backlight: lp855x: Switch to atomic PWM API

Remove legacy PWM interface (pwm_config, pwm_enable, pwm_disable) and
replace it for the atomic PWM API.
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220714215334.78226-1-mairacanal@riseup.net

drivers/video/backlight/lp855x_bl.c

@@ -218,9 +218,8 @@ static int lp855x_configure(struct lp855x *lp)
 
 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 {
-	unsigned int period = lp->pdata->period_ns;
-	unsigned int duty = br * period / max_br;
 	struct pwm_device *pwm;
+	struct pwm_state state;
 
 	/* request pwm device with the consumer name */
 	if (!lp->pwm) {
@@ -230,18 +229,16 @@ static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 
 		lp->pwm = pwm;
 
-		/*
-		 * FIXME: pwm_apply_args() should be removed when switching to
-		 * the atomic PWM API.
-		 */
-		pwm_apply_args(pwm);
+		pwm_init_state(lp->pwm, &state);
+	} else {
+		pwm_get_state(lp->pwm, &state);
 	}
 
-	pwm_config(lp->pwm, duty, period);
-	if (duty)
-		pwm_enable(lp->pwm);
-	else
-		pwm_disable(lp->pwm);
+	state.period = lp->pdata->period_ns;
+	state.duty_cycle = div_u64(br * state.period, max_br);
+	state.enabled = state.duty_cycle;
+
+	pwm_apply_state(lp->pwm, &state);
 }
 
 static int lp855x_bl_update_status(struct backlight_device *bl)