staging: iio: adc: Enable driver support for ad799x AD converters

Driver for ad7991, ad7995, ad7999, ad7992, ad7993, ad7994, ad7997 and
ad7998 multichannel ADC.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/adc/Kconfig

@@ -26,3 +26,23 @@ config MAX1363_RING_BUFFER
 	help
 	  Say yes here to include ring buffer support in the MAX1363
 	  ADC driver.
+
+config AD799X
+	tristate "Analog Devices AD799x ADC driver"
+	depends on I2C
+	select IIO_TRIGGER if IIO_RING_BUFFER
+	select AD799X_RING_BUFFER
+	help
+	  Say yes here to build support for Analog Devices:
+	  ad7991, ad7995, ad7999, ad7992, ad7993, ad7994, ad7997, ad7998
+	  i2c analog to digital convertors (ADC). Provides direct access
+	  via sysfs.
+
+config AD799X_RING_BUFFER
+	bool "Analog Devices AD799x: use ring buffer"
+	depends on AD799X
+	select IIO_RING_BUFFER
+	select IIO_SW_RING
+	help
+	  Say yes here to include ring buffer support in the AD799X
+	  ADC driver.

drivers/staging/iio/adc/Makefile

@@ -6,3 +6,7 @@ max1363-y := max1363_core.o
 max1363-y += max1363_ring.o
 
 obj-$(CONFIG_MAX1363) += max1363.o
+
+ad799x-y := ad799x_core.o
+ad799x-$(CONFIG_AD799X_RING_BUFFER) += ad799x_ring.o
+obj-$(CONFIG_AD799X) += ad799x.o

drivers/staging/iio/adc/ad799x.h

@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2010 Michael Hennerich, Analog Devices Inc.
+ * Copyright (C) 2008-2010 Jonathan Cameron
+ *
+ * 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.
+ *
+ * ad799x.h
+ */
+
+#ifndef _AD799X_H_
+#define  _AD799X_H_
+
+#define AD799X_CHANNEL_SHIFT			4
+
+/*
+ * AD7991, AD7995 and AD7999 defines
+ */
+
+#define AD7991_REF_SEL				0x08
+#define AD7991_FLTR				0x04
+#define AD7991_BIT_TRIAL_DELAY			0x02
+#define AD7991_SAMPLE_DELAY			0x01
+
+/*
+ * AD7992, AD7993, AD7994, AD7997 and AD7998 defines
+ */
+
+#define AD7998_FLTR				0x08
+#define AD7998_ALERT_EN				0x04
+#define AD7998_BUSY_ALERT			0x02
+#define AD7998_BUSY_ALERT_POL			0x01
+
+#define AD7998_CONV_RES_REG			0x0
+#define AD7998_ALERT_STAT_REG			0x1
+#define AD7998_CONF_REG				0x2
+#define AD7998_CYCLE_TMR_REG			0x3
+#define AD7998_DATALOW_CH1_REG			0x4
+#define AD7998_DATAHIGH_CH1_REG			0x5
+#define AD7998_HYST_CH1_REG			0x6
+#define AD7998_DATALOW_CH2_REG			0x7
+#define AD7998_DATAHIGH_CH2_REG			0x8
+#define AD7998_HYST_CH2_REG			0x9
+#define AD7998_DATALOW_CH3_REG			0xA
+#define AD7998_DATAHIGH_CH3_REG			0xB
+#define AD7998_HYST_CH3_REG			0xC
+#define AD7998_DATALOW_CH4_REG			0xD
+#define AD7998_DATAHIGH_CH4_REG			0xE
+#define AD7998_HYST_CH4_REG			0xF
+
+#define AD7998_CYC_MASK				0x7
+#define AD7998_CYC_DIS				0x0
+#define AD7998_CYC_TCONF_32			0x1
+#define AD7998_CYC_TCONF_64			0x2
+#define AD7998_CYC_TCONF_128			0x3
+#define AD7998_CYC_TCONF_256			0x4
+#define AD7998_CYC_TCONF_512			0x5
+#define AD7998_CYC_TCONF_1024			0x6
+#define AD7998_CYC_TCONF_2048			0x7
+
+#define AD7998_ALERT_STAT_CLEAR			0xFF
+
+/*
+ * AD7997 and AD7997 defines
+ */
+
+#define AD7997_8_READ_SINGLE			0x80
+#define AD7997_8_READ_SEQUENCE			0x70
+
+enum {
+	ad7991,
+	ad7995,
+	ad7999,
+	ad7992,
+	ad7993,
+	ad7994,
+	ad7997,
+	ad7998
+};
+
+struct ad799x_state;
+
+/**
+ * struct ad799x_chip_info - chip specifc information
+ * @num_inputs:		number of physical inputs on chip
+ * @bits:		accuracy of the adc in bits
+ * @int_vref_mv:	the internal reference voltage
+ * @monitor_mode:	whether the chip supports monitor interrupts
+ * @default_config:	device default configuration
+ * @dev_attrs:		pointer to the device attribute group
+ * @scan_attrs:		pointer to the scan element attribute group
+ * @event_attrs:	pointer to the monitor event attribute group
+ * @ad799x_set_scan_mode: function pointer to the device specific mode function
+
+ */
+struct ad799x_chip_info {
+	u8				num_inputs;
+	u8				bits;
+	u16				int_vref_mv;
+	bool				monitor_mode;
+	u16				default_config;
+	struct attribute_group		*dev_attrs;
+	struct attribute_group		*scan_attrs;
+	struct attribute_group		*event_attrs;
+	int (*ad799x_set_scan_mode)	(struct ad799x_state *st,
+					unsigned mask);
+};
+
+struct ad799x_state {
+	struct iio_dev			*indio_dev;
+	struct i2c_client		*client;
+	const struct ad799x_chip_info	*chip_info;
+	struct work_struct		poll_work;
+	struct work_struct		work_thresh;
+	atomic_t			protect_ring;
+	struct iio_trigger		*trig;
+	struct regulator		*reg;
+	s64				last_timestamp;
+	u16				int_vref_mv;
+	unsigned			id;
+	char				*name;
+	u16				config;
+};
