Date:   Thu, 22 Jun 2017 12:31:25 -1000
From:   Jack Andersen <jackoalan@...il.com>
To:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Jack Andersen <jackoalan@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>
Subject: [PATCH v2] iio: adc: Add support for DLN2 ADC

This patch adds support for Diolan DLN2 ADC via IIO's ADC interface.
ADC is the fourth and final component of the DLN2 for the kernel.

Signed-off-by: Jack Andersen <jackoalan@...il.com>
---
 drivers/iio/adc/Kconfig    |   9 +
 drivers/iio/adc/Makefile   |   1 +
 drivers/iio/adc/dln2-adc.c | 644 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/mfd/dln2.c         |  12 +
 4 files changed, 666 insertions(+)
 create mode 100644 drivers/iio/adc/dln2-adc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 401f47b..78d7455 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -239,6 +239,15 @@ config DA9150_GPADC
 	  To compile this driver as a module, choose M here: the module will be
 	  called berlin2-adc.
 
+config DLN2_ADC
+	tristate "Diolan DLN-2 ADC driver support"
+	depends on MFD_DLN2
+	help
+	  Say yes here to build support for Diolan DLN-2 ADC.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called adc_dln2.
+
 config ENVELOPE_DETECTOR
 	tristate "Envelope detector using a DAC and a comparator"
 	depends on OF
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 9339bec..378bc65 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
 obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
 obj-$(CONFIG_CPCAP_ADC) += cpcap-adc.o
 obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
+obj-$(CONFIG_DLN2_ADC) += dln2-adc.o
 obj-$(CONFIG_ENVELOPE_DETECTOR) += envelope-detector.o
 obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
 obj-$(CONFIG_FSL_MX25_ADC) += fsl-imx25-gcq.o
diff --git a/drivers/iio/adc/dln2-adc.c b/drivers/iio/adc/dln2-adc.c
new file mode 100644
index 0000000..6c58b76
--- /dev/null
+++ b/drivers/iio/adc/dln2-adc.c
@@ -0,0 +1,644 @@
+/*
+ * Driver for the Diolan DLN-2 USB-ADC adapter
+ *
+ * Copyright (c) 2017 Jack Andersen
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/dln2.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.h>
+
+#define DLN2_ADC_MOD_NAME "dln2-adc"
+
+#define DLN2_ADC_ID             0x06
+
+#define DLN2_ADC_GET_CHANNEL_COUNT	DLN2_CMD(0x01, DLN2_ADC_ID)
+#define DLN2_ADC_ENABLE			DLN2_CMD(0x02, DLN2_ADC_ID)
+#define DLN2_ADC_DISABLE		DLN2_CMD(0x03, DLN2_ADC_ID)
+#define DLN2_ADC_CHANNEL_ENABLE		DLN2_CMD(0x05, DLN2_ADC_ID)
+#define DLN2_ADC_CHANNEL_DISABLE	DLN2_CMD(0x06, DLN2_ADC_ID)
+#define DLN2_ADC_SET_RESOLUTION		DLN2_CMD(0x08, DLN2_ADC_ID)
+#define DLN2_ADC_CHANNEL_GET_VAL	DLN2_CMD(0x0A, DLN2_ADC_ID)
+#define DLN2_ADC_CHANNEL_GET_ALL_VAL	DLN2_CMD(0x0B, DLN2_ADC_ID)
+#define DLN2_ADC_CHANNEL_SET_CFG	DLN2_CMD(0x0C, DLN2_ADC_ID)
+#define DLN2_ADC_CHANNEL_GET_CFG	DLN2_CMD(0x0D, DLN2_ADC_ID)
