iio: ina2xx: add support for TI INA2xx Power Monitors

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).

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@baylibre.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 668 insertions, 0 deletions

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
new file mode 100644
index 000000000000..707bd69a7353
--- /dev/null
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -0,0 +1,668 @@
+/*
+ * 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@ti.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 */
+#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)
+
+#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 inline bool is_signed_reg(unsigned int reg)
+{
+	return (reg == INA2XX_SHUNT_VOLTAGE) || (reg == INA2XX_CURRENT);
+}
+
+static const struct regmap_config ina2xx_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.max_register = INA2XX_MAX_REGISTERS,
+	.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 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,
+		    .shunt_div = 100,
+		    .bus_voltage_shift = 3,
+		    .bus_voltage_lsb = 4000,
+		    .power_lsb = 20000,
+		    },
+	[ina226] = {
+		    .config_default = INA226_CONFIG_DEFAULT,
+		    .calibration_factor = 5120000,
+		    .shunt_div = 400,
+		    .bus_voltage_shift = 0,
+		    .bus_voltage_lsb = 1250,
+		    .power_lsb = 25000,
+		    },
+};
+
+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;
+
+		if (is_signed_reg(chan->address))
+			*val = (s16) regval;
+		else
+			*val  = regval;
+
+		return IIO_VAL_INT;
+
+	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;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		/*
+		 * Sample freq is read only, it is a consequence of
+		 * 1/AVG*(CT_bus+CT_shunt).
+		 */
+		*val = DIV_ROUND_CLOSEST(1000000, SAMPLING_PERIOD(chip));
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->address) {
+		case INA2XX_SHUNT_VOLTAGE:
+			/* processed (mV) = raw*1000/shunt_div */
+			*val2 = chip->config->shunt_div;
+			*val = 1000;
+			return IIO_VAL_FRACTIONAL;
+
+		case INA2XX_BUS_VOLTAGE:
+			/* processed (mV) = raw*lsb (uV) / (1000 << shift) */
+			*val = chip->config->bus_voltage_lsb;
+			*val2 = 1000 << chip->config->bus_voltage_shift;
+			return IIO_VAL_FRACTIONAL;
+
+		case INA2XX_POWER:
+			/* processed (mW) = raw*lsb (uW) / 1000 */
+			*val = chip->config->power_lsb;
+			*val2 = 1000;
+			return IIO_VAL_FRACTIONAL;
+
+		case INA2XX_CURRENT:
+			/* processed (mA) = raw (mA) */
+			*val = 1;
+			return IIO_VAL_INT;
+		}
+	}
+
+	return -EINVAL;
+}
+
+/*
+ * 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;
+	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), \
+	.indexed = 1, \
+	.channel = (_index), \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
+	| BIT(IIO_CHAN_INFO_SCALE), \
+	.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_LE, \
+	} \
+}
+
+/*
+ * Sampling Freq is a consequence of the integration times of
+ * the Voltage channels.
+ */
+#define INA2XX_CHAN_VOLTAGE(_index, _address) { \
+	.type = IIO_VOLTAGE, \
+	.address = (_address), \
+	.indexed = 1, \
+	.channel = (_index), \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+			      BIT(IIO_CHAN_INFO_SCALE) | \
+			      BIT(IIO_CHAN_INFO_INT_TIME), \
+	.scan_index = (_index), \
+	.scan_type = { \
+		.sign = 'u', \
+		.realbits = 16, \
+		.storagebits = 16, \
+		.endianness = IIO_LE, \
+	} \
+}
+
+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, i = 0;
+	unsigned long 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)
+			return ret;
+
+		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)
+			return ret;
+
+		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;
+
+	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);
+	int 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 (buffer_us < 0)
+			return buffer_us;
+
+		if (sampling_us > buffer_us)
+			udelay(sampling_us - buffer_us);
+
+	} while (!kthread_should_stop());
+
+	return 0;
+}
+
+static 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);
+}
+
+static 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,
+	.predisable = &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;
+
+	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@baylibre.com>");
+MODULE_DESCRIPTION("Texas Instruments INA2XX ADC driver");
+MODULE_LICENSE("GPL v2");