static int atmel_tcb_pwm_enable()

in pwm-atmel-tcb.c [206:288]

• 55 lines of code
• 11 McCabe index (conditional complexity)

static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
	struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
	u32 cmr;
	enum pwm_polarity polarity = tcbpwm->polarity;

	/*
	 * If duty is 0 the timer will be stopped and we have to
	 * configure the output correctly on software trigger:
	 *  - set output to high if PWM_POLARITY_INVERSED
	 *  - set output to low if PWM_POLARITY_NORMAL
	 *
	 * This is why we're reverting polarity in this case.
	 */
	if (tcbpwm->duty == 0)
		polarity = !polarity;

	spin_lock(&tcbpwmc->lock);
	regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), &cmr);

	/* flush old setting and set the new one */
	cmr &= ~ATMEL_TC_TCCLKS;

	if (pwm->hwpwm == 0) {
		cmr &= ~ATMEL_TC_ACMR_MASK;

		/* Set CMR flags according to given polarity */
		if (polarity == PWM_POLARITY_INVERSED)
			cmr |= ATMEL_TC_ASWTRG_CLEAR;
		else
			cmr |= ATMEL_TC_ASWTRG_SET;
	} else {
		cmr &= ~ATMEL_TC_BCMR_MASK;
		if (polarity == PWM_POLARITY_INVERSED)
			cmr |= ATMEL_TC_BSWTRG_CLEAR;
		else
			cmr |= ATMEL_TC_BSWTRG_SET;
	}

	/*
	 * If duty is 0 or equal to period there's no need to register
	 * a specific action on RA/RB and RC compare.
	 * The output will be configured on software trigger and keep
	 * this config till next config call.
	 */
	if (tcbpwm->duty != tcbpwm->period && tcbpwm->duty > 0) {
		if (pwm->hwpwm == 0) {
			if (polarity == PWM_POLARITY_INVERSED)
				cmr |= ATMEL_TC_ACPA_SET | ATMEL_TC_ACPC_CLEAR;
			else
				cmr |= ATMEL_TC_ACPA_CLEAR | ATMEL_TC_ACPC_SET;
		} else {
			if (polarity == PWM_POLARITY_INVERSED)
				cmr |= ATMEL_TC_BCPB_SET | ATMEL_TC_BCPC_CLEAR;
			else
				cmr |= ATMEL_TC_BCPB_CLEAR | ATMEL_TC_BCPC_SET;
		}
	}

	cmr |= (tcbpwm->div & ATMEL_TC_TCCLKS);

	regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), cmr);

	if (pwm->hwpwm == 0)
		regmap_write(tcbpwmc->regmap,
			     ATMEL_TC_REG(tcbpwmc->channel, RA),
			     tcbpwm->duty);
	else
		regmap_write(tcbpwmc->regmap,
			     ATMEL_TC_REG(tcbpwmc->channel, RB),
			     tcbpwm->duty);

	regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, RC),
		     tcbpwm->period);

	/* Use software trigger to apply the new setting */
	regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CCR),
		     ATMEL_TC_SWTRG | ATMEL_TC_CLKEN);
	tcbpwmc->bkup.enabled = 1;
	spin_unlock(&tcbpwmc->lock);
	return 0;
}