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Date:	Thu, 18 Sep 2014 15:35:34 -0700
From:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:	Hartmut Knaack <knaack.h@....de>
Cc:	IIO <linux-iio@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	DEVICE TREE <devicetree@...r.kernel.org>,
	Lee Jones <lee.jones@...aro.org>,
	Carlo Caione <carlo@...one.org>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Aaron Lu <aaron.lu@...el.com>, Alan Cox <alan@...ux.intel.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh+dt@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Fugang Duan <B38611@...escale.com>,
	Arnd Bergmann <arnd@...db.de>,
	Zubair Lutfullah <zubair.lutfullah@...il.com>,
	Sebastian Reichel <sre@...ian.org>,
	Johannes Thumshirn <johannes.thumshirn@....de>,
	Philippe Reynes <tremyfr@...oo.fr>,
	Angelo Compagnucci <angelo.compagnucci@...il.com>,
	Doug Anderson <dianders@...omium.org>,
	Ramakrishna Pallala <ramakrishna.pallala@...el.com>,
	Peter Meerwald <pmeerw@...erw.net>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Rafael Wysocki <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH v4 2/3] iio/adc: add support for axp288 adc

On Thu, 18 Sep 2014 23:52:01 +0200
Hartmut Knaack <knaack.h@....de> wrote:

> Jacob Pan schrieb, Am 18.09.2014 01:13:
> > On Thu, 18 Sep 2014 00:20:00 +0200
> > Hartmut Knaack <knaack.h@....de> wrote:
> > 
> >> Jacob Pan schrieb, Am 17.09.2014 02:11:
> >>> Platform driver for X-Powers AXP288 ADC, which is a sub-device of
> >>> the customized AXP288 PMIC for Intel Baytrail-CR platforms. GPADC
> >>> device enumerates as one of the MFD cell devices. It uses IIO
> >>> infrastructure to communicate with userspace and consumer drivers.
> >>>
> >>> Usages of ADC channels include battery charging and thermal
> >>> sensors.
> >>>
> >> You are progressing, but still a few issues left. One thing is
> >> indentation in some places (I feel like being pretty annoying about
> >> this), others are commented in line.
> > I don't see the indentation issue, perhaps it is the difference in
> > the editors we use?
> > 
> >>> Based on initial work by:
> >>> Ramakrishna Pallala <ramakrishna.pallala@...el.com>
> >>>
> >>> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> >>> ---
> >>>  drivers/iio/adc/Kconfig      |   8 ++
> >>>  drivers/iio/adc/Makefile     |   1 +
> >>>  drivers/iio/adc/axp288_adc.c | 254
> >>> +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 263
> >>> insertions(+) create mode 100644 drivers/iio/adc/axp288_adc.c
> >>>
> >>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> >>> index 11b048a..db2681b 100644
> >>> --- a/drivers/iio/adc/Kconfig
> >>> +++ b/drivers/iio/adc/Kconfig
> >>> @@ -127,6 +127,14 @@ config AT91_ADC
> >>>  	help
> >>>  	  Say yes here to build support for Atmel AT91 ADC.
> >>>  
> >>> +config AXP288_ADC
> >>> +	tristate "X-Powers AXP288 ADC driver"
> >>> +	depends on MFD_AXP20X
> >>> +	help
> >>> +	  Say yes here to have support for X-Powers power
> >>> management IC (PMIC) ADC
> >>> +	  device. Depending on platform configuration, this
> >>> general purpose ADC can
> >>> +	  be used for sampling sensors such as thermal resistors.
> >>> +
> >>>  config EXYNOS_ADC
> >>>  	tristate "Exynos ADC driver support"
> >>>  	depends on ARCH_EXYNOS || (OF && COMPILE_TEST)
> >>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> >>> index ad81b51..19640f9 100644
> >>> --- a/drivers/iio/adc/Makefile
> >>> +++ b/drivers/iio/adc/Makefile
> >>> @@ -14,6 +14,7 @@ obj-$(CONFIG_AD7793) += ad7793.o
> >>>  obj-$(CONFIG_AD7887) += ad7887.o
> >>>  obj-$(CONFIG_AD799X) += ad799x.o
> >>>  obj-$(CONFIG_AT91_ADC) += at91_adc.o
> >>> +obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
> >>>  obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
> >>>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
> >>>  obj-$(CONFIG_MAX1027) += max1027.o
> >>> diff --git a/drivers/iio/adc/axp288_adc.c
> >>> b/drivers/iio/adc/axp288_adc.c new file mode 100644
> >>> index 0000000..333c624
> >>> --- /dev/null
> >>> +++ b/drivers/iio/adc/axp288_adc.c
> >>> @@ -0,0 +1,254 @@
> >>> +/*
> >>> + * axp288_adc.c - X-Powers AXP288 PMIC ADC Driver
> >>> + *
> >>> + * Copyright (C) 2014 Intel Corporation
> >>> + *
> >>> + *
> >>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>> + *
> >>> + * This program is free software; you can redistribute it and/or
> >>> modify
> >>> + * it under the terms of the GNU General Public License as
> >>> published by
> >>> + * the Free Software Foundation; version 2 of the License.
