Date:   Sun, 12 Dec 2021 18:12:24 +0000
From:   Jonathan Cameron <jic23@kernel.org>
To:     Caleb Connolly <caleb.connolly@linaro.org>
Cc:     sumit.semwal@linaro.org, amit.pundir@linaro.org,
        john.stultz@linaro.org, Lars-Peter Clausen <lars@metafoo.de>,
        Rob Herring <robh+dt@kernel.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Lee Jones <lee.jones@linaro.org>, linux-iio@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH 3/7] iio: adc: qcom-spmi-rradc: introduce round robin
 adc
Message-ID: <20211212181224.6aead071@jic23-huawei>
In-Reply-To: <20211211022224.3488860-4-caleb@connolly.tech>
References: <20211211022224.3488860-1-caleb@connolly.tech>
        <20211211022224.3488860-4-caleb@connolly.tech>
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On Sat, 11 Dec 2021 02:22:20 +0000
Caleb Connolly <caleb.connolly@linaro.org> wrote:

> From: Caleb Connolly <caleb.connolly@linaro.org>
> 
> The Round Robin ADC is responsible for reading data about the rate of
> charge from the USB or DC in jacks, it can also read the battery
> ID (resistence) and some temperatures. It is found on the PMI8998 and
> PM660 Qualcomm PMICs.
> 
> Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>

Hi Caleb,

Welcome to IIO.

Comments inline,

Thanks,

Jonathan

> ---
>  drivers/iio/adc/Kconfig           |   13 +
>  drivers/iio/adc/Makefile          |    1 +
>  drivers/iio/adc/qcom-spmi-rradc.c | 1020 +++++++++++++++++++++++++++++
>  3 files changed, 1034 insertions(+)
>  create mode 100644 drivers/iio/adc/qcom-spmi-rradc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 8bf5b62a73f4..d7765b177cd3 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -812,6 +812,19 @@ config QCOM_PM8XXX_XOADC
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called qcom-pm8xxx-xoadc.
>  
> +config QCOM_SPMI_RRADC
> +	tristate "Qualcomm SPMI RRADC"
> +	depends on MFD_SPMI_PMIC
> +	help
> +	  This is for the PMIC Round Robin ADC driver.
> +
> +	  This driver exposes the battery ID resistor, battery thermal, PMIC die
> +	  temperature, charger USB in and DC in voltage and current.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called qcom-qpmi-rradc.
> +
> +
>  config QCOM_SPMI_IADC
>  	tristate "Qualcomm SPMI PMIC current ADC"
>  	depends on SPMI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index d3f53549720c..ca8bad549175 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -77,6 +77,7 @@ obj-$(CONFIG_NPCM_ADC) += npcm_adc.o
>  obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
>  obj-$(CONFIG_QCOM_SPMI_ADC5) += qcom-spmi-adc5.o
>  obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
> +obj-$(CONFIG_QCOM_SPMI_RRADC) += qcom-spmi-rradc.o
>  obj-$(CONFIG_QCOM_VADC_COMMON) += qcom-vadc-common.o
>  obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
>  obj-$(CONFIG_QCOM_PM8XXX_XOADC) += qcom-pm8xxx-xoadc.o
> diff --git a/drivers/iio/adc/qcom-spmi-rradc.c b/drivers/iio/adc/qcom-spmi-rradc.c
> new file mode 100644
> index 000000000000..ce2bbb8c5c25
> --- /dev/null
> +++ b/drivers/iio/adc/qcom-spmi-rradc.c
> @@ -0,0 +1,1020 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2021 Linaro Limited.
> + *  Author: Caleb Connolly <caleb.connolly@linaro.org>
> + *
> + * This driver is for the Round Robin ADC found in the pmi8998 and pm660 PMICs.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/types.h>
> +#include <linux/kernel.h>
> +#include <linux/math64.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
?

