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gpio: mvebu: improve handling of pwm zero on/off values

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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: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Analyzed-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
This commit is contained in:
Baruch Siach 2021-01-20 18:16:28 +02:00 committed by Bartosz Golaszewski
parent 2bee255a5e
commit 0b68d02b6a
1 changed files with 23 additions and 16 deletions
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39
drivers/gpio/gpio-mvebu.c
View file

@ -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;