pwm: Add the pwm_is_enabled() helper

Some PWM drivers are testing the PWMF_ENABLED flag. Create a helper
function to hide the logic behind enabled test. This will allow us to
smoothly move from the current approach to an atomic PWM update
approach.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 36262d0..ec34f4d 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -92,6 +92,11 @@
 	enum pwm_polarity	polarity;
 };
 
+static inline bool pwm_is_enabled(const struct pwm_device *pwm)
+{
+	return test_bit(PWMF_ENABLED, &pwm->flags);
+}
+
 static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
 {
 	if (pwm)