staging:iio:adc: Add AD7791 driver

This patch adds support for the Analog Devices AD7787, AD7788, AD7789, AD7790
and AD7791 Sigma Delta Analog-to-Digital converters.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/Kconfig

···
 	  Say yes here to build support for Analog Devices AD7265 and AD7266
 	  ADCs.
 
+config AD7791
+	tristate "Analog Devices AD7791 ADC driver"
+	depends on SPI
+	select AD_SIGMA_DELTA
+	help
+	  Say yes here to build support for Analog Devices AD7787, AD7788, AD7789,
+	  AD7790 and AD7791 SPI analog to digital converters (ADC). If unsure, say
+	  N (but it is safe to say "Y").
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad7791.
+
 config AT91_ADC
 	tristate "Atmel AT91 ADC"
 	depends on ARCH_AT91

drivers/iio/adc/Makefile

···
 
 obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o
 obj-$(CONFIG_AD7266) += ad7266.o
+obj-$(CONFIG_AD7791) += ad7791.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o

drivers/iio/adc/ad7791.c

···
+/*
+ * AD7787/AD7788/AD7789/AD7790/AD7791 SPI ADC driver
+ *
+ * Copyright 2012 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <[e-mail]>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/spi/spi.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/adc/ad_sigma_delta.h>
+
+#include <linux/platform_data/ad7791.h>
+
+#define AD7791_REG_COMM			0x0 /* For writes */
+#define AD7791_REG_STATUS		0x0 /* For reads */
+#define AD7791_REG_MODE			0x1
+#define AD7791_REG_FILTER		0x2
+#define AD7791_REG_DATA			0x3
+
+#define AD7791_MODE_CONTINUOUS		0x00
+#define AD7791_MODE_SINGLE		0x02
+#define AD7791_MODE_POWERDOWN		0x03
+
+#define AD7791_CH_AIN1P_AIN1N		0x00
+#define AD7791_CH_AIN2			0x01
+#define AD7791_CH_AIN1N_AIN1N		0x02
+#define AD7791_CH_AVDD_MONITOR		0x03
+
+#define AD7791_FILTER_CLK_DIV_1		(0x0 << 4)
+#define AD7791_FILTER_CLK_DIV_2		(0x1 << 4)
+#define AD7791_FILTER_CLK_DIV_4		(0x2 << 4)
+#define AD7791_FILTER_CLK_DIV_8		(0x3 << 4)
+#define AD7791_FILTER_CLK_MASK		(0x3 << 4)
+#define AD7791_FILTER_RATE_120		0x0
+#define AD7791_FILTER_RATE_100		0x1
+#define AD7791_FILTER_RATE_33_3		0x2
+#define AD7791_FILTER_RATE_20		0x3
+#define AD7791_FILTER_RATE_16_6		0x4
+#define AD7791_FILTER_RATE_16_7		0x5
+#define AD7791_FILTER_RATE_13_3		0x6
+#define AD7791_FILTER_RATE_9_5		0x7
+#define AD7791_FILTER_RATE_MASK		0x7
+
+#define AD7791_MODE_BUFFER		BIT(1)
+#define AD7791_MODE_UNIPOLAR		BIT(2)
+#define AD7791_MODE_BURNOUT		BIT(3)
+#define AD7791_MODE_SEL_MASK		(0x3 << 6)
+#define AD7791_MODE_SEL(x)		((x) << 6)
+
+#define DECLARE_AD7787_CHANNELS(name, bits, storagebits) \
+const struct iio_chan_spec name[] = { \
+	AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
+		(bits), (storagebits), 0), \
+	AD_SD_CHANNEL(1, 1, AD7791_CH_AIN2, (bits), (storagebits), 0), \
+	AD_SD_SHORTED_CHANNEL(2, 0, AD7791_CH_AIN1N_AIN1N, \
+		(bits), (storagebits), 0), \
+	AD_SD_SUPPLY_CHANNEL(3, 2, AD7791_CH_AVDD_MONITOR,  \
+		(bits), (storagebits), 0), \
+	IIO_CHAN_SOFT_TIMESTAMP(4), \
+}
+
+#define DECLARE_AD7791_CHANNELS(name, bits, storagebits) \
+const struct iio_chan_spec name[] = { \
+	AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
+		(bits), (storagebits), 0), \
+	AD_SD_SHORTED_CHANNEL(1, 0, AD7791_CH_AIN1N_AIN1N, \
+		(bits), (storagebits), 0), \
