Message-ID: <56632CFE.6090409@kernel.org>
Date:	Sat, 5 Dec 2015 18:29:18 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Peter Meerwald-Stadler <pmeerw@...erw.net>,
	Marc Titinger <mtitinger@...libre.com>
Cc:	knaack.h@....de, lars@...afoo.de, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] iio: ina2xx: add support for TI INA2xx Power
 Monitors

On 30/11/15 12:16, Peter Meerwald-Stadler wrote:
> 
>> in SOFTWARE buffer mode, a kthread will capture the active scan_elements
>> into a kfifo, then compute the remaining time until the next capture tick
>> and do an active wait (udelay).
> 
> some minor comments below
other than the points Peter notes below, I'm basically happy with this
driver.  Will take a final look at v3 of course!

Jonathan
>  
>> This will produce a stream of up to fours channels plus a 64bits
>> timestamps (ns).
>>
>> Tested with ina226, on BeagleBoneBlack.
>>
>> Datasheet: http://www.ti.com/lit/gpn/ina226
>>
>> Signed-off-by: Marc Titinger <mtitinger@...libre.com>
>> ---
>>  drivers/iio/adc/Kconfig      |   9 +
>>  drivers/iio/adc/Makefile     |   1 +
>>  drivers/iio/adc/ina2xx-iio.c | 678 +++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 688 insertions(+)
>>  create mode 100644 drivers/iio/adc/ina2xx-iio.c
>>
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index eb0cd89..beea041 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -170,6 +170,15 @@ config EXYNOS_ADC
>>  	  of SoCs for drivers such as the touchscreen and hwmon to use to share
>>  	  this resource.
>>  
>> +config INA2XX_IIO
>> +	tristate "Texas Instruments INA2xx Power Monitors IIO driver"
>> +	depends on I2C
>> +	select REGMAP_I2C
>> +	select IIO_BUFFER
>> +	select IIO_KFIFO_BUF
>> +	help
>> +	  Say yes here to build support for TI INA2xx family Power Monitors.
> 
> 'of Power Monitors' probably
> 
>> +
>>  config LP8788_ADC
>>  	tristate "LP8788 ADC driver"
>>  	depends on MFD_LP8788
>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>> index a096210..74e4341 100644
>> --- a/drivers/iio/adc/Makefile
>> +++ b/drivers/iio/adc/Makefile
>> @@ -19,6 +19,7 @@ obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
>>  obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
>>  obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
>>  obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
>> +obj-$(CONFIG_INA2XX_IIO) += ina2xx-iio.o
>>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>>  obj-$(CONFIG_MAX1027) += max1027.o
>>  obj-$(CONFIG_MAX1363) += max1363.o
>> diff --git a/drivers/iio/adc/ina2xx-iio.c b/drivers/iio/adc/ina2xx-iio.c
>> new file mode 100644
>> index 0000000..99fb73c
>> --- /dev/null
>> +++ b/drivers/iio/adc/ina2xx-iio.c
>> @@ -0,0 +1,678 @@
>> +/*
>> + * INA2XX Current and Power Monitors
>> + *
>> + * Copyright 2015 Baylibre SAS.
>> + *
>> + * 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.
>> + *
>> + * Based on linux/drivers/iio/adc/ad7291.c
>> + * Copyright 2010-2011 Analog Devices Inc.
>> + *
>> + * Based on linux/drivers/hwmon/ina2xx.c
>> + * Copyright 2012 Lothar Felten <l-felten@...com>
>> + *
>> + * Licensed under the GPL-2 or later.
