Date:   Fri, 23 Jun 2017 16:04:04 -0700
From:   Ismail Kose <Ismail.Kose@...imintegrated.com>
To:     jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
        pmeerw@...erw.net, robh+dt@...nel.org, mark.rutland@....com,
        vilhelm.gray@...il.com, linus.walleij@...aro.org,
        jeff.dagenais@...il.com, fabrice.gasnier@...com
Cc:     gwenhael.goavec-merou@...bucayre.com, peda@...ntia.se,
        maxime.roussinbelanger@...il.com, ihkose@...il.com,
        Ismail.Kose@...imintegrated.com, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] iio: dac: DS4424: add Maxim DS4422/DS4424 DAC driver support

From: "Ismail H. Kose" <ihkose@...il.com>

Add iio driver for DS4422/DS4424 chips that support two/four channel 7-bit
Sink/Source Current DAC.

The driver supports device tree and platfrom files for the configurations.

Datasheet publicly available at:
https://datasheets.maximintegrated.com/en/ds/DS4422-DS4424.pdf

Signed-off-by: Ismail Kose <Ismail.Kose@...imintegrated.com>
---
 .../devicetree/bindings/iio/dac/ds4424.txt         |  41 ++
 drivers/iio/dac/Kconfig                            |   9 +
 drivers/iio/dac/Makefile                           |   1 +
 drivers/iio/dac/ds4424.c                           | 733 +++++++++++++++++++++
 include/linux/iio/dac/ds4424.h                     |  29 +
 5 files changed, 813 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/dac/ds4424.txt
 create mode 100644 drivers/iio/dac/ds4424.c
 create mode 100644 include/linux/iio/dac/ds4424.h

diff --git a/Documentation/devicetree/bindings/iio/dac/ds4424.txt b/Documentation/devicetree/bindings/iio/dac/ds4424.txt
new file mode 100644
index 000000000000..03c1b575a6db
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/dac/ds4424.txt
@@ -0,0 +1,41 @@
+Maxim Integrated DS4422/DS4424 DAC device driver
+
+Required properties:
+	- compatible: Must be "maxim,ds4422" or "maxim,ds4424"
+	- reg: Should contain the DAC I2C address
+	- min_rfs, max_rfs: In order to get the correct processed data values,
+		   these resistor values should be changed to the correct values
+		   that match the user's system resistor values for RFS0 to RFS1.
+		   Resistance values for rfs_resistor are listed in 100 Ohm units;
+		   ie, 800 is 80K. Acceptable RFS values are 40K to 160K.
+	- ifs_scale: 61000*100 = 6100000 = 100,000,000 * .976/16
+	- max_picoamp: Should contain DAC maximum pico amper value.
+	- rfs_resistor: Should contain reference resistor
+	- iio map: Should contain IIO Map info
+
+Optional properties:
+	- vcc-supply: Power supply us optional. If not defined, driver will ignore it.
+
+Example:
+	ds4224@10 {
+		compatible = "maxim,ds4424";
+		reg = <0x10>; /* When A0, A1 pins are ground */
+		vcc-supply = "dac_vcc_3v3";
+		max-picoamp = <200000000>; /* 200uA */
+		ifs-scale = <61000>;
+		/* In order to get the correct processed data values,
+		   these resistor values should be changed to the correct values that match the
+		   user's system resistor values for RFS0 to RFS1.
+		   Resistance values for rfs_resistor are listed in 100 Ohm units;
+		   ie, 800 is 80K. Acceptable RFS values are 40K to 160K.
+		*/
+		min-rfs = <400>;
+		max-rfs = <1600>;
+		rfs-resistors = <400 800 1000 1600>;
+		dac-iio-map =
+		/*	consumer_dev_name, consumer_channel, adc_channel_label */
+			"ds4424_dac-consumer-dev_name-1", "ds4424_dac1", "OUT1",
+			"ds4424_dac-consumer-dev_name-2", "ds4424_dac2", "OUT2",
+			"ds4424_dac-consumer-dev_name-3", "ds4424_dac3", "OUT3",
+			"ds4424_dac-consumer-dev_name-4", "ds4424_dac4", "OUT4";
+	};
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index df5abc46cd3f..6f569c0ac88a 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -309,4 +309,13 @@ config VF610_DAC
 	  This driver can also be built as a module. If so, the module will
 	  be called vf610_dac.
 