> +#include <linux/regmap.h>
> +#include <linux/spmi.h>
> +#include <linux/types.h>
> +#include <soc/qcom/qcom-pmic.h>
> +
> +#define RR_ADC_EN_CTL				0x46
> +#define RR_ADC_SKIN_TEMP_LSB			0x50
> +#define RR_ADC_SKIN_TEMP_MSB			0x51
> +#define RR_ADC_RR_ADC_CTL			0x52
> +#define RR_ADC_ADC_CTL_CONTINUOUS_SEL		BIT(3)
> +#define RR_ADC_ADC_LOG				0x53
> +#define RR_ADC_ADC_LOG_CLR_CTRL			BIT(0)
> +
> +#define RR_ADC_FAKE_BATT_LOW_LSB		0x58
> +#define RR_ADC_FAKE_BATT_LOW_MSB		0x59
> +#define RR_ADC_FAKE_BATT_HIGH_LSB		0x5A
> +#define RR_ADC_FAKE_BATT_HIGH_MSB		0x5B
> +
> +#define RR_ADC_BATT_ID_CTRL			0x60
> +#define RR_ADC_BATT_ID_CTRL_CHANNEL_CONV	BIT(0)
> +#define RR_ADC_BATT_ID_TRIGGER			0x61
> +#define RR_ADC_BATT_ID_TRIGGER_CTL		BIT(0)
> +#define RR_ADC_BATT_ID_STS			0x62
> +#define RR_ADC_BATT_ID_CFG			0x63
> +#define RR_ADC_BATT_ID_5_LSB			0x66
> +#define RR_ADC_BATT_ID_5_MSB			0x67
> +#define RR_ADC_BATT_ID_15_LSB			0x68
> +#define RR_ADC_BATT_ID_15_MSB			0x69
> +#define RR_ADC_BATT_ID_150_LSB			0x6A
> +#define RR_ADC_BATT_ID_150_MSB			0x6B
> +
> +#define RR_ADC_BATT_THERM_CTRL			0x70
> +#define RR_ADC_BATT_THERM_TRIGGER		0x71
> +#define RR_ADC_BATT_THERM_STS			0x72
> +#define RR_ADC_BATT_THERM_CFG			0x73
> +#define RR_ADC_BATT_THERM_LSB			0x74
> +#define RR_ADC_BATT_THERM_MSB			0x75
> +#define RR_ADC_BATT_THERM_FREQ			0x76
> +
> +#define RR_ADC_AUX_THERM_CTRL			0x80
> +#define RR_ADC_AUX_THERM_TRIGGER		0x81
> +#define RR_ADC_AUX_THERM_STS			0x82
> +#define RR_ADC_AUX_THERM_CFG			0x83
> +#define RR_ADC_AUX_THERM_LSB			0x84
> +#define RR_ADC_AUX_THERM_MSB			0x85
> +
> +#define RR_ADC_SKIN_HOT				0x86
> +#define RR_ADC_SKIN_TOO_HOT			0x87
> +
> +#define RR_ADC_AUX_THERM_C1			0x88
> +#define RR_ADC_AUX_THERM_C2			0x89
> +#define RR_ADC_AUX_THERM_C3			0x8A
> +#define RR_ADC_AUX_THERM_HALF_RANGE		0x8B
> +
> +#define RR_ADC_USB_IN_V_CTRL			0x90
> +#define RR_ADC_USB_IN_V_TRIGGER			0x91
> +#define RR_ADC_USB_IN_V_EVERY_CYCLE		BIT(7)
> +#define RR_ADC_USB_IN_V_STS			0x92
> +#define RR_ADC_USB_IN_V_LSB			0x94
> +#define RR_ADC_USB_IN_V_MSB			0x95
> +#define RR_ADC_USB_IN_I_CTRL			0x98
> +#define RR_ADC_USB_IN_I_TRIGGER			0x99
> +#define RR_ADC_USB_IN_I_STS			0x9A
> +#define RR_ADC_USB_IN_I_LSB			0x9C
> +#define RR_ADC_USB_IN_I_MSB			0x9D
> +
> +#define RR_ADC_DC_IN_V_CTRL			0xA0
> +#define RR_ADC_DC_IN_V_TRIGGER			0xA1
> +#define RR_ADC_DC_IN_V_STS			0xA2
> +#define RR_ADC_DC_IN_V_LSB			0xA4
> +#define RR_ADC_DC_IN_V_MSB			0xA5
> +#define RR_ADC_DC_IN_I_CTRL			0xA8
> +#define RR_ADC_DC_IN_I_TRIGGER			0xA9
> +#define RR_ADC_DC_IN_I_STS			0xAA
> +#define RR_ADC_DC_IN_I_LSB			0xAC
> +#define RR_ADC_DC_IN_I_MSB			0xAD
> +
> +#define RR_ADC_PMI_DIE_TEMP_CTRL		0xB0
> +#define RR_ADC_PMI_DIE_TEMP_TRIGGER		0xB1
> +#define RR_ADC_PMI_DIE_TEMP_STS			0xB2
> +#define RR_ADC_PMI_DIE_TEMP_CFG			0xB3
> +#define RR_ADC_PMI_DIE_TEMP_LSB			0xB4
> +#define RR_ADC_PMI_DIE_TEMP_MSB			0xB5
> +
> +#define RR_ADC_CHARGER_TEMP_CTRL		0xB8
> +#define RR_ADC_CHARGER_TEMP_TRIGGER		0xB9
> +#define RR_ADC_CHARGER_TEMP_STS			0xBA
> +#define RR_ADC_CHARGER_TEMP_CFG			0xBB
> +#define RR_ADC_CHARGER_TEMP_LSB			0xBC
> +#define RR_ADC_CHARGER_TEMP_MSB			0xBD
> +#define RR_ADC_CHARGER_HOT			0xBE
> +#define RR_ADC_CHARGER_TOO_HOT			0xBF
> +
> +#define RR_ADC_GPIO_CTRL			0xC0
> +#define RR_ADC_GPIO_TRIGGER			0xC1
> +#define RR_ADC_GPIO_STS				0xC2
> +#define RR_ADC_GPIO_LSB				0xC4
> +#define RR_ADC_GPIO_MSB				0xC5
> +
> +#define RR_ADC_ATEST_CTRL			0xC8
> +#define RR_ADC_ATEST_TRIGGER			0xC9
> +#define RR_ADC_ATEST_STS			0xCA
> +#define RR_ADC_ATEST_LSB			0xCC
> +#define RR_ADC_ATEST_MSB			0xCD
> +#define RR_ADC_SEC_ACCESS			0xD0
> +
> +#define RR_ADC_PERPH_RESET_CTL2			0xD9
> +#define RR_ADC_PERPH_RESET_CTL3			0xDA
> +#define RR_ADC_PERPH_RESET_CTL4			0xDB
> +#define RR_ADC_INT_TEST1			0xE0
> +#define RR_ADC_INT_TEST_VAL			0xE1
> +
> +#define RR_ADC_TM_TRIGGER_CTRLS			0xE2
> +#define RR_ADC_TM_ADC_CTRLS			0xE3
> +#define RR_ADC_TM_CNL_CTRL			0xE4
> +#define RR_ADC_TM_BATT_ID_CTRL			0xE5
> +#define RR_ADC_TM_THERM_CTRL			0xE6
> +#define RR_ADC_TM_CONV_STS			0xE7
> +#define RR_ADC_TM_ADC_READ_LSB			0xE8
> +#define RR_ADC_TM_ADC_READ_MSB			0xE9
> +#define RR_ADC_TM_ATEST_MUX_1			0xEA
> +#define RR_ADC_TM_ATEST_MUX_2			0xEB
> +#define RR_ADC_TM_REFERENCES			0xED
> +#define RR_ADC_TM_MISC_CTL			0xEE
> +#define RR_ADC_TM_RR_CTRL			0xEF
> +
> +#define RR_ADC_BATT_ID_5_MA			5
> +#define RR_ADC_BATT_ID_15_MA			15
> +#define RR_ADC_BATT_ID_150_MA			150
Defines that define from something with the number in it to a number 
are usually not that helpful.  Just use the values and ensure
the variable naming makes units etc clear.

> +#define RR_ADC_BATT_ID_RANGE			820
> +
> +#define RR_ADC_BITS				10
> +#define RR_ADC_MAX_READINGS			(1 << RR_ADC_BITS)

What is this?  I'd expect ADC_MAX_READINGS to be the number of
readings, whereas I suspect it's maximum value?