>> + *
>> + * IIO driver for INA219-220-226-230-231
>> + *
>> + * Configurable 7-bit I2C slave address from 0x40 to 0x4F
>> + */
>> +#include <linux/module.h>
>> +#include <linux/kthread.h>
>> +#include <linux/delay.h>
>> +#include <linux/iio/kfifo_buf.h>
>> +#include <linux/iio/sysfs.h>
>> +#include <linux/i2c.h>
>> +#include <linux/regmap.h>
>> +#include <linux/platform_data/ina2xx.h>
>> +
>> +#include <linux/util_macros.h>
>> +
>> +/*
>> + * INA2XX registers definition
>> + */
> 
> a single-line comment would do as well
> 
>> +#define INA2XX_CONFIG                   0x00
>> +#define INA2XX_SHUNT_VOLTAGE            0x01	/* readonly */
>> +#define INA2XX_BUS_VOLTAGE              0x02	/* readonly */
>> +#define INA2XX_POWER                    0x03	/* readonly */
>> +#define INA2XX_CURRENT                  0x04	/* readonly */
>> +#define INA2XX_CALIBRATION              0x05
>> +
>> +#define INA226_ALERT_MASK		0x06
>> +#define INA266_CVRF			BIT(3)
>> +
>> +/* register count */
>> +#define INA219_REGISTERS                6
>> +#define INA226_REGISTERS                8
>> +#define INA2XX_MAX_REGISTERS            8
>> +
>> +/* settings - depend on use case */
>> +#define INA219_CONFIG_DEFAULT           0x399F	/* PGA=8 */
>> +#define INA226_CONFIG_DEFAULT           0x4327
>> +#define INA226_DEFAULT_AVG              4
>> +#define INA226_DEFAULT_IT		1110
>> +
>> +#define INA2XX_RSHUNT_DEFAULT           10000
>> +
>> +/*
>> + * bit mask for reading the averaging setting in the configuration register
>> + * FIXME: use regmap_fields.
>> + */
>> +#define INA2XX_MODE_MASK	GENMASK(3, 0)
>> +
>> +#define INA226_AVG_MASK		GENMASK(11, 9)
>> +#define INA226_SHIFT_AVG(val)	((val) << 9)
>> +
>> +/* Integration time for VBus */
>> +#define INA226_ITB_MASK		GENMASK(8, 6)
>> +#define INA226_SHIFT_ITB(val)	((val) << 6)
>> +
>> +/* Integration time for VShunt */
>> +#define INA226_ITS_MASK		GENMASK(5, 3)
>> +#define INA226_SHIFT_ITS(val)	((val) << 3)
>> +
>> +/* Cosmetic macro giving the sampling period for a full P=UxI cycle */
>> +#define SAMPLING_PERIOD(c)	((c->int_time_vbus + c->int_time_vshunt) \
>> +				 * c->avg)
>> +
>> +static bool ina2xx_is_writeable_reg(struct device *dev, unsigned int reg)
>> +{
>> +	return (reg == INA2XX_CONFIG) || (reg > INA2XX_CURRENT);
>> +}
>> +
>> +static bool ina2xx_is_volatile_reg(struct device *dev, unsigned int reg)
>> +{
>> +	return (reg != INA2XX_CONFIG);
>> +}
>> +
>> +static struct regmap_config ina2xx_regmap_config = {
> 
> would be nice if this could be const; maybe add variants to chip_info
> 
>> +	.reg_bits = 8,
>> +	.val_bits = 16,
>> +
>> +	.writeable_reg = ina2xx_is_writeable_reg,
>> +	.volatile_reg = ina2xx_is_volatile_reg,
>> +};
>> +
>> +enum ina2xx_ids { ina219, ina226 };
>> +
>> +struct ina2xx_config {
>> +	u16 config_default;
>> +	int calibration_factor;
>> +	int registers;
>> +	int shunt_div;
>> +	int bus_voltage_shift;
>> +	int bus_voltage_lsb;	/* uV */
>> +	int power_lsb;		/* uW */
>> +};
>> +
>> +struct ina2xx_chip_info {
>> +	struct regmap *regmap;
>> +	struct task_struct *task;
>> +	const struct ina2xx_config *config;
>> +	struct mutex state_lock;
>> +	long rshunt;
>> +	int avg;
>> +	s64 prev_ns;	/* track buffer capture time check, for underruns*/
