From: Neil Armstrong <narmstrong@baylibre.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
linux-amlogic@lists.infradead.org, linux-pwm@vger.kernel.org,
thierry.reding@gmail.com, u.kleine-koenig@pengutronix.de
Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 11/14] pwm: meson: read the full hardware state in meson_pwm_get_state()
Date: Mon, 27 May 2019 14:31:00 +0200 [thread overview]
Message-ID: <c80dcb3f-13a6-7b9d-a7c6-a81110dcddda@baylibre.com> (raw)
In-Reply-To: <20190525181133.4875-12-martin.blumenstingl@googlemail.com>
On 25/05/2019 20:11, Martin Blumenstingl wrote:
> 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>
> ---
> 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 = {
>
Thanks for that !!!
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
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next prev parent reply other threads:[~2019-05-27 12:31 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-25 18:11 [PATCH 00/14] pwm-meson: cleanups and improvements Martin Blumenstingl
2019-05-25 18:11 ` [PATCH 01/14] pwm: meson: unify the parameter list of meson_pwm_{enable, disable} Martin Blumenstingl
2019-05-27 12:25 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 02/14] pwm: meson: use devm_clk_get_optional() to get the input clock Martin Blumenstingl
2019-05-27 12:25 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 03/14] pwm: meson: use GENMASK and FIELD_PREP for the lo and hi values Martin Blumenstingl
2019-05-27 12:25 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 04/14] pwm: meson: change MISC_CLK_SEL_WIDTH to MISC_CLK_SEL_MASK Martin Blumenstingl
2019-05-27 12:26 ` Neil Armstrong
2019-05-27 17:46 ` Martin Blumenstingl
2019-05-27 18:00 ` Uwe Kleine-König
2019-05-28 18:04 ` Martin Blumenstingl
2019-05-25 18:11 ` [PATCH 05/14] pwm: meson: don't duplicate the polarity internally Martin Blumenstingl
2019-05-27 12:26 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 06/14] pwm: meson: pass struct pwm_device to meson_pwm_calc() Martin Blumenstingl
2019-05-27 12:27 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 07/14] pwm: meson: add the meson_pwm_channel data to struct meson_pwm Martin Blumenstingl
2019-05-27 12:27 ` Neil Armstrong
2019-05-27 17:52 ` Martin Blumenstingl
2019-05-25 18:11 ` [PATCH 08/14] pwm: meson: add the per-channel register offsets and bits in a struct Martin Blumenstingl
2019-05-27 12:28 ` Neil Armstrong
2019-05-27 17:57 ` Martin Blumenstingl
2019-05-28 8:11 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 09/14] pwm: meson: move pwm_set_chip_data() to meson_pwm_request() Martin Blumenstingl
2019-05-27 12:30 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 10/14] pwm: meson: simplify the calculation of the pre-divider and count Martin Blumenstingl
2019-05-26 19:41 ` Uwe Kleine-König
2019-05-27 12:37 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 11/14] pwm: meson: read the full hardware state in meson_pwm_get_state() Martin Blumenstingl
2019-05-27 12:31 ` Neil Armstrong [this message]
2019-05-25 18:11 ` [PATCH 12/14] pwm: meson: don't cache struct pwm_state internally Martin Blumenstingl
2019-05-27 12:31 ` Neil Armstrong
2019-05-25 18:11 ` [PATCH 13/14] pwm: meson: add support PWM_POLARITY_INVERSED when disabling Martin Blumenstingl
2019-05-27 12:33 ` Neil Armstrong
2019-05-27 17:50 ` Martin Blumenstingl
2019-05-25 18:11 ` [PATCH 14/14] pwm: meson: add documentation to the driver Martin Blumenstingl
2019-05-27 12:33 ` Neil Armstrong
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