+#define DLN2_ADC_CONDITION_MET_EV	DLN2_CMD(0x10, DLN2_ADC_ID)
+
+#define DLN2_ADC_EVENT_NONE		0
+#define DLN2_ADC_EVENT_BELOW		1
+#define DLN2_ADC_EVENT_LEVEL_ABOVE	2
+#define DLN2_ADC_EVENT_OUTSIDE		3
+#define DLN2_ADC_EVENT_INSIDE		4
+#define DLN2_ADC_EVENT_ALWAYS		5
+
+#define DLN2_ADC_MAX_CHANNELS 8
+#define DLN2_ADC_DATA_BITS 10
+
+struct dln2_adc {
+	struct platform_device *pdev;
+	int port;
+	struct iio_trigger *trig;
+	struct mutex mutex;
+	/* Set once initialized */
+	bool port_enabled;
+	/* Set once resolution request made to HW */
+	bool resolution_set;
+	/* Bitmask requesting enabled channels */
+	unsigned long chans_requested;
+	/* Bitmask indicating enabled channels on HW */
+	unsigned long chans_enabled;
+	/* Channel that is arbitrated for event trigger */
+	int trigger_chan;
+};
+
+struct dln2_adc_port_chan {
+	u8 port;
+	u8 chan;
+};
+
+struct dln2_adc_get_all_vals {
+	__le16 channel_mask;
+	__le16 values[DLN2_ADC_MAX_CHANNELS];
+};
+
+static int dln2_adc_get_chan_count(struct dln2_adc *dln2)
+{
+	int ret;
+	u8 port = dln2->port;
+	u8 count;
+	int olen = sizeof(count);
+
+	ret = dln2_transfer(dln2->pdev, DLN2_ADC_GET_CHANNEL_COUNT,
+			    &port, sizeof(port), &count, &olen);
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+	if (olen < sizeof(count))
+		return -EPROTO;
+
+	return count;
+}
+
+static int dln2_adc_set_port_resolution(struct dln2_adc *dln2)
+{
+	int ret;
+	struct dln2_adc_port_chan port_chan = {
+		.port = dln2->port,
+		.chan = DLN2_ADC_DATA_BITS,
+	};
+
+	ret = dln2_transfer_tx(dln2->pdev, DLN2_ADC_SET_RESOLUTION,
+			       &port_chan, sizeof(port_chan));
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int dln2_adc_set_chan_enabled(struct dln2_adc *dln2,
+				     int channel, bool enable)
+{
+	int ret;
+	struct dln2_adc_port_chan port_chan = {
+		.port = dln2->port,
+		.chan = channel,
+	};
+
+	u16 cmd = enable ? DLN2_ADC_CHANNEL_ENABLE : DLN2_ADC_CHANNEL_DISABLE;
+
+	ret = dln2_transfer_tx(dln2->pdev, cmd, &port_chan, sizeof(port_chan));
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int dln2_adc_set_port_enabled(struct dln2_adc *dln2, bool enable)
+{
+	int ret;
+	u8 port = dln2->port;
+	__le16 conflict;
+	int olen = sizeof(conflict);
+
+	u16 cmd = enable ? DLN2_ADC_ENABLE : DLN2_ADC_DISABLE;
+
+	ret = dln2_transfer(dln2->pdev, cmd, &port, sizeof(port),
+			    &conflict, &olen);
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s(%d)\n",
+			__func__, (int)enable);
+		return ret;
+	}
+	if (enable && olen < sizeof(conflict))
+		return -EPROTO;
+
+	return 0;
+}
+
+/*
+ * ADC channels are lazily enabled due to the pins being shared with GPIO
+ * channels. Enabling channels requires taking the ADC port offline, specifying
+ * the resolution, individually enabling channels, then putting the port back
+ * online. If GPIO pins have already been exported by gpio_dln2, EINVAL is
+ * reported.