>> +	int int_time_vbus; /* Bus voltage integration time uS */
>> +	int int_time_vshunt; /* Shunt voltage integration time uS */
>> +};
>> +
>> +static const struct ina2xx_config ina2xx_config[] = {
>> +	[ina219] = {
>> +		    .config_default = INA219_CONFIG_DEFAULT,
>> +		    .calibration_factor = 40960000,
>> +		    .registers = INA219_REGISTERS,
>> +		    .shunt_div = 100,
>> +		    .bus_voltage_shift = 3,
>> +		    .bus_voltage_lsb = 4000,
>> +		    .power_lsb = 20000,
>> +		    },
>> +	[ina226] = {
>> +		    .config_default = INA226_CONFIG_DEFAULT,
>> +		    .calibration_factor = 5120000,
>> +		    .registers = INA226_REGISTERS,
>> +		    .shunt_div = 400,
>> +		    .bus_voltage_shift = 0,
>> +		    .bus_voltage_lsb = 1250,
>> +		    .power_lsb = 25000,
>> +		    },
>> +};
>> +
>> +static int ina2xx_get_value(struct ina2xx_chip_info *chip, u8 reg,
>> +			    unsigned int regval, int *val, int *uval)
>> +{
>> +	*val = 0;
>> +
>> +	switch (reg) {
>> +	case INA2XX_SHUNT_VOLTAGE:
>> +		/* signed register */
>> +		*uval = DIV_ROUND_CLOSEST((s16) regval,
>> +					  chip->config->shunt_div);
>> +		return IIO_VAL_INT_PLUS_MICRO;
>> +
>> +	case INA2XX_BUS_VOLTAGE:
>> +		*uval = (regval >> chip->config->bus_voltage_shift)
>> +			* chip->config->bus_voltage_lsb;
>> +		*val = *uval / 1000000;
>> +		*uval = *uval % 1000000;
>> +		return IIO_VAL_INT_PLUS_MICRO;
>> +
>> +	case INA2XX_POWER:
>> +		*uval = regval * chip->config->power_lsb;
>> +		*val = *uval / 1000000;
>> +		*uval = *uval % 1000000;
>> +		return IIO_VAL_INT_PLUS_MICRO;
>> +
>> +	case INA2XX_CURRENT:
>> +		/* signed register, LSB=1mA (selected), in mA */
>> +		*uval = (s16) regval * 1000;
>> +		return IIO_VAL_INT_PLUS_MICRO;
>> +
>> +	default:
>> +		/* programmer goofed */
>> +		WARN_ON_ONCE(1);
>> +	}
>> +	return -EINVAL;
>> +}
>> +
>> +static int ina2xx_read_raw(struct iio_dev *indio_dev,
>> +			   struct iio_chan_spec const *chan,
>> +			   int *val, int *val2, long mask)
>> +{
>> +	int ret;
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +	unsigned int regval;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		ret = regmap_read(chip->regmap, chan->address, &regval);
>> +		if (ret < 0)
>> +			return ret;
>> +
>> +		return ina2xx_get_value(chip, chan->address, regval, val, val2);
>> +
>> +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
>> +		*val = chip->avg;
>> +		return IIO_VAL_INT;
>> +
>> +	case IIO_CHAN_INFO_INT_TIME:
>> +		*val = 0;
>> +		if (chan->address == INA2XX_SHUNT_VOLTAGE)
>> +			*val2 = chip->int_time_vshunt;
>> +		else
>> +			*val2 = chip->int_time_vbus;
>> +
>> +		return IIO_VAL_INT_PLUS_MICRO;
>> +	/*
>> +	 * Sample freq is read only, it is a consequence of
>> +	 * 1/AVG*(CT_bus+CT_shunt).
>> +	 */
> 
> I'd move the comment below the case
> 
>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>> +		*val = DIV_ROUND_CLOSEST(1000000, SAMPLING_PERIOD(chip));
>> +
>> +		return IIO_VAL_INT;
>> +
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Available averaging rates for ina226. The indices correspond with
>> + * the bit values expected by the chip (according to the ina226 datasheet,
>> + * table 3 AVG bit settings, found at
>> + * http://www.ti.com/lit/ds/symlink/ina226.pdf.