+config DAC_DS4424
+	tristate "Maxim Integrated DS4422/DS4424 DAC driver"
+	depends on I2C
+	help
+	  If you say yes here you get support for Maxim chip DS4422, DS4424.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called DAC_DS4424.
+
 endmenu
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 603587cc2f07..fa77510a5538 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -33,3 +33,4 @@ obj-$(CONFIG_MCP4922) += mcp4922.o
 obj-$(CONFIG_STM32_DAC_CORE) += stm32-dac-core.o
 obj-$(CONFIG_STM32_DAC) += stm32-dac.o
 obj-$(CONFIG_VF610_DAC) += vf610_dac.o
+obj-$(CONFIG_DAC_DS4424) += ds4424.o
diff --git a/drivers/iio/dac/ds4424.c b/drivers/iio/dac/ds4424.c
new file mode 100644
index 000000000000..d13590a00c79
--- /dev/null
+++ b/drivers/iio/dac/ds4424.c
@@ -0,0 +1,733 @@
+/*
+ * Maxim Integrated
+ * 7-bit, Multi-Channel Sink/Source Current DAC Driver
+ * Copyright (C) 2017 Maxim Integrated
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/iio/machine.h>
+#include <linux/iio/dac/ds4424.h>
+
+#define DS4424_DAC_ADDR(chan)   ((chan) + 0xf8)
+#define SOURCE_I	1
+#define SINK_I		0
+
+#define PWR_ON		true
+#define PWR_OFF		false
+
+#define DS4424_CHANNEL(chan) { \
+	.type = IIO_CURRENT, \
+	.indexed = 1, \
+	.output = 1, \
+	.channel = chan, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+			BIT(IIO_CHAN_INFO_PROCESSED) | \
+			BIT(IIO_CHAN_INFO_SCALE),\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET), \
+	.address = DS4424_DAC_ADDR(chan),	\
+	.scan_type = { \
+		.sign = 'u', \
+		.realbits = 8, \
+		.storagebits = 8, \
+		.shift = 0, \
+		}, \
+}
+
+union raw_data {
+	struct {
+		u8 dx:7;
+		u8 source_bit:1;  /* 1 is source, 0 is sink */
+	};
+	u8 bits;
+};
+
+enum ds4424_device_ids {
+	ID_DS4422,
+	ID_DS4424,
+};
+
+struct ds4424_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	uint16_t raw[DS442X_MAX_DAC_CHANNELS];
+#ifdef CONFIG_PM_SLEEP
+	uint16_t save[DS442X_MAX_DAC_CHANNELS];
+#endif
+	uint32_t max_rfs;
+	uint32_t min_rfs;
+	uint32_t ifs_scale;
+	uint32_t max_picoamp;
+	uint32_t rfs_res[DS442X_MAX_DAC_CHANNELS];
+	struct iio_map dac_iio_map[DS442X_MAX_DAC_CHANNELS + 1];
+	struct regulator *vcc_reg;
+	const char *vcc_reg_name;
+	bool regulator_state;
+};
+
+static const struct ds4424_pdata ds4424_pdata_default = {
+	/* .vcc_supply_name = "dac_vdd_3v3", */
+	.min_rfs = 400,
+	.max_rfs = 1600,
+	.ifs_scale = 61000, /* 61000*100 = 6100000 = 100,000,000 * .976/16 */
+	.max_picoamp = 200000000,
+	.rfs_res = {400, 800, 1000, 1600},
+	.dac_iio_map = {
+		{	.consumer_dev_name = "ds4424_dac-consumer-dev_name-1",
+			.consumer_channel = "ds4424_dac1",
+			.adc_channel_label = "OUT1"
+		},
+		{
+			.consumer_dev_name = "ds4424_dac-consumer-dev_name-2",
+			.consumer_channel = "ds4424_dac2",
+			.adc_channel_label = "OUT2"
+		},
+		{
+			.consumer_dev_name = "ds4424_dac-consumer-dev_name-3",
+			.consumer_channel = "ds4424_dac3",
+			.adc_channel_label = "OUT3"
+		},
+		{
+			.consumer_dev_name = "ds4424_dac-consumer-dev_name-4",
+			.consumer_channel = "ds4424_dac4",
+			.adc_channel_label = "OUT4"
+		},
+		{},
+	},
+};
+
+static const struct iio_chan_spec ds4424_channels[] = {
+	DS4424_CHANNEL(0),
+	DS4424_CHANNEL(1),
+	DS4424_CHANNEL(2),
+	DS4424_CHANNEL(3)
+};
+
+int ds4424_regulator_onoff(struct iio_dev *indio_dev, bool enable)
+{
