polling work for this governor if value is set.

[Table of governor flag for devfreq governors]
------------------------------------------------------------------------------
                      | simple    | perfor | power | user | passive | tegra30
		      | ondemand  | mance  | save  | space|         |
------------------------------------------------------------------------------
immutable             | X         | X      | X     | X    | O       | O
interrupt_driven      | X(polling)| X      | X     | X    | X       | O (irq)
------------------------------------------------------------------------------

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
---
 drivers/devfreq/devfreq.c          | 18 ++++++++++--------
 drivers/devfreq/governor.h         | 18 ++++++++++++------
 drivers/devfreq/governor_passive.c |  2 +-
 drivers/devfreq/tegra30-devfreq.c  |  4 ++--
 4 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 861c100f9fac..ce793fc9a558 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -31,6 +31,7 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/devfreq.h>
 
+#define IS_SUPPORTED_FLAG(f, name) ((f & DEVFREQ_GOV_FLAG_##name) ? true : false)
 #define HZ_PER_KHZ	1000
 
 static struct class *devfreq_class;
@@ -456,7 +457,7 @@ static void devfreq_monitor(struct work_struct *work)
  */
 void devfreq_monitor_start(struct devfreq *devfreq)
 {
-	if (devfreq->governor->interrupt_driven)
+	if (IS_SUPPORTED_FLAG(devfreq->governor->flag, IRQ_DRIVEN))
 		return;
 
 	switch (devfreq->profile->timer) {
@@ -486,7 +487,7 @@ EXPORT_SYMBOL(devfreq_monitor_start);
  */
 void devfreq_monitor_stop(struct devfreq *devfreq)
 {
-	if (devfreq->governor->interrupt_driven)
+	if (IS_SUPPORTED_FLAG(devfreq->governor->flag, IRQ_DRIVEN))
 		return;
 
 	cancel_delayed_work_sync(&devfreq->work);
@@ -517,7 +518,7 @@ void devfreq_monitor_suspend(struct devfreq *devfreq)
 	devfreq->stop_polling = true;
 	mutex_unlock(&devfreq->lock);
 
-	if (devfreq->governor->interrupt_driven)
+	if (IS_SUPPORTED_FLAG(devfreq->governor->flag, IRQ_DRIVEN))
 		return;
 
 	cancel_delayed_work_sync(&devfreq->work);
@@ -540,7 +541,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
 	if (!devfreq->stop_polling)
 		goto out;
 
-	if (devfreq->governor->interrupt_driven)
+	if (IS_SUPPORTED_FLAG(devfreq->governor->flag, IRQ_DRIVEN))
 		goto out_update;
 
 	if (!delayed_work_pending(&devfreq->work) &&
@@ -580,7 +581,7 @@ void devfreq_update_interval(struct devfreq *devfreq, unsigned int *delay)
 	if (devfreq->stop_polling)
 		goto out;
 
-	if (devfreq->governor->interrupt_driven)
+	if (IS_SUPPORTED_FLAG(devfreq->governor->flag, IRQ_DRIVEN))
 		goto out;
 
 	/* if new delay is zero, stop polling */
@@ -1347,7 +1348,8 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 	if (df->governor == governor) {
 		ret = 0;
 		goto out;
-	} else if (df->governor->immutable || governor->immutable) {
+	} else if (IS_SUPPORTED_FLAG(df->governor->flag, IMMUTABLE)
+		|| IS_SUPPORTED_FLAG(governor->flag, IMMUTABLE)) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -1402,7 +1404,7 @@ static ssize_t available_governors_show(struct device *d,
 	 * The devfreq with immutable governor (e.g., passive) shows
 	 * only own governor.
 	 */
-	if (df->governor->immutable) {
+	if (IS_SUPPORTED_FLAG(df->governor->flag, IMMUTABLE)) {
 		count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
 				  "%s ", df->governor_name);
 	/*
@@ -1413,7 +1415,7 @@ static ssize_t available_governors_show(struct device *d,
 		struct devfreq_governor *governor;
 
 		list_for_each_entry(governor, &devfreq_governor_list, node) {
-			if (governor->immutable)
+			if (IS_SUPPORTED_FLAG(governor->flag, IMMUTABLE))
 				continue;
 			count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 					   "%s ", governor->name);
diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index ae4d0cc18359..540e59ef467c 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h
@@ -25,14 +25,21 @@
 #define DEVFREQ_MIN_FREQ			0
 #define DEVFREQ_MAX_FREQ			ULONG_MAX
 
+/*
+ * Definition of the governor feature flags
+ * - DEVFREQ_GOV_FLAG_IMMUTABLE
+ *   : This governor is never changeable to other governors.
+ * - DEVFREQ_GOV_FLAG_IRQ_DRIVEN
+ *   : The devfreq won't schedule the work for this governor.
+ */
+#define DEVFREQ_GOV_FLAG_IMMUTABLE			BIT(0)
+#define DEVFREQ_GOV_FLAG_IRQ_DRIVEN			BIT(1)
+
 /**
  * struct devfreq_governor - Devfreq policy governor
  * @node:		list node - contains registered devfreq governors
  * @name:		Governor's name
- * @immutable:		Immutable flag for governor. If the value is 1,
- *			this governor is never changeable to other governor.
- * @interrupt_driven:	Devfreq core won't schedule polling work for this
- *			governor if value is set to 1.
+ * @flag:		Governor's feature flag
  * @get_target_freq:	Returns desired operating frequency for the device.
  *			Basically, get_target_freq will run
  *			devfreq_dev_profile.get_dev_status() to get the
@@ -50,8 +57,7 @@ struct devfreq_governor {
 	struct list_head node;
 
 	const char name[DEVFREQ_NAME_LEN];
-	const unsigned int immutable;
-	const unsigned int interrupt_driven;
+	const u64 flag;
 	int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 	int (*event_handler)(struct devfreq *devfreq,
 				unsigned int event, void *data);
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
index be6eeab9c814..432a4cc683f7 100644
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -180,7 +180,7 @@ static int devfreq_passive_event_handler(struct devfreq *devfreq,
 
 static struct devfreq_governor devfreq_passive = {
 	.name = DEVFREQ_GOV_PASSIVE,
-	.immutable = 1,
+	.flag = DEVFREQ_GOV_FLAG_IMMUTABLE,
 	.get_target_freq = devfreq_passive_get_target_freq,
 	.event_handler = devfreq_passive_event_handler,
 };
diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index f5e74c2ede85..868c72cc0276 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -765,10 +765,10 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
 
 static struct devfreq_governor tegra_devfreq_governor = {
 	.name = "tegra_actmon",
+	.flag = DEVFREQ_GOV_FLAG_IMMUTABLE
+		| DEVFREQ_GOV_FLAG_IRQ_DRIVEN,
 	.get_target_freq = tegra_governor_get_target,
 	.event_handler = tegra_governor_event_handler,
-	.immutable = true,
-	.interrupt_driven = true,
 };
 
 static int tegra_devfreq_probe(struct platform_device *pdev)
-- 
2.17.1

