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Date:   Sun, 28 Jan 2018 21:52:36 +0800
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Subject: Re: [PATCH 07/16] iio: adc: sun4i-gpadc-iio: rework: support nvmem calibration data
To:     linux-arm-kernel@lists.infradead.org,
        Philipp Rossak <embed3d@gmail.com>,
        Jonathan Cameron <jic23@kernel.org>
CC:     mark.rutland@arm.com, sean@mess.org, linux-iio@vger.kernel.org,
        linux-sunxi@googlegroups.com, clabbe.montjoie@gmail.com,
        pmeerw@pmeerw.net, lee.jones@linaro.org, lars@metafoo.de,
        edu.molinas@gmail.com, linux@armlinux.org.uk, krzk@kernel.org,
        wens@csie.org, hans.verkuil@cisco.com, rask@formelder.dk,
        devicetree@vger.kernel.org, mchehab@kernel.org, robh+dt@kernel.org,
        singhalsimran0@gmail.com, linux-kernel@vger.kernel.org,
        quentin.schulz@free-electrons.com, knaack.h@gmx.de,
        maxime.ripard@free-electrons.com, davem@davemloft.net
From:   Icenowy Zheng <icenowy@aosc.io>
Message-ID: <1927F24D-D3ED-49CF-9B7C-A7C8C873F0CF@aosc.io>
Sender: linux-kernel-owner@vger.kernel.org
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于 2018年1月28日 GMT+08:00 下午9:46:18, Philipp Rossak <embed3d@gmail.com> 写到:
>
>
>On 28.01.2018 10:02, Jonathan Cameron wrote:
>> On Fri, 26 Jan 2018 16:19:32 +0100
>> Philipp Rossak <embed3d@gmail.com> wrote:
>> 
>>> This patch reworks the driver to support nvmem calibration cells.
>>> The driver checks if the nvmem calibration is supported and reads
>out
>>> the nvmem. At the beginning of the startup process the calibration
>data
>>> is written to the related registers.
>>>
>>> Signed-off-by: Philipp Rossak <embed3d@gmail.com>
>> 
>> A few minor suggestions inline.
>> 
>> Jonathan
>> 
>>> ---
>>>   drivers/iio/adc/sun4i-gpadc-iio.c | 52
>+++++++++++++++++++++++++++++++++++++++
>>>   include/linux/mfd/sun4i-gpadc.h   |  2 ++
>>>   2 files changed, 54 insertions(+)
>>>
>>> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c
>b/drivers/iio/adc/sun4i-gpadc-iio.c
>>> index bff06f2798e8..7b12666cdd9e 100644
>>> --- a/drivers/iio/adc/sun4i-gpadc-iio.c
>>> +++ b/drivers/iio/adc/sun4i-gpadc-iio.c
>>> @@ -27,6 +27,7 @@
>>>   #include <linux/interrupt.h>
>>>   #include <linux/io.h>
>>>   #include <linux/module.h>
>>> +#include <linux/nvmem-consumer.h>
>>>   #include <linux/of.h>
>>>   #include <linux/of_device.h>
>>>   #include <linux/platform_device.h>
>>> @@ -81,6 +82,7 @@ struct gpadc_data {
>>>   	bool		has_bus_rst;
>>>   	bool		has_mod_clk;
>>>   	int		sensor_count;
>>> +	bool		supports_nvmem;
>>>   };
>>>   
>>>   static const struct gpadc_data sun4i_gpadc_data = {
>>> @@ -94,6 +96,7 @@ static const struct gpadc_data sun4i_gpadc_data =
>{
>>>   	.sample_start = sun4i_gpadc_sample_start,
>>>   	.sample_end = sun4i_gpadc_sample_end,
>>>   	.sensor_count = 1,
>>> +	.supports_nvmem = false,
>>>   };
>>>   
>>>   static const struct gpadc_data sun5i_gpadc_data = {
>>> @@ -107,6 +110,7 @@ static const struct gpadc_data sun5i_gpadc_data
>= {
>>>   	.sample_start = sun4i_gpadc_sample_start,
>>>   	.sample_end = sun4i_gpadc_sample_end,
>>>   	.sensor_count = 1,
>>> +	.supports_nvmem = false,
>>>   };
>>>   
>>>   static const struct gpadc_data sun6i_gpadc_data = {
>>> @@ -120,6 +124,7 @@ static const struct gpadc_data sun6i_gpadc_data
>= {
>>>   	.sample_start = sun4i_gpadc_sample_start,
>>>   	.sample_end = sun4i_gpadc_sample_end,
>>>   	.sensor_count = 1,
>>> +	.supports_nvmem = false,
>>>   };
>>>   
>>>   static const struct gpadc_data sun8i_a33_gpadc_data = {
>>> @@ -130,6 +135,7 @@ static const struct gpadc_data
>sun8i_a33_gpadc_data = {
>>>   	.sample_start = sun4i_gpadc_sample_start,
>>>   	.sample_end = sun4i_gpadc_sample_end,
>>>   	.sensor_count = 1,
>>> +	.supports_nvmem = false,

BTW A33 claims to support calibration data according to the manual.

