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SubjectRe: [PATCH 2/2] iio: adc: stm32: allow to tune analog clock
On Sun, 3 Nov 2019 12:30:42 +0000
Jonathan Cameron <jic23@kernel.org> wrote:

> On Mon, 28 Oct 2019 17:11:48 +0100
> Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
>
> > Add new optional dt property to tune analog clock prescaler.
> > Driver looks for optional "st,max-clk-rate-hz", then computes
> > best approximation below that rate, using ADC internal prescaler.
> >
> > Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> If the previous email I wrote on this got to anyone before I hit
> cancel, please ignore. Had completely failed to read the code correctly.
>
> Anyhow this seems fine to me, but given there are a lot of existing
> clk related bindings I'd like to give a little longer for Rob to
> have a chance to take a look at the binding.
>
> Give me a poke if I seem to have lost this in a week or so.

Applied to the togreg branch of iio.git. Shortly to be pushed out
as testing for the autobuilders to poke at it.

Thanks,

Jonathan

>
> Thanks,
>
> Jonathan
>
>
>
> > ---
> > drivers/iio/adc/stm32-adc-core.c | 16 +++++++++++++---
> > 1 file changed, 13 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c
> > index 20c626c..6537f4f 100644
> > --- a/drivers/iio/adc/stm32-adc-core.c
> > +++ b/drivers/iio/adc/stm32-adc-core.c
> > @@ -79,6 +79,7 @@ struct stm32_adc_priv_cfg {
> > * @domain: irq domain reference
> > * @aclk: clock reference for the analog circuitry
> > * @bclk: bus clock common for all ADCs, depends on part used
> > + * @max_clk_rate: desired maximum clock rate
> > * @booster: booster supply reference
> > * @vdd: vdd supply reference
> > * @vdda: vdda analog supply reference
> > @@ -95,6 +96,7 @@ struct stm32_adc_priv {
> > struct irq_domain *domain;
> > struct clk *aclk;
> > struct clk *bclk;
> > + u32 max_clk_rate;
> > struct regulator *booster;
> > struct regulator *vdd;
> > struct regulator *vdda;
> > @@ -141,7 +143,7 @@ static int stm32f4_adc_clk_sel(struct platform_device *pdev,
> > }
> >
> > for (i = 0; i < ARRAY_SIZE(stm32f4_pclk_div); i++) {
> > - if ((rate / stm32f4_pclk_div[i]) <= priv->cfg->max_clk_rate_hz)
> > + if ((rate / stm32f4_pclk_div[i]) <= priv->max_clk_rate)
> > break;
> > }
> > if (i >= ARRAY_SIZE(stm32f4_pclk_div)) {
> > @@ -230,7 +232,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev,
> > if (ckmode)
> > continue;
> >
> > - if ((rate / div) <= priv->cfg->max_clk_rate_hz)
> > + if ((rate / div) <= priv->max_clk_rate)
> > goto out;
> > }
> > }
> > @@ -250,7 +252,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev,
> > if (!ckmode)
> > continue;
> >
> > - if ((rate / div) <= priv->cfg->max_clk_rate_hz)
> > + if ((rate / div) <= priv->max_clk_rate)
> > goto out;
> > }
> >
> > @@ -655,6 +657,7 @@ static int stm32_adc_probe(struct platform_device *pdev)
> > struct device *dev = &pdev->dev;
> > struct device_node *np = pdev->dev.of_node;
> > struct resource *res;
> > + u32 max_rate;
> > int ret;
> >
> > if (!pdev->dev.of_node)
> > @@ -731,6 +734,13 @@ static int stm32_adc_probe(struct platform_device *pdev)
> > priv->common.vref_mv = ret / 1000;
> > dev_dbg(&pdev->dev, "vref+=%dmV\n", priv->common.vref_mv);
> >
> > + ret = of_property_read_u32(pdev->dev.of_node, "st,max-clk-rate-hz",
> > + &max_rate);
> > + if (!ret)
> > + priv->max_clk_rate = min(max_rate, priv->cfg->max_clk_rate_hz);
> > + else
> > + priv->max_clk_rate = priv->cfg->max_clk_rate_hz;
> > +
> > ret = priv->cfg->clk_sel(pdev, priv);
> > if (ret < 0)
> > goto err_hw_stop;
>

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