> +#define RR_ADC_FS_VOLTAGE_MV			2500
> +
> +/* BATT_THERM 0.25K/LSB */
> +#define RR_ADC_BATT_THERM_LSB_K			4
> +
> +#define RR_ADC_TEMP_FS_VOLTAGE_NUM		5000000
> +#define RR_ADC_TEMP_FS_VOLTAGE_DEN		3
> +#define RR_ADC_DIE_TEMP_OFFSET			601400
> +#define RR_ADC_DIE_TEMP_SLOPE			2
> +#define RR_ADC_DIE_TEMP_OFFSET_MILLI_DEGC	25000
> +
> +#define RR_ADC_CHG_TEMP_GF_OFFSET_UV		1303168
> +#define RR_ADC_CHG_TEMP_GF_SLOPE_UV_PER_C	3784
> +#define RR_ADC_CHG_TEMP_SMIC_OFFSET_UV		1338433
> +#define RR_ADC_CHG_TEMP_SMIC_SLOPE_UV_PER_C	3655
> +#define RR_ADC_CHG_TEMP_660_GF_OFFSET_UV	1309001
> +#define RR_ADC_CHG_TEMP_660_GF_SLOPE_UV_PER_C	3403
> +#define RR_ADC_CHG_TEMP_660_SMIC_OFFSET_UV	1295898
> +#define RR_ADC_CHG_TEMP_660_SMIC_SLOPE_UV_PER_C	3596
> +#define RR_ADC_CHG_TEMP_660_MGNA_OFFSET_UV	1314779
> +#define RR_ADC_CHG_TEMP_660_MGNA_SLOPE_UV_PER_C	3496
> +#define RR_ADC_CHG_TEMP_OFFSET_MILLI_DEGC	25000
> +#define RR_ADC_CHG_THRESHOLD_SCALE		4
> +
> +#define RR_ADC_VOLT_INPUT_FACTOR		8
> +#define RR_ADC_CURR_INPUT_FACTOR		2000
> +#define RR_ADC_CURR_USBIN_INPUT_FACTOR_MIL	1886
> +#define RR_ADC_CURR_USBIN_660_FACTOR_MIL	9
> +#define RR_ADC_CURR_USBIN_660_UV_VAL		579500
> +
> +#define RR_ADC_SCALE_MILLI_FACTOR		1000

There are standard kernel defines for things like this.
see linux/units.h


> +#define RR_ADC_KELVINMIL_CELSIUSMIL		273150

Also in linux/units.h

> +
> +#define RR_ADC_GPIO_FS_RANGE			5000
> +#define RR_ADC_COHERENT_CHECK_RETRY		5
> +#define RR_ADC_MAX_CONTINUOUS_BUFFER_LEN	16
> +
> +#define RR_ADC_STS_CHANNEL_READING_MASK		0x3
> +#define RR_ADC_STS_CHANNEL_STS			0x2
> +
> +#define RR_ADC_CONV_TIME_MIN_US			499
> +#define RR_ADC_CONV_TIME_MAX_US			501
Can't see where these are used. I was wondering why they would make
sense so went looking :)

> +#define RR_ADC_CONV_MAX_RETRY_CNT		100

Things like retry counts need a comment justifying the value.
Maybe you tried smaller values and sometimes it failed or something
like that?  100 is a lot of retries.

> +#define RR_ADC_TP_REV_VERSION1			21
> +#define RR_ADC_TP_REV_VERSION2			29
> +#define RR_ADC_TP_REV_VERSION3			32
> +
> +#define BATT_ID_SETTLE_SHIFT			5
> +#define RRADC_BATT_ID_DELAY_MAX			8
> +
> +/*
> + * Used to index rradc_chip.chans[] array.

Not sure the comment adds much as if anyone cares they can grep :)

> + */
> +enum rradc_channel_id {
> +	RR_ADC_BATT_ID = 0,
> +	RR_ADC_BATT_THERM,
> +	RR_ADC_SKIN_TEMP,
> +	RR_ADC_USBIN_I,
> +	RR_ADC_USBIN_V,
> +	RR_ADC_DCIN_I,
> +	RR_ADC_DCIN_V,
> +	RR_ADC_DIE_TEMP,
> +	RR_ADC_CHG_TEMP,
> +	RR_ADC_GPIO,
> +	RR_ADC_CHG_HOT_TEMP,
> +	RR_ADC_CHG_TOO_HOT_TEMP,
> +	RR_ADC_SKIN_HOT_TEMP,
> +	RR_ADC_SKIN_TOO_HOT_TEMP,
> +	RR_ADC_MAX
> +};
> +
> +struct rradc_chip;
> +
> +/**
> + * struct rradc_channel - rradc channel data
> + * @datasheet_name:	Name of the channel
> + * @type:		Channel type
> + * @info_mask:		Channel mask
> + * @enabled:		Enable/disable flag
> + * @lsb:		Channel least significant byte
> + * @msb:		Channel most significant byte
> + * @status:		Channel status address
> + * @size:		number of bytes to read
> + * @trigger_addr:	Trigger address
> + * @trigger_mask:	Trigger mask
> + * @scale:		Channel scale callback
> + */
> +struct rradc_channel {
> +	const char			*datasheet_name;
> +	enum iio_chan_type		type;
> +	long				info_mask;
> +	bool				enabled;
> +	u8				lsb;
> +	u8				msb;
> +	u8				status;
> +	int				size;
> +	int				trigger_addr;
> +	int				trigger_mask;
> +	int (*scale)(struct rradc_chip *chip, u16 adc_code, int *result);
> +};
> +
> +struct rradc_chip {
> +	struct device			*dev;
> +	struct qcom_spmi_pmic		*pmic;
> +	struct mutex			lock;
> +	struct regmap			*regmap;
> +	u32				base;
> +	int				batt_id_delay;
> +	struct iio_chan_spec		*iio_chans;
> +	unsigned int			nchannels;
> +	struct rradc_channel		*chans;
> +	u16				batt_id_data;
> +};
> +
> +static const int batt_id_delays[] = {0, 1, 4, 12, 20, 40, 60, 80};
> +
> +static int rradc_masked_write(struct rradc_chip *chip, u16 addr, u8 mask,
> +						u8 val)

I'm not sure this wrapper adds anything significantly useful.
Would prefer you just called regmap_update_bits() inline.

> +{
> +	int ret;
> +
> +	ret = regmap_update_bits(chip->regmap, chip->base + addr,
> +								mask, val);
> +	if (ret) {
> +		dev_err(chip->dev, "spmi write failed: addr=%03X, ret=%d\n", addr, ret);
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static int rradc_read(struct rradc_chip *chip, u16 addr, u8 *data, int len)

I'm hoping the device will provide atomic reads of single registers?
If so, just use a regmap_read() for cases where len = 1.
Keep this magic for the more complex cases.

> +{
> +	int ret = 0, retry_cnt = 0, i = 0;
> +	u8 data_check[RR_ADC_MAX_CONTINUOUS_BUFFER_LEN];
> +	bool coherent_err = false;
> +
> +	if (len > RR_ADC_MAX_CONTINUOUS_BUFFER_LEN) {
> +		dev_err(chip->dev, "Increase the buffer length\n");

That's not very helpful as a user is going to wonder how to do that and
assume there is some control somewhere for it...