>> + */
>> +static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };
>> +
>> +static int ina226_set_average(struct ina2xx_chip_info *chip, unsigned int val,
>> +			      unsigned int *config)
>> +{
>> +	int bits;
>> +
>> +	if (val > 1024 || val < 1)
>> +		return -EINVAL;
>> +
>> +	bits = find_closest(val, ina226_avg_tab,
>> +			    ARRAY_SIZE(ina226_avg_tab));
>> +
>> +	chip->avg = ina226_avg_tab[bits];
>> +
>> +	*config &= ~INA226_AVG_MASK;
>> +	*config |= INA226_SHIFT_AVG(bits) & INA226_AVG_MASK;
>> +
>> +	return 0;
>> +}
>> +
>> +/* Conversion times in uS */
>> +static const int ina226_conv_time_tab[] = { 140, 204, 332, 588, 1100,
>> +					    2116, 4156, 8244 };
>> +
>> +static int ina226_set_int_time_vbus(struct ina2xx_chip_info *chip,
>> +				    unsigned int val_us, unsigned int *config)
>> +{
>> +	int bits;
>> +
>> +	if (val_us > 8244 || val_us < 140)
>> +		return -EINVAL;
>> +
>> +	bits = find_closest(val_us, ina226_conv_time_tab,
>> +			ARRAY_SIZE(ina226_conv_time_tab));
>> +
>> +	chip->int_time_vbus = ina226_conv_time_tab[bits];
>> +
>> +	*config &= ~INA226_ITB_MASK;
>> +	*config |= INA226_SHIFT_ITB(bits) & INA226_ITB_MASK;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ina226_set_int_time_vshunt(struct ina2xx_chip_info *chip,
>> +				      unsigned int val_us, unsigned int *config)
>> +{
>> +	int bits;
>> +
>> +	if (val_us > 8244 || val_us < 140)
>> +		return -EINVAL;
>> +
>> +	bits = find_closest(val_us, ina226_conv_time_tab,
>> +			ARRAY_SIZE(ina226_conv_time_tab));
>> +
>> +	chip->int_time_vshunt = ina226_conv_time_tab[bits];
>> +
>> +	*config &= ~INA226_ITS_MASK;
>> +	*config |= INA226_SHIFT_ITS(bits) & INA226_ITS_MASK;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ina2xx_write_raw(struct iio_dev *indio_dev,
>> +			    struct iio_chan_spec const *chan,
>> +			    int val, int val2, long mask)
>> +{
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +	int ret = 0;
> 
> no need to init ret
> 
>> +	unsigned int config, tmp;
>> +
>> +	if (iio_buffer_enabled(indio_dev))
>> +		return -EBUSY;
>> +
>> +	mutex_lock(&chip->state_lock);
>> +
>> +	ret = regmap_read(chip->regmap, INA2XX_CONFIG, &config);
>> +	if (ret < 0)
>> +		goto _err;
>> +
>> +	tmp = config;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
>> +		ret = ina226_set_average(chip, val, &tmp);
>> +		break;
>> +
>> +	case IIO_CHAN_INFO_INT_TIME:
>> +		if (chan->address == INA2XX_SHUNT_VOLTAGE)
>> +			ret = ina226_set_int_time_vshunt(chip, val2, &tmp);
>> +		else
>> +			ret = ina226_set_int_time_vbus(chip, val2, &tmp);
>> +		break;
>> +	default:
>> +		ret = -EINVAL;
>> +	}
>> +
>> +	if (!ret && (tmp != config))
>> +		ret = regmap_write(chip->regmap, INA2XX_CONFIG, tmp);
>> +_err:
>> +	mutex_unlock(&chip->state_lock);
>> +
>> +	return ret;
>> +}
>> +
>> +
>> +#define INA2XX_CHAN(_type, _index, _address) { \
>> +	.type = _type, \
>> +	.address = _address, \
> 
> maybe (_type), (_address) for consistency
> 
>> +	.indexed = 1, \
>> +	.channel = (_index), \
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
>> +	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
>> +				   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
>> +	.scan_index = (_index), \
>> +	.scan_type = { \
>> +		.sign = 'u', \
>> +		.realbits = 16, \
>> +		.storagebits = 16, \
>> +	.endianness = IIO_BE, \
> 
> indentation
> 
>> +	} \
>> +}
>> +
>> +/*
>> + * Sampling Freq is a consequence of the integration times of
>> + * the Voltage channels.
