static int __pwm_samsung_config()

in pwm-samsung.c [317:396]

• 43 lines of code
• 7 McCabe index (conditional complexity)

static int __pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
				int duty_ns, int period_ns, bool force_period)
{
	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
	struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
	u32 tin_ns = chan->tin_ns, tcnt, tcmp, oldtcmp;

	/*
	 * We currently avoid using 64bit arithmetic by using the
	 * fact that anything faster than 1Hz is easily representable
	 * by 32bits.
	 */
	if (period_ns > NSEC_PER_SEC)
		return -ERANGE;

	tcnt = readl(our_chip->base + REG_TCNTB(pwm->hwpwm));
	oldtcmp = readl(our_chip->base + REG_TCMPB(pwm->hwpwm));

	/* We need tick count for calculation, not last tick. */
	++tcnt;

	/* Check to see if we are changing the clock rate of the PWM. */
	if (chan->period_ns != period_ns || force_period) {
		unsigned long tin_rate;
		u32 period;

		period = NSEC_PER_SEC / period_ns;

		dev_dbg(our_chip->chip.dev, "duty_ns=%d, period_ns=%d (%u)\n",
						duty_ns, period_ns, period);

		tin_rate = pwm_samsung_calc_tin(our_chip, pwm->hwpwm, period);

		dev_dbg(our_chip->chip.dev, "tin_rate=%lu\n", tin_rate);

		tin_ns = NSEC_PER_SEC / tin_rate;
		tcnt = period_ns / tin_ns;
	}

	/* Period is too short. */
	if (tcnt <= 1)
		return -ERANGE;

	/* Note that counters count down. */
	tcmp = duty_ns / tin_ns;

	/* 0% duty is not available */
	if (!tcmp)
		++tcmp;

	tcmp = tcnt - tcmp;

	/* Decrement to get tick numbers, instead of tick counts. */
	--tcnt;
	/* -1UL will give 100% duty. */
	--tcmp;

	dev_dbg(our_chip->chip.dev,
				"tin_ns=%u, tcmp=%u/%u\n", tin_ns, tcmp, tcnt);

	/* Update PWM registers. */
	writel(tcnt, our_chip->base + REG_TCNTB(pwm->hwpwm));
	writel(tcmp, our_chip->base + REG_TCMPB(pwm->hwpwm));

	/*
	 * In case the PWM is currently at 100% duty cycle, force a manual
	 * update to prevent the signal staying high if the PWM is disabled
	 * shortly afer this update (before it autoreloaded the new values).
	 */
	if (oldtcmp == (u32) -1) {
		dev_dbg(our_chip->chip.dev, "Forcing manual update");
		pwm_samsung_manual_update(our_chip, pwm);
	}

	chan->period_ns = period_ns;
	chan->tin_ns = tin_ns;
	chan->duty_ns = duty_ns;

	return 0;
}