> +		return -EINVAL;
> +	}
> +
> +	while (retry_cnt < RR_ADC_COHERENT_CHECK_RETRY) {
> +		ret = regmap_bulk_read(chip->regmap, chip->base + addr,
> +							data, len);
> +		if (ret < 0) {
> +			dev_err(chip->dev, "rr_adc reg 0x%x failed :%d\n", addr, ret);
> +			return ret;
> +		}
> +
> +		ret = regmap_bulk_read(chip->regmap, chip->base + addr,
> +							data_check, len);
> +		if (ret < 0) {
> +			dev_err(chip->dev, "rr_adc reg 0x%x failed :%d\n", addr, ret);
> +			return ret;
> +		}
> +
> +		for (i = 0; i < len; i++) {
> +			if (data[i] != data_check[i])
> +				coherent_err = true;

if (memcmp() != 0)?

> +		}
> +
> +		if (coherent_err) {
> +			retry_cnt++;
> +			coherent_err = false;
> +			dev_dbg(chip->dev, "%s() retry_cnt = %d\n", __func__, retry_cnt);
> +		} else {

I'd flip this

		if (!coherent_err)
			break;

		retry_cnt++;
		coherent_err = false; //I'd move this before the checking loop above...

> +			break;
> +		}
> +	}
> +
> +	if (retry_cnt == RR_ADC_COHERENT_CHECK_RETRY)
> +		dev_err(chip->dev, "Retry exceeded for coherrency check\n");
> +
> +	return ret;
> +}
> +
> +static int rradc_get_fab_coeff(struct rradc_chip *chip,
> +		int64_t *offset, int64_t *slope)
> +{
> +	if (chip->pmic->subtype == PM660_SUBTYPE) {
> +		switch (chip->pmic->fab_id) {
> +		case PM660_FAB_ID_GF:
> +			*offset = RR_ADC_CHG_TEMP_660_GF_OFFSET_UV;
> +			*slope = RR_ADC_CHG_TEMP_660_GF_SLOPE_UV_PER_C;
> +			break;
> +		case PM660_FAB_ID_TSMC:
> +			*offset = RR_ADC_CHG_TEMP_660_SMIC_OFFSET_UV;
> +			*slope = RR_ADC_CHG_TEMP_660_SMIC_SLOPE_UV_PER_C;
> +			break;
> +		default:
> +			*offset = RR_ADC_CHG_TEMP_660_MGNA_OFFSET_UV;
> +			*slope = RR_ADC_CHG_TEMP_660_MGNA_SLOPE_UV_PER_C;
> +	}

Indent of this bracket is wrong.

> +	} else if (chip->pmic->subtype == PMI8998_SUBTYPE) {
> +		switch (chip->pmic->fab_id) {
> +		case PMI8998_FAB_ID_GF:
> +			*offset = RR_ADC_CHG_TEMP_GF_OFFSET_UV;
> +			*slope = RR_ADC_CHG_TEMP_GF_SLOPE_UV_PER_C;
> +			break;
> +		case PMI8998_FAB_ID_SMIC:
> +			*offset = RR_ADC_CHG_TEMP_SMIC_OFFSET_UV;
> +			*slope = RR_ADC_CHG_TEMP_SMIC_SLOPE_UV_PER_C;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +	} else {
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_batt_id(struct rradc_chip *chip, u16 adc_code,
> +			int *result_ohms)
> +{
> +	uint32_t current_value;
> +	int64_t r_id;
> +
> +	current_value = chip->batt_id_data;
> +	r_id = ((int64_t)adc_code * RR_ADC_FS_VOLTAGE_MV);
> +	r_id = div64_s64(r_id, (RR_ADC_MAX_READINGS * current_value));
> +	*result_ohms = (r_id * RR_ADC_SCALE_MILLI_FACTOR);
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_therm(struct rradc_chip *chip, u16 adc_code,
> +			int *result_millidegc)
> +{
> +	int64_t temp;
> +
> +	/* K = code/4 */
> +	temp = ((int64_t)adc_code * RR_ADC_SCALE_MILLI_FACTOR);
> +	temp = div64_s64(temp, RR_ADC_BATT_THERM_LSB_K);
> +	*result_millidegc = temp - RR_ADC_KELVINMIL_CELSIUSMIL;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_volt(struct rradc_chip *chip, u16 adc_code,
> +			int *result_uv)
> +{
> +	int64_t uv = 0;
> +
> +	/* 8x input attenuation; 2.5V ADC full scale */
> +	uv = ((int64_t)adc_code * RR_ADC_VOLT_INPUT_FACTOR);
> +	uv *= (RR_ADC_FS_VOLTAGE_MV * RR_ADC_SCALE_MILLI_FACTOR);
> +	uv = div64_s64(uv, RR_ADC_MAX_READINGS);
> +	*result_uv = uv;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_usbin_curr(struct rradc_chip *chip, u16 adc_code,
> +			int *result_ua)
> +{
> +	int64_t ua = 0;
> +
> +	/* scale * V/A; 2.5V ADC full scale */
> +	ua = ((int64_t)adc_code * RR_ADC_CURR_USBIN_INPUT_FACTOR_MIL);
> +	ua *= (RR_ADC_FS_VOLTAGE_MV * RR_ADC_SCALE_MILLI_FACTOR);
> +	ua = div64_s64(ua, (RR_ADC_MAX_READINGS * 10));
> +	*result_ua = ua;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_dcin_curr(struct rradc_chip *chip, u16 adc_code,
> +			int *result_ua)
> +{
> +	int64_t ua = 0;
> +
> +	/* 0.5 V/A; 2.5V ADC full scale */
> +	ua = ((int64_t)adc_code * RR_ADC_CURR_INPUT_FACTOR);
> +	ua *= (RR_ADC_FS_VOLTAGE_MV * RR_ADC_SCALE_MILLI_FACTOR);
> +	ua = div64_s64(ua, (RR_ADC_MAX_READINGS * 1000));
> +	*result_ua = ua;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_die_temp(struct rradc_chip *chip, u16 adc_code,
> +			int *result_millidegc)
> +{
> +	int64_t temp = 0;
> +
> +	temp = ((int64_t)adc_code * RR_ADC_TEMP_FS_VOLTAGE_NUM);
> +	temp = div64_s64(temp, (RR_ADC_TEMP_FS_VOLTAGE_DEN *
> +					RR_ADC_MAX_READINGS));
> +	temp -= RR_ADC_DIE_TEMP_OFFSET;
> +	temp = div64_s64(temp, RR_ADC_DIE_TEMP_SLOPE);
> +	temp += RR_ADC_DIE_TEMP_OFFSET_MILLI_DEGC;
> +	*result_millidegc = temp;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_chg_temp_hot(struct rradc_chip *chip, u16 adc_code,
> +			int *result_millidegc)
> +{
> +	int64_t uv = 0, offset = 0, slope = 0;
> +	int ret = 0;
> +
> +	ret = rradc_get_fab_coeff(chip, &offset, &slope);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Unable to get fab id coefficients\n");
> +		return -EINVAL;
> +	}
> +
> +	uv = (int64_t) adc_code * RR_ADC_CHG_THRESHOLD_SCALE;
> +	uv = uv * RR_ADC_TEMP_FS_VOLTAGE_NUM;
> +	uv = div64_s64(uv, (RR_ADC_TEMP_FS_VOLTAGE_DEN *
> +					RR_ADC_MAX_READINGS));
> +	uv = offset - uv;
> +	uv = div64_s64((uv * RR_ADC_SCALE_MILLI_FACTOR), slope);
> +	uv = uv + RR_ADC_CHG_TEMP_OFFSET_MILLI_DEGC;
> +	*result_millidegc = uv;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_skin_temp_hot(struct rradc_chip *chip, u16 adc_code,
> +			int *result_millidegc)
> +{
> +	int64_t temp = 0;
More initialization that isn't needed I'll not bother raising this again but pleas
clear out all instances in v2.
> +
> +	temp = (int64_t) adc_code;
> +	temp = div64_s64(temp, 2);
> +	temp = temp - 30;
> +	temp *= RR_ADC_SCALE_MILLI_FACTOR;

