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allwinner: aw_pwm: Read value at attach

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The booloaded might have configured the pwm controller so read the values.
This commit is contained in:
Emmanuel Vadot 2018-12-14 18:39:17 +00:00
parent 50a123aad8
commit ad5bce19bf
1 changed files with 22 additions and 1 deletions
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23
sys/arm/allwinner/aw_pwm.c
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@ -136,7 +136,8 @@ static int
aw_pwm_attach(device_t dev)
{
struct aw_pwm_softc *sc;
/* uint32_t reg; */
uint64_t clk_freq;
uint32_t reg;
int error;
sc = device_get_softc(dev);
@ -160,6 +161,26 @@ aw_pwm_attach(device_t dev)
if ((sc->busdev = pwmbus_attach_bus(dev)) == NULL)
device_printf(dev, "Cannot attach pwm bus\n");
/* Read the configuration left by U-Boot */
reg = AW_PWM_READ(sc, AW_PWM_CTRL);
if (reg & (AW_PWM_CTRL_GATE | AW_PWM_CTRL_EN))
sc->enabled = true;
reg = AW_PWM_READ(sc, AW_PWM_CTRL);
reg &= AW_PWM_CTRL_PRESCALE_MASK;
if (reg > nitems(aw_pwm_clk_prescaler)) {
device_printf(dev, "Bad prescaler %x, cannot guess current settings\n", reg);
goto out;
}
clk_freq = sc->clk_freq / aw_pwm_clk_prescaler[reg];
reg = AW_PWM_READ(sc, AW_PWM_PERIOD);
sc->period = NS_PER_SEC /
(clk_freq / ((reg >> AW_PWM_PERIOD_TOTAL_SHIFT) & AW_PWM_PERIOD_TOTAL_MASK));
sc->duty = NS_PER_SEC /
(clk_freq / ((reg >> AW_PWM_PERIOD_ACTIVE_SHIFT) & AW_PWM_PERIOD_ACTIVE_MASK));
out:
return (0);
fail: