Re: [RFC v2 1/2] iio: ina2xx: add direct IO support for TI INA2xx Power Monitors

From: Jonathan Cameron
Date: Sat Nov 14 2015 - 14:00:22 EST

On 12/11/15 12:57, Marc Titinger wrote:
> Basic support or direct IO raw read, with averaging attribute.
> Values are RAW, INT_PLUS_MICRO (Volt/Ampere/Watt).
>
> Output of iio_info:
>
> iio:device0: ina226
> 4 channels found:
> power3: (input)
> 1 channel-specific attributes found:
> attr 0: raw value: 1.150000
> voltage0: (input)
> 1 channel-specific attributes found:
> attr 0: raw value: 0.000003
> voltage1: (input)
> 1 channel-specific attributes found:
> attr 0: raw value: 4.277500
> current2: (input)
> 1 channel-specific attributes found:
> attr 0: raw value: 0.268000
> 2 device-specific attributes found:
> attr 0: in_calibscale value: 10000
> attr 1: in_mean_raw value: 4
> attr 2: in_sampling_frequency value: 455
>
> Tested with ina226, on BeagleBoneBlack.
>
> Datasheet: http://www.ti.com/lit/gpn/ina226
>
> Signed-off-by: Marc Titinger <mtitinger@xxxxxxxxxxxx>
Hi Marc

To express a personal preference, please don't have series of patches as
replies to the original thread. It gets really hard to follow after
a couple of revisions!

May seem a random question, but what do you want to gain from an IIO
driver over what the hwmon provides?

Various bits inline..

Mostly looks pretty good though.

Jonathan
> ---
>
> v2 of series https://lkml.org/lkml/2015/11/10/370 :
>
> - squash patches adding SAMPL_FREQ and debugfs interface
> - add regmap is_volatile and is_writeable callbacks
> - fix Kconfig deps and alphabetical sorting
> - simplification: use devm_iio_device_register
>
> ---
>
> drivers/iio/adc/Kconfig | 9 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/ina2xx-iio.c | 472 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 482 insertions(+)
> create mode 100644 drivers/iio/adc/ina2xx-iio.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index eb0cd89..087e5bd 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
> + help
> + Say yes here to build support for TI INA2xx familly Power Monitors.
> +
> + Note that this is not the existing hwmon interface for this device.
> +
> 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..28b7919
> --- /dev/null
> +++ b/drivers/iio/adc/ina2xx-iio.c
> @@ -0,0 +1,472 @@
> +/*
> + * 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@xxxxxx>
> + *
> + * 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/iio/iio.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
> +#include <linux/platform_data/ina2xx.h>
> +
> +#include <linux/util_macros.h>
> +
> +/*
> + * INA2XX registers definition
> + */
> +/* common register definitions */
> +#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
> +
> +/* 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_FREQ 454
> +
> +#define INA2XX_RSHUNT_DEFAULT 10000
> +
> +/* bit mask for reading the averaging setting in the configuration register */
> +#define INA226_AVG_RD_MASK 0x0E00
genmask is always good for these.

> +#define INA226_READ_AVG(reg) (((reg) & INA226_AVG_RD_MASK) >> 9)
> +#define INA226_SHIFT_AVG(val) ((val) << 9)
> +
> +#define INA226_SFREQ_RD_MASK 0x01f8
> +
> +
> +static bool ina2xx_is_writeable_reg(struct device *dev, unsigned int reg)
> +{
> + return (reg == INA2XX_CONFIG)
> + || (reg == INA2XX_CALIBRATION);
On one line I think this is still way less than 80 chars..
> +}
> +
> +static bool ina2xx_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> + return (reg != INA2XX_CONFIG);
> +}
> +
> +static struct regmap_config ina2xx_regmap_config = {
> + .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 iio_dev *indio_dev;
Having a pointer back to the indio_dev is usually a sign of
something 'unusual' going on... Will be interesting to see what it is for ;)

Ah, that was easy, you don't use it that I can see.