>> + */
>> +#define INA2XX_CHAN_VOLTAGE(_index, _address) { \
>> +	.type = IIO_VOLTAGE, \
>> +	.address = _address, \
> 
> (_address)
> 
>> +	.indexed = 1, \
>> +	.channel = (_index), \
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
>> +			      BIT(IIO_CHAN_INFO_INT_TIME), \
>> +	.scan_index = (_index), \
>> +	.scan_type = { \
>> +		.sign = 'u', \
>> +		.realbits = 16, \
>> +		.storagebits = 16, \
>> +	.endianness = IIO_BE, \
>> +	} \
>> +}
>> +
>> +static const struct iio_chan_spec ina2xx_channels[] = {
>> +	INA2XX_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
>> +	INA2XX_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
>> +	INA2XX_CHAN(IIO_CURRENT, 2, INA2XX_CURRENT),
>> +	INA2XX_CHAN(IIO_POWER, 3, INA2XX_POWER),
>> +	IIO_CHAN_SOFT_TIMESTAMP(4),
>> +};
>> +
>> +static int ina2xx_work_buffer(struct iio_dev *indio_dev)
>> +{
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +	unsigned short data[8];
>> +	int bit, ret = 0, i = 0;
> 
> no need to init ret
> 
>> +	unsigned long buffer_us = 0, elapsed_us = 0;
> 
> no need to init buffer_us, elapsed_us
> 
>> +	s64 time_a, time_b;
>> +	unsigned int alert;
>> +
>> +	time_a = iio_get_time_ns();
>> +
>> +	/*
>> +	 * Because the timer thread and the chip conversion clock
>> +	 * are asynchronous, the period difference will eventually
>> +	 * result in reading V[k-1] again, or skip V[k] at time Tk.
>> +	 * In order to resync the timer with the conversion process
>> +	 * we check the ConVersionReadyFlag.
>> +	 * On hardware that supports using the ALERT pin to toggle a
>> +	 * GPIO a triggered buffer could be used instead.
>> +	 * For now, we pay for that extra read of the ALERT register
>> +	 */
>> +	do {
>> +		ret = regmap_read(chip->regmap, INA226_ALERT_MASK,
>> +				  &alert);
>> +		if (ret < 0)
>> +			goto _err;
>> +
>> +		alert &= INA266_CVRF;
>> +		trace_printk("Conversion ready: %d\n", !!alert);
>> +
>> +	} while (!alert);
>> +
>> +	/*
>> +	 * Single register reads: bulk_read will not work with ina226
>> +	 * as there is no auto-increment of the address register for
>> +	 * data length longer than 16bits.
>> +	 */
>> +	for_each_set_bit(bit, indio_dev->active_scan_mask,
>> +			 indio_dev->masklength) {
>> +		unsigned int val;
>> +
>> +		ret = regmap_read(chip->regmap,
>> +				  INA2XX_SHUNT_VOLTAGE + bit, &val);
>> +		if (ret < 0)
>> +			goto _err;
>> +
>> +		data[i++] = val;
>> +	}
>> +
>> +	time_b = iio_get_time_ns();
>> +
>> +	iio_push_to_buffers_with_timestamp(indio_dev,
>> +					   (unsigned int *)data, time_a);
>> +
>> +	buffer_us = (unsigned long)(time_b - time_a) / 1000;
>> +	elapsed_us = (unsigned long)(time_a - chip->prev_ns) / 1000;
>> +
>> +	trace_printk("uS: elapsed: %lu, buf: %lu\n", elapsed_us, buffer_us);
>> +
>> +	chip->prev_ns = time_a;
>> +
>> +_err:
>> +	return buffer_us;
>> +};
>> +
>> +static int ina2xx_capture_thread(void *data)
>> +{
>> +	struct iio_dev *indio_dev = (struct iio_dev *)data;
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +	unsigned int sampling_us = SAMPLING_PERIOD(chip);
>> +	unsigned long buffer_us;
>> +
>> +	/*
>> +	 * Poll a bit faster than the chip internal Fs, in case
>> +	 * we wish to sync with the conversion ready flag.
