Merge branch 'for-4.8/core' into for-next

1 files changed, 88 insertions, 1 deletions

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index c038ae36b10e..47e66bfb8cb4 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -148,6 +148,94 @@ static inline void pwm_get_args(const struct pwm_device *pwm,
 }
 
 /**
+ * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
+ * @pwm: PWM device
+ * @state: state to fill with the prepared PWM state
+ *
+ * This functions prepares a state that can later be tweaked and applied
+ * to the PWM device with pwm_apply_state(). This is a convenient function
+ * that first retrieves the current PWM state and the replaces the period
+ * and polarity fields with the reference values defined in pwm->args.
+ * Once the function returns, you can adjust the ->enabled and ->duty_cycle
+ * fields according to your needs before calling pwm_apply_state().
+ *
+ * ->duty_cycle is initially set to zero to avoid cases where the current
+ * ->duty_cycle value exceed the pwm_args->period one, which would trigger
+ * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
+ * first.
+ */
+static inline void pwm_init_state(const struct pwm_device *pwm,
+				  struct pwm_state *state)
+{
+	struct pwm_args args;
+
+	/* First get the current state. */
+	pwm_get_state(pwm, state);
+
+	/* Then fill it with the reference config */
+	pwm_get_args(pwm, &args);
+
+	state->period = args.period;
+	state->polarity = args.polarity;
+	state->duty_cycle = 0;
+}
+
+/**
+ * pwm_get_relative_duty_cycle() - Get a relative duty cycle value
+ * @state: PWM state to extract the duty cycle from
+ * @scale: target scale of the relative duty cycle
+ *
+ * This functions converts the absolute duty cycle stored in @state (expressed
+ * in nanosecond) into a value relative to the period.
+ *
+ * For example if you want to get the duty_cycle expressed in percent, call:
+ *
+ * pwm_get_state(pwm, &state);
+ * duty = pwm_get_relative_duty_cycle(&state, 100);
+ */
+static inline unsigned int
+pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
+{
+	if (!state->period)
+		return 0;
+
+	return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
+				     state->period);
+}
+
+/**
+ * pwm_set_relative_duty_cycle() - Set a relative duty cycle value
+ * @state: PWM state to fill
+ * @duty_cycle: relative duty cycle value
+ * @scale: scale in which @duty_cycle is expressed
+ *
+ * This functions converts a relative into an absolute duty cycle (expressed
+ * in nanoseconds), and puts the result in state->duty_cycle.
+ *
+ * For example if you want to configure a 50% duty cycle, call:
+ *
+ * pwm_init_state(pwm, &state);
+ * pwm_set_relative_duty_cycle(&state, 50, 100);
+ * pwm_apply_state(pwm, &state);
+ *
+ * This functions returns -EINVAL if @duty_cycle and/or @scale are
+ * inconsistent (@scale == 0 or @duty_cycle > @scale).
+ */
+static inline int
+pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
+			    unsigned int scale)
+{
+	if (!scale || duty_cycle > scale)
+		return -EINVAL;
+
+	state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
+						  state->period,
+						  scale);
+
+	return 0;
+}
+
+/**
  * struct pwm_ops - PWM controller operations
  * @request: optional hook for requesting a PWM
  * @free: optional hook for freeing a PWM
@@ -323,7 +411,6 @@ static inline void pwm_disable(struct pwm_device *pwm)
 	pwm_apply_state(pwm, &state);
 }
 
-
 /* PWM provider APIs */
 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 void *pwm_get_chip_data(struct pwm_device *pwm);