pwm: Add relative duty cycle manipulation helpers
The PWM framework expects PWM users to configure the duty cycle in nano- seconds, but many users want to express the duty cycle relatively to the period value (i.e. duty_cycle = 33% of the period). Add the pwm_{get,set}_relative_duty_cycle() helpers to ease this kind of conversion. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Tested-by: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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@ -180,6 +180,61 @@ static inline void pwm_init_state(const struct pwm_device *pwm,
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state->duty_cycle = 0;
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state->duty_cycle = 0;
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}
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}
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/**
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* pwm_get_relative_duty_cycle() - Get a relative duty cycle value
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* @state: PWM state to extract the duty cycle from
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* @scale: target scale of the relative duty cycle
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*
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* This functions converts the absolute duty cycle stored in @state (expressed
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* in nanosecond) into a value relative to the period.
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*
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* For example if you want to get the duty_cycle expressed in percent, call:
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*
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* pwm_get_state(pwm, &state);
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* duty = pwm_get_relative_duty_cycle(&state, 100);
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*/
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static inline unsigned int
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pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
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{
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if (!state->period)
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return 0;
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return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
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state->period);
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}
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/**
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* pwm_set_relative_duty_cycle() - Set a relative duty cycle value
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* @state: PWM state to fill
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* @duty_cycle: relative duty cycle value
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* @scale: scale in which @duty_cycle is expressed
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*
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* This functions converts a relative into an absolute duty cycle (expressed
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* in nanoseconds), and puts the result in state->duty_cycle.
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*
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* For example if you want to configure a 50% duty cycle, call:
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*
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* pwm_init_state(pwm, &state);
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* pwm_set_relative_duty_cycle(&state, 50, 100);
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* pwm_apply_state(pwm, &state);
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*
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* This functions returns -EINVAL if @duty_cycle and/or @scale are
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* inconsistent (@scale == 0 or @duty_cycle > @scale).
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*/
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static inline int
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pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
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unsigned int scale)
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{
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if (!scale || duty_cycle > scale)
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return -EINVAL;
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state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
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state->period,
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scale);
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return 0;
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}
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/**
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/**
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* struct pwm_ops - PWM controller operations
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* struct pwm_ops - PWM controller operations
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* @request: optional hook for requesting a PWM
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* @request: optional hook for requesting a PWM
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