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

[Jonathan Cameron]

On Fri, 26 Jan 2018 16:19:30 +0100
Philipp Rossak <embed3d@xxxxxxxxx> 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@xxxxxxxxx>
> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>

Both clock and reset code is safe against null parameters, so you can
drop a lot of 'is it here' checks in this.  They could be argued to
act as documentation of the fact we really don't expect them in some cases
I suppose... 

> ---
>  drivers/iio/adc/sun4i-gpadc-iio.c | 80 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 80 insertions(+)
> 
> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
> index 363936b37c5a..1a80744bd472 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>
>  
> @@ -75,6 +77,9 @@ struct gpadc_data {
>  	u32		ctrl2_map;
>  	u32		sensor_en_map;
>  	u32		filter_map;
> +	bool		has_bus_clk;
> +	bool		has_bus_rst;
> +	bool		has_mod_clk;
>  };
>  
>  static const struct gpadc_data sun4i_gpadc_data = {
> @@ -134,6 +139,9 @@ 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;
> @@ -435,6 +443,12 @@ static int sun4i_gpadc_runtime_suspend(struct device *dev)
>  {
>  	struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
>  
> +	if (info->data->has_mod_clk)
> +		clk_disable(info->mod_clk);

Safe against null parameter... (see below)

> +
> +	if (info->data->has_bus_clk)
> +		clk_disable(info->bus_clk);
> +
>  	return info->data->sample_end(info);
>  }
>  
> @@ -483,6 +497,12 @@ static int sun4i_gpadc_runtime_resume(struct device *dev)
>  {
>  	struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
>  
> +	if (info->data->has_mod_clk)
> +		clk_enable(info->mod_clk);

clk_enable is safe against null parameter so could do without the checks.

> +
> +	if (info->data->has_bus_clk)
> +		clk_enable(info->bus_clk);
> +
>  	return info->data->sample_start(info);
>  }
>  
> @@ -597,10 +617,61 @@ 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);
> +		if (ret)
> +			goto disable_bus_clk;
> +
> +		ret = clk_prepare_enable(info->mod_clk);
> +		if (ret)
> +			goto disable_bus_clk;
> +	}
> +
>  	if (IS_ENABLED(CONFIG_THERMAL_OF))
>  		info->sensor_device = &pdev->dev;
>  
>  	return 0;
> +
> +disable_bus_clk:
> +	if (info->data->has_bus_clk)
> +		clk_disable_unprepare(info->bus_clk);
> +
> +assert_reset:
> +	if (info->data->has_bus_rst)
> +		reset_control_assert(info->reset);
> +
> +	return ret;
>  }
>  
>  static int sun4i_gpadc_probe_mfd(struct platform_device *pdev,
> @@ -766,6 +837,15 @@ static int sun4i_gpadc_remove(struct platform_device *pdev)
>  	if (!info->no_irq)
>  		iio_map_array_unregister(indio_dev);
>  
> +	if (info->data->has_mod_clk)
> +		clk_disable_unprepare(info->mod_clk);

clk_disable_unprepare is safe against a null parameter
so I don't think the checks are needed.

> +
> +	if (info->data->has_bus_clk)
> +		clk_disable_unprepare(info->bus_clk);
> +
> +	if (info->data->has_bus_rst)
> +		reset_control_assert(info->reset);

Safe against null parameter...

> +
>  	return 0;
>  }
>