Message-ID: <f4b3e9dd-926c-c98a-30a2-89907ab2e09e@kernel.org>
Date:   Sat, 28 Jan 2017 14:49:39 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Quentin Schulz <quentin.schulz@...e-electrons.com>,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        robh+dt@...nel.org, mark.rutland@....com, wens@...e.org,
        sre@...nel.org, linux@...linux.org.uk,
        maxime.ripard@...e-electrons.com, lee.jones@...aro.org
Cc:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        thomas.petazzoni@...e-electrons.com, icenowy@...c.xyz,
        bonbons@...ux-vserver.org
Subject: Re: [PATCH v2 04/25] iio: adc: add support for X-Powers AXP20X and
 AXP22X PMICs ADCs

On 27/01/17 08:54, Quentin Schulz wrote:
> The X-Powers AXP20X and AXP22X PMICs have multiple ADCs. They expose the
> battery voltage, battery charge and discharge currents, AC-in and VBUS
> voltages and currents, 2 GPIOs muxable in ADC mode and PMIC temperature.
> 
> This adds support for most of AXP20X and AXP22X ADCs.
> 
> Signed-off-by: Quentin Schulz <quentin.schulz@...e-electrons.com>
Pretty good, but not everything seems to be cleaned up on error paths
in probe.

A few other suggestions / questions inline.

Jonathan
> ---
> 
> v2:
>  - removed unused defines,
>  - changed BIT(x) to 1 << x when describing bits purpose for which 2 <<
>  x or 3 << x exists, to be consistent,
>  - changed ADC rate defines to macro formulas,
>  - reordered IIO channels, now different measures (current/voltage) of
>  the same part of the PMIC (e.g. battery), have the same IIO channel in
>  their respective IIO type. When a part of the PMIC have only one
>  measure, a number is jumped,
>  - left IIO channel mapping in DT to use iio_map structure,
>  - removed indexing of ADC internal temperature,
>  - removed unused iio_dev structure in axp20x_adc_iio,
>  - added a structure for data specific to AXP20X or AXP22X PMICs instead
>  of using an ID and an if condition when needing to separate the
>  behaviour of both,
>  - added a comment on batt_chrg_i really being on 12bits rather than
>  what the Chinese datasheets say (13 bits),
>  - corrected the offset for AXP22X PMIC temperature,
>  - set the ADC rate to a value (100Hz) shared by the AXP20X and AXP22X,
>  - created macro formulas to compute the ADC rate for each,
>  - added a condition on presence of ADC_EN2 reg before setting/resetting
>  it,
>  - switched from devm_iio_device_unregister to the non-devm function
>  because of the need for a remove function,
>  - removed some dead code,
> 
>  drivers/iio/adc/Kconfig      |  10 +
>  drivers/iio/adc/Makefile     |   1 +
>  drivers/iio/adc/axp20x_adc.c | 572 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 583 insertions(+)
>  create mode 100644 drivers/iio/adc/axp20x_adc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 9c8b558..ed17fe1 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -154,6 +154,16 @@ config AT91_SAMA5D2_ADC
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called at91-sama5d2_adc.
>  
> +config AXP20X_ADC
> +	tristate "X-Powers AXP20X and AXP22X ADC driver"
> +	depends on MFD_AXP20X
> +	help
> +	  Say yes here to have support for X-Powers power management IC (PMIC)
> +	  AXP20X and AXP22X ADC devices.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called axp20x_adc.
> +
>  config AXP288_ADC
>  	tristate "X-Powers AXP288 ADC driver"
>  	depends on MFD_AXP20X
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index d36c4be..f5c28a5 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_AD7887) += ad7887.o
>  obj-$(CONFIG_AD799X) += ad799x.o
>  obj-$(CONFIG_AT91_ADC) += at91_adc.o
>  obj-$(CONFIG_AT91_SAMA5D2_ADC) += at91-sama5d2_adc.o
> +obj-$(CONFIG_AXP20X_ADC) += axp20x_adc.o
>  obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
>  obj-$(CONFIG_BCM_IPROC_ADC) += bcm_iproc_adc.o
>  obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
> diff --git a/drivers/iio/adc/axp20x_adc.c b/drivers/iio/adc/axp20x_adc.c
> new file mode 100644
> index 0000000..bacde92
> --- /dev/null
> +++ b/drivers/iio/adc/axp20x_adc.c
> @@ -0,0 +1,572 @@
> +/* ADC driver for AXP20X and AXP22X PMICs
> + *
> + * Copyright (c) 2016 Free Electrons NextThing Co.