+ */
+static int dln2_adc_update_enabled_chans(struct dln2_adc *dln2)
+{
+	int ret, i, chan_count;
+	struct iio_dev *indio_dev;
+
+	if (dln2->chans_enabled == dln2->chans_requested)
+		return 0;
+
+	indio_dev = platform_get_drvdata(dln2->pdev);
+	chan_count = indio_dev->num_channels;
+
+	if (dln2->port_enabled) {
+		ret = dln2_adc_set_port_enabled(dln2, false);
+		if (ret < 0)
+			return ret;
+		dln2->port_enabled = false;
+	}
+
+	if (!dln2->resolution_set) {
+		ret = dln2_adc_set_port_resolution(dln2);
+		if (ret < 0)
+			return ret;
+		dln2->resolution_set = true;
+	}
+
+	for (i = 0; i < chan_count; ++i) {
+		bool requested = dln2->chans_requested & (1 << i);
+		bool enabled = dln2->chans_enabled & (1 << i);
+
+		if (requested == enabled)
+			continue;
+		ret = dln2_adc_set_chan_enabled(dln2, i, requested);
+		if (ret < 0)
+			return ret;
+	}
+
+	dln2->chans_enabled = dln2->chans_requested;
+
+	ret = dln2_adc_set_port_enabled(dln2, true);
+	if (ret < 0)
+		return ret;
+	dln2->port_enabled = true;
+
+	return 0;
+}
+
+static int dln2_adc_get_chan_freq(struct dln2_adc *dln2, unsigned int channel)
+{
+	int ret;
+	struct dln2_adc_port_chan port_chan = {
+		.port = dln2->port,
+		.chan = channel,
+	};
+	struct {
+		__u8 type;
+		__le16 period;
+		__le16 low;
+		__le16 high;
+	} __packed get_cfg;
+	int olen = sizeof(get_cfg);
+
+	ret = dln2_transfer(dln2->pdev, DLN2_ADC_CHANNEL_GET_CFG,
+			    &port_chan, sizeof(port_chan), &get_cfg, &olen);
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+	if (olen < sizeof(get_cfg))
+		return -EPROTO;
+
+	return get_cfg.period;
+}
+
+static int dln2_adc_set_chan_freq(struct dln2_adc *dln2, unsigned int channel,
+				  unsigned int freq)
+{
+	int ret;
+	struct {
+		struct dln2_adc_port_chan port_chan;
+		__u8 type;
+		__le16 period;
+		__le16 low;
+		__le16 high;
+	} __packed set_cfg = {
+		.port_chan.port = dln2->port,
+		.port_chan.chan = channel,
+		.type = freq ? DLN2_ADC_EVENT_ALWAYS : DLN2_ADC_EVENT_NONE,
+		.period = cpu_to_le16(freq)
+	};
+
+	ret = dln2_transfer_tx(dln2->pdev, DLN2_ADC_CHANNEL_SET_CFG,
+			       &set_cfg, sizeof(set_cfg));
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+	return 0;
+}
+
+static int dln2_adc_read(struct dln2_adc *dln2, unsigned int channel)
+{
+	int ret;
+	int old_chans_requested = dln2->chans_requested;
+
+	dln2->chans_requested |= (1 << channel);
+	ret = dln2_adc_update_enabled_chans(dln2);
+	if (ret < 0) {
+		dln2->chans_requested = old_chans_requested;
+		return ret;
+	}
+	dln2->port_enabled = true;
+
+	struct dln2_adc_port_chan port_chan = {
+		.port = dln2->port,
+		.chan = channel,
+	};
+	__le16 value;
+	int olen = sizeof(value);
+
+	ret = dln2_transfer(dln2->pdev, DLN2_ADC_CHANNEL_GET_VAL,
+			    &port_chan, sizeof(port_chan), &value, &olen);
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+	if (olen < sizeof(value))
+		return -EPROTO;
+
+	return le16_to_cpu(value);
+}
+
+static int dln2_adc_read_all(struct dln2_adc *dln2,
+			     struct dln2_adc_get_all_vals *get_all_vals)
+{
+	int ret;
+	__u8 port = dln2->port;
+	int olen = sizeof(*get_all_vals);