There is little benefit in having so many lines here. Combine at least some of them.

> +	*result_millidegc = temp;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_chg_temp(struct rradc_chip *chip, u16 adc_code,
> +			int *result_millidegc)
> +{
> +	int64_t uv = 0, offset = 0, slope = 0;
> +	int ret = 0;
> +
> +	ret = rradc_get_fab_coeff(chip, &offset, &slope);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Unable to get fab id coefficients\n");
> +		return -EINVAL;
> +	}
> +
> +	uv = ((int64_t) adc_code * RR_ADC_TEMP_FS_VOLTAGE_NUM);
> +	uv = div64_s64(uv, (RR_ADC_TEMP_FS_VOLTAGE_DEN *
> +					RR_ADC_MAX_READINGS));
> +	uv = offset - uv;
> +	uv = div64_s64((uv * RR_ADC_SCALE_MILLI_FACTOR), slope);
> +	uv += RR_ADC_CHG_TEMP_OFFSET_MILLI_DEGC;
> +	*result_millidegc = uv;
> +
> +	return 0;
> +}
> +
> +static int rradc_post_process_gpio(struct rradc_chip *chip, u16 adc_code,
> +			int *result_mv)
> +{
> +	int64_t mv = 0;
> +
> +	/* 5V ADC full scale, 10 bit */
> +	mv = ((int64_t)adc_code * RR_ADC_GPIO_FS_RANGE);
> +	mv = div64_s64(mv, RR_ADC_MAX_READINGS);

this returns an s64, so if you want to be safe you'll need to clamp it to range of
the int. It is probably fine, but that doesn't mean the various static analysis
tools will be able to tell.

> +	*result_mv = mv;
> +
> +	return 0;
> +}
> +
> +static int rradc_enable_continuous_mode(struct rradc_chip *chip)
> +{
> +	int ret = 0;
> +
> +	/* Clear channel log */
> +	ret = rradc_masked_write(chip, RR_ADC_ADC_LOG,
> +			RR_ADC_ADC_LOG_CLR_CTRL,
> +			RR_ADC_ADC_LOG_CLR_CTRL);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "log ctrl update to clear failed:%d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = rradc_masked_write(chip, RR_ADC_ADC_LOG,
> +		RR_ADC_ADC_LOG_CLR_CTRL, 0);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "log ctrl update to not clear failed:%d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Switch to continuous mode */
> +	ret = rradc_masked_write(chip, RR_ADC_RR_ADC_CTL,
> +		RR_ADC_ADC_CTL_CONTINUOUS_SEL,
> +		RR_ADC_ADC_CTL_CONTINUOUS_SEL);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Update to continuous mode failed:%d\n", ret);
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static int rradc_disable_continuous_mode(struct rradc_chip *chip)
> +{
> +	int ret = 0;
> +
> +	/* Switch to non continuous mode */
> +	ret = rradc_masked_write(chip, RR_ADC_RR_ADC_CTL,
> +			RR_ADC_ADC_CTL_CONTINUOUS_SEL, 0);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Update to non-continuous mode failed:%d\n", ret);
> +		return ret;

Drop this as we'll return ret anyway in next line.  Do the same
for similar cases throughout the driver.

> +	}
> +
> +	return ret;
> +}
> +
> +static bool rradc_is_ready(struct rradc_chip *chip,
> +		enum rradc_channel_id chan_id)
> +{
> +	struct rradc_channel *chan = &chip->chans[chan_id];
> +	int ret = 0;
> +	u8 status = 0, mask;
> +
> +	/* BATT_ID STS bit does not get set initially */
> +	switch (chan_id) {
> +	case RR_ADC_BATT_ID:
> +		mask = RR_ADC_STS_CHANNEL_STS;
> +		break;
> +	default:
> +		mask = RR_ADC_STS_CHANNEL_READING_MASK;
> +		break;
> +	}
> +
> +	ret = rradc_read(chip, chan->status, &status, 1);
> +	if (ret < 0 || !(status & mask)) {
> +		dev_dbg(chip->dev, "Chip not ready, ret=%d\n", status);
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static int rradc_read_status_in_cont_mode(struct rradc_chip *chip,
> +		enum rradc_channel_id chan_id)
Run checkpatch over this + sparse at very least.

One thing you'll get is warnings about parameter alignment which
should be aligned with opening brackets.

> +{
> +	struct rradc_channel *chan = &chip->chans[chan_id];
> +	int ret = 0;

As below.  Nothing should be initialized where the value is unused.

> +
> +	ret = rradc_masked_write(chip, chan->trigger_addr,
> +				chan->trigger_mask,

Don't wrap lines unless they are over 80 chars unwrapped.

> +				chan->trigger_mask);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Failed to apply trigger for channel '%s' ret=%d\n",
> +			chan->datasheet_name, ret);
> +		return ret;
> +	}
> +
> +	ret = rradc_enable_continuous_mode(chip);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Failed to switch to continuous mode\n");
> +		goto disable_trigger;
> +	}
> +
> +	if (!rradc_is_ready(chip, chan_id))
> +		dev_err(chip->dev, "%s() channel isn't ready: %d\n", __func__, ret);
> +
> +	ret = rradc_disable_continuous_mode(chip);
> +	if (ret < 0)
> +		dev_err(chip->dev, "Failed to switch to non continuous mode\n");
> +
> +disable_trigger:
> +	ret = rradc_masked_write(chip, chan->trigger_addr,
> +				chan->trigger_mask,
> +				0);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Failed to apply trigger for channel '%s' ret=%d\n",
> +			chan->datasheet_name, ret);
> +	}
> +
> +	return ret;
> +}
> +
> +static int rradc_prepare_batt_id_conversion(struct rradc_chip *chip,
> +		enum rradc_channel_id chan_id, u16 *data)
> +{
> +	int ret = 0, batt_id_delay;

Check for any initializations that aren't needed.