> + *	Quentin Schulz <quentin.schulz@...e-electrons.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it under
> + * the terms of the GNU General Public License version 2 as published by the
> + * Free Software Foundation.
> + */
> +
> +#include <linux/completion.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/thermal.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/driver.h>
> +#include <linux/iio/machine.h>
> +#include <linux/mfd/axp20x.h>
> +
> +#define AXP20X_ADC_EN1_MASK			GENMASK(7, 0)
> +
> +#define AXP20X_ADC_EN2_MASK			(GENMASK(3, 2) | BIT(7))
> +#define AXP22X_ADC_EN1_MASK			(GENMASK(7, 5) | BIT(0))
> +
> +#define AXP20X_GPIO10_IN_RANGE_GPIO0		BIT(0)
> +#define AXP20X_GPIO10_IN_RANGE_GPIO1		BIT(1)
> +#define AXP20X_GPIO10_IN_RANGE_GPIO0_VAL(x)	((x) & BIT(0))
> +#define AXP20X_GPIO10_IN_RANGE_GPIO1_VAL(x)	(((x) & BIT(0)) << 1)
> +
> +#define AXP20X_ADC_RATE_MASK			GENMASK(7, 6)
> +#define AXP20X_ADC_RATE_HZ(x)			((ilog2((x) / 25) << 6) & AXP20X_ADC_RATE_MASK)
> +#define AXP22X_ADC_RATE_HZ(x)			((ilog2((x) / 100) << 6) & AXP20X_ADC_RATE_MASK)
> +
> +#define AXP20X_ADC_CHANNEL(_channel, _name, _type, _reg)	\
> +	{							\
> +		.type = _type,					\
> +		.indexed = 1,					\
> +		.channel = _channel,				\
> +		.address = _reg,				\
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
> +				      BIT(IIO_CHAN_INFO_SCALE),	\
> +		.datasheet_name = _name,			\
> +	}
> +
> +#define AXP20X_ADC_CHANNEL_OFFSET(_channel, _name, _type, _reg) \
> +	{							\
> +		.type = _type,					\
> +		.indexed = 1,					\
> +		.channel = _channel,				\
> +		.address = _reg,				\
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
> +				      BIT(IIO_CHAN_INFO_SCALE) |\
> +				      BIT(IIO_CHAN_INFO_OFFSET),\
> +		.datasheet_name = _name,			\
> +	}
> +
> +struct axp_data;
> +
> +struct axp20x_adc_iio {
> +	struct regmap		*regmap;
> +	struct axp_data		*data;
> +};
> +
> +enum axp20x_adc_channel_v {
> +	AXP20X_ACIN_V = 0,
> +	AXP20X_VBUS_V,
> +	AXP20X_TS_IN,
> +	AXP20X_GPIO0_V,
> +	AXP20X_GPIO1_V,
> +	AXP20X_IPSOUT_V,
> +	AXP20X_BATT_V,
> +};
> +
> +enum axp20x_adc_channel_i {
> +	AXP20X_ACIN_I = 0,
> +	AXP20X_VBUS_I,
> +	AXP20X_BATT_CHRG_I,
> +	AXP20X_BATT_DISCHRG_I,
> +};
> +
> +enum axp22x_adc_channel_v {
> +	AXP22X_TS_IN = 0,
> +	AXP22X_BATT_V,
> +};
> +
> +enum axp22x_adc_channel_i {
> +	AXP22X_BATT_CHRG_I = 1,
> +	AXP22X_BATT_DISCHRG_I,
> +};
> +
> +static struct iio_map axp20x_maps[] = {
> +	{
> +		.consumer_dev_name = "axp20x-usb-power-supply",
> +		.consumer_channel = "vbus_v",
> +		.adc_channel_label = "vbus_v",
> +	}, {
> +		.consumer_dev_name = "axp20x-usb-power-supply",
> +		.consumer_channel = "vbus_i",
> +		.adc_channel_label = "vbus_i",
> +	}, { /* sentinel */ }
> +};
> +
> +/*
> + * Channels are mapped by physical system. Their channels share the same index.