+
+	ret = dln2_transfer(dln2->pdev, DLN2_ADC_CHANNEL_GET_ALL_VAL,
+			    &port, sizeof(port), get_all_vals, &olen);
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+	if (olen < sizeof(*get_all_vals))
+		return -EPROTO;
+
+	return 0;
+}
+
+static int dln2_adc_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val,
+			     int *val2,
+			     long mask)
+{
+	int ret;
+	struct dln2_adc *dln2 = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&dln2->mutex);
+		ret = dln2_adc_read(dln2, chan->channel);
+		mutex_unlock(&dln2->mutex);
+
+		if (ret < 0)
+			return ret;
+
+		*val = ret;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		/* 3.3 / (1 << 10) * 1000000000 */
+		*val2 = 3222656;
+		return IIO_VAL_INT_PLUS_NANO;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		mutex_lock(&dln2->mutex);
+		if (dln2->trigger_chan == -1)
+			ret = 0;
+		else
+			ret = dln2_adc_get_chan_freq(dln2, dln2->trigger_chan);
+		mutex_unlock(&dln2->mutex);
+
+		if (ret < 0)
+			return ret;
+
+		*val = ret / 1000;
+		*val2 = (ret % 1000) * 1000;
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int dln2_adc_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val,
+			      int val2,
+			      long mask)
+{
+	int ret;
+	unsigned int freq;
+	struct dln2_adc *dln2 = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		freq = val * 1000 + val2 / 1000;
+		if (freq > 65535) {
+			freq = 65535;
+			dev_warn(&dln2->pdev->dev,
+				 "clamping freq to 65535ms\n");
+		}
+		mutex_lock(&dln2->mutex);
+
+		/*
+		 * The first requested channel is arbitrated as a shared
+		 * trigger source, so only one event is registered with the DLN.
+		 * The event handler will then read all enabled channel values
+		 * using DLN2_ADC_CHANNEL_GET_ALL_VAL to maintain
+		 * synchronization between ADC readings.
+		 */
+		if (dln2->trigger_chan == -1)
+			dln2->trigger_chan = chan->channel;
+		ret = dln2_adc_set_chan_freq(dln2, dln2->trigger_chan, freq);
+
+		mutex_unlock(&dln2->mutex);
+
+		if (ret < 0)
+			return ret;
+
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+#define DLN2_ADC_CHAN(idx) {					\
+	.type = IIO_VOLTAGE,					\
+	.channel = idx,						\
+	.indexed = 1,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE) |	\
+				   BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+	.scan_index = idx,					\
+	.scan_type.sign = 'u',					\
+	.scan_type.realbits = DLN2_ADC_DATA_BITS,		\
+	.scan_type.storagebits = 16,				\
+	.scan_type.endianness = IIO_LE,				\
+}
+
+static const struct iio_chan_spec dln2_adc_iio_channels[] = {
+	DLN2_ADC_CHAN(0),
+	DLN2_ADC_CHAN(1),
+	DLN2_ADC_CHAN(2),
+	DLN2_ADC_CHAN(3),
+	DLN2_ADC_CHAN(4),
+	DLN2_ADC_CHAN(5),
+	DLN2_ADC_CHAN(6),
+	DLN2_ADC_CHAN(7),
+	IIO_CHAN_SOFT_TIMESTAMP(8),
+};
+
+static const struct iio_info dln2_adc_info = {
+	.read_raw = dln2_adc_read_raw,
+	.write_raw = dln2_adc_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static irqreturn_t dln2_adc_trigger_h(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct {
+		__le16 values[DLN2_ADC_MAX_CHANNELS];
+		int64_t timestamp_space;
+	} data;
