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Subject[PATCH v2 11/14] pwm: meson: read the full hardware state in meson_pwm_get_state()
Date
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.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
---
drivers/pwm/pwm-meson.c | 52 ++++++++++++++++++++++++++++++++++++++---
1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index 9afa1e5aaebf..010212166d5d 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -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 = {
--
2.21.0
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