+	struct ds4424_data *data = iio_priv(indio_dev);
+	int ret = 0;
+
+	if (data->vcc_reg == NULL)
+		return ret;
+
+	if (data->regulator_state == PWR_OFF && enable == PWR_ON) {
+		ret = regulator_enable(data->vcc_reg);
+		if (ret) {
+			pr_err("%s - enable vcc_reg failed, ret=%d\n",
+				__func__, ret);
+			goto done;
+		}
+	} else if (data->regulator_state == PWR_ON && enable == PWR_OFF) {
+		ret = regulator_disable(data->vcc_reg);
+		if (ret) {
+			pr_err("%s - disable vcc_reg failed, ret=%d\n",
+				__func__, ret);
+			goto done;
+		}
+	}
+
+	data->regulator_state = enable;
+done:
+	return ret;
+}
+
+static int ds4424_get_value(struct iio_dev *indio_dev,
+			     int *val, int channel)
+{
+	struct ds4424_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+	u8 outbuf[1];
+	u8 inbuf[1];
+	int ret;
+
+	if ((channel < 0) && (channel >= indio_dev->num_channels))
+		return -EINVAL;
+
+	outbuf[0] = DS4424_DAC_ADDR(channel);
+	mutex_lock(&data->lock);
+	ret = i2c_master_send(client, outbuf, 1);
+	if (ret < 0) {
+		mutex_unlock(&data->lock);
+		return ret;
+	} else if (ret != 1) {
+		mutex_unlock(&data->lock);
+		return -EIO;
+	}
+
+	ret = i2c_master_recv(client, inbuf, 1);
+	if (ret < 0) {
+		mutex_unlock(&data->lock);
+		return ret;
+	} else if (ret != 1) {
+		mutex_unlock(&data->lock);
+		return -EIO;
+	}
+
+	mutex_unlock(&data->lock);
+
+	*val = inbuf[0];
+	return 0;
+}
+
+/*
+ * DS4432 DAC control register 8 bits
+ * [7]		0: to sink; 1: to source
+ * [6:0]	steps to sink/source
+ * bit[7] looks like a sign bit, but the value of the register is
+ * not a complemental code considering the bit[6:0] is a absolute
+ * distance from the zero point.
+ */
+
+/*
+ * val is positive if sourcing
+ *  val is negative if sinking
+ *  val can be -127 to 127
+ */
+static int ds4424_set_value(struct iio_dev *indio_dev,
+			     int val, struct iio_chan_spec const *chan)
+{
+	struct ds4424_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+	u8 outbuf[2];
+	int ret;
+	int max_val = ((1 << chan->scan_type.realbits) - 1);
+
+	if (val < 0 || val > max_val)
+		return -EINVAL;
+
+	if ((chan->channel < 0)
+		&& (chan->channel >= indio_dev->num_channels))
+		return -EINVAL;
+
+	outbuf[0] = DS4424_DAC_ADDR(chan->channel);
+	outbuf[1] = (val & 0xff);
+
+	mutex_lock(&data->lock);
+	ret = i2c_master_send(client, outbuf, ARRAY_SIZE(outbuf));
+	mutex_unlock(&data->lock);
+
+	if (ret < 0)
+		return ret;
+	else if (ret >= 0 && ret != ARRAY_SIZE(outbuf))
+		return -EIO;
+
+	data->raw[chan->channel] = outbuf[1];
+	return 0;
+}
+
+static int ds4424_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	union raw_data raw;
+	int round_up, ret;
+	struct ds4424_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/* Raw is processed a little bit
+		 * outputs positive values for sourcing
+		 * and negative values for sinking
+		 */
+		ret = ds4424_get_value(indio_dev, val, chan->channel);
+		if (ret < 0) {
+			pr_err("%s : ds4424_get_value returned %d\n",
+							__func__, ret);
+			return ret;
+		}
+		raw.bits = *val;
+		*val = raw.dx;
+		if (raw.source_bit == SINK_I)
+			*val = -*val;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_PROCESSED:
+		/**
+		 * To get the processed current using the 8-bit raw data:
+		 * bit 7 is a 1 if sourcing current and it's a 0 if sinking
+		 * current.
+		 * The current full scale (Ifs) depends on the Rfs resistor