+	struct dln2_adc_get_all_vals dev_data;
+	struct dln2_adc *dln2 = iio_priv(indio_dev);
+	int old_chans_requested;
+	int i, j;
+
+	mutex_lock(&dln2->mutex);
+
+	old_chans_requested = dln2->chans_requested;
+	dln2->chans_requested |= *indio_dev->active_scan_mask;
+	if (dln2_adc_update_enabled_chans(dln2) < 0) {
+		dln2->chans_requested = old_chans_requested;
+		mutex_unlock(&dln2->mutex);
+		goto done;
+	}
+
+	if (dln2_adc_read_all(dln2, &dev_data) < 0) {
+		mutex_unlock(&dln2->mutex);
+		goto done;
+	}
+
+	mutex_unlock(&dln2->mutex);
+
+	for (i = 0, j = 0;
+	     i < bitmap_weight(indio_dev->active_scan_mask,
+			       indio_dev->masklength); i++, j++) {
+		j = find_next_bit(indio_dev->active_scan_mask,
+				  indio_dev->masklength, j);
+		data.values[i] = dev_data.values[j];
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &data,
+					   iio_get_time_ns(indio_dev));
+
+done:
+	iio_trigger_notify_done(indio_dev->trig);
+	return IRQ_HANDLED;
+}
+
+static int dln2_adc_triggered_buffer_postenable(struct iio_dev *indio_dev)
+{
+	int ret;
+	struct dln2_adc *dln2 = iio_priv(indio_dev);
+
+	mutex_lock(&dln2->mutex);
+	dln2->chans_requested |= *indio_dev->active_scan_mask;
+	ret = dln2_adc_update_enabled_chans(dln2);
+	mutex_unlock(&dln2->mutex);
+	if (ret < 0) {
+		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
+		return ret;
+	}
+
+	return iio_triggered_buffer_postenable(indio_dev);
+}
+
+static const struct iio_buffer_setup_ops dln2_adc_buffer_setup_ops = {
+	.postenable = dln2_adc_triggered_buffer_postenable,
+	.predisable = iio_triggered_buffer_predisable,
+};
+
+static void dln2_adc_event(struct platform_device *pdev, u16 echo,
+			   const void *data, int len)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct dln2_adc *dln2 = iio_priv(indio_dev);
+
+	iio_trigger_poll(dln2->trig);
+}
+
+static const struct iio_trigger_ops dln2_adc_trigger_ops = {
+	.owner = THIS_MODULE,
+};
+
+static int dln2_adc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct dln2_adc *dln2;
+	struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct iio_dev *indio_dev;
+	struct iio_buffer *buffer;
+	int ret;
+	int chans;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(struct dln2_adc));
+	if (!indio_dev) {
+		dev_err(dev, "failed allocating iio device\n");
+		return -ENOMEM;
+	}
+
+	dln2 = iio_priv(indio_dev);
+	dln2->pdev = pdev;
+	dln2->port = pdata->port;
+	mutex_init(&dln2->mutex);
+	dln2->port_enabled = false;
+	dln2->resolution_set = false;
+	dln2->chans_requested = 0;
+	dln2->chans_enabled = 0;
+	dln2->trigger_chan = -1;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	chans = dln2_adc_get_chan_count(dln2);
+	if (chans < 0) {
+		dev_err(dev, "failed to get channel count: %d\n", chans);
+		ret = chans;
+		goto dealloc_dev;
+	}
+	if (chans > DLN2_ADC_MAX_CHANNELS) {
+		chans = DLN2_ADC_MAX_CHANNELS;
+		dev_warn(dev, "clamping channels to %d\n",
+			 DLN2_ADC_MAX_CHANNELS);
+	}
+
+	indio_dev->name = DLN2_ADC_MOD_NAME;
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &dln2_adc_info;
+	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
