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drivers: pwm: add support for inverted PWM signals

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Add support for requesting an inverted PWM pulse (active-low) when
setting up the period and pulse width of a PWM pin. This is useful
when driving external, active-low circuitry (e.g. an LED) with a PWM
signal.

All in-tree PWM drivers is updated to match the new API signature, but
no driver support for inverted PWM signals is added yet.

All in-tree PWM consumers are updated to pass a flags value of 0
(0 meaning default, which is normal PWM polarity).

Fixes #21384.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
This commit is contained in:
Henrik Brix Andersen 2019-11-13 14:46:37 +01:00 • committed by Carles Cufí
commit db611e6781
24 changed files with 152 additions and 38 deletions
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27
include/dt-bindings/pwm/pwm.h Normal file
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/*
* Copyright (c) 2019 Vestas Wind Systems A/S
*
* SPDX-License-Identifier: Apache-2.0
*/
#ifndef ZEPHYR_INCLUDE_DT_BINDINGS_PWM_PWM_H_
#define ZEPHYR_INCLUDE_DT_BINDINGS_PWM_PWM_H_
/**
* @name PWM polarity flags
* The `PWM_POLARITY_*` flags are used with pwm_pin_set_cycles(),
* pwm_pin_set_usec(), or pwm_pin_set_nsec() to specify the polarity
* of a PWM pin.
* @{
*/
/** PWM pin normal polarity (active-high pulse). */
#define PWM_POLARITY_NORMAL (0 << 0)
/** PWM pin inverted polarity (active-low pulse). */
#define PWM_POLARITY_INVERTED (1 << 0)
/** @cond INTERNAL_HIDDEN */
#define PWM_POLARITY_MASK 0x1
/** @endcond */
/** @} */
#endif /* ZEPHYR_INCLUDE_DT_BINDINGS_PWM_PWM_H_ */