+
+/*
+ * TODO: struct ad799x_platform_data needs to go into inlude/linux/iio
+ */
+
+struct ad799x_platform_data {
+	u16				vref_mv;
+};
+
+int ad799x_set_scan_mode(struct ad799x_state *st, unsigned mask);
+
+#ifdef CONFIG_AD799X_RING_BUFFER
+int ad799x_single_channel_from_ring(struct ad799x_state *st, long mask);
+int ad799x_register_ring_funcs_and_init(struct iio_dev *indio_dev);
+void ad799x_ring_cleanup(struct iio_dev *indio_dev);
+#else /* CONFIG_AD799X_RING_BUFFER */
+int ad799x_single_channel_from_ring(struct ad799x_state *st, long mask)
+{
+	return -EINVAL;
+}
+
+
+static inline int
+ad799x_register_ring_funcs_and_init(struct iio_dev *indio_dev)
+{
+	return 0;
+}
+
+static inline void ad799x_ring_cleanup(struct iio_dev *indio_dev)
+{
+}
+#endif /* CONFIG_AD799X_RING_BUFFER */
+#endif /* _AD799X_H_ */

drivers/staging/iio/adc/ad799x_core.c

@@ -0,0 +1,918 @@
+/*
+ * iio/adc/ad799x.c
+ * Copyright (C) 2010 Michael Hennerich, Analog Devices Inc.
+ *
+ * based on iio/adc/max1363
+ * Copyright (C) 2008-2010 Jonathan Cameron
+ *
+ * based on linux/drivers/i2c/chips/max123x
+ * Copyright (C) 2002-2004 Stefan Eletzhofer
+ *
+ * based on linux/drivers/acron/char/pcf8583.c
+ * Copyright (C) 2000 Russell King
+ *
+ * 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.
+ *
+ * ad799x.c
+ *
+ * Support for ad7991, ad7995, ad7999, ad7992, ad7993, ad7994, ad7997,
+ * ad7998 and similar chips.
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/i2c.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/err.h>
+
+#include "../iio.h"
+#include "../sysfs.h"
+
+#include "../ring_generic.h"
+#include "adc.h"
+#include "ad799x.h"
+
+/*
+ * ad799x register access by I2C
+ */
+static int ad799x_i2c_read16(struct ad799x_state *st, u8 reg, u16 *data)
+{
+	struct i2c_client *client = st->client;
+	int ret = 0;
+
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C read error\n");
+		return ret;
+	}
+
+	*data = swab16((u16)ret);
+
+	return 0;
+}
+
+static int ad799x_i2c_read8(struct ad799x_state *st, u8 reg, u8 *data)
+{
+	struct i2c_client *client = st->client;
+	int ret = 0;
+
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C read error\n");
+		return ret;
+	}
+
+	*data = ret;
+
+	return 0;
+}
+
+static int ad799x_i2c_write16(struct ad799x_state *st, u8 reg, u16 data)
+{
+	struct i2c_client *client = st->client;
+	int ret = 0;
+
+	ret = i2c_smbus_write_word_data(client, reg, swab16(data));
+	if (ret < 0)
+		dev_err(&client->dev, "I2C write error\n");
+
+	return ret;
+}
+
+static int ad799x_i2c_write8(struct ad799x_state *st, u8 reg, u8 data)
+{
+	struct i2c_client *client = st->client;
+	int ret = 0;
+
+	ret = i2c_smbus_write_byte_data(client, reg, data);
+	if (ret < 0)
+		dev_err(&client->dev, "I2C write error\n");
+
+	return ret;
+}
+
+static int ad799x_scan_el_set_state(struct iio_scan_el *scan_el,
+				       struct iio_dev *indio_dev,
+				       bool state)
+{
+	struct ad799x_state *st = indio_dev->dev_data;
+	return ad799x_set_scan_mode(st, st->indio_dev->ring->scan_mask);
+}
+
+/* Here we claim all are 16 bits. This currently does no harm and saves
+ * us a lot of scan element listings */
+
+#define AD799X_SCAN_EL(number)						\
+	IIO_SCAN_EL_C(in##number, number, 0, ad799x_scan_el_set_state);
+
+static AD799X_SCAN_EL(0);
+static AD799X_SCAN_EL(1);
+static AD799X_SCAN_EL(2);
+static AD799X_SCAN_EL(3);
+static AD799X_SCAN_EL(4);
+static AD799X_SCAN_EL(5);
+static AD799X_SCAN_EL(6);
+static AD799X_SCAN_EL(7);
+
+static ssize_t ad799x_show_precision(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+	return sprintf(buf, "%d\n", st->chip_info->bits);
+}
+
+static IIO_DEVICE_ATTR(in_precision, S_IRUGO, ad799x_show_precision,
+		       NULL, 0);
+
+static int ad7991_5_9_set_scan_mode(struct ad799x_state *st, unsigned mask)
+{
+	return i2c_smbus_write_byte(st->client,
+		st->config | (mask << AD799X_CHANNEL_SHIFT));
+}
+
+static int ad7992_3_4_set_scan_mode(struct ad799x_state *st, unsigned mask)
+{
+	return ad799x_i2c_write8(st, AD7998_CONF_REG,
+		st->config | (mask << AD799X_CHANNEL_SHIFT));
+}
+
+static int ad7997_8_set_scan_mode(struct ad799x_state *st, unsigned mask)
+{
+	return ad799x_i2c_write16(st, AD7998_CONF_REG,
+		st->config | (mask << AD799X_CHANNEL_SHIFT));
+}
+
+int ad799x_set_scan_mode(struct ad799x_state *st, unsigned mask)
+{
+	int ret;
+
+	if (st->chip_info->ad799x_set_scan_mode != NULL) {
+		ret = st->chip_info->ad799x_set_scan_mode(st, mask);