+	AD_SD_SUPPLY_CHANNEL(2, 1, AD7791_CH_AVDD_MONITOR, \
+		(bits), (storagebits), 0), \
+	IIO_CHAN_SOFT_TIMESTAMP(3), \
+}
+
+static DECLARE_AD7787_CHANNELS(ad7787_channels, 24, 32);
+static DECLARE_AD7791_CHANNELS(ad7790_channels, 16, 16);
+static DECLARE_AD7791_CHANNELS(ad7791_channels, 24, 32);
+
+enum {
+	AD7787,
+	AD7788,
+	AD7789,
+	AD7790,
+	AD7791,
+};
+
+enum ad7791_chip_info_flags {
+	AD7791_FLAG_HAS_FILTER		= (1 << 0),
+	AD7791_FLAG_HAS_BUFFER		= (1 << 1),
+	AD7791_FLAG_HAS_UNIPOLAR	= (1 << 2),
+	AD7791_FLAG_HAS_BURNOUT		= (1 << 3),
+};
+
+struct ad7791_chip_info {
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+	enum ad7791_chip_info_flags flags;
+};
+
+static const struct ad7791_chip_info ad7791_chip_infos[] = {
+	[AD7787] = {
+		.channels = ad7787_channels,
+		.num_channels = ARRAY_SIZE(ad7787_channels),
+		.flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
+			AD7791_FLAG_HAS_UNIPOLAR | AD7791_FLAG_HAS_BURNOUT,
+	},
+	[AD7788] = {
+		.channels = ad7790_channels,
+		.num_channels = ARRAY_SIZE(ad7790_channels),
+		.flags = AD7791_FLAG_HAS_UNIPOLAR,
+	},
+	[AD7789] = {
+		.channels = ad7791_channels,
+		.num_channels = ARRAY_SIZE(ad7791_channels),
+		.flags = AD7791_FLAG_HAS_UNIPOLAR,
+	},
+	[AD7790] = {
+		.channels = ad7790_channels,
+		.num_channels = ARRAY_SIZE(ad7790_channels),
+		.flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
+			AD7791_FLAG_HAS_BURNOUT,
+	},
+	[AD7791] = {
+		.channels = ad7791_channels,
+		.num_channels = ARRAY_SIZE(ad7791_channels),
+		.flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
+			AD7791_FLAG_HAS_UNIPOLAR | AD7791_FLAG_HAS_BURNOUT,
+	},
+};
+
+struct ad7791_state {
+	struct ad_sigma_delta sd;
+	uint8_t mode;
+	uint8_t filter;
+
+	struct regulator *reg;
+	const struct ad7791_chip_info *info;
+};
+
+static struct ad7791_state *ad_sigma_delta_to_ad7791(struct ad_sigma_delta *sd)
+{
+	return container_of(sd, struct ad7791_state, sd);
+}
+
+static int ad7791_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
+{
+	ad_sd_set_comm(sd, channel);
+
+	return 0;
+}
+
+static int ad7791_set_mode(struct ad_sigma_delta *sd,
+	enum ad_sigma_delta_mode mode)
+{
+	struct ad7791_state *st = ad_sigma_delta_to_ad7791(sd);
+
+	switch (mode) {
+	case AD_SD_MODE_CONTINUOUS:
+		mode = AD7791_MODE_CONTINUOUS;
+		break;
+	case AD_SD_MODE_SINGLE:
+		mode = AD7791_MODE_SINGLE;
+		break;
+	case AD_SD_MODE_IDLE:
+	case AD_SD_MODE_POWERDOWN:
+		mode = AD7791_MODE_POWERDOWN;
+		break;
+	}
+
+	st->mode &= ~AD7791_MODE_SEL_MASK;
+	st->mode |= AD7791_MODE_SEL(mode);
+
+	return ad_sd_write_reg(sd, AD7791_REG_MODE, sizeof(st->mode), st->mode);
+}
+
+static const struct ad_sigma_delta_info ad7791_sigma_delta_info = {
+	.set_channel = ad7791_set_channel,
+	.set_mode = ad7791_set_mode,
+	.has_registers = true,
+	.addr_shift = 4,
+	.read_mask = BIT(3),
+};
+
+static int ad7791_read_raw(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan, int *val, int *val2, long info)
+{
+	struct ad7791_state *st = iio_priv(indio_dev);
+	bool unipolar = !!(st->mode & AD7791_MODE_UNIPOLAR);
+	unsigned long long scale_pv;
+
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+		return ad_sigma_delta_single_conversion(indio_dev, chan, val);
+	case IIO_CHAN_INFO_OFFSET:
+		/**
+		 * Unipolar: 0 to VREF
+		 * Bipolar -VREF to VREF