> >>> + *
> >>> + * This program is distributed in the hope that it will be
> >>> useful, but
> >>> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> >>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> >>> See the GNU
> >>> + * General Public License for more details.
> >>> + *
> >>> + */
> >>> +
> >>> +#include <linux/module.h>
> >>> +#include <linux/kernel.h>
> >>> +#include <linux/device.h>
> >>> +#include <linux/regmap.h>
> >>> +#include <linux/mfd/axp20x.h>
> >>> +#include <linux/platform_device.h>
> >>> +
> >>> +#include <linux/iio/iio.h>
> >>> +#include <linux/iio/machine.h>
> >>> +#include <linux/iio/driver.h>
> >>> +
> >>> +#define AXP288_ADC_EN_MASK		0xF1
> >>> +#define AXP288_ADC_TS_PIN_GPADC		0xF2
> >>> +#define AXP288_ADC_TS_PIN_ON		0xF3
> >>> +
> >>> +enum axp288_adc_id {
> >>> +	AXP288_ADC_TS,
> >>> +	AXP288_ADC_PMIC,
> >>> +	AXP288_ADC_GP,
> >>> +	AXP288_ADC_BATT_CHRG_I,
> >>> +	AXP288_ADC_BATT_DISCHRG_I,
> >>> +	AXP288_ADC_BATT_V,
> >>> +	AXP288_ADC_NR_CHAN,
> >>> +};
> >>> +
> >>> +struct axp288_adc_info {
> >>> +	int irq;
> >>> +	struct device *dev;
> >>> +	struct regmap *regmap;
> >>> +};
> >>> +
> >>> +static const struct iio_chan_spec const axp288_adc_channels[] = {
> >>> +	{
> >>> +		.indexed = 1,
> >>> +		.type = IIO_TEMP,
> >>> +		.channel = 0,
> >>> +		.address = AXP288_TS_ADC_H,
> >>> +		.datasheet_name = "CH0",
> >>> +	}, {
> >>> +		.indexed = 1,
> >>> +		.type = IIO_TEMP,
> >>> +		.channel = 1,
> >>> +		.address = AXP288_PMIC_ADC_H,
> >>> +		.datasheet_name = "CH1",
> >>> +	}, {
> >>> +		.indexed = 1,
> >>> +		.type = IIO_TEMP,
> >>> +		.channel = 2,
> >>> +		.address = AXP288_GP_ADC_H,
> >>> +		.datasheet_name = "CH2",
> >>> +	}, {
> >>> +		.indexed = 1,
> >>> +		.type = IIO_CURRENT,
> >>> +		.channel = 3,
> >>> +		.address = AXP20X_BATT_CHRG_I_H,
> >>> +		.datasheet_name = "CH3",
> >>> +		.info_mask_separate =
> >>> BIT(IIO_CHAN_INFO_PROCESSED),
> >>> +	}, {
> >>> +		.indexed = 1,
> >>> +		.type = IIO_CURRENT,
> >>> +		.channel = 4,
> >>> +		.address = AXP20X_BATT_DISCHRG_I_H,
> >>> +		.datasheet_name = "CH4",
> >>> +		.info_mask_separate =
> >>> BIT(IIO_CHAN_INFO_PROCESSED),
> >>> +	}, {
> >>> +		.indexed = 1,
> >>> +		.type = IIO_VOLTAGE,
> >>> +		.channel = 5,
> >>> +		.address = AXP20X_BATT_V_H,
> >>> +		.datasheet_name = "CH5",
> >>> +		.info_mask_separate =
> >>> BIT(IIO_CHAN_INFO_PROCESSED),
> >>> +	},
> >>> +};
> >>> +
> >>> +#define AXP288_ADC_MAP(_adc_channel_label,
> >>> _consumer_dev_name,	\
> >>> +
> >>> _consumer_channel)				\
> >>> +	{
> >>> \
> >>> +		.adc_channel_label = _adc_channel_label,	\
> >>> +		.consumer_dev_name = _consumer_dev_name,	\
> >>> +		.consumer_channel =
> >>> _consumer_channel,		\
> >>> +	}
> >>> +
> >>> +/* for consumer drivers */
> >>> +static struct iio_map axp288_adc_default_maps[] = {
> >>> +	AXP288_ADC_MAP("TS_PIN", "axp288-batt",
> >>> "axp288-batt-temp"),
> >>> +	AXP288_ADC_MAP("PMIC_TEMP", "axp288-pmic",
> >>> "axp288-pmic-temp"),
> >>> +	AXP288_ADC_MAP("GPADC", "axp288-gpadc",
> >>> "axp288-system-temp"),
> >>> +	AXP288_ADC_MAP("BATT_CHG_I", "axp288-chrg",
> >>> "axp288-chrg-curr"),
> >>> +	AXP288_ADC_MAP("BATT_DISCHRG_I", "axp288-chrg",
> >>> "axp288-chrg-d-curr"),
> >>> +	AXP288_ADC_MAP("BATT_V", "axp288-batt",
> >>> "axp288-batt-volt"),
> >>> +	{},
> >>> +};
> >>> +
> >>> +static int axp288_adc_read_raw(struct iio_dev *indio_dev,
> >>> +			struct iio_chan_spec const *chan,
> >>> +			int *val, int *val2, long mask)
> Here is an indentation issue. See [1] how it can look like (although
> it is fine to have several parameters in every line).