+		 * value in ohms:
+		 * Ifs = (0.976/Rfs)*(127/16)
+		 * Then the current sourced or sinked can be determined as
+		 * follows:
+		 * I = Ifs * (Dx/127)
+		 * where Dx is the value of the seven bits 6 to 0.
+		 */
+		if (data->rfs_res[chan->channel] < data->min_rfs ||
+				data->rfs_res[chan->channel] > data->max_rfs) {
+			pr_err("%s : rfs_res out of range. rfs_res[%d]: %d\n",
+					__func__,
+					chan->channel,
+					data->rfs_res[chan->channel]);
+			return -EINVAL;
+		}
+
+		ret = ds4424_get_value(indio_dev, val, chan->channel);
+		if (ret < 0) {
+			pr_err("%s : ds4424_get_value returned %d\n",
+					__func__, ret);
+			return ret;
+		}
+		raw.bits = *val;
+		*val = data->ifs_scale * raw.dx * 100;
+		round_up = data->rfs_res[chan->channel] / 2;
+		*val = (*val + round_up) / data->rfs_res[chan->channel];
+
+		if (raw.source_bit == SINK_I)
+			*val = -*val;
+		*val = *val * 100;	/* picoAmps */
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		round_up = data->rfs_res[chan->channel] / 2;
+		/* picoAmps */
+		*val = (data->ifs_scale * 10000 + round_up) /
+			data->rfs_res[chan->channel];
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_OFFSET:
+		*val = 0;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+/**
+ * val is positive if sourcing
+ * val is negative if sinking
+ */
+static int ds4424_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	union raw_data raw;
+	struct ds4424_data *data = iio_priv(indio_dev);
+	int val0, max_val, min_val, tmp_scale;
+
+	if (val2 != 0)
+		return -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+
+		max_val = ((1 << chan->scan_type.realbits)/2) - 1;
+		min_val = -max_val;
+		if ((val > max_val) || (val < min_val))
+			return -EINVAL;
+
+		if (val > 0) {
+			raw.source_bit = SOURCE_I;
+			raw.dx = val;
+		} else {
+			raw.source_bit = SINK_I;
+			raw.dx = -val;
+		}
+
+		return ds4424_set_value(indio_dev, raw.bits, chan);
+
+	case IIO_CHAN_INFO_PROCESSED:  /* val input is picoAmps */
+		/*   val can be 0 to 200,000,000 (200 picoAmps)  */
+		val0 = val;
+		raw.source_bit = SOURCE_I;
+		if (val < 0) {
+			raw.source_bit = SINK_I;
+			val = -val;
+		}
+		if (val > data->max_picoamp) {
+			pr_err("%s : Requested current %d ", __func__, val);
+			pr_err("exceeds %d picoAmps\n",	data->max_picoamp);
+			return -EINVAL;
+		}
+		if (data->rfs_res[chan->channel] < data->min_rfs ||
+				data->rfs_res[chan->channel] > data->max_rfs) {
+			pr_info("%s : Resistor values out of range\n",
+				__func__);
+			return -EINVAL;
+		}
+		val = val / 1000;
+		tmp_scale = data->ifs_scale / 10;  /* preserve resolution */
+		val = (val * data->rfs_res[chan->channel]) /
+			tmp_scale;
+		val = (val + 50) / 100;
+		val2 = ((1 << chan->scan_type.realbits) / 2) - 1;
+		if (val > val2) {
+			pr_info("%s : Requested current %d %d",
+				__func__, val0, val);
+			pr_info("exceeds maximum. DAC set to maximum %d\n",
+				val2);
+			val = val2;
+		}
+		raw.dx = val;
+		return ds4424_set_value(indio_dev, raw.bits, chan);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ds4424_verify_chip(struct iio_dev *indio_dev)
+{
+	int ret = 0, val;
+	int i;
+
+	usleep_range(1000, 1200);
+	for (i = 0; i < indio_dev->num_channels; i++) {
+		ret = ds4424_get_value(indio_dev, &val, i);
+		if (ret < 0) {
+			pr_err("%s : read %d