+		return (ret > 0) ? 0 : ret;
+	}
+
+	return 0;
+}
+
+static ssize_t ad799x_read_single_channel(struct device *dev,
+				   struct device_attribute *attr,
+				   char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	int ret = 0, len = 0;
+	u32 data ;
+	u16 rxbuf[1];
+	u8 cmd;
+	long mask;
+
+	mutex_lock(&dev_info->mlock);
+	mask = 1 << this_attr->address;
+	/* If ring buffer capture is occuring, query the buffer */
+	if (iio_ring_enabled(dev_info)) {
+		data = ad799x_single_channel_from_ring(st, mask);
+		if (data < 0) {
+			ret = data;
+			goto error_ret;
+		}
+	} else {
+		switch (st->id) {
+		case ad7991:
+		case ad7995:
+		case ad7999:
+			cmd = st->config | (mask << AD799X_CHANNEL_SHIFT);
+			break;
+		case ad7992:
+		case ad7993:
+		case ad7994:
+			cmd = mask << AD799X_CHANNEL_SHIFT;
+			break;
+		case ad7997:
+		case ad7998:
+			cmd = (this_attr->address <<
+				AD799X_CHANNEL_SHIFT) | AD7997_8_READ_SINGLE;
+			break;
+		default:
+			cmd = 0;
+
+		}
+		ret = ad799x_i2c_read16(st, cmd, rxbuf);
+		if (ret < 0)
+			goto error_ret;
+
+		data = rxbuf[0] & 0xFFF;
+	}
+
+	/* Pretty print the result */
+	len = sprintf(buf, "%u\n", data);
+
+error_ret:
+	mutex_unlock(&dev_info->mlock);
+	return ret ? ret : len;
+}
+
+static ssize_t ad799x_read_frequency(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+
+	int ret, len = 0;
+	u8 val;
+	ret = ad799x_i2c_read8(st, AD7998_CYCLE_TMR_REG, &val);
+	if (ret)
+		return ret;
+
+	val &= AD7998_CYC_MASK;
+
+	switch (val) {
+	case AD7998_CYC_DIS:
+		len = sprintf(buf, "0\n");
+		break;
+	case AD7998_CYC_TCONF_32:
+		len = sprintf(buf, "15625\n");
+		break;
+	case AD7998_CYC_TCONF_64:
+		len = sprintf(buf, "7812\n");
+		break;
+	case AD7998_CYC_TCONF_128:
+		len = sprintf(buf, "3906\n");
+		break;
+	case AD7998_CYC_TCONF_256:
+		len = sprintf(buf, "1953\n");
+		break;
+	case AD7998_CYC_TCONF_512:
+		len = sprintf(buf, "976\n");
+		break;
+	case AD7998_CYC_TCONF_1024:
+		len = sprintf(buf, "488\n");
+		break;
+	case AD7998_CYC_TCONF_2048:
+		len = sprintf(buf, "244\n");
+		break;
+	}
+	return len;
+}
+
+static ssize_t ad799x_write_frequency(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf,
+					 size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+
+	long val;
+	int ret;
+	u8 t;
+
+	ret = strict_strtol(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dev_info->mlock);
+	ret = ad799x_i2c_read8(st, AD7998_CYCLE_TMR_REG, &t);
+	if (ret)
+		goto error_ret_mutex;
+	/* Wipe the bits clean */
+	t &= ~AD7998_CYC_MASK;
+
+	switch (val) {
+	case 15625:
+		t |= AD7998_CYC_TCONF_32;
+		break;
+	case 7812:
+		t |= AD7998_CYC_TCONF_64;
+		break;
+	case 3906:
+		t |= AD7998_CYC_TCONF_128;
+		break;
+	case 1953:
+		t |= AD7998_CYC_TCONF_256;
+		break;
+	case 976:
+		t |= AD7998_CYC_TCONF_512;
+		break;
+	case 488:
+		t |= AD7998_CYC_TCONF_1024;
+		break;
+	case 244:
+		t |= AD7998_CYC_TCONF_2048;
+		break;
+	case  0:
+		t |= AD7998_CYC_DIS;
+		break;
+	default:
+		ret = -EINVAL;
+		goto error_ret_mutex;
+	}
+
+	ret = ad799x_i2c_write8(st, AD7998_CYCLE_TMR_REG, t);
+
+error_ret_mutex:
+	mutex_unlock(&dev_info->mlock);
+
+	return ret ? ret : len;
+}
+
+
+static ssize_t ad799x_read_channel_config(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+	struct iio_event_attr *this_attr = to_iio_event_attr(attr);
+
+	int ret;
+	u16 val;
+	ret = ad799x_i2c_read16(st, this_attr->mask, &val);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "%d\n", val);
+}
+
+static ssize_t ad799x_write_channel_config(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf,
+					 size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+	struct iio_event_attr *this_attr = to_iio_event_attr(attr);
+
+	long val;
+	int ret;
+
+	ret = strict_strtol(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dev_info->mlock);
+	ret = ad799x_i2c_write16(st, this_attr->mask, val);
+	mutex_unlock(&dev_info->mlock);
+
+	return ret ? ret : len;
+}
+
+static void ad799x_interrupt_bh(struct work_struct *work_s)
+{
+	struct ad799x_state *st = container_of(work_s,
+		struct ad799x_state, work_thresh);
+	u8 status;
+	int i;
+
+	if (ad799x_i2c_read8(st, AD7998_ALERT_STAT_REG, &status))
+		goto err_out;
+
+	if (!status)
+		goto err_out;
+
+	ad799x_i2c_write8(st, AD7998_ALERT_STAT_REG, AD7998_ALERT_STAT_CLEAR);
+
+	for (i = 0; i < 8; i++) {
+		if (status & (1 << i))
+			iio_push_event(st->indio_dev, 0,
+				i & 0x1 ?