> 
> [1]
> https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/max1363.c?h=testing#n414
> 
> >>> +{
> >>> +	int ret;
> >>> +	struct axp288_adc_info *info = iio_priv(indio_dev);
> >>> +	u8 buf[2];
> >> You could use __be16 instead. Then you just need to use
> >> be16_to_cpu(), shift 4 bits to the right and mask the result with
> >> 0xFF.
> >>> +
> >>> +	mutex_lock(&indio_dev->mlock);
> >>> +	switch (mask) {
> >>> +	case IIO_CHAN_INFO_RAW:
> >>> +		/* special case for GPADC sample */
> >>> +		if (chan->address == AXP288_GP_ADC_H) {
> >>> +			ret = regmap_write(info->regmap,
> >>> AXP288_ADC_TS_PIN_CTRL,
> >>> +					AXP288_ADC_TS_PIN_GPADC);
> >>> +			if (ret) {
> >>> +				dev_err(&indio_dev->dev, "GPADC
> >>> mode\n");
> >>> +				mutex_unlock(&indio_dev->mlock);
> >>> +				return ret;
> >> You may even just goto the mutex_unlock at the end of the function.
> >> Would safe a few bytes here in the source - up to you. More
> >> interesting is, if the error message is required, as you don't have
> >> one below, when switching to TS_PIN_ON.
> > i don't have preference, the previous reviews don't like goto.
> Yeah, that's probably always a decision between quick exit path vs.
> low code duplication. They weight pretty equal in this case.
> >>> +			}
> >>> +		}
> >>> +	case IIO_CHAN_INFO_PROCESSED:
> >>> +		ret = regmap_bulk_read(info->regmap,
> >>> chan->address, buf, 2);
> >>> +		if (ret) {
> >>> +			dev_err(&indio_dev->dev, "sample raw data
> >>> failed\n");
> >>> +			break;
> >>> +		}
> >>> +		*val = (buf[0] << 4) + ((buf[1] >> 4) & 0x0F);
> >>> +		ret = IIO_VAL_INT;
> >>> +		break;
> >>> +	default:
> >>> +		ret = -EINVAL;
> >>> +	}
> >>> +
> >>> +	if (mask == IIO_CHAN_INFO_RAW && chan->address ==
> >>> AXP288_GP_ADC_H)
> >>> +		ret = regmap_write(info->regmap,
> >>> AXP288_ADC_TS_PIN_CTRL,
> >>> +			AXP288_ADC_TS_PIN_ON);
> >>> +
> >>> +	mutex_unlock(&indio_dev->mlock);
> >>> +
> >>> +	return ret;
> >>> +}
> >>> +
> >>> +static int axp288_adc_enable(struct regmap *regmap, bool enable)
> >>> +{
> >>> +	unsigned int pin_on, adc_en;
> >>> +
> >>> +	if (enable) {
> >>> +		pin_on = AXP288_ADC_TS_PIN_ON;
> >>> +		adc_en = AXP288_ADC_EN_MASK;
> This one, adc_en ^^^^^ is what I meant. It gets set here and below,
> but not used again. I would expect, that you intended to write it to
> AXP20X_ADC_EN1 at the end of this function.
you are right, my mistake. thanks.
> >>> +	} else {
> >>> +		pin_on = ~AXP288_ADC_TS_PIN_ON;
> >>> +		adc_en = ~AXP288_ADC_EN_MASK;
> >>> +	}
> >>> +	if (regmap_write(regmap, AXP288_ADC_TS_PIN_CTRL, pin_on))
> >>> +		return -EIO;
> >>> +
> >>> +	return regmap_write(regmap, AXP20X_ADC_EN1,
> >>> ~AXP288_ADC_EN_MASK);
> >> So, what's the deal about the variable adc_en?
