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Date:   Fri, 31 Aug 2018 11:03:07 +0200
From:   Maxime Ripard <maxime.ripard@...tlin.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,
        eugen.hristev@...rochip.com, rdunlap@...radead.org,
        vilhelm.gray@...il.com, clabbe.montjoie@...il.com,
        quentin.schulz@...tlin.com, geert+renesas@...der.be,
        lukas@...ner.de, icenowy@...c.io, arnd@...db.de,
        broonie@...nel.org, arnaud.pouliquen@...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 v3 17/30] iio: adc: sun4i-gpadc-iio: rework: support
 clocks and reset

On Thu, Aug 30, 2018 at 05:45:05PM +0200, 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>
> ---
>  drivers/iio/adc/sun4i-gpadc-iio.c | 72 +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 70 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
> index c278e165e161..c12de48c4e86 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>
>  
> @@ -63,6 +65,9 @@ struct gpadc_data {
>  	int		(*ths_suspend)(struct sun4i_gpadc_iio *info);
>  	int		(*ths_resume)(struct sun4i_gpadc_iio *info);
>  	bool		support_irq;
> +	bool		has_bus_clk;
> +	bool		has_bus_rst;
> +	bool		has_mod_clk;
>  	u32		temp_data_base;
>  };
>  
> @@ -127,6 +132,9 @@ struct sun4i_gpadc_iio {
>  	struct mutex			mutex;
>  	struct thermal_zone_device	*tzd;
>  	struct device			*sensor_device;
> +	struct clk			*bus_clk;
> +	struct clk			*mod_clk;
> +	struct reset_control		*reset;
>  };
>  
>  static const struct iio_chan_spec sun4i_gpadc_channels[] = {
> @@ -472,8 +480,13 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
>  	if (IS_ERR(base))
>  		return PTR_ERR(base);
>  
> -	info->regmap = devm_regmap_init_mmio(&pdev->dev, base,
> -					     &sun4i_gpadc_regmap_config);
> +	if (info->data->has_bus_clk)
> +		info->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "bus",
> +				base, &sun4i_gpadc_regmap_config);
> +	else
> +		info->regmap = devm_regmap_init_mmio(&pdev->dev, base,
> +				&sun4i_gpadc_regmap_config);
> +
>  	if (IS_ERR(info->regmap)) {
>  		ret = PTR_ERR(info->regmap);
>  		dev_err(&pdev->dev, "failed to init regmap: %d\n", ret);
> @@ -498,9 +511,58 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
>  		}
>  	}
>  
> +	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;

That should be done in the runtime_resume hook

> +	}
> +
> +	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 4MHz */
> +		ret = clk_set_rate(info->mod_clk, 4000000);
> +		if (ret)
> +			goto disable_bus_clk;

Why?

> +		ret = clk_prepare_enable(info->mod_clk);
> +		if (ret)
> +			goto disable_bus_clk;
> +	}
> +
>  	info->sensor_device = &pdev->dev;
>  
>  	return 0;
> +
> +disable_bus_clk:
> +	clk_disable_unprepare(info->bus_clk);
> +
> +assert_reset:
> +	reset_control_assert(info->reset);

You should check for the variables here before calling those
functions, if you end up here with your variable not set, you'll have
improper refcounting.

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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