+				IIO_EVENT_CODE_IN_HIGH_THRESH(i >> 1) :
+				IIO_EVENT_CODE_IN_LOW_THRESH(i >> 1),
+				st->last_timestamp);
+	}
+
+err_out:
+	enable_irq(st->client->irq);
+}
+
+static int ad799x_interrupt(struct iio_dev *dev_info,
+		int index,
+		s64 timestamp,
+		int no_test)
+{
+	struct ad799x_state *st = dev_info->dev_data;
+
+	st->last_timestamp = timestamp;
+	schedule_work(&st->work_thresh);
+	return 0;
+}
+
+IIO_EVENT_SH(ad799x, &ad799x_interrupt);
+
+/* Direct read attribtues */
+static IIO_DEV_ATTR_IN_RAW(0, ad799x_read_single_channel, 0);
+static IIO_DEV_ATTR_IN_RAW(1, ad799x_read_single_channel, 1);
+static IIO_DEV_ATTR_IN_RAW(2, ad799x_read_single_channel, 2);
+static IIO_DEV_ATTR_IN_RAW(3, ad799x_read_single_channel, 3);
+static IIO_DEV_ATTR_IN_RAW(4, ad799x_read_single_channel, 4);
+static IIO_DEV_ATTR_IN_RAW(5, ad799x_read_single_channel, 5);
+static IIO_DEV_ATTR_IN_RAW(6, ad799x_read_single_channel, 6);
+static IIO_DEV_ATTR_IN_RAW(7, ad799x_read_single_channel, 7);
+
+static ssize_t ad799x_show_scale(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	/* Driver currently only support internal vref */
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+	/* Corresponds to Vref / 2^(bits) */
+
+	if ((1 << (st->chip_info->bits + 1))
+	    > st->int_vref_mv)
+		return sprintf(buf, "0.5\n");
+	else
+		return sprintf(buf, "%d\n",
+			st->int_vref_mv >> st->chip_info->bits);
+}
+
+static IIO_DEVICE_ATTR(in_scale, S_IRUGO, ad799x_show_scale, NULL, 0);
+
+static ssize_t ad799x_show_name(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct ad799x_state *st = iio_dev_get_devdata(dev_info);
+	return sprintf(buf, "%s\n", st->client->name);
+}
+
+static IIO_DEVICE_ATTR(name, S_IRUGO, ad799x_show_name, NULL, 0);
+
+static struct attribute *ad7991_5_9_3_4_device_attrs[] = {
+	&iio_dev_attr_in0_raw.dev_attr.attr,
+	&iio_dev_attr_in1_raw.dev_attr.attr,
+	&iio_dev_attr_in2_raw.dev_attr.attr,
+	&iio_dev_attr_in3_raw.dev_attr.attr,
+	&iio_dev_attr_name.dev_attr.attr,
+	&iio_dev_attr_in_scale.dev_attr.attr,
+	NULL
+};
+
+static struct attribute_group ad7991_5_9_3_4_dev_attr_group = {
+	.attrs = ad7991_5_9_3_4_device_attrs,
+};
+
+static struct attribute *ad7991_5_9_3_4_scan_el_attrs[] = {
+	&iio_scan_el_in0.dev_attr.attr,
+	&iio_const_attr_in0_index.dev_attr.attr,
+	&iio_scan_el_in1.dev_attr.attr,
+	&iio_const_attr_in1_index.dev_attr.attr,
+	&iio_scan_el_in2.dev_attr.attr,
+	&iio_const_attr_in2_index.dev_attr.attr,
+	&iio_scan_el_in3.dev_attr.attr,
+	&iio_const_attr_in3_index.dev_attr.attr,
+	&iio_dev_attr_in_precision.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad7991_5_9_3_4_scan_el_group = {
+	.name = "scan_elements",
+	.attrs = ad7991_5_9_3_4_scan_el_attrs,
+};
+
+static struct attribute *ad7992_device_attrs[] = {
+	&iio_dev_attr_in0_raw.dev_attr.attr,
+	&iio_dev_attr_in1_raw.dev_attr.attr,
+	&iio_dev_attr_name.dev_attr.attr,
+	&iio_dev_attr_in_scale.dev_attr.attr,
+	NULL
+};
+
+static struct attribute_group ad7992_dev_attr_group = {
+	.attrs = ad7992_device_attrs,
+};
+
+static struct attribute *ad7992_scan_el_attrs[] = {
+	&iio_scan_el_in0.dev_attr.attr,
+	&iio_const_attr_in0_index.dev_attr.attr,
+	&iio_scan_el_in1.dev_attr.attr,
+	&iio_const_attr_in1_index.dev_attr.attr,
+	&iio_dev_attr_in_precision.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad7992_scan_el_group = {
+	.name = "scan_elements",
+	.attrs = ad7992_scan_el_attrs,
+};
+
+static struct attribute *ad7997_8_device_attrs[] = {
+	&iio_dev_attr_in0_raw.dev_attr.attr,
+	&iio_dev_attr_in1_raw.dev_attr.attr,
+	&iio_dev_attr_in2_raw.dev_attr.attr,
+	&iio_dev_attr_in3_raw.dev_attr.attr,
+	&iio_dev_attr_in4_raw.dev_attr.attr,
+	&iio_dev_attr_in5_raw.dev_attr.attr,
+	&iio_dev_attr_in6_raw.dev_attr.attr,
+	&iio_dev_attr_in7_raw.dev_attr.attr,
+	&iio_dev_attr_name.dev_attr.attr,
+	&iio_dev_attr_in_scale.dev_attr.attr,
+	NULL
+};
+
+static struct attribute_group ad7997_8_dev_attr_group = {
+	.attrs = ad7997_8_device_attrs,
+};
+
+static struct attribute *ad7997_8_scan_el_attrs[] = {
+	&iio_scan_el_in0.dev_attr.attr,
+	&iio_const_attr_in0_index.dev_attr.attr,
+	&iio_scan_el_in1.dev_attr.attr,
+	&iio_const_attr_in1_index.dev_attr.attr,
