Fw: [PATCH v2] pwm: meson: external clock configuration for s4
Neil Armstrong
narmstrong at baylibre.com
Thu Apr 21 01:42:15 PDT 2022
Hi Junyi,
On 19/04/2022 09:39, junyi.zhao at amlogic.com wrote:
>
> Hi Neil Armstrong，have u check this？
> Because of jiayi's personnel changes, this pwm upstream flow under my charge now.
What's the state of the patchset ?
On my side, I did a review of the v2 patchset, if you have some questions on my
comments, please ask them in-line.
Overall, the patchset could be much simpler since basically the PWM mux is
now in the clock controller.
Thanks,
Neil
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> junyi.zhao at amlogic.com
>
> *From:* jiayi.zhou at amlogic.com <mailto:jiayi.zhou at amlogic.com>
> *Date:* 2022-04-08 17:00
> *To:* junyi.zhao <mailto:junyi.zhao at amlogic.com>
> *Subject:* Fw: Re: [PATCH v2] pwm: meson: external clock configuration for s4
>
>
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> jiayi.zhou at amlogic.com
>
> *From:* Neil Armstrong <mailto:narmstrong at baylibre.com>
> *Date:* 2022-01-14 18:16
> *To:* Jiayi.Zhou <mailto:Jiayi.Zhou at amlogic.com>; jbrunet <mailto:jbrunet at baylibre.com>; thierry.reding <mailto:thierry.reding at gmail.com>; u.kleine-koenig <mailto:u.kleine-koenig at pengutronix.de>; lee.jones <mailto:lee.jones at linaro.org>; khilman <mailto:khilman at baylibre.com>; martin.blumenstingl <mailto:martin.blumenstingl at googlemail.com>
> *CC:* linux-arm-kernel <mailto:linux-arm-kernel at lists.infradead.org>; linux-amlogic <mailto:linux-amlogic at lists.infradead.org>; linux-kernel <mailto:linux-kernel at vger.kernel.org>
> *Subject:* Re: [PATCH v2] pwm: meson: external clock configuration for s4
> [ EXTERNAL EMAIL ]
> Hi,
> On 14/01/2022 10:07, Jiayi.Zhou at amlogic.com wrote:
> > From: "Jiayi.zhou" <jiayi.zhou at amlogic.com>
> >
> > For PWM controller in the Meson-S4 SoC,
> > PWM needs to obtain an external clock source.
> > This patch tries to describe them in the DT compatible data.
> Can you be more explicit here ? On which SoC ? Why ?
> As I understand while reading the S805X2 datasheet, now the PWM clock input is
> done in independent CLKCTRL registers and no more in the PWM registers, right ?
> So with S4, instead of passing the mux input clock of clkin0 & clkin1, now you pass
> the PWM mux output clock.
> >
> > Signed-off-by: Jiayi.zhou <jiayi.zhou at amlogic.com>
> > ---
> > drivers/pwm/pwm-meson.c | 145 ++++++++++++++++++++++++++++++----------
> > 1 file changed, 110 insertions(+), 35 deletions(-)
> >
> > diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> > index 3cf3bcf5ddfc..54db56c95be2 100644
> > --- a/drivers/pwm/pwm-meson.c
> > +++ b/drivers/pwm/pwm-meson.c
> > @@ -51,6 +51,7 @@
> > #define REG_MISC_AB 0x8
> > #define MISC_B_CLK_EN BIT(23)
> > #define MISC_A_CLK_EN BIT(15)
> > +
> > #define MISC_CLK_DIV_MASK 0x7f
> > #define MISC_B_CLK_DIV_SHIFT 16
> > #define MISC_A_CLK_DIV_SHIFT 8
> > @@ -93,11 +94,13 @@ struct meson_pwm_channel {
> > struct clk *clk_parent;
> > struct clk_mux mux;
> > struct clk *clk;
> > + struct clk *clk_mux;
> Why do you add a mux ?
> > };
> >
> > struct meson_pwm_data {
> > const char * const *parent_names;
> > unsigned int num_parents;
> > + unsigned int extern_clk;
> > };
> >
> > struct meson_pwm {
> > @@ -105,6 +108,7 @@ struct meson_pwm {
> > const struct meson_pwm_data *data;
> > struct meson_pwm_channel channels[MESON_NUM_PWMS];
> > void __iomem *base;
> > +
> > /*
> > * Protects register (write) access to the REG_MISC_AB register
> > * that is shared between the two PWMs.