> +
> +	ret = rradc_masked_write(chip, RR_ADC_BATT_ID_CTRL,
> +				RR_ADC_BATT_ID_CTRL_CHANNEL_CONV,
> +				RR_ADC_BATT_ID_CTRL_CHANNEL_CONV);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "Enabling BATT ID channel failed:%d\n", ret);
> +		return ret;
> +	}
> +
> +	if (chip->batt_id_delay != -EINVAL) {
> +		batt_id_delay = chip->batt_id_delay << BATT_ID_SETTLE_SHIFT;

Using FIELD_PREP() and FIELD_GET() to set up fields within registers.
That way you can fully specify the field using just a mask.

> +		ret = rradc_masked_write(chip, RR_ADC_BATT_ID_CFG,
> +				batt_id_delay, batt_id_delay);
> +		if (ret < 0)
> +			dev_err(chip->dev, "BATT_ID settling time config failed:%d\n", ret);

Why not error out?

> +	}
> +
> +	ret = rradc_masked_write(chip, RR_ADC_BATT_ID_TRIGGER,
> +				RR_ADC_BATT_ID_TRIGGER_CTL,
> +				RR_ADC_BATT_ID_TRIGGER_CTL);
> +	if (ret < 0) {
> +		dev_err(chip->dev, "BATT_ID trigger set failed:%d\n", ret);
> +		goto out_disable_batt_id;
> +	}
> +
> +	ret = rradc_read_status_in_cont_mode(chip, chan_id);
> +	if (ret < 0)
> +		dev_err(chip->dev, "Error reading in continuous mode:%d\n", ret);

The mixture of error out and continue regardless is inconsistent.  If there is
a reason for this, then comments needed.

> +
> +	ret = rradc_masked_write(chip, RR_ADC_BATT_ID_TRIGGER,
> +			RR_ADC_BATT_ID_TRIGGER_CTL, 0);
> +	if (ret < 0)
> +		dev_err(chip->dev, "BATT_ID trigger re-set failed:%d\n", ret);
> +
> +out_disable_batt_id:
> +	ret = rradc_masked_write(chip, RR_ADC_BATT_ID_CTRL,
> +				RR_ADC_BATT_ID_CTRL_CHANNEL_CONV, 0);
> +	if (ret < 0)
> +		dev_err(chip->dev, "Disabling BATT ID channel failed:%d\n", ret);
> +
> +	return ret;
> +}
> +
> +static int rradc_do_conversion(struct rradc_chip *chip, enum rradc_channel_id chan_id, u16 *data)
> +{
> +	struct rradc_channel *chan = &chip->chans[chan_id];
> +	int ret = 0;
> +	u8 buf[6];
> +	u16 batt_id_5 = 0, batt_id_15 = 0, batt_id_150 = 0;

Push these into the branch where they are used.

> +
> +	mutex_lock(&chip->lock);
> +
> +	/*
> +	 * First we need to do channel specific configuration.

As below, no need to talk us through things we can see from the code.

> +	 */
> +	switch (chan_id) {
> +	case RR_ADC_BATT_ID:
> +		ret = rradc_prepare_batt_id_conversion(chip, chan_id, data);
> +		if (ret < 0) {
> +			dev_err(chip->dev, "Battery ID conversion failed:%d\n", ret);
> +			goto unlock_out;
> +		}
> +		break;
> +
> +	case RR_ADC_USBIN_V:
> +	case RR_ADC_DIE_TEMP:
> +		ret = rradc_read_status_in_cont_mode(chip, chan_id);
> +		if (ret < 0) {
> +			dev_err(chip->dev, "Error reading in continuous mode:%d\n", ret);
> +			goto unlock_out;
> +		}
> +		break;
> +	case RR_ADC_CHG_HOT_TEMP:
> +	case RR_ADC_CHG_TOO_HOT_TEMP:
> +	case RR_ADC_SKIN_HOT_TEMP:
> +	case RR_ADC_SKIN_TOO_HOT_TEMP:
> +		break;
> +	default:
> +		if (!rradc_is_ready(chip, chan_id)) {
> +			dev_err(chip->dev, "%s() channel '%s' is not ready\n", __func__,
> +				chan->datasheet_name);
> +			ret = -ENODATA;
> +			goto unlock_out;
> +		}
> +		break;
> +	}
> +
> +	/*
> +	 * Then we can read the data.

Check to see if the comments add information.  Given function is called rradc_read() I don't think
this one does.  Comments rot over time, so use them only where they provide
significant benefit.

> +	 */
> +	ret = rradc_read(chip, chan->lsb, buf, chan->size);
> +	if (ret) {
> +		dev_err(chip->dev, "read data failed\n");
> +		goto unlock_out;
> +	}
> +
> +	/*
> +	 * For the battery ID we read the register for every ID ADC and then
> +	 * see which one is actually connected.
> +	 */
> +	if (chan_id == RR_ADC_BATT_ID) {
> +		batt_id_150 = (buf[5] << 8) | buf[4];

get_unaligned_le16()  Though given the values always seem to
be le16, maybe just change the type of buf so you can access them
directly.

> +		batt_id_15 = (buf[3] << 8) | buf[2];
> +		batt_id_5 = (buf[1] << 8) | buf[0];
> +		if ((!batt_id_150) && (!batt_id_15) && (!batt_id_5)) {

Probably better to drop the excess brackets in here.

