Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a6a0dbbc authored by Boris Brezillon's avatar Boris Brezillon Committed by Thierry Reding
Browse files

pwm: Add a helper to prepare a new PWM state 



The pwm_init_state() helper prepares a new state object containing the
current PWM state except for the polarity and period fields which are
set to the reference values (those in struct pwm_args).

This is particularly useful for PWM users who want to apply a new duty-
cycle expressed relatively to the reference period without changing the
enable state.

Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: default avatarHeiko Stuebner <heiko@sntech.de>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 1a695a90

include/linux/pwm.h

+33 −0
Original line number Diff line number Diff line
@@ -147,6 +147,39 @@ static inline void pwm_get_args(const struct pwm_device *pwm, 
	*args = pwm->args;

}



/**

 * 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;

}



/**

 * struct pwm_ops - PWM controller operations

 * @request: optional hook for requesting a PWM