> > @@ -130,13 +134,15 @@ static int meson_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> >
> > channel = &meson->channels[pwm->hwpwm];
> >
> > - if (channel->clk_parent) {
> > - err = clk_set_parent(channel->clk, channel->clk_parent);
> > - if (err < 0) {
> > - dev_err(dev, "failed to set parent %s for %s: %d\n",
> > - __clk_get_name(channel->clk_parent),
> > - __clk_get_name(channel->clk), err);
> > - return err;
> > + if (!meson->data->extern_clk) {
> > + if (channel->clk_parent) {
> > + err = clk_set_parent(channel->clk, channel->clk_parent);
> > + if (err < 0) {
> > + dev_err(dev, "failed to set parent %s for %s: %d\n",
> > + __clk_get_name(channel->clk_parent),
> > + __clk_get_name(channel->clk), err);
> > + return err;
> > + }
> > }
> > }
> >
> > @@ -171,7 +177,11 @@ static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
> > if (state->polarity == PWM_POLARITY_INVERSED)
> > duty = period - duty;
> >
> > - fin_freq = clk_get_rate(channel->clk);
> > + if (meson->data->extern_clk) {
> > + fin_freq = clk_get_rate(channel->clk_mux);> + } else {
> > + fin_freq = clk_get_rate(channel->clk);
> > + }
> > if (fin_freq == 0) {
> > dev_err(meson->chip.dev, "invalid source clock frequency\n");
> > return -EINVAL;
> > @@ -228,17 +238,32 @@ static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
> > struct meson_pwm_channel_data *channel_data;
> > unsigned long flags;
> > u32 value;
> > + unsigned long set_clk;
> > + u32 err;
> >
> > channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
> >
> > - spin_lock_irqsave(&meson->lock, flags);
> > -
> > value = readl(meson->base + REG_MISC_AB);
> > - value &= ~(MISC_CLK_DIV_MASK << channel_data->clk_div_shift);
> > - value |= channel->pre_div << channel_data->clk_div_shift;
> > - value |= channel_data->clk_en_mask;
> > - writel(value, meson->base + REG_MISC_AB);
> > + if (meson->data->extern_clk) {
> > + set_clk = clk_get_rate(channel->clk_mux);
> > +
> > + if (set_clk == 0)
> > + dev_err(meson->chip.dev, "invalid source clock frequency\n");
> > + set_clk /= channel->pre_div + 1;
> > + err = clk_set_rate(channel->clk, set_clk);
> > + if (err)
> > + dev_err(meson->chip.dev, "%s: error in setting pwm rate!\n", __func__);
> > + } else {
> > + spin_lock_irqsave(&meson->lock, flags);
> > +
> > + value &= ~(MISC_CLK_DIV_MASK << channel_data->clk_div_shift);
> > + value |= channel->pre_div << channel_data->clk_div_shift;
> > + value |= channel_data->clk_en_mask;
> > + writel(value, meson->base + REG_MISC_AB);
> >
> > + spin_unlock_irqrestore(&meson->lock, flags);
> > + }
> > + spin_lock_irqsave(&meson->lock, flags);
> > value = FIELD_PREP(PWM_HIGH_MASK, channel->hi) |
> > FIELD_PREP(PWM_LOW_MASK, channel->lo);
> > writel(value, meson->base + channel_data->reg_offset);
> > @@ -246,7 +271,6 @@ static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
> > value = readl(meson->base + REG_MISC_AB);
> > value |= channel_data->pwm_en_mask;
> > writel(value, meson->base + REG_MISC_AB);
> > -
> > spin_unlock_irqrestore(&meson->lock, flags);
> > }
> >
> > @@ -333,7 +357,8 @@ static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > struct meson_pwm *meson = to_meson_pwm(chip);
> > struct meson_pwm_channel_data *channel_data;
> > struct meson_pwm_channel *channel;
> > - u32 value, tmp;
> > + u32 value_pwm, value, tmp;
> > + unsigned long gate_clk, fre;
> >
> > if (!state)
> > return;
> > @@ -341,30 +366,42 @@ static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > channel = &meson->channels[pwm->hwpwm];
> > channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
> >
> > - value = readl(meson->base + REG_MISC_AB);
> > -
> > - 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_pwm = readl(meson->base + REG_MISC_AB);
> > 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);
> > + if (meson->data->extern_clk) {
> > + gate_clk = clk_get_rate(channel->clk);
> > + fre = gate_clk / (channel->lo + channel->hi);
> > + state->period = div_u64(NSEC_PER_SEC, fre);
> > + state->duty_cycle = div_u64(state->period * channel->hi, channel->lo + channel->hi);
> > + tmp = channel_data->pwm_en_mask;
> > +
> > + if (((value_pwm & tmp) == tmp) && __clk_is_enabled(channel->clk))
> > + state->enabled = true;
> > + else
> > + state->enabled = false;
> > } else {
> > - state->period = 0;
> > - state->duty_cycle = 0;
> > + tmp = channel_data->pwm_en_mask | channel_data->clk_en_mask;
> > +
> > + state->enabled = (value_pwm & tmp) == tmp;
> > +
> > + tmp = value_pwm >> channel_data->clk_div_shift;
> > + channel->pre_div = FIELD_GET(MISC_CLK_DIV_MASK, tmp);
> > +
> > + 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;
> > + }
> > }
> > }
> You need to rewrite the clock calculation entirely, instead of relying on a fin_freq, you need
> to set_rate() the needed rate to the input clock, then calculate the periods on the rate
> set by CCF.