> + * i.e. acin_i is in_current0_raw and acin_v is in_voltage0_raw.
> + * The only exception is for the battery. batt_v will be in_voltage6_raw and
> + * charge current in_current6_raw and discharge current will be in_current7_raw.
> + */
> +static const struct iio_chan_spec axp20x_adc_channels[] = {
> +	AXP20X_ADC_CHANNEL(AXP20X_ACIN_V, "acin_v", IIO_VOLTAGE,
> +			   AXP20X_ACIN_V_ADC_H),
> +	AXP20X_ADC_CHANNEL(AXP20X_ACIN_I, "acin_i", IIO_CURRENT,
> +			   AXP20X_ACIN_I_ADC_H),
> +	AXP20X_ADC_CHANNEL(AXP20X_VBUS_V, "vbus_v", IIO_VOLTAGE,
> +			   AXP20X_VBUS_V_ADC_H),
> +	AXP20X_ADC_CHANNEL(AXP20X_VBUS_I, "vbus_i", IIO_CURRENT,
> +			   AXP20X_VBUS_I_ADC_H),
> +	{
> +		.type = IIO_TEMP,
> +		.address = AXP20X_TEMP_ADC_H,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
> +				      BIT(IIO_CHAN_INFO_OFFSET),
> +		.datasheet_name = "pmic_temp",
> +	},
> +	AXP20X_ADC_CHANNEL_OFFSET(AXP20X_GPIO0_V, "gpio0_v", IIO_VOLTAGE,
> +				  AXP20X_GPIO0_V_ADC_H),
> +	AXP20X_ADC_CHANNEL_OFFSET(AXP20X_GPIO1_V, "gpio1_v", IIO_VOLTAGE,
> +				  AXP20X_GPIO1_V_ADC_H),
> +	AXP20X_ADC_CHANNEL(AXP20X_IPSOUT_V, "ipsout_v", IIO_VOLTAGE,
> +			   AXP20X_IPSOUT_V_HIGH_H),
> +	AXP20X_ADC_CHANNEL(AXP20X_BATT_V, "batt_v", IIO_VOLTAGE,
> +			   AXP20X_BATT_V_H),
> +	AXP20X_ADC_CHANNEL(AXP20X_BATT_CHRG_I, "batt_chrg_i", IIO_CURRENT,
> +			   AXP20X_BATT_CHRG_I_H),
> +	AXP20X_ADC_CHANNEL(AXP20X_BATT_DISCHRG_I, "batt_dischrg_i", IIO_CURRENT,
> +			   AXP20X_BATT_DISCHRG_I_H),
> +};
> +
> +static const struct iio_chan_spec axp22x_adc_channels[] = {
> +	{
> +		.type = IIO_TEMP,
> +		.address = AXP22X_PMIC_TEMP_H,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
> +				      BIT(IIO_CHAN_INFO_OFFSET),
> +		.datasheet_name = "pmic_temp",
> +	},
> +	AXP20X_ADC_CHANNEL(AXP22X_BATT_V, "batt_v", IIO_VOLTAGE,
> +			   AXP20X_BATT_V_H),
> +	AXP20X_ADC_CHANNEL(AXP22X_BATT_CHRG_I, "batt_chrg_i", IIO_CURRENT,
> +			   AXP20X_BATT_CHRG_I_H),
> +	AXP20X_ADC_CHANNEL(AXP22X_BATT_DISCHRG_I, "batt_dischrg_i", IIO_CURRENT,
> +			   AXP20X_BATT_DISCHRG_I_H),
> +};
> +
> +static int axp20x_adc_raw(struct iio_dev *indio_dev,
> +			  struct iio_chan_spec const *chan, int *val)
> +{
> +	struct axp20x_adc_iio *info = iio_priv(indio_dev);
> +	int size = 12;
> +
> +	switch (chan->type) {
> +	case IIO_CURRENT:
> +		/*
> +		 * Unlike the Chinese datasheets tell, the charging current is
> +		 * stored on 12 bits, not 13 bits.