+		 **/
+		if (unipolar)
+			*val = 0;
+		else
+			*val = -(1 << (chan->scan_type.realbits - 1));
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/* The monitor channel uses an internal reference. */
+		if (chan->address == AD7791_CH_AVDD_MONITOR) {
+			scale_pv = 5850000000000ULL;
+		} else {
+			int voltage_uv;
+
+			voltage_uv = regulator_get_voltage(st->reg);
+			if (voltage_uv < 0)
+				return voltage_uv;
+			scale_pv = (unsigned long long)voltage_uv * 1000000;
+		}
+		if (unipolar)
+			scale_pv >>= chan->scan_type.realbits;
+		else
+			scale_pv >>= chan->scan_type.realbits - 1;
+		*val2 = do_div(scale_pv, 1000000000);
+		*val = scale_pv;
+
+		return IIO_VAL_INT_PLUS_NANO;
+	}
+
+	return -EINVAL;
+}
+
+static const char * const ad7791_sample_freq_avail[] = {
+	[AD7791_FILTER_RATE_120] = "120",
+	[AD7791_FILTER_RATE_100] = "100",
+	[AD7791_FILTER_RATE_33_3] = "33.3",
+	[AD7791_FILTER_RATE_20] = "20",
+	[AD7791_FILTER_RATE_16_6] = "16.6",
+	[AD7791_FILTER_RATE_16_7] = "16.7",
+	[AD7791_FILTER_RATE_13_3] = "13.3",
+	[AD7791_FILTER_RATE_9_5] = "9.5",
+};
+
+static ssize_t ad7791_read_frequency(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ad7791_state *st = iio_priv(indio_dev);
+	unsigned int rate = st->filter & AD7791_FILTER_RATE_MASK;
+
+	return sprintf(buf, "%s\n", ad7791_sample_freq_avail[rate]);
+}
+
+static ssize_t ad7791_write_frequency(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ad7791_state *st = iio_priv(indio_dev);
+	int i, ret;
+
+	mutex_lock(&indio_dev->mlock);
+	if (iio_buffer_enabled(indio_dev)) {
+		mutex_unlock(&indio_dev->mlock);
+		return -EBUSY;
+	}
+	mutex_unlock(&indio_dev->mlock);
+
+	ret = -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(ad7791_sample_freq_avail); i++) {
+		if (sysfs_streq(ad7791_sample_freq_avail[i], buf)) {
+
+			mutex_lock(&indio_dev->mlock);
+			st->filter &= ~AD7791_FILTER_RATE_MASK;
+			st->filter |= i;
+			ad_sd_write_reg(&st->sd, AD7791_REG_FILTER,
+					 sizeof(st->filter), st->filter);
+			mutex_unlock(&indio_dev->mlock);
+			ret = 0;
+			break;
+		}
+	}
+
+	return ret ? ret : len;
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
+		ad7791_read_frequency,
+		ad7791_write_frequency);
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("120 100 33.3 20 16.7 16.6 13.3 9.5");
+
+static struct attribute *ad7791_attributes[] = {
+	&iio_dev_attr_sampling_frequency.dev_attr.attr,
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group ad7791_attribute_group = {
+	.attrs = ad7791_attributes,
+};
+
+static const struct iio_info ad7791_info = {
+	.read_raw = &ad7791_read_raw,
+	.attrs = &ad7791_attribute_group,
+	.validate_trigger = ad_sd_validate_trigger,
+	.driver_module = THIS_MODULE,
+};
+
+static const struct iio_info ad7791_no_filter_info = {
+	.read_raw = &ad7791_read_raw,
+	.validate_trigger = ad_sd_validate_trigger,
+	.driver_module = THIS_MODULE,
+};
+
+static int __devinit ad7791_setup(struct ad7791_state *st,
+	struct ad7791_platform_data *pdata)
+{
+	/* Set to poweron-reset default values */
+	st->mode = AD7791_MODE_BUFFER;
+	st->filter = AD7791_FILTER_RATE_16_6;
+
+	if (!pdata)
+		return 0;
+
+	if ((st->info->flags & AD7791_FLAG_HAS_BUFFER) && !pdata->buffered)
+		st->mode &= ~AD7791_MODE_BUFFER;
+
+	if ((st->info->flags & AD7791_FLAG_HAS_BURNOUT) &&
