Commit 0b68d02b authored by Baruch Siach's avatar Baruch Siach Committed by Bartosz Golaszewski
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gpio: mvebu: improve handling of pwm zero on/off values 



Hardware appears to treat zero value as 2^32. Take advantage of this
fact to support on/off values of up to UINT_MAX+1 == 2^32. Adjust both
.apply and .get_state to handle zero as a special case.

Rounded up division result in .get_state can't be zero, since the
dividend is now larger than 0. Remove check for this case.

Reported-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Analyzed-by: default avatarRussell King <linux@armlinux.org.uk>
Signed-off-by: default avatarBaruch Siach <baruch@tkos.co.il>
Reviewed-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
parent 2bee255a

drivers/gpio/gpio-mvebu.c

+23 −16
Original line number Diff line number Diff line
@@ -667,22 +667,21 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip, 
	spin_lock_irqsave(&mvpwm->lock, flags);



	regmap_read(mvpwm->regs, mvebu_pwmreg_blink_on_duration(mvpwm), &u);

	val = (unsigned long long) u * NSEC_PER_SEC;

	val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);

	if (val)

		state->duty_cycle = val;

	/* Hardware treats zero as 2^32. See mvebu_pwm_apply(). */

	if (u > 0)

		val = u;

	else

		state->duty_cycle = 1;

		val = UINT_MAX + 1ULL;

	state->duty_cycle = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC,

			mvpwm->clk_rate);



	val = (unsigned long long) u; /* on duration */

	regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);

	val += (unsigned long long) u; /* period = on + off duration */

	val *= NSEC_PER_SEC;

	val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);

	if (val)

		state->period = val;

	/* period = on + off duration */

	if (u > 0)

		val += u;

	else

		state->period = 1;

		val += UINT_MAX + 1ULL;

	state->period = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC, mvpwm->clk_rate);



	regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u);

	if (u)
@@ -704,9 +703,15 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 


	val = (unsigned long long) mvpwm->clk_rate * state->duty_cycle;

	do_div(val, NSEC_PER_SEC);

	if (val > UINT_MAX)

	if (val > UINT_MAX + 1ULL)

		return -EINVAL;

	if (val)

	/*

	 * Zero on/off values don't work as expected. Experimentation shows

	 * that zero value is treated as 2^32. This behavior is not documented.

	 */

	if (val == UINT_MAX + 1ULL)

		on = 0;

	else if (val)

		on = val;

	else

		on = 1;
@@ -714,9 +719,11 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 
	val = (unsigned long long) mvpwm->clk_rate * state->period;

	do_div(val, NSEC_PER_SEC);

	val -= on;

	if (val > UINT_MAX)

	if (val > UINT_MAX + 1ULL)

		return -EINVAL;

	if (val)

	if (val == UINT_MAX + 1ULL)

		off = 0;

	else if (val)

		off = val;

	else

		off = 1;