u-boot/include/pwm.h
Alper Nebi Yasak fefa713b18 video: backlight: Support PWMs without a known period_ns
The PWM device provided by Chrome OS EC doesn't really support anything
other than setting a relative duty cycle. To support it as a backlight,
this patch makes the PWM period optional in the device tree and pretends
the valid brightness range is its period_ns.

Also adds a sandbox test for a PWM channel that has a fixed period,
checking that the resulting duty_cycle matches on a set_config() even if
the requested period_ns can't be set.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2021-04-10 16:07:12 +02:00

99 lines
2.7 KiB
C

/* SPDX-License-Identifier: GPL-2.0+ */
/*
* header file for pwm driver.
*
* Copyright 2016 Google Inc.
* Copyright (c) 2011 samsung electronics
* Donghwa Lee <dh09.lee@samsung.com>
*/
#ifndef _pwm_h_
#define _pwm_h_
struct udevice;
/* struct pwm_ops: Operations for the PWM uclass */
struct pwm_ops {
/**
* set_config() - Set the PWM configuration
*
* Change both the PWM device's period and it's duty period if
* possible. Otherwise, set an appropriate duty period that best
* matches the given period_ns / duty_ns ratio for the device.
*
* @dev: PWM device to update
* @channel: PWM channel to update
* @period_ns: PWM period in nanoseconds
* @duty_ns: PWM duty period in nanoseconds
* @return 0 if OK, -ve on error
*/
int (*set_config)(struct udevice *dev, uint channel, uint period_ns,
uint duty_ns);
/**
* set_enable() - Enable or disable the PWM
*
* @dev: PWM device to update
* @channel: PWM channel to update
* @enable: true to enable, false to disable
* @return 0 if OK, -ve on error
*/
int (*set_enable)(struct udevice *dev, uint channel, bool enable);
/**
* set_invert() - Set the PWM invert
*
* @dev: PWM device to update
* @channel: PWM channel to update
* @polarity: true to invert, false to keep normal polarity
* @return 0 if OK, -ve on error
*/
int (*set_invert)(struct udevice *dev, uint channel, bool polarity);
};
#define pwm_get_ops(dev) ((struct pwm_ops *)(dev)->driver->ops)
/**
* pwm_set_config() - Set the PWM configuration
*
* Change both the PWM device's period and it's duty period if
* possible. Otherwise, set an appropriate duty period that best
* matches the given period_ns / duty_ns ratio for the device.
*
* @dev: PWM device to update
* @channel: PWM channel to update
* @period_ns: PWM period in nanoseconds
* @duty_ns: PWM duty period in nanoseconds
* @return 0 if OK, -ve on error
*/
int pwm_set_config(struct udevice *dev, uint channel, uint period_ns,
uint duty_ns);
/**
* pwm_set_enable() - Enable or disable the PWM
*
* @dev: PWM device to update
* @channel: PWM channel to update
* @enable: true to enable, false to disable
* @return 0 if OK, -ve on error
*/
int pwm_set_enable(struct udevice *dev, uint channel, bool enable);
/**
* pwm_set_invert() - Set pwm default polarity
*
* @dev: PWM device to update
* @channel: PWM channel to update
* @polarity: true to invert, false to keep normal polarity
* @return 0 if OK, -ve on error
*/
int pwm_set_invert(struct udevice *dev, uint channel, bool polarity);
/* Legacy interface */
#ifndef CONFIG_DM_PWM
int pwm_init (int pwm_id, int div, int invert);
int pwm_config (int pwm_id, int duty_ns, int period_ns);
int pwm_enable (int pwm_id);
void pwm_disable (int pwm_id);
#endif
#endif /* _pwm_h_ */