linux-kernel - Re: [PATCH v2 05/16] iio: adc: sun4i-gpadc-iio: rework: support clocks and reset

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Date:   Mon, 29 Jan 2018 10:31:14 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Philipp Rossak <embed3d@...il.com>
Cc:     lee.jones@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
        wens@...e.org, linux@...linux.org.uk, jic23@...nel.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        davem@...emloft.net, hans.verkuil@...co.com, mchehab@...nel.org,
        rask@...melder.dk, clabbe.montjoie@...il.com, sean@...s.org,
        krzk@...nel.org, quentin.schulz@...e-electrons.com,
        icenowy@...c.io, edu.molinas@...il.com, singhalsimran0@...il.com,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 05/16] iio: adc: sun4i-gpadc-iio: rework: support
 clocks and reset

On Mon, Jan 29, 2018 at 12:29:08AM +0100, Philipp Rossak wrote:
> For adding newer sensor some basic rework of the code is necessary.
> 
> The SoCs after H3 has newer thermal sensor ADCs, which have two clock
> inputs (bus clock and sampling clock) and a reset. The registers are
> also re-arranged.
> 
> This commit reworks the code, adds the process of the clocks and
> resets.
> 
> Signed-off-by: Philipp Rossak <embed3d@...il.com>
> Signed-off-by: Icenowy Zheng <icenowy@...c.io>

Same remark for the SoB

> ---
>  drivers/iio/adc/sun4i-gpadc-iio.c | 71 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 71 insertions(+)
> 
> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
> index db57d9fffe48..51ec0104d678 100644
> --- a/drivers/iio/adc/sun4i-gpadc-iio.c
> +++ b/drivers/iio/adc/sun4i-gpadc-iio.c
> @@ -22,6 +22,7 @@
>   * shutdown for not being used.
>   */
>  
> +#include <linux/clk.h>
>  #include <linux/completion.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
> @@ -31,6 +32,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/regmap.h>
> +#include <linux/reset.h>
>  #include <linux/thermal.h>
>  #include <linux/delay.h>
>  
> @@ -68,6 +70,9 @@ struct gpadc_data {
>  	unsigned int	temp_data;
>  	int		(*sample_start)(struct sun4i_gpadc_iio *info);
>  	int		(*sample_end)(struct sun4i_gpadc_iio *info);
> +	bool		has_bus_clk;
> +	bool		has_bus_rst;
> +	bool		has_mod_clk;

Is there SoCs where this insn't all true, or all false?

>  };
>  
>  static const struct gpadc_data sun4i_gpadc_data = {
> @@ -127,6 +132,9 @@ struct sun4i_gpadc_iio {
>  	atomic_t			ignore_temp_data_irq;
>  	const struct gpadc_data		*data;
>  	bool				no_irq;
> +	struct clk			*bus_clk;
> +	struct clk			*mod_clk;
> +	struct reset_control		*reset;
>  	/* prevents concurrent reads of temperature and ADC */
>  	struct mutex			mutex;
>  	struct thermal_zone_device	*tzd;
> @@ -420,6 +428,10 @@ static int sun4i_gpadc_runtime_suspend(struct device *dev)
>  {
>  	struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
>  
> +	clk_disable(info->mod_clk);
> +

Why clk_disable?

> +	clk_disable(info->bus_clk);
> +

You can tie the bus_clk to the regmap directly, instead of having to
maintain it yourself here.

And you can probably put the device in reset and out of reset here as
well.

>  	return info->data->sample_end(info);
>  }
>  
> @@ -446,6 +458,10 @@ static int sun4i_gpadc_runtime_resume(struct device *dev)
>  {
>  	struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
>  
> +	clk_enable(info->mod_clk);
> +
> +	clk_enable(info->bus_clk);
> +
>  	return info->data->sample_start(info);
>  }
>  
> @@ -560,10 +576,59 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
>  		return ret;
>  	}
>  
> +	if (info->data->has_bus_rst) {
> +		info->reset = devm_reset_control_get(&pdev->dev, NULL);
> +		if (IS_ERR(info->reset)) {
> +			ret = PTR_ERR(info->reset);
> +			return ret;
> +		}
> +
> +		ret = reset_control_deassert(info->reset);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (info->data->has_bus_clk) {
> +		info->bus_clk = devm_clk_get(&pdev->dev, "bus");
> +		if (IS_ERR(info->bus_clk)) {
> +			ret = PTR_ERR(info->bus_clk);
> +			goto assert_reset;
> +		}
> +
> +		ret = clk_prepare_enable(info->bus_clk);
> +		if (ret)
> +			goto assert_reset;
> +	}
> +
> +	if (info->data->has_mod_clk) {
> +		info->mod_clk = devm_clk_get(&pdev->dev, "mod");
> +		if (IS_ERR(info->mod_clk)) {
> +			ret = PTR_ERR(info->mod_clk);
> +			goto disable_bus_clk;
> +		}
> +
> +		/* Running at 6MHz */
> +		ret = clk_set_rate(info->mod_clk, 4000000);

Your comment and the line below doesn't really make much sense :)

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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