> One way is to forget trying to set a rate of the input clock, simply get_rate() of the input clock
> and try to calculate periods on it.
> Instead rely on assignes-clock-parent & assigned-clock-rate in DT to set the right parent of the mux
> and rate of the mux post divider to feed to correct rate to the PWM controller.
> >
> > @@ -452,6 +489,10 @@ static const struct meson_pwm_data pwm_g12a_ee_data = {
> > .num_parents = ARRAY_SIZE(pwm_g12a_ee_parent_names),
> > };
> >
> > +static const struct meson_pwm_data pwm_meson_data = {
> > + .extern_clk = true,
> > +};
> > +
> > static const struct of_device_id meson_pwm_matches[] = {
> > {
> > .compatible = "amlogic,meson8b-pwm",
> > @@ -485,6 +526,10 @@ static const struct of_device_id meson_pwm_matches[] = {
> > .compatible = "amlogic,meson-g12a-ao-pwm-cd",
> > .data = &pwm_g12a_ao_cd_data
> > },
> > + {
> > + .compatible = "amlogic,meson-s4-pwm",
> > + .data = &pwm_meson_data
> > + },
> > {},
> > };
> > MODULE_DEVICE_TABLE(of, meson_pwm_matches);
> > @@ -534,6 +579,33 @@ static int meson_pwm_init_channels(struct meson_pwm *meson)
> > return 0;
> > }
> >
> > +static int meson_pwm_extern_init_channels(struct meson_pwm *meson)
> > +{
> > + struct meson_pwm_channel *channels = meson->channels;
> > + struct device *dev = meson->chip.dev;
> > + unsigned int i;
> > + char name[255];
> > +
> > + for (i = 0; i < meson->chip.npwm; i++) {
> > + snprintf(name, sizeof(name), "clkin%u", i);
> > + (channels + i)->clk = devm_clk_get(dev, name);
> > + if (IS_ERR((channels + i)->clk)) {
> > + dev_err_probe(meson->chip.dev, PTR_ERR((channels + i)->clk),
> > + "can't get device clock\n");
> > + return PTR_ERR((channels + i)->clk);
> > + }
> > + snprintf(name, sizeof(name), "mux%u", i);
> > + (channels + i)->clk_mux = devm_clk_get(dev, name);
> > + if (IS_ERR((channels + i)->clk_mux)) {
> > + dev_err_probe(meson->chip.dev, PTR_ERR((channels + i)->clk_mux),
> > + "can't get device clock\n");
> > + return PTR_ERR((channels + i)->clk_mux);
> If you add mux you'll need to changes the bindings.
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static int meson_pwm_probe(struct platform_device *pdev)
> > {
> > struct meson_pwm *meson;
> > @@ -553,8 +625,11 @@ static int meson_pwm_probe(struct platform_device *pdev)
> > meson->chip.npwm = MESON_NUM_PWMS;
> >
> > meson->data = of_device_get_match_data(&pdev->dev);
> > + if (meson->data->extern_clk)
> > + err = meson_pwm_extern_init_channels(meson);
> > + else
> > + err = meson_pwm_init_channels(meson);
> >
> > - err = meson_pwm_init_channels(meson);
> > if (err < 0)
> > return err;
> >
> >
>
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