> +		 */
> +		if (chan->channel == AXP20X_BATT_DISCHRG_I)
> +			size = 13;
Given I don't think you can get here without it being current, voltage or temp;
couldn't this be done more cleanly with
if ((chan->type == IIO_CURRENT) && (chan->channel == AXP20X_BAT_DISCHRG_I))
   size = 13;

and have the rest in the normal code flow?

> +	case IIO_VOLTAGE:
> +	case IIO_TEMP:
> +		*val = axp20x_read_variable_width(info->regmap, chan->address,
> +						  size);
> +		if (*val < 0)
> +			return *val;
> +
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp22x_adc_raw(struct iio_dev *indio_dev,
> +			  struct iio_chan_spec const *chan, int *val)
> +{
> +	struct axp20x_adc_iio *info = iio_priv(indio_dev);
> +	int size = 12;
> +
> +	switch (chan->type) {
> +	case IIO_CURRENT:
> +		/*
> +		 * Unlike the Chinese datasheets tell, the charging current is
> +		 * stored on 12 bits, not 13 bits.
> +		 */
> +		if (chan->channel == AXP22X_BATT_DISCHRG_I)
> +			size = 13;
> +	case IIO_VOLTAGE:
> +	case IIO_TEMP:
> +		*val = axp20x_read_variable_width(info->regmap, chan->address,
> +						  size);
> +		if (*val < 0)
> +			return *val;
> +
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp20x_adc_scale_voltage(int channel, int *val, int *val2)
> +{
> +	switch (channel) {
> +	case AXP20X_ACIN_V:
> +	case AXP20X_VBUS_V:
> +		*val = 1;
> +		*val2 = 700000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	case AXP20X_GPIO0_V:
> +	case AXP20X_GPIO1_V:
> +		*val = 0;
> +		*val2 = 500000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	case AXP20X_BATT_V:
> +		*val = 1;
> +		*val2 = 100000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	case AXP20X_IPSOUT_V:
> +		*val = 1;
> +		*val2 = 400000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp20x_adc_scale_current(int channel, int *val, int *val2)
> +{
> +	switch (channel) {
> +	case AXP20X_ACIN_I:
> +		*val = 0;
> +		*val2 = 625000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	case AXP20X_VBUS_I:
> +		*val = 0;
> +		*val2 = 375000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	case AXP20X_BATT_DISCHRG_I:
> +	case AXP20X_BATT_CHRG_I:
> +		*val = 0;
> +		*val2 = 500000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp20x_adc_scale(struct iio_chan_spec const *chan, int *val,
> +			    int *val2)
> +{
> +	switch (chan->type) {
> +	case IIO_VOLTAGE:
> +		return axp20x_adc_scale_voltage(chan->channel, val, val2);
> +
> +	case IIO_CURRENT:
> +		return axp20x_adc_scale_current(chan->channel, val, val2);
> +
> +	case IIO_TEMP:
> +		*val = 100;
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp22x_adc_scale(struct iio_chan_spec const *chan, int *val,
> +			    int *val2)
> +{
> +	switch (chan->type) {
> +	case IIO_VOLTAGE:
> +		if (chan->channel != AXP22X_BATT_V)
> +			return -EINVAL;
> +
> +		*val = 1;
> +		*val2 = 100000;
> +		return IIO_VAL_INT_PLUS_MICRO;
A fixed scale of 1.1x? (just checking)
> +
> +	case IIO_CURRENT:
> +		*val = 0;
> +		*val2 = 500000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	case IIO_TEMP:
> +		*val = 100;
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp20x_adc_offset_voltage(struct iio_dev *indio_dev, int channel,
> +				     int *val)
> +{
> +	struct axp20x_adc_iio *info = iio_priv(indio_dev);
> +	int ret, reg;
> +
> +	if (channel != AXP20X_GPIO0_V && channel != AXP20X_GPIO1_V)
> +		return -EINVAL;
> +
> +	ret = regmap_read(info->regmap, AXP20X_GPIO10_IN_RANGE, &reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (channel == AXP20X_GPIO0_V)