+	&iio_scan_el_in2.dev_attr.attr,
+	&iio_const_attr_in2_index.dev_attr.attr,
+	&iio_scan_el_in3.dev_attr.attr,
+	&iio_const_attr_in3_index.dev_attr.attr,
+	&iio_scan_el_in4.dev_attr.attr,
+	&iio_const_attr_in4_index.dev_attr.attr,
+	&iio_scan_el_in5.dev_attr.attr,
+	&iio_const_attr_in5_index.dev_attr.attr,
+	&iio_scan_el_in6.dev_attr.attr,
+	&iio_const_attr_in6_index.dev_attr.attr,
+	&iio_scan_el_in7.dev_attr.attr,
+	&iio_const_attr_in7_index.dev_attr.attr,
+	&iio_dev_attr_in_precision.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad7997_8_scan_el_group = {
+	.name = "scan_elements",
+	.attrs = ad7997_8_scan_el_attrs,
+};
+
+IIO_EVENT_ATTR_SH(in0_thresh_low_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATALOW_CH1_REG);
+
+IIO_EVENT_ATTR_SH(in0_thresh_high_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATAHIGH_CH1_REG);
+
+IIO_EVENT_ATTR_SH(in0_thresh_both_hyst_raw,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_HYST_CH1_REG);
+
+IIO_EVENT_ATTR_SH(in1_thresh_low_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATALOW_CH2_REG);
+
+IIO_EVENT_ATTR_SH(in1_thresh_high_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATAHIGH_CH2_REG);
+
+IIO_EVENT_ATTR_SH(in1_thresh_both_hyst_raw,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_HYST_CH2_REG);
+
+IIO_EVENT_ATTR_SH(in2_thresh_low_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATALOW_CH3_REG);
+
+IIO_EVENT_ATTR_SH(in2_thresh_high_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATAHIGH_CH3_REG);
+
+IIO_EVENT_ATTR_SH(in2_thresh_both_hyst_raw,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_HYST_CH3_REG);
+
+IIO_EVENT_ATTR_SH(in3_thresh_low_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATALOW_CH4_REG);
+
+IIO_EVENT_ATTR_SH(in3_thresh_high_value,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_DATAHIGH_CH4_REG);
+
+IIO_EVENT_ATTR_SH(in3_thresh_both_hyst_raw,
+		  iio_event_ad799x,
+		  ad799x_read_channel_config,
+		  ad799x_write_channel_config,
+		  AD7998_HYST_CH4_REG);
+
+static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
+			      ad799x_read_frequency,
+			      ad799x_write_frequency);
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("15625 7812 3906 1953 976 488 244 0");
+
+static struct attribute *ad7993_4_7_8_event_attributes[] = {
+	&iio_event_attr_in0_thresh_low_value.dev_attr.attr,
+	&iio_event_attr_in0_thresh_high_value.dev_attr.attr,
+	&iio_event_attr_in0_thresh_both_hyst_raw.dev_attr.attr,
+	&iio_event_attr_in1_thresh_low_value.dev_attr.attr,
+	&iio_event_attr_in1_thresh_high_value.dev_attr.attr,
+	&iio_event_attr_in1_thresh_both_hyst_raw.dev_attr.attr,
+	&iio_event_attr_in2_thresh_low_value.dev_attr.attr,
+	&iio_event_attr_in2_thresh_high_value.dev_attr.attr,
+	&iio_event_attr_in2_thresh_both_hyst_raw.dev_attr.attr,
+	&iio_event_attr_in3_thresh_low_value.dev_attr.attr,
+	&iio_event_attr_in3_thresh_high_value.dev_attr.attr,
+	&iio_event_attr_in3_thresh_both_hyst_raw.dev_attr.attr,
+	&iio_dev_attr_sampling_frequency.dev_attr.attr,
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad7993_4_7_8_event_attrs_group = {
+	.attrs = ad7993_4_7_8_event_attributes,
+};
+
+static struct attribute *ad7992_event_attributes[] = {
+	&iio_event_attr_in0_thresh_low_value.dev_attr.attr,
+	&iio_event_attr_in0_thresh_high_value.dev_attr.attr,
+	&iio_event_attr_in0_thresh_both_hyst_raw.dev_attr.attr,
+	&iio_event_attr_in1_thresh_low_value.dev_attr.attr,
+	&iio_event_attr_in1_thresh_high_value.dev_attr.attr,
+	&iio_event_attr_in1_thresh_both_hyst_raw.dev_attr.attr,
+	&iio_dev_attr_sampling_frequency.dev_attr.attr,
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad7992_event_attrs_group = {
+	.attrs = ad7992_event_attributes,
+};
+
+static const struct ad799x_chip_info ad799x_chip_info_tbl[] = {
+	[ad7991] = {
+		.num_inputs = 4,
+		.bits = 12,
+		.int_vref_mv = 4096,
+		.dev_attrs = &ad7991_5_9_3_4_dev_attr_group,
+		.scan_attrs = &ad7991_5_9_3_4_scan_el_group,
+		.ad799x_set_scan_mode = ad7991_5_9_set_scan_mode,
+	},
+	[ad7995] = {
+		.num_inputs = 4,
+		.bits = 10,
+		.int_vref_mv = 1024,
+		.dev_attrs = &ad7991_5_9_3_4_dev_attr_group,