> +			dev_err(chip->dev, "Invalid batt_id values with all zeros\n");
> +			ret = -EINVAL;
> +			goto unlock_out;
> +		}
> +
> +		if (batt_id_150 <= RR_ADC_BATT_ID_RANGE) {
> +			*data = batt_id_150;
> +			chip->batt_id_data = RR_ADC_BATT_ID_150_MA;
> +		} else if (batt_id_15 <= RR_ADC_BATT_ID_RANGE) {
> +			*data = batt_id_15;
> +			chip->batt_id_data = RR_ADC_BATT_ID_15_MA;
> +		} else {
> +			*data = batt_id_5;
> +			chip->batt_id_data = RR_ADC_BATT_ID_5_MA;
> +		}
> +	} else {
> +		/*
> +		 * All of the other channels are either 1 or 2 bytes.
> +		 * We can rely on the second byte being 0 for 1-byte channels.
> +		 */
> +		*data = (buf[1] << 8) | buf[0];

		get_unaligned_le16()

> +	}
> +
> +unlock_out:
> +	mutex_unlock(&chip->lock);
> +
> +	return ret;
> +}
> +
> +static int rradc_read_raw(struct iio_dev *indio_dev,
> +			 struct iio_chan_spec const *chan_spec, int *val, int *val2,
> +			 long mask)
> +{
> +	struct rradc_chip *chip = iio_priv(indio_dev);
> +	struct rradc_channel *chan;
> +	int ret;
> +	u16 adc_code;
> +
> +	if (chan_spec->address >= RR_ADC_MAX) {
> +		dev_err(chip->dev, "Invalid channel index:%ld\n", chan_spec->address);
> +		return -EINVAL;
> +	}
> +
> +	chan = &chip->chans[chan_spec->address];
> +	ret = rradc_do_conversion(chip, chan_spec->address, &adc_code);
> +	if (ret < 0)
> +		return ret;
> +	dev_dbg(chip->dev, "channel: %s, raw adc value = %d\n", chan->datasheet_name, adc_code);

Consider dropping these dev_dbg() as I'd just count them as noise at this point.

> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		*val = (int) adc_code;

That cast shouldn't be needed.

> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_PROCESSED:
> +		chan->scale(chip, adc_code, val);
> +		dev_dbg(chip->dev, "%s() processed chan_id = %ld, data = %d, ret = %d",
> +			__func__, chan_spec->address, *val, ret);
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info rradc_info = {
> +	.read_raw	= &rradc_read_raw,

Don't use tab alignment in cases like this. It comes back to bite us far too often.
	.read_raw = &rradc_read_raw,

> +};
> +
> +#define CHAN_INIT(_name, _type, _mask, _scale, _lsb, _msb, _sts, _bytes, _trig, _trig_mask) \
> +	{ \
> +		.datasheet_name = _name, \
> +		.type = _type, \
> +		.info_mask = _mask, \
> +		.scale = _scale, \
> +		.lsb = _lsb, \
> +		.msb = _msb, \
> +		.status = _sts, \
> +		.enabled = true, \
> +		.size = _bytes, \
> +		.trigger_addr = _trig, \
> +		.trigger_mask = _trig_mask, \
> +	}
> +
> +static int rradc_init_channels(struct rradc_chip *chip)
> +{
> +	int i = 0;
> +
> +	chip->nchannels = RR_ADC_MAX;

At least at first glance it looks to me like everything in here is static.
If so then I'd much prefer to see this whole thing converted to static const
data rather than dynamic allocation and a function filling in the values.


> +	chip->chans = devm_kcalloc(chip->dev, chip->nchannels,
> +			sizeof(*chip->chans), GFP_KERNEL);
> +	if (!chip->chans)
> +		return -ENOMEM;
> +
> +	chip->iio_chans = devm_kcalloc(chip->dev, chip->nchannels,
> +				       sizeof(*chip->iio_chans), GFP_KERNEL);
> +	if (!chip->iio_chans)
> +		return -ENOMEM;
> +
> +	chip->chans[RR_ADC_BATT_ID] =
> +		(struct rradc_channel) CHAN_INIT("batt_id", IIO_RESISTANCE,
> +			BIT(IIO_CHAN_INFO_PROCESSED), rradc_post_process_batt_id,
> +			RR_ADC_BATT_ID_5_LSB, RR_ADC_BATT_ID_5_MSB, RR_ADC_BATT_ID_STS, 6,
> +			RR_ADC_BATT_ID_TRIGGER, RR_ADC_BATT_ID_TRIGGER_CTL);
> +	chip->chans[RR_ADC_BATT_THERM] =
> +		(struct rradc_channel) CHAN_INIT("batt_therm", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_RAW), rradc_post_process_therm,
> +			RR_ADC_BATT_THERM_LSB, RR_ADC_BATT_THERM_MSB, RR_ADC_BATT_THERM_STS, 2,
> +			RR_ADC_BATT_THERM_TRIGGER, RR_ADC_BATT_THERM_TRIGGER);
> +	chip->chans[RR_ADC_SKIN_TEMP] =
> +		(struct rradc_channel) CHAN_INIT("skin_temp", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_therm,
> +			RR_ADC_SKIN_TEMP_LSB, RR_ADC_SKIN_TEMP_MSB, RR_ADC_AUX_THERM_STS, 2,
> +			RR_ADC_AUX_THERM_TRIGGER, RR_ADC_AUX_THERM_TRIGGER);
> +	chip->chans[RR_ADC_USBIN_I] =
> +		(struct rradc_channel) CHAN_INIT("usbin_i", IIO_CURRENT,
> +			BIT(IIO_CHAN_INFO_PROCESSED), rradc_post_process_usbin_curr,
> +			RR_ADC_USB_IN_I_LSB, RR_ADC_USB_IN_I_MSB, RR_ADC_USB_IN_I_STS, 2,
> +			RR_ADC_USB_IN_I_TRIGGER, RR_ADC_USB_IN_I_TRIGGER);
> +	chip->chans[RR_ADC_USBIN_V] =
> +		(struct rradc_channel) CHAN_INIT("usbin_v", IIO_VOLTAGE,
> +			BIT(IIO_CHAN_INFO_PROCESSED), rradc_post_process_volt,
> +			RR_ADC_USB_IN_V_LSB, RR_ADC_USB_IN_V_MSB, RR_ADC_USB_IN_V_STS, 2,
> +			RR_ADC_USB_IN_V_TRIGGER, RR_ADC_USB_IN_V_EVERY_CYCLE);
> +	chip->chans[RR_ADC_DCIN_I] =
> +		(struct rradc_channel) CHAN_INIT("dcin_i", IIO_CURRENT,
> +			BIT(IIO_CHAN_INFO_PROCESSED), rradc_post_process_dcin_curr,
> +			RR_ADC_DC_IN_I_LSB, RR_ADC_DC_IN_I_MSB, RR_ADC_DC_IN_I_STS, 2,
> +			RR_ADC_DC_IN_I_TRIGGER, RR_ADC_DC_IN_I_TRIGGER);
> +	chip->chans[RR_ADC_DCIN_V] =
> +		(struct rradc_channel) CHAN_INIT("dcin_v", IIO_VOLTAGE,
> +			BIT(IIO_CHAN_INFO_PROCESSED), rradc_post_process_volt,
> +			RR_ADC_DC_IN_V_LSB, RR_ADC_DC_IN_V_MSB, RR_ADC_DC_IN_V_STS, 2,
> +			RR_ADC_DC_IN_V_TRIGGER, RR_ADC_DC_IN_V_TRIGGER);
> +	chip->chans[RR_ADC_DIE_TEMP] =
> +		(struct rradc_channel) CHAN_INIT("die_temp", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_die_temp,
> +			RR_ADC_PMI_DIE_TEMP_LSB, RR_ADC_PMI_DIE_TEMP_MSB, RR_ADC_PMI_DIE_TEMP_STS,
> +			2, RR_ADC_PMI_DIE_TEMP_TRIGGER,
> +			RR_ADC_PMI_DIE_TEMP_TRIGGER);
> +	chip->chans[RR_ADC_CHG_TEMP] =
> +		(struct rradc_channel) CHAN_INIT("chg_temp", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_chg_temp,
> +			RR_ADC_CHARGER_TEMP_LSB, RR_ADC_CHARGER_TEMP_MSB,
> +			RR_ADC_CHARGER_TEMP_STS, 2, RR_ADC_CHARGER_TEMP_TRIGGER,
> +			RR_ADC_CHARGER_TEMP_TRIGGER);
> +	chip->chans[RR_ADC_GPIO] =
> +		(struct rradc_channel) CHAN_INIT("gpio", IIO_VOLTAGE,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_gpio,
> +			RR_ADC_GPIO_LSB, RR_ADC_GPIO_MSB, RR_ADC_GPIO_STS, 2,
> +			RR_ADC_GPIO_TRIGGER, RR_ADC_GPIO_TRIGGER);
> +	chip->chans[RR_ADC_CHG_HOT_TEMP] =
> +		(struct rradc_channel) CHAN_INIT("chg_temp_hot", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_chg_temp_hot,
> +			RR_ADC_CHARGER_HOT, RR_ADC_CHARGER_HOT, RR_ADC_CHARGER_TEMP_STS, 1,
> +			RR_ADC_CHARGER_TEMP_TRIGGER, RR_ADC_CHARGER_TEMP_TRIGGER);
> +	chip->chans[RR_ADC_CHG_TOO_HOT_TEMP] =
> +		(struct rradc_channel) CHAN_INIT("chg_temp_too_hot", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_chg_temp_hot,
> +			RR_ADC_CHARGER_TOO_HOT, RR_ADC_CHARGER_TOO_HOT, RR_ADC_CHARGER_TEMP_STS, 1,
> +			RR_ADC_CHARGER_TEMP_TRIGGER, RR_ADC_CHARGER_TEMP_TRIGGER);
> +	chip->chans[RR_ADC_SKIN_HOT_TEMP] =
> +		(struct rradc_channel) CHAN_INIT("skin_temp_hot", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_skin_temp_hot,
> +			RR_ADC_SKIN_HOT, RR_ADC_SKIN_HOT, RR_ADC_AUX_THERM_STS, 1,
> +			RR_ADC_AUX_THERM_TRIGGER, RR_ADC_AUX_THERM_TRIGGER);
> +	chip->chans[RR_ADC_SKIN_TOO_HOT_TEMP] =
> +		(struct rradc_channel) CHAN_INIT("skin_temp_too_hot", IIO_TEMP,
> +			BIT(IIO_CHAN_INFO_PROCESSED) | BIT(IIO_CHAN_INFO_PROCESSED),
> +			rradc_post_process_skin_temp_hot,
> +			RR_ADC_SKIN_TOO_HOT, RR_ADC_SKIN_TOO_HOT, RR_ADC_AUX_THERM_STS, 1,
> +			RR_ADC_AUX_THERM_TRIGGER, RR_ADC_AUX_THERM_TRIGGER);
> +
> +	for (i = 0; i < RR_ADC_MAX; i++) {
> +		chip->iio_chans[i].datasheet_name = chip->chans[i].datasheet_name;