> + const struct ina2xx_config *config;
> + struct mutex state_lock;
> + long rshunt;
> + int avg;
> + int freq;
> + int period_us;
> + struct regmap *regmap;
> +};
> +
> +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);
> + *val = *uval/1000000;
> + *uval = *uval - *val*1000000;
> + return IIO_VAL_INT_PLUS_MICRO;
I'm somewhat unconvinced that this wrapper is adding anything over
just doing this where you care about the result.
Also, this is a straight forward linear conversion. Do it in userspace
by providing the relevant 'scale' element.
> +
> + case INA2XX_BUS_VOLTAGE:
> + *uval = (regval >> chip->config->bus_voltage_shift)
> + * chip->config->bus_voltage_lsb;
> + *val = *uval/1000000;
> + *uval = *uval - *val*1000000;
> + return IIO_VAL_INT_PLUS_MICRO;
> +
> + case INA2XX_POWER:
> + *uval = regval * chip->config->power_lsb;
> + *val = *uval/1000000;
> + *uval = *uval - *val*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;
> +
> + case INA2XX_CALIBRATION:
> + *val = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
> + regval);
> + return IIO_VAL_INT;
> +
> + 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_AVERAGE_RAW:
> + *val = chip->avg;
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_CALIBSCALE:
> + ret = regmap_read(chip->regmap, INA2XX_CALIBRATION, &regval);
> + if (ret < 0)
> + return ret;
> +
> + return ina2xx_get_value(chip, INA2XX_CALIBRATION, regval,
> + val, val2);
> +
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + *val = chip->freq;
> + return IIO_VAL_INT;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int ina2xx_calibrate(struct ina2xx_chip_info *chip)
> +{
> + u16 val = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
> + chip->rshunt);
> +
> + return regmap_write(chip->regmap, INA2XX_CALIBRATION, val);
> +}
> +
> +
> +/*
> + * 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 unsigned 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_RD_MASK;
> + *config |= INA226_SHIFT_AVG(bits) & INA226_AVG_RD_MASK;
> +
> + return 0;
> +}
> +
> +/*
> + * Conversion times in uS
> + */
> +static const int ina226_conv_time_tab[] = { 140, 204, 332, 588, 1100,
> + 2116, 4156, 8244};
> +
> +static unsigned int ina226_set_frequency(struct ina2xx_chip_info *chip,
> + unsigned int val,
> + unsigned int *config)
> +{
> + int bits;
> +
> + if (val > 3550 || val < 50)
> + return -EINVAL;
> +
> + /* integration time in uS, for both voltage channels */
> + val = DIV_ROUND_CLOSEST(1000000, 2 * val);
> +
> + bits = find_closest(val, ina226_conv_time_tab,
> + ARRAY_SIZE(ina226_conv_time_tab));
> +
> + chip->period_us = 2 * ina226_conv_time_tab[bits];
> +
> + chip->freq = DIV_ROUND_CLOSEST(1000000, chip->period_us);
> +
> + *config &= ~INA226_SFREQ_RD_MASK;
> + *config |= (bits << 3) | (bits << 6);
> +
> + 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;
> + unsigned int config, tmp;
> +
> + 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_AVERAGE_RAW:
> +
> + ret = ina226_set_average(chip, val, &tmp);
This isn't what the ABI uses the info_average_raw attribute for - it's
for outputing the average of a channel rather than setting a mean
filter width (which is what you have here). Probably need some new ABI
for this as our current filter description ABI is rather limited!

> + break;
> +
> + case IIO_CHAN_INFO_SAMP_FREQ:
> +
> + ret = ina226_set_frequency(chip, val, &tmp);
> + break;
> +
> + default:
> + ret = -EINVAL;
> + }
> +
> + if (!ret && (tmp != config))
> + ret = regmap_write(chip->regmap, INA2XX_CONFIG, config);
> +_err:
> + mutex_unlock(&chip->state_lock);
> +
> + return ret;
> +}
> +
> +#define INA2XX_CHAN(_type, _index, _address) { \
> + .type = _type, \
> + .address = _address, \
> + .indexed = 1, \
> + .channel = (_index), \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_AVERAGE_RAW) | \
> + BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> + BIT(IIO_CHAN_INFO_CALIBSCALE), \
> + .scan_index = (_index), \
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = 16, \
> + .storagebits = 16, \
> + .shift = 0, \
> + .endianness = IIO_BE, \
> + } \
> +}
> +
> +static const struct iio_chan_spec ina2xx_channels[] = {
> + INA2XX_CHAN(IIO_VOLTAGE, 0, INA2XX_SHUNT_VOLTAGE),
> + INA2XX_CHAN(IIO_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_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);
> +}
> +
> +static const struct iio_info ina2xx_info = {
> + .debugfs_reg_access = &ina2xx_debug_reg,
> + .read_raw = &ina2xx_read_raw,
> + .write_raw = &ina2xx_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +/*
Single line comment, use single line comment syntax.
> +* Initialize the configuration and calibration registers.
> +*/
> +static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
> +{
> + 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).
> + */
> + return ina2xx_calibrate(chip);
> +}
> +
> +static int ina2xx_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct ina2xx_chip_info *chip;
> + struct iio_dev *indio_dev;
> + 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->indio_dev = indio_dev;
> +
> + /* set the device type */
> + 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;
> +
> + 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_frequency(chip, INA226_DEFAULT_FREQ, &val);
> + }
> +
> + ret = ina2xx_init(chip, val);
> + if (ret < 0) {
> + dev_err(&client->dev, "error configuring the device: %d\n",
> + ret);
> + return -ENODEV;
> + }
> +
> + return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +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,
> + .id_table = ina2xx_id,
> +};
> +
> +module_i2c_driver(ina2xx_driver);
> +
> +MODULE_AUTHOR("Marc Titinger <marc.titinger@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Texas Instruments INA2XX ADC driver");
> +MODULE_LICENSE("GPL v2");
>

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