> > well, I am trying to be consistent with the data sheet. in axp202
> > datasheet, register 82h is named "ADC Enable 1". In axp288
> > datasheet, the same register 82h is named ADC Enable. I am going
> > with adc_en1 to better scale for more "ADC Enable X".
> >>> +}
> >>> +
> >>> +static const struct iio_info axp288_adc_iio_info = {
> >>> +	.read_raw = &axp288_adc_read_raw,
> >>> +	.driver_module = THIS_MODULE,
> >>> +};
> >>> +
> >>> +static int axp288_adc_probe(struct platform_device *pdev)
> >>> +{
> >>> +	int ret;
> >>> +	struct axp288_adc_info *info;
> >>> +	struct iio_dev *indio_dev;
> >>> +	struct axp20x_dev *axp20x =
> >>> dev_get_drvdata(pdev->dev.parent); +
> >>> +	indio_dev = devm_iio_device_alloc(&pdev->dev,
> >>> sizeof(*info));
> >>> +	if (!indio_dev)
> >>> +		return -ENOMEM;
> >>> +
> >>> +	info = iio_priv(indio_dev);
> >>> +	info->irq = platform_get_irq(pdev, 0);
> >>> +	if (info->irq < 0) {
> >>> +		dev_err(&pdev->dev, "no irq resource?\n");
> >>> +		return info->irq;
> >>> +	}
> >>> +	platform_set_drvdata(pdev, indio_dev);
> >>> +	info->regmap = axp20x->regmap;
> >>> +	ret = axp288_adc_enable(axp20x->regmap, true);
> >>> +	if (ret) {
> >>> +		dev_err(&pdev->dev, "Unable to enable ADC
> >>> device\n");
> >>> +		return ret;
> >>> +	}
> >>> +
> >>> +	indio_dev->dev.parent = &pdev->dev;
> >>> +	indio_dev->name = pdev->name;
> >>> +	indio_dev->channels = axp288_adc_channels;
> >>> +	indio_dev->num_channels =
> >>> ARRAY_SIZE(axp288_adc_channels);
> >>> +	indio_dev->info = &axp288_adc_iio_info;
> >>> +	indio_dev->modes = INDIO_DIRECT_MODE;
> >>> +	ret = iio_map_array_register(indio_dev,
> >>> axp288_adc_default_maps);
> >>> +	if (ret < 0)
> >>> +		goto err_disable_dev;
> >>> +
> >>> +	ret = iio_device_register(indio_dev);
> >>> +	if (ret < 0) {
> >>> +		dev_err(&pdev->dev, "unable to register iio
> >>> device\n");
> >>> +		goto err_array_unregister;
> >>> +	}
> >>> +
> >>> +	return 0;
> >>> +
> >>> +err_array_unregister:
> >>> +	iio_map_array_unregister(indio_dev);
> >>> +err_disable_dev:
> >>> +	ret = axp288_adc_enable(axp20x->regmap, false);
> >> Don't set ret here. We want to return the error code from the
> >> function that failed above.
> >>> +
> > good point. thanks for the review.
> > 
> >>> +	return ret;
> >>> +}
> >>> +
> >>> +static int axp288_adc_remove(struct platform_device *pdev)
> >>> +{
> >>> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> >>> +	struct axp20x_dev *axp20x =
> >>> dev_get_drvdata(pdev->dev.parent); +
> >>> +	if (axp288_adc_enable(axp20x->regmap, false))
> >>> +		dev_err(&pdev->dev, "Unable to disable ADC
> >>> device\n");
> >>> +	iio_device_unregister(indio_dev);
> >>> +	iio_map_array_unregister(indio_dev);
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>> +static struct platform_driver axp288_adc_driver = {
> >>> +	.probe = axp288_adc_probe,
> >>> +	.remove = axp288_adc_remove,
> >>> +	.driver = {
> >>> +		.name = "axp288_adc",
> >>> +		.owner = THIS_MODULE,
> >>> +	},
> >>> +};
> >>> +
> >>> +module_platform_driver(axp288_adc_driver);
> >>> +
> >>> +MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@...ux.intel.com>");
> >>> +MODULE_DESCRIPTION("X-Powers AXP288 ADC Driver");
> >>> +MODULE_LICENSE("GPL");
> >>>
> >>
> > 
> > [Jacob Pan]
> > --
> > To unsubscribe from this list: send the line "unsubscribe
> > linux-iio" in the body of a message to majordomo@...r.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> 

[Jacob Pan]
--
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