>> +	 */
>> +	sampling_us -= 200;
>> +
>> +	do {
>> +		buffer_us = ina2xx_work_buffer(indio_dev);
>> +
>> +		if (sampling_us > buffer_us)
>> +			udelay(sampling_us - buffer_us);
>> +
>> +	} while (!kthread_should_stop());
>> +
>> +	return 0;
>> +}
>> +
>> +int ina2xx_buffer_enable(struct iio_dev *indio_dev)
>> +{
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +	unsigned int sampling_us = SAMPLING_PERIOD(chip);
>> +
>> +	trace_printk("Enabling buffer w/ scan_mask %02x, freq = %d, avg =%u\n",
>> +		     (unsigned int)(*indio_dev->active_scan_mask),
>> +		     1000000/sampling_us, chip->avg);
>> +
>> +	trace_printk("Expected work period: %u us\n", sampling_us);
>> +
>> +	chip->prev_ns = iio_get_time_ns();
>> +
>> +	chip->task = kthread_run(ina2xx_capture_thread, (void *)indio_dev,
>> +				 "ina2xx-%uus", sampling_us);
>> +
>> +	return PTR_ERR_OR_ZERO(chip->task);
>> +}
>> +
>> +int ina2xx_buffer_disable(struct iio_dev *indio_dev)
>> +{
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +
>> +	if (chip->task) {
>> +		kthread_stop(chip->task);
>> +		chip->task = NULL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct iio_buffer_setup_ops ina2xx_setup_ops = {
>> +	.postenable = &ina2xx_buffer_enable,
>> +	.postdisable = &ina2xx_buffer_disable,
>> +};
>> +
>> +static int ina2xx_debug_reg(struct iio_dev *indio_dev,
>> +			    unsigned reg, unsigned writeval, unsigned *readval)
>> +{
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +
>> +	if (!readval)
>> +		return regmap_write(chip->regmap, reg, writeval);
>> +
>> +	return regmap_read(chip->regmap, reg, readval);
>> +}
>> +
>> +/* Possible integration times for vshunt and vbus */
>> +static IIO_CONST_ATTR_INT_TIME_AVAIL \
>> + ("0.000140 0.000204 0.000332 0.000588 0.001100 0.002116 0.004156 0.008244");
>> +
>> +static struct attribute *ina2xx_attributes[] = {
>> +	&iio_const_attr_integration_time_available.dev_attr.attr,
>> +	NULL,
>> +};
>> +
>> +static const struct attribute_group ina2xx_attribute_group = {
>> +	.attrs = ina2xx_attributes,
>> +};
>> +
>> +static const struct iio_info ina2xx_info = {
>> +	.debugfs_reg_access = &ina2xx_debug_reg,
>> +	.read_raw = &ina2xx_read_raw,
>> +	.write_raw = &ina2xx_write_raw,
>> +	.attrs = &ina2xx_attribute_group,
>> +	.driver_module = THIS_MODULE,
>> +};
>> +
>> +/* Initialize the configuration and calibration registers. */
>> +static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
>> +{
>> +	u16 regval;
>> +	int ret = regmap_write(chip->regmap, INA2XX_CONFIG, config);
>> +
>> +	if (ret < 0)
>> +		return ret;
>> +	/*
>> +	 * Set current LSB to 1mA, shunt is in uOhms
>> +	 * (equation 13 in datasheet). We hardcode a Current_LSB
>> +	 * of 1.0 x10-6. The only remaining parameter is RShunt.
>> +	 * There is no need to expose the CALIBRATION register
>> +	 * to the user for now.