I don't get the reason behind having two copies of most of this stuff. Just fill it in directly.
As mentioned above - even better if you just have a nice static const array.

> +		chip->iio_chans[i].extend_name = chip->chans[i].datasheet_name;
> +		chip->iio_chans[i].info_mask_separate = chip->chans[i].info_mask;
> +		chip->iio_chans[i].type = chip->chans[i].type;
> +		chip->iio_chans[i].address = i;
> +		chip->iio_chans[i].channel = i;
> +	}
> +
> +	return 0;
> +}
> +
> +static int rradc_probe(struct platform_device *pdev)
> +{
> +	struct device_node *node = pdev->dev.of_node;
> +	struct device *dev = &pdev->dev;
> +	struct iio_dev *indio_dev;
> +	struct rradc_chip *chip;
> +	int ret = 0, i;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*chip));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	chip = iio_priv(indio_dev);
> +	chip->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!chip->regmap) {
> +		dev_err(dev, "Couldn't get parent's regmap\n");
> +		return -EINVAL;
> +	}
> +
> +	chip->dev = dev;
> +	mutex_init(&chip->lock);
> +
> +	/* Get the peripheral address */
> +	ret = of_property_read_u32(node, "reg", &chip->base);

Whilst it's fairly unlikely anyone will use this with firmware other than
dt, please use the generic device properties from
include/linux/property.h instead of the of specific ones.


> +	if (ret < 0) {
> +		dev_err(chip->dev,
> +			"Couldn't find reg in node = %s ret = %d\n",
> +			node->name, ret);
> +		return ret;
> +	}
> +
> +	chip->batt_id_delay = -EINVAL;
> +	ret = of_property_read_u32(node, "qcom,batt-id-delay-ms",
> +			&chip->batt_id_delay);
> +	if (!ret) {
> +		for (i = 0; i < RRADC_BATT_ID_DELAY_MAX; i++) {
> +			if (chip->batt_id_delay == batt_id_delays[i])
> +				break;
> +		}
> +		if (i == RRADC_BATT_ID_DELAY_MAX)
> +			chip->batt_id_delay = -EINVAL;
> +	}
> +
> +	/* Get the PMIC revision ID, we need to handle some varying coefficients */
> +	chip->pmic = (struct qcom_spmi_pmic *)
> +		spmi_device_get_drvdata(to_spmi_device(pdev->dev.parent));
> +	qcom_pmic_print_info(chip->dev, chip->pmic);
> +
> +	ret = rradc_init_channels(chip);
> +	if (ret < 0) {
> +		dev_err(dev, "Couldn't initialize channels\n");
> +		return ret;
> +	}
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->dev.of_node = node;

IIRC the IIO core should set both of these for you.

> +	indio_dev->name = pdev->name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &rradc_info;
> +	indio_dev->channels = chip->iio_chans;
> +	indio_dev->num_channels = chip->nchannels;
> +
> +	ret = devm_iio_device_register(dev, indio_dev);
> +	return ret;

	return devm_iio_device_register()

> +}
> +