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Subject: Re: [PATCH 05/16] iio: adc: sun4i-gpadc-iio: rework: support clocks
 and reset
To:     Jonathan Cameron <jic23@kernel.org>
Cc:     lee.jones@linaro.org, robh+dt@kernel.org, mark.rutland@arm.com,
        maxime.ripard@free-electrons.com, wens@csie.org,
        linux@armlinux.org.uk, knaack.h@gmx.de, lars@metafoo.de,
        pmeerw@pmeerw.net, davem@davemloft.net, hans.verkuil@cisco.com,
        mchehab@kernel.org, rask@formelder.dk, clabbe.montjoie@gmail.com,
        sean@mess.org, krzk@kernel.org, quentin.schulz@free-electrons.com,
        icenowy@aosc.io, edu.molinas@gmail.com, singhalsimran0@gmail.com,
        linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-sunxi@googlegroups.com
References: <20180126151941.12183-1-embed3d@gmail.com>
 <20180126151941.12183-6-embed3d@gmail.com>
 <20180128085036.389c2dfb@archlinux>
From:   Philipp Rossak <embed3d@gmail.com>
Message-ID: <489c4e33-13ca-e6fe-bb49-8795fb793fd0@gmail.com>
Date:   Sun, 28 Jan 2018 12:34:14 +0100
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On 28.01.2018 09:50, Jonathan Cameron wrote:
> On Fri, 26 Jan 2018 16:19:30 +0100
> Philipp Rossak <embed3d@gmail.com> 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@gmail.com>
>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
> 
> 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...
> 
Ok, this sounds good for me!
I will fix that in the next version of this patch series.

>> ---
>>   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;
>>   }
>>   
> 
Thanks,
Philipp