[PATCH 12/15] counter: rz-mtu3-cnt: cache direction values

[Cosmin Tanislav]

Reading registers without the count being enabled is an issue as the
ch->is_busy check inside rz_mtu3_lock_if_count_is_enabled() can race
with PWM operations.

Cache the direction value on every read and on disable, and return the
cached value if the count is disabled.

Since runtime PM is ensured to be resumed if the count is enabled, drop
the pm_runtime_get_sync() and pm_runtime_put() calls.

Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@xxxxxxxxxxx>
---
 drivers/counter/rz-mtu3-cnt.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/counter/rz-mtu3-cnt.c b/drivers/counter/rz-mtu3-cnt.c
index a26b8b71c9a6..5fd12941df4c 100644
--- a/drivers/counter/rz-mtu3-cnt.c
+++ b/drivers/counter/rz-mtu3-cnt.c
@@ -79,6 +79,7 @@ struct rz_mtu3_cnt {
 	u32 count[RZ_MTU3_MAX_LOGICAL_CNTR_CHANNELS];
 	u8 timer_mode[RZ_MTU3_MAX_LOGICAL_CNTR_CHANNELS];
 	bool count_is_enabled[RZ_MTU3_MAX_LOGICAL_CNTR_CHANNELS];
+	bool direction[RZ_MTU3_MAX_LOGICAL_CNTR_CHANNELS];
 	bool mtclkc_mtclkd;
 };
 
@@ -187,6 +188,13 @@ static void rz_mtu3_set_phcksel(struct rz_mtu3_channel *const ch, bool enable)
 				      enable);
 }
 
+static bool rz_mtu3_get_direction(struct rz_mtu3_channel *const ch)
+{
+	u8 tsr = rz_mtu3_8bit_ch_read(ch, RZ_MTU3_TSR);
+
+	return !!(tsr & RZ_MTU3_TSR_TCFD);
+}
+
 static int rz_mtu3_count_read(struct counter_device *counter,
 			      struct counter_count *count, u64 *val)
 {
@@ -315,18 +323,17 @@ static int rz_mtu3_count_direction_read(struct counter_device *counter,
 	struct rz_mtu3_channel *const ch = rz_mtu3_get_ch(counter, count->id);
 	struct rz_mtu3_cnt *const priv = counter_priv(counter);
 	int ret;
-	u8 tsr;
 
 	ret = rz_mtu3_lock_if_count_is_enabled(ch, priv, count->id);
 	if (ret)
 		return ret;
 
-	pm_runtime_get_sync(counter->parent);
-	tsr = rz_mtu3_8bit_ch_read(ch, RZ_MTU3_TSR);
-	pm_runtime_put(counter->parent);
+	if (priv->count_is_enabled[count->id])
+		priv->direction[count->id] = rz_mtu3_get_direction(ch);
 
-	*direction = (tsr & RZ_MTU3_TSR_TCFD) ?
+	*direction = priv->direction[count->id] ?
 		COUNTER_COUNT_DIRECTION_FORWARD : COUNTER_COUNT_DIRECTION_BACKWARD;
+
 	mutex_unlock(&priv->lock);
 
 	return 0;
@@ -469,6 +476,7 @@ static void rz_mtu3_terminate_counter(struct counter_device *counter, int id)
 	struct rz_mtu3_cnt *const priv = counter_priv(counter);
 
 	priv->count[id] = rz_mtu3_get_count(ch, id);
+	priv->direction[id] = rz_mtu3_get_direction(ch);
 
 	if (id == RZ_MTU3_32_BIT_CH) {
 		rz_mtu3_disable(ch2);
-- 
2.55.0