+		.scan_attrs = &ad7991_5_9_3_4_scan_el_group,
+		.ad799x_set_scan_mode = ad7991_5_9_set_scan_mode,
+	},
+	[ad7999] = {
+		.num_inputs = 4,
+		.bits = 10,
+		.int_vref_mv = 1024,
+		.dev_attrs = &ad7991_5_9_3_4_dev_attr_group,
+		.scan_attrs = &ad7991_5_9_3_4_scan_el_group,
+		.ad799x_set_scan_mode = ad7991_5_9_set_scan_mode,
+	},
+	[ad7992] = {
+		.num_inputs = 2,
+		.bits = 12,
+		.int_vref_mv = 4096,
+		.monitor_mode = true,
+		.default_config = AD7998_ALERT_EN,
+		.dev_attrs = &ad7992_dev_attr_group,
+		.scan_attrs = &ad7992_scan_el_group,
+		.event_attrs = &ad7992_event_attrs_group,
+		.ad799x_set_scan_mode = ad7992_3_4_set_scan_mode,
+	},
+	[ad7993] = {
+		.num_inputs = 4,
+		.bits = 10,
+		.int_vref_mv = 1024,
+		.monitor_mode = true,
+		.default_config = AD7998_ALERT_EN,
+		.dev_attrs = &ad7991_5_9_3_4_dev_attr_group,
+		.scan_attrs = &ad7991_5_9_3_4_scan_el_group,
+		.event_attrs = &ad7993_4_7_8_event_attrs_group,
+		.ad799x_set_scan_mode = ad7992_3_4_set_scan_mode,
+	},
+	[ad7994] = {
+		.num_inputs = 4,
+		.bits = 12,
+		.int_vref_mv = 4096,
+		.monitor_mode = true,
+		.default_config = AD7998_ALERT_EN,
+		.dev_attrs = &ad7991_5_9_3_4_dev_attr_group,
+		.scan_attrs = &ad7991_5_9_3_4_scan_el_group,
+		.event_attrs = &ad7993_4_7_8_event_attrs_group,
+		.ad799x_set_scan_mode = ad7992_3_4_set_scan_mode,
+	},
+	[ad7997] = {
+		.num_inputs = 8,
+		.bits = 10,
+		.int_vref_mv = 1024,
+		.monitor_mode = true,
+		.default_config = AD7998_ALERT_EN,
+		.dev_attrs = &ad7997_8_dev_attr_group,
+		.scan_attrs = &ad7997_8_scan_el_group,
+		.event_attrs = &ad7993_4_7_8_event_attrs_group,
+		.ad799x_set_scan_mode = ad7997_8_set_scan_mode,
+	},
+	[ad7998] = {
+		.num_inputs = 8,
+		.bits = 12,
+		.int_vref_mv = 4096,
+		.monitor_mode = true,
+		.default_config = AD7998_ALERT_EN,
+		.dev_attrs = &ad7997_8_dev_attr_group,
+		.scan_attrs = &ad7997_8_scan_el_group,
+		.event_attrs = &ad7993_4_7_8_event_attrs_group,
+		.ad799x_set_scan_mode = ad7997_8_set_scan_mode,
+	},
+};
+
+static int __devinit ad799x_probe(struct i2c_client *client,
+				   const struct i2c_device_id *id)
+{
+	int ret, regdone = 0;
+	struct ad799x_platform_data *pdata = client->dev.platform_data;
+	struct ad799x_state *st = kzalloc(sizeof(*st), GFP_KERNEL);
+	if (st == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	/* this is only used for device removal purposes */
+	i2c_set_clientdata(client, st);
+
+	atomic_set(&st->protect_ring, 0);
+	st->id = id->driver_data;
+	st->chip_info = &ad799x_chip_info_tbl[st->id];
+	st->config = st->chip_info->default_config;
+
+	/* TODO: Add pdata options for filtering and bit delay */
+
+	if (pdata)
+		st->int_vref_mv = pdata->vref_mv;
+	else
+		st->int_vref_mv = st->chip_info->int_vref_mv;
+
+	st->reg = regulator_get(&client->dev, "vcc");
+	if (!IS_ERR(st->reg)) {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			goto error_put_reg;
+	}
+	st->client = client;
+
+	st->indio_dev = iio_allocate_device();
+	if (st->indio_dev == NULL) {
+		ret = -ENOMEM;
+		goto error_disable_reg;
+	}
+
+	/* Estabilish that the iio_dev is a child of the i2c device */
+	st->indio_dev->dev.parent = &client->dev;
+	st->indio_dev->attrs = st->chip_info->dev_attrs;
+	st->indio_dev->event_attrs = st->chip_info->event_attrs;
+
+	st->indio_dev->dev_data = (void *)(st);
+	st->indio_dev->driver_module = THIS_MODULE;
+	st->indio_dev->modes = INDIO_DIRECT_MODE;
+	st->indio_dev->num_interrupt_lines = 1;
+
+	ret = ad799x_set_scan_mode(st, 0);
+	if (ret)
+		goto error_free_device;
+
+	ret = ad799x_register_ring_funcs_and_init(st->indio_dev);
+	if (ret)
+		goto error_free_device;
+
+	ret = iio_device_register(st->indio_dev);
+	if (ret)
+		goto error_cleanup_ring;
+	regdone = 1;
+
+	ret = iio_ring_buffer_register(st->indio_dev->ring, 0);
+	if (ret)
+		goto error_cleanup_ring;
+
+	if (client->irq > 0 && st->chip_info->monitor_mode) {
+		INIT_WORK(&st->work_thresh, ad799x_interrupt_bh);
+
+		ret = iio_register_interrupt_line(client->irq,
+				st->indio_dev,
+				0,
+				IRQF_TRIGGER_FALLING,
+				client->name);
+		if (ret)
+			goto error_cleanup_ring;
+
+		/*
+		 * The event handler list element refer to iio_event_ad799x.