>>>   };
>>>   
>>>   struct sun4i_gpadc_iio {
>>> @@ -148,6 +154,8 @@ struct sun4i_gpadc_iio {
>>>   	struct clk			*mod_clk;
>>>   	struct reset_control		*reset;
>>>   	int				sensor_id;
>>> +	u32				calibration_data[2];
>>> +	bool				has_calibration_data[2];
>>>   	/* prevents concurrent reads of temperature and ADC */
>>>   	struct mutex			mutex;
>>>   	struct thermal_zone_device	*tzd;
>>> @@ -459,6 +467,17 @@ static int sun4i_gpadc_runtime_suspend(struct
>device *dev)
>>>   	return info->data->sample_end(info);
>>>   }
>>>   
>>> +static void sunxi_calibrate(struct sun4i_gpadc_iio *info)
>>> +{
>>> +	if (info->has_calibration_data[0])
>>> +		regmap_write(info->regmap, SUNXI_THS_CDATA_0_1,
>>> +			info->calibration_data[0]);
>>> +
>>> +	if (info->has_calibration_data[1])
>>> +		regmap_write(info->regmap, SUNXI_THS_CDATA_2_3,
>>> +			info->calibration_data[1]);
>>> +}
>>> +
>>>   static int sun4i_gpadc_sample_start(struct sun4i_gpadc_iio *info)
>>>   {
>>>   	/* clkin = 6MHz */
>>> @@ -481,6 +500,7 @@ static int sun4i_gpadc_sample_start(struct
>sun4i_gpadc_iio *info)
>>>   static int sunxi_ths_sample_start(struct sun4i_gpadc_iio *info)
>>>   {
>>>   	u32 value;
>>> +	sunxi_calibrate(info);
>>>   
>>>   	if (info->data->ctrl0_map)
>>>   		regmap_write(info->regmap, SUNXI_THS_CTRL0,
>>> @@ -602,6 +622,9 @@ static int sun4i_gpadc_probe_dt(struct
>platform_device *pdev,
>>>   	struct resource *mem;
>>>   	void __iomem *base;
>>>   	int ret;
>>> +	struct nvmem_cell *cell;
>>> +	ssize_t cell_size;
>>> +	u64 *cell_data;
>>>   
>>>   	info->data = of_device_get_match_data(&pdev->dev);
>>>   	if (!info->data)
>>> @@ -616,6 +639,35 @@ static int sun4i_gpadc_probe_dt(struct
>platform_device *pdev,
>>>   	if (IS_ERR(base))
>>>   		return PTR_ERR(base);
>>>   
>>> +	info->has_calibration_data[0] = false;
>>> +	info->has_calibration_data[1] = false;
>>> +
>>> +	if (!info->data->supports_nvmem)
>>> +		goto no_nvmem;
>>> +
>>> +	cell = devm_nvmem_cell_get(&pdev->dev, "calibration");
>>> +	if (IS_ERR(cell)) {
>>> +		if (PTR_ERR(cell) == -EPROBE_DEFER)
>>> +			return PTR_ERR(cell);
>> Use a goto here to no_nvmem.
>> 
>> Then you can drop the below else to make things more readable.
>>> +	} else {
>>> +		cell_data = (u64 *)nvmem_cell_read(cell, &cell_size);
>>> +		devm_nvmem_cell_put(&pdev->dev, cell);
>> 
>> I'm really not keen on use of devm for things we are intending
>> to drop almost immediately.  Just use the non managed versions
>> and clean up properly in the error paths (if there are any
>> where it is needed - which there aren't that I can see)
>> 
>
>^^ Ok, I will rework that.
>
>>> +		if (cell_size <= 4) {
>> Is it valid if it is anything other than 4?
>
>For sensors with only one sensor would be also a 2 valid, for those
>with 
>2 sensors ==> 4, with 3 sensors ==> 6 and with and with 4 sensors ==>
>8.
>
>In hardware we have in total to 32bit registers for calibration, thus I
>
>thought it would be a good idea to use always four bytes per register. 
>If two bytes are used, they should be the default value.
>
>But I agree, this needs a rework.
>
>>> +			info->has_calibration_data[0] = true;
>>> +			info->calibration_data[0] = be32_to_cpu(cell_data[0] &
>>> +					GENMASK(31, 0));
>> 
>> Masking isn't needed,  If you want to be paranoid there is the
>lower_32_bits
>> function..
>> 
>^^ Ok, I will rework that.
>>> +		} else if (cell_size <= 8) {
>>> +			info->has_calibration_data[0] = true;
>>> +			info->calibration_data[0] = be32_to_cpu(cell_data[0] &
>>> +					GENMASK(31, 0));
>> 
>> This first block is repeated.  Easy enough to avoid I think...
>> 
>
>^^ Ok, I will rework that.
>
>>> +			info->has_calibration_data[1] = true;
>>> +			info->calibration_data[1] = be32_to_cpu(
>>> +					(cell_data[0] >> 32) & GENMASK(31, 0));
>>> +		}
>>> +	}
>>> +
>>> +no_nvmem:
>>> +
>>>   	info->regmap = devm_regmap_init_mmio(&pdev->dev, base,
>>>   					     &sun4i_gpadc_regmap_config);
>>>   	if (IS_ERR(info->regmap)) {
>>> diff --git a/include/linux/mfd/sun4i-gpadc.h
>b/include/linux/mfd/sun4i-gpadc.h
>>> index 40b4dd9d2405..c251002431bd 100644
>>> --- a/include/linux/mfd/sun4i-gpadc.h
>>> +++ b/include/linux/mfd/sun4i-gpadc.h
>>> @@ -90,6 +90,8 @@
>>>   #define SUNXI_THS_CTRL0					0x00
>>>   #define SUNXI_THS_CTRL2					0x40
>>>   #define SUNXI_THS_FILTER				0x70
>>> +#define SUNXI_THS_CDATA_0_1				0x74
>>> +#define SUNXI_THS_CDATA_2_3				0x78
>>>   #define SUNXI_THS_TDATA0				0x80
>>>   #define SUNXI_THS_TDATA1				0x84
>>>   #define SUNXI_THS_TDATA2				0x88
>> 
>Thanks,
>Philipp
>
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