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pwm: meson: Read the full hardware state in meson_pwm_get_state() 

Update the meson_pwm_get_state() implementation to take care of all
information in the registers instead of only reading the "enabled"
state.

The PWM output is only enabled if two conditions are met:
1. the per-channel clock is enabled
2. the PWM output is enabled

Calculate the PWM period and duty cycle using the reverse formula which
we already have in meson_pwm_calc() and update struct pwm_state with the
results.

As result of this /sys/kernel/debug/pwm now shows the PWM state set by
the bootloader (or firmware) after booting Linux.

Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Martin Blumenstingl 2019-06-12 21:59:08 +02:00 committed by Thierry Reding
parent fb2081e870
commit c375bcbaab
1 changed files with 49 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
drivers/pwm/pwm-meson.c
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@ -287,19 +287,65 @@ static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
return 0;
}
static unsigned int meson_pwm_cnt_to_ns(struct pwm_chip *chip,
struct pwm_device *pwm, u32 cnt)
{
struct meson_pwm *meson = to_meson_pwm(chip);
struct meson_pwm_channel *channel;
unsigned long fin_freq;
u32 fin_ns;
/* to_meson_pwm() can only be used after .get_state() is called */
channel = &meson->channels[pwm->hwpwm];
fin_freq = clk_get_rate(channel->clk);
if (fin_freq == 0)
return 0;
fin_ns = div_u64(NSEC_PER_SEC, fin_freq);
return cnt * fin_ns * (channel->pre_div + 1);
}
static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct meson_pwm *meson = to_meson_pwm(chip);
u32 value, mask;
struct meson_pwm_channel_data *channel_data;
struct meson_pwm_channel *channel;
u32 value, tmp;
if (!state)
return;
mask = meson_pwm_per_channel_data[pwm->hwpwm].pwm_en_mask;
channel = &meson->channels[pwm->hwpwm];
channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
value = readl(meson->base + REG_MISC_AB);
state->enabled = (value & mask) != 0;
tmp = channel_data->pwm_en_mask | channel_data->clk_en_mask;
state->enabled = (value & tmp) == tmp;
tmp = value >> channel_data->clk_div_shift;
channel->pre_div = FIELD_GET(MISC_CLK_DIV_MASK, tmp);
value = readl(meson->base + channel_data->reg_offset);
channel->lo = FIELD_GET(PWM_LOW_MASK, value);
channel->hi = FIELD_GET(PWM_HIGH_MASK, value);
if (channel->lo == 0) {
state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
state->duty_cycle = state->period;
} else if (channel->lo >= channel->hi) {
state->period = meson_pwm_cnt_to_ns(chip, pwm,
channel->lo + channel->hi);
state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm,
channel->hi);
} else {
state->period = 0;
state->duty_cycle = 0;
}
}
static const struct pwm_ops meson_pwm_ops = {