+		 * All event attributes bind to the same event handler.
+		 * So, only register event handler once.
+		 */
+		iio_add_event_to_list(&iio_event_ad799x,
+				&st->indio_dev->interrupts[0]->ev_list);
+	}
+
+	return 0;
+error_cleanup_ring:
+	ad799x_ring_cleanup(st->indio_dev);
+error_free_device:
+	if (!regdone)
+		iio_free_device(st->indio_dev);
+	else
+		iio_device_unregister(st->indio_dev);
+error_disable_reg:
+	if (!IS_ERR(st->reg))
+		regulator_disable(st->reg);
+error_put_reg:
+	if (!IS_ERR(st->reg))
+		regulator_put(st->reg);
+	kfree(st);
+error_ret:
+	return ret;
+}
+
+static __devexit int ad799x_remove(struct i2c_client *client)
+{
+	struct ad799x_state *st = i2c_get_clientdata(client);
+	struct iio_dev *indio_dev = st->indio_dev;
+
+	if (client->irq > 0 && st->chip_info->monitor_mode)
+		iio_unregister_interrupt_line(indio_dev, 0);
+
+	iio_ring_buffer_unregister(indio_dev->ring);
+	ad799x_ring_cleanup(indio_dev);
+	iio_device_unregister(indio_dev);
+	if (!IS_ERR(st->reg)) {
+		regulator_disable(st->reg);
+		regulator_put(st->reg);
+	}
+	kfree(st);
+
+	return 0;
+}
+
+static const struct i2c_device_id ad799x_id[] = {
+	{ "ad7991", ad7991 },
+	{ "ad7995", ad7995 },
+	{ "ad7999", ad7999 },
+	{ "ad7992", ad7992 },
+	{ "ad7993", ad7993 },
+	{ "ad7994", ad7994 },
+	{ "ad7997", ad7997 },
+	{ "ad7998", ad7998 },
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ad799x_id);
+
+static struct i2c_driver ad799x_driver = {
+	.driver = {
+		.name = "ad799x",
+	},
+	.probe = ad799x_probe,
+	.remove = __devexit_p(ad799x_remove),
+	.id_table = ad799x_id,
+};
+
+static __init int ad799x_init(void)
+{
+	return i2c_add_driver(&ad799x_driver);
+}
+
+static __exit void ad799x_exit(void)
+{
+	i2c_del_driver(&ad799x_driver);
+}
+
+MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
+MODULE_DESCRIPTION("Analog Devices AD799x ADC");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("i2c:ad799x");
+
+module_init(ad799x_init);
+module_exit(ad799x_exit);

drivers/staging/iio/adc/ad799x_ring.c

@@ -0,0 +1,246 @@
+/*
+ * Copyright (C) 2010 Michael Hennerich, Analog Devices Inc.
+ * Copyright (C) 2008-2010 Jonathan Cameron
+ *
+ * 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.
+ *
+ * ad799x_ring.c
+ */
+
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/i2c.h>
+#include <linux/bitops.h>
+
+#include "../iio.h"
+#include "../ring_generic.h"
+#include "../ring_sw.h"
+#include "../trigger.h"
+#include "../sysfs.h"
+
+#include "ad799x.h"
+
+int ad799x_single_channel_from_ring(struct ad799x_state *st, long mask)
+{
+	unsigned long numvals;
+	int count = 0, ret;
+	u16 *ring_data;
+	if (!(st->indio_dev->ring->scan_mask & mask)) {
+		ret = -EBUSY;
+		goto error_ret;
+	}
+	numvals = st->indio_dev->ring->scan_count;
+
+	ring_data = kmalloc(numvals*2, GFP_KERNEL);
+	if (ring_data == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	ret = st->indio_dev->ring->access.read_last(st->indio_dev->ring,
+						(u8 *) ring_data);
+	if (ret)
+		goto error_free_ring_data;
+	/* Need a count of channels prior to this one */
+	mask >>= 1;
+	while (mask) {
+		if (mask & st->indio_dev->ring->scan_mask)
+			count++;
+		mask >>= 1;
+	}
+
+	ret = be16_to_cpu(ring_data[count]) & 0xFFF;
+
+error_free_ring_data:
+	kfree(ring_data);
+error_ret:
+	return ret;
+}
+
+/**
+ * ad799x_ring_preenable() setup the parameters of the ring before enabling
+ *
+ * The complex nature of the setting of the nuber of bytes per datum is due
+ * to this driver currently ensuring that the timestamp is stored at an 8
+ * byte boundary.
+ **/
+static int ad799x_ring_preenable(struct iio_dev *indio_dev)
+{
+	struct ad799x_state *st = indio_dev->dev_data;
+	size_t d_size;
+	unsigned long numvals;
+
+	/*
+	 * Need to figure out the current mode based upon the requested
+	 * scan mask in iio_dev
+	 */
+
+	if (st->id == ad7997 || st->id == ad7998)
+		ad799x_set_scan_mode(st, st->indio_dev->ring->scan_mask);
+
+	numvals = st->indio_dev->ring->scan_count;
+
+	if (indio_dev->ring->access.set_bytes_per_datum) {
+		d_size = numvals*2 + sizeof(s64);
+		if (d_size % 8)
+			d_size += 8 - (d_size % 8);
+		indio_dev->ring->access.set_bytes_per_datum(indio_dev->ring,
+							    d_size);
+	}
+
+	return 0;
+}
+
+/**
+ * ad799x_poll_func_th() th of trigger launched polling to ring buffer
+ *
+ * As sampling only occurs on i2c comms occuring, leave timestamping until
+ * then.  Some triggers will generate their own time stamp.  Currently
+ * there is no way of notifying them when no one cares.