+		pdata->burnout_current)
+		st->mode |= AD7791_MODE_BURNOUT;
+
+	if ((st->info->flags & AD7791_FLAG_HAS_UNIPOLAR) && pdata->unipolar)
+		st->mode |= AD7791_MODE_UNIPOLAR;
+
+	return ad_sd_write_reg(&st->sd, AD7791_REG_MODE, sizeof(st->mode),
+		st->mode);
+}
+
+static int __devinit ad7791_probe(struct spi_device *spi)
+{
+	struct ad7791_platform_data *pdata = spi->dev.platform_data;
+	struct iio_dev *indio_dev;
+	struct ad7791_state *st;
+	int ret;
+
+	if (!spi->irq) {
+		dev_err(&spi->dev, "Missing IRQ.\n");
+		return -ENXIO;
+	}
+
+	indio_dev = iio_device_alloc(sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	st->reg = regulator_get(&spi->dev, "refin");
+	if (IS_ERR(st->reg)) {
+		ret = PTR_ERR(st->reg);
+		goto err_iio_free;
+	}
+
+	ret = regulator_enable(st->reg);
+	if (ret)
+		goto error_put_reg;
+
+	st->info = &ad7791_chip_infos[spi_get_device_id(spi)->driver_data];
+	ad_sd_init(&st->sd, indio_dev, spi, &ad7791_sigma_delta_info);
+
+	spi_set_drvdata(spi, indio_dev);
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = st->info->channels;
+	indio_dev->num_channels = st->info->num_channels;
+	if (st->info->flags & AD7791_FLAG_HAS_FILTER)
+		indio_dev->info = &ad7791_info;
+	else
+		indio_dev->info = &ad7791_no_filter_info;
+
+	ret = ad_sd_setup_buffer_and_trigger(indio_dev);
+	if (ret)
+		goto error_disable_reg;
+
+	ret = ad7791_setup(st, pdata);
+	if (ret)
+		goto error_remove_trigger;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto error_remove_trigger;
+
+	return 0;
+
+error_remove_trigger:
+	ad_sd_cleanup_buffer_and_trigger(indio_dev);
+error_disable_reg:
+	regulator_disable(st->reg);
+error_put_reg:
+	regulator_put(st->reg);
+err_iio_free:
+	iio_device_free(indio_dev);
+
+	return ret;
+}
+
+static int __devexit ad7791_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ad7791_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	ad_sd_cleanup_buffer_and_trigger(indio_dev);
+
+	regulator_disable(st->reg);
+	regulator_put(st->reg);
+
+	iio_device_free(indio_dev);
+
+	return 0;
+}
+
+static const struct spi_device_id ad7791_spi_ids[] = {
+	{ "ad7787", AD7787 },
+	{ "ad7788", AD7788 },
+	{ "ad7789", AD7789 },
+	{ "ad7790", AD7790 },
+	{ "ad7791", AD7791 },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, ad7791_spi_ids);
+
+static struct spi_driver ad7791_driver = {
+	.driver = {
+		.name	= "ad7791",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= ad7791_probe,
+	.remove		= __devexit_p(ad7791_remove),
+	.id_table	= ad7791_spi_ids,
+};
+module_spi_driver(ad7791_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <[e-mail]>");
+MODULE_DESCRIPTION("Analog Device AD7787/AD7788/AD7789/AD7790/AD7791 ADC driver");
+MODULE_LICENSE("GPL v2");

include/linux/platform_data/ad7791.h

···
+#ifndef __LINUX_PLATFORM_DATA_AD7791__
+#define __LINUX_PLATFORM_DATA_AD7791__
+
+/**
+ * struct ad7791_platform_data - AD7791 device platform data
+ * @buffered: If set to true configure the device for buffered input mode.
+ * @burnout_current: If set to true the 100mA burnout current is enabled.
+ * @unipolar: If set to true sample in unipolar mode, if set to false sample in
+ *		bipolar mode.
+ */
+struct ad7791_platform_data {
+	bool buffered;
+	bool burnout_current;
+	bool unipolar;
+};
+
+#endif