> +		*val = reg & AXP20X_GPIO10_IN_RANGE_GPIO0;
> +	else
> +		*val = reg & AXP20X_GPIO10_IN_RANGE_GPIO1;
> +
> +	*val = !!(*val) * 700000;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int axp20x_adc_offset(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan, int *val)
> +{
> +	switch (chan->type) {
> +	case IIO_VOLTAGE:
> +		return axp20x_adc_offset_voltage(indio_dev, chan->channel, val);
> +
> +	case IIO_TEMP:
> +		*val = -1447;
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp20x_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan, int *val,
> +			   int *val2, long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_OFFSET:
> +		return axp20x_adc_offset(indio_dev, chan, val);
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		return axp20x_adc_scale(chan, val, val2);
> +
> +	case IIO_CHAN_INFO_RAW:
> +		return axp20x_adc_raw(indio_dev, chan, val);
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp22x_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan, int *val,
> +			   int *val2, long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_OFFSET:
> +		*val = -2677;
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		return axp22x_adc_scale(chan, val, val2);
> +
> +	case IIO_CHAN_INFO_RAW:
> +		return axp22x_adc_raw(indio_dev, chan, val);
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int axp20x_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan, int val, int val2,
> +			    long mask)
> +{
> +	struct axp20x_adc_iio *info = iio_priv(indio_dev);
> +
> +	/*
> +	 * The AXP20X PMIC allows the user to choose between 0V and 0.7V offsets
> +	 * for (independently) GPIO0 and GPIO1 when in ADC mode.
> +	 */
> +	if (mask != IIO_CHAN_INFO_OFFSET)
> +		return -EINVAL;
> +
> +	if (chan->channel != AXP20X_GPIO0_V && chan->channel != AXP20X_GPIO1_V)
> +		return -EINVAL;
> +
> +	if (val != 0 && val != 700000)
> +		return -EINVAL;
> +
> +	if (chan->channel == AXP20X_GPIO0_V)
> +		return regmap_update_bits(info->regmap, AXP20X_GPIO10_IN_RANGE,
> +					  AXP20X_GPIO10_IN_RANGE_GPIO0,
> +					  AXP20X_GPIO10_IN_RANGE_GPIO0_VAL(!!val));
> +
> +	return regmap_update_bits(info->regmap, AXP20X_GPIO10_IN_RANGE,
> +				  AXP20X_GPIO10_IN_RANGE_GPIO1,
> +				  AXP20X_GPIO10_IN_RANGE_GPIO1_VAL(!!val));
> +}
> +
> +static const struct iio_info axp20x_adc_iio_info = {
> +	.read_raw = axp20x_read_raw,
> +	.write_raw = axp20x_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static const struct iio_info axp22x_adc_iio_info = {
> +	.read_raw = axp22x_read_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int axp20x_adc_rate(int rate)
> +{
> +	return AXP20X_ADC_RATE_HZ(rate);
> +}
> +
> +static int axp22x_adc_rate(int rate)
> +{
> +	return AXP22X_ADC_RATE_HZ(rate);
> +}
> +
> +struct axp_data {
> +	const struct iio_info		*iio_info;
> +	int				num_channels;
> +	struct iio_chan_spec const	*channels;
> +	unsigned long			adc_en1_mask;
> +	int				(*adc_rate)(int rate);
> +	bool				adc_en2;
> +	struct iio_map			*maps;
> +};
> +
> +static const struct axp_data axp20x_data = {
> +	.iio_info = &axp20x_adc_iio_info,
> +	.num_channels = ARRAY_SIZE(axp20x_adc_channels),
> +	.channels = axp20x_adc_channels,
> +	.adc_en1_mask = AXP20X_ADC_EN1_MASK,
> +	.adc_rate = axp20x_adc_rate,
> +	.adc_en2 = true,
> +	.maps = axp20x_maps,
> +};
> +
> +static const struct axp_data axp22x_data = {
> +	.iio_info = &axp22x_adc_iio_info,
> +	.num_channels = ARRAY_SIZE(axp22x_adc_channels),
> +	.channels = axp22x_adc_channels,