+	indio_dev->channels = dln2_adc_iio_channels;
+	indio_dev->num_channels = chans + 1;
+	indio_dev->setup_ops = &dln2_adc_buffer_setup_ops;
+
+	dln2->trig = devm_iio_trigger_alloc(dev, "samplerate");
+	if (!dln2->trig) {
+		dev_err(dev, "failed to allocate trigger\n");
+		ret = -ENOMEM;
+		goto dealloc_dev;
+	}
+	dln2->trig->ops = &dln2_adc_trigger_ops;
+	iio_trigger_set_drvdata(dln2->trig, dln2);
+	iio_trigger_register(dln2->trig);
+	iio_trigger_set_immutable(indio_dev, dln2->trig);
+
+	buffer = devm_iio_kfifo_allocate(dev);
+	if (!buffer) {
+		dev_err(dev, "failed to allocate kfifo\n");
+		ret = -ENOMEM;
+		goto dealloc_trigger;
+	}
+
+	iio_device_attach_buffer(indio_dev, buffer);
+
+	indio_dev->pollfunc = iio_alloc_pollfunc(NULL,
+						 &dln2_adc_trigger_h,
+						 IRQF_ONESHOT,
+						 indio_dev,
+						 "samplerate");
+
+	if (!indio_dev->pollfunc) {
+		ret = -ENOMEM;
+		goto dealloc_kfifo;
+	}
+
+	ret = dln2_register_event_cb(pdev, DLN2_ADC_CONDITION_MET_EV,
+				     dln2_adc_event);
+	if (ret) {
+		dev_err(dev, "failed to register event cb: %d\n", ret);
+		goto dealloc_pollfunc;
+	}
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "failed to register iio device: %d\n", ret);
+		goto dealloc_pollfunc;
+	}
+
+	return 0;
+
+dealloc_pollfunc:
+	iio_dealloc_pollfunc(indio_dev->pollfunc);
+dealloc_kfifo:
+dealloc_trigger:
+	iio_trigger_unregister(dln2->trig);
+dealloc_dev:
+
+	return ret;
+}
+
+static int dln2_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct dln2_adc *dln2 = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	dln2_unregister_event_cb(pdev, DLN2_ADC_CONDITION_MET_EV);
+	iio_trigger_unregister(dln2->trig);
+	iio_dealloc_pollfunc(indio_dev->pollfunc);
+
+	return 0;
+}
+
+static struct platform_driver dln2_adc_driver = {
+	.driver.name	= DLN2_ADC_MOD_NAME,
+	.probe		= dln2_adc_probe,
+	.remove		= dln2_adc_remove,
+};
+
+module_platform_driver(dln2_adc_driver);
+
+MODULE_AUTHOR("Jack Andersen <jackoalan@...il.com");
+MODULE_DESCRIPTION("Driver for the Diolan DLN2 ADC interface");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:dln2-adc");
diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
index 704e189..a22ab8c 100644
--- a/drivers/mfd/dln2.c
+++ b/drivers/mfd/dln2.c
@@ -53,6 +53,7 @@ enum dln2_handle {
 	DLN2_HANDLE_GPIO,
 	DLN2_HANDLE_I2C,
 	DLN2_HANDLE_SPI,
+	DLN2_HANDLE_ADC,
 	DLN2_HANDLES
 };
 
@@ -663,6 +664,12 @@ static int dln2_start_rx_urbs(struct dln2_dev *dln2, gfp_t gfp)
 	.port = 0,
 };
 
+/* Only one ADC port supported */
+static struct dln2_platform_data dln2_pdata_adc = {
+	.handle = DLN2_HANDLE_ADC,
+	.port = 0,
+};
+
 static const struct mfd_cell dln2_devs[] = {
 	{
 		.name = "dln2-gpio",
@@ -679,6 +686,11 @@ static int dln2_start_rx_urbs(struct dln2_dev *dln2, gfp_t gfp)
 		.platform_data = &dln2_pdata_spi,
 		.pdata_size = sizeof(struct dln2_platform_data),
 	},
+	{
+		.name = "dln2-adc",
+		.platform_data = &dln2_pdata_adc,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
 };
 
 static void dln2_stop(struct dln2_dev *dln2)
-- 
1.9.1

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