>> +	 */
>> +	regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
>> +			    chip->rshunt);
>> +
>> +	return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
>> +}
>> +
>> +static int ina2xx_probe(struct i2c_client *client,
>> +			const struct i2c_device_id *id)
>> +{
>> +	struct ina2xx_chip_info *chip;
>> +	struct iio_dev *indio_dev;
>> +	struct iio_buffer *buffer;
>> +	int ret;
>> +	unsigned int val;
>> +
>> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
>> +	if (!indio_dev)
>> +		return -ENOMEM;
>> +
>> +	chip = iio_priv(indio_dev);
>> +
>> +	chip->config = &ina2xx_config[id->driver_data];
>> +
>> +	if (of_property_read_u32(client->dev.of_node,
>> +				 "shunt-resistor", &val) < 0) {
>> +		struct ina2xx_platform_data *pdata =
>> +		    dev_get_platdata(&client->dev);
>> +
>> +		if (pdata)
>> +			val = pdata->shunt_uohms;
>> +		else
>> +			val = INA2XX_RSHUNT_DEFAULT;
>> +	}
>> +
>> +	if (val <= 0 || val > chip->config->calibration_factor)
>> +		return -ENODEV;
>> +
>> +	chip->rshunt = val;
>> +
>> +	ina2xx_regmap_config.max_register = chip->config->registers;
>> +
>> +	mutex_init(&chip->state_lock);
>> +
>> +	/* This is only used for device removal purposes. */
>> +	i2c_set_clientdata(client, indio_dev);
>> +
>> +	indio_dev->name = id->name;
>> +	indio_dev->channels = ina2xx_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(ina2xx_channels);
>> +
>> +	indio_dev->dev.parent = &client->dev;
>> +	indio_dev->info = &ina2xx_info;
>> +	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
>> +
>> +	chip->regmap = devm_regmap_init_i2c(client, &ina2xx_regmap_config);
>> +	if (IS_ERR(chip->regmap)) {
>> +		dev_err(&client->dev, "failed to allocate register map\n");
>> +		return PTR_ERR(chip->regmap);
>> +	}
>> +
>> +	/* Patch the current config register with default. */
>> +	val = chip->config->config_default;
>> +
>> +	if (id->driver_data == ina226) {
>> +		ina226_set_average(chip, INA226_DEFAULT_AVG, &val);
>> +		ina226_set_int_time_vbus(chip, INA226_DEFAULT_IT, &val);
>> +		ina226_set_int_time_vshunt(chip, INA226_DEFAULT_IT, &val);
>> +	}
>> +
>> +	ret = ina2xx_init(chip, val);
>> +	if (ret < 0) {
>> +		dev_err(&client->dev, "error configuring the device: %d\n",
>> +			ret);
>> +		return -ENODEV;
>> +	}
>> +
>> +	buffer = devm_iio_kfifo_allocate(&indio_dev->dev);
>> +	if (!buffer)
>> +		return -ENOMEM;
>> +
>> +	indio_dev->setup_ops = &ina2xx_setup_ops;
>> +
>> +	iio_device_attach_buffer(indio_dev, buffer);
>> +
>> +	return iio_device_register(indio_dev);
>> +}
>> +
>> +
>> +static int ina2xx_remove(struct i2c_client *client)
>> +{
>> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
>> +	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>> +
>> +	iio_device_unregister(indio_dev);
>> +
>> +	/* Powerdown */
>> +	return regmap_update_bits(chip->regmap, INA2XX_CONFIG,
>> +				  INA2XX_MODE_MASK, 0);
>> +}
>> +
>> +
>> +static const struct i2c_device_id ina2xx_id[] = {
>> +	{"ina219", ina219},
>> +	{"ina220", ina219},
>> +	{"ina226", ina226},
>> +	{"ina230", ina226},
>> +	{"ina231", ina226},
>> +	{}
>> +};
>> +
>> +MODULE_DEVICE_TABLE(i2c, ina2xx_id);
>> +
>> +static struct i2c_driver ina2xx_driver = {
>> +	.driver = {
>> +		   .name = KBUILD_MODNAME,
>> +	},
>> +	.probe = ina2xx_probe,
>> +	.remove = ina2xx_remove,
>> +	.id_table = ina2xx_id,
>> +};
>> +
>> +module_i2c_driver(ina2xx_driver);
>> +
>> +MODULE_AUTHOR("Marc Titinger <marc.titinger@...libre.com>");
>> +MODULE_DESCRIPTION("Texas Instruments INA2XX ADC driver");
>> +MODULE_LICENSE("GPL v2");
>>
> 

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