> +	.adc_en1_mask = AXP22X_ADC_EN1_MASK,
> +	.adc_rate = axp22x_adc_rate,
> +	.adc_en2 = false,
> +};
> +
> +static const struct of_device_id axp20x_adc_of_match[] = {
> +	{ .compatible = "x-powers,axp209-adc", .data = (void *)&axp20x_data, },
> +	{ .compatible = "x-powers,axp221-adc", .data = (void *)&axp22x_data, },
> +	{ /* sentinel */ },
> +};
> +
> +static int axp20x_probe(struct platform_device *pdev)
> +{
> +	struct axp20x_adc_iio *info;
> +	struct iio_dev *indio_dev;
> +	struct axp20x_dev *axp20x_dev;
> +	int ret;
> +
> +	axp20x_dev = 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);
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	info->regmap = axp20x_dev->regmap;
> +	indio_dev->name = dev_name(&pdev->dev);
Not sure on this name - what does end up as?  Expected to be
a description of the part so in this case something like axp209-adc.
I've been lax at picking up on this in the past and it's led to some
crazy naming that is no use at all to userspace.  Basically this
name just provides a convenient user readable name for userspace apps to
use.

> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->dev.of_node = pdev->dev.of_node;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	info->data = (struct axp_data *)of_device_get_match_data(&pdev->dev);
> +
> +	indio_dev->info = info->data->iio_info;
> +	indio_dev->num_channels = info->data->num_channels;
> +	indio_dev->channels = info->data->channels;
> +
> +	/* Enable the ADCs on IP */
> +	regmap_write(info->regmap, AXP20X_ADC_EN1, info->data->adc_en1_mask);
> +
> +	if (info->data->adc_en2)
> +		/* Enable GPIO0/1 and internal temperature ADCs */
> +		regmap_update_bits(info->regmap, AXP20X_ADC_EN2,
> +				   AXP20X_ADC_EN2_MASK, AXP20X_ADC_EN2_MASK);
> +
> +	/* Configure ADCs rate */
> +	regmap_update_bits(info->regmap, AXP20X_ADC_RATE, AXP20X_ADC_RATE_MASK,
> +			   info->data->adc_rate(100));
> +
> +	ret = iio_map_array_register(indio_dev, info->data->maps);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to register IIO maps: %d\n", ret);
This should be disabling channels.
> +		return ret;
> +	}
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "could not register the device\n");
> +		regmap_write(info->regmap, AXP20X_ADC_EN1, 0);
> +
> +		if (info->data->adc_en2)
> +			regmap_write(info->regmap, AXP20X_ADC_EN2, 0);
I'd expect to see a complete unwind of what has been done earlier in probe
including iio_map_array_unregister.

The traditional goto error* approach is probably worth having here to
make sure the unwind makes sense.
> +
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int axp20x_remove(struct platform_device *pdev)
> +{
> +	struct axp20x_adc_iio *info;
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +
> +	info = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
iio_map_array_unregister?
> +
> +	regmap_write(info->regmap, AXP20X_ADC_EN1, 0);
> +
> +	if (info->data->adc_en2)
> +		regmap_write(info->regmap, AXP20X_ADC_EN2, 0);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver axp20x_adc_driver = {
> +	.driver = {
> +		.name = "axp20x-adc",
> +		.of_match_table = axp20x_adc_of_match,
> +	},
> +	.probe = axp20x_probe,
> +	.remove = axp20x_remove,
> +};
> +
> +module_platform_driver(axp20x_adc_driver);
> +
> +MODULE_DESCRIPTION("ADC driver for AXP20X and AXP22X PMICs");
> +MODULE_AUTHOR("Quentin Schulz <quentin.schulz@...e-electrons.com>");
> +MODULE_LICENSE("GPL");
> 

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