+ **/
+static void ad799x_poll_func_th(struct iio_dev *indio_dev, s64 time)
+{
+	struct ad799x_state *st = indio_dev->dev_data;
+
+	schedule_work(&st->poll_work);
+
+	return;
+}
+/**
+ * ad799x_poll_bh_to_ring() bh of trigger launched polling to ring buffer
+ * @work_s:	the work struct through which this was scheduled
+ *
+ * Currently there is no option in this driver to disable the saving of
+ * timestamps within the ring.
+ * I think the one copy of this at a time was to avoid problems if the
+ * trigger was set far too high and the reads then locked up the computer.
+ **/
+static void ad799x_poll_bh_to_ring(struct work_struct *work_s)
+{
+	struct ad799x_state *st = container_of(work_s, struct ad799x_state,
+						  poll_work);
+	struct iio_dev *indio_dev = st->indio_dev;
+	struct iio_sw_ring_buffer *ring = iio_to_sw_ring(indio_dev->ring);
+	s64 time_ns;
+	__u8 *rxbuf;
+	int b_sent;
+	size_t d_size;
+	u8 cmd;
+
+	unsigned long numvals = st->indio_dev->ring->scan_count;
+
+	/* Ensure the timestamp is 8 byte aligned */
+	d_size = numvals*2 + sizeof(s64);
+
+	if (d_size % sizeof(s64))
+		d_size += sizeof(s64) - (d_size % sizeof(s64));
+
+	/* Ensure only one copy of this function running at a time */
+	if (atomic_inc_return(&st->protect_ring) > 1)
+		return;
+
+	/* Monitor mode prevents reading. Whilst not currently implemented
+	 * might as well have this test in here in the meantime as it does
+	 * no harm.
+	 */
+	if (numvals == 0)
+		return;
+
+	rxbuf = kmalloc(d_size,	GFP_KERNEL);
+	if (rxbuf == NULL)
+		return;
+
+	switch (st->id) {
+	case ad7991:
+	case ad7995:
+	case ad7999:
+		cmd = st->config | (st->indio_dev->ring->scan_mask <<
+			AD799X_CHANNEL_SHIFT);
+		break;
+	case ad7992:
+	case ad7993:
+	case ad7994:
+		cmd = (st->indio_dev->ring->scan_mask <<
+			AD799X_CHANNEL_SHIFT) | AD7998_CONV_RES_REG;
+		break;
+	case ad7997:
+	case ad7998:
+		cmd = AD7997_8_READ_SEQUENCE | AD7998_CONV_RES_REG;
+		break;
+	default:
+		cmd = 0;
+	}
+
+	b_sent = i2c_smbus_read_i2c_block_data(st->client,
+			cmd, numvals*2, rxbuf);
+	if (b_sent < 0)
+		goto done;
+
+	time_ns = iio_get_time_ns();
+
+	memcpy(rxbuf + d_size - sizeof(s64), &time_ns, sizeof(time_ns));
+
+	indio_dev->ring->access.store_to(&ring->buf, rxbuf, time_ns);
+done:
+	kfree(rxbuf);
+	atomic_dec(&st->protect_ring);
+}
+
+
+int ad799x_register_ring_funcs_and_init(struct iio_dev *indio_dev)
+{
+	struct ad799x_state *st = indio_dev->dev_data;
+	int ret = 0;
+
+	indio_dev->ring = iio_sw_rb_allocate(indio_dev);
+	if (!indio_dev->ring) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	/* Effectively select the ring buffer implementation */
+	iio_ring_sw_register_funcs(&st->indio_dev->ring->access);
+	indio_dev->pollfunc = kzalloc(sizeof(*indio_dev->pollfunc), GFP_KERNEL);
+	if (indio_dev->pollfunc == NULL) {
+		ret = -ENOMEM;
+		goto error_deallocate_sw_rb;
+	}
+	/* Configure the polling function called on trigger interrupts */
+	indio_dev->pollfunc->poll_func_main = &ad799x_poll_func_th;
+	indio_dev->pollfunc->private_data = indio_dev;
+
+	/* Ring buffer functions - here trigger setup related */
+
+	indio_dev->ring->preenable = &ad799x_ring_preenable;
+	indio_dev->ring->postenable = &iio_triggered_ring_postenable;
+	indio_dev->ring->predisable = &iio_triggered_ring_predisable;
+
+	INIT_WORK(&st->poll_work, &ad799x_poll_bh_to_ring);
+
+	indio_dev->ring->scan_el_attrs = st->chip_info->scan_attrs;
+
+	/* Flag that polled ring buffering is possible */
+	indio_dev->modes |= INDIO_RING_TRIGGERED;
+	return 0;
+error_deallocate_sw_rb:
+	iio_sw_rb_free(indio_dev->ring);
+error_ret:
+	return ret;
+}
+
+void ad799x_ring_cleanup(struct iio_dev *indio_dev)
+{
+	/* ensure that the trigger has been detached */
+	if (indio_dev->trig) {
+		iio_put_trigger(indio_dev->trig);
+		iio_trigger_dettach_poll_func(indio_dev->trig,
+					      indio_dev->pollfunc);
+	}
+	kfree(indio_dev->pollfunc);
+	iio_sw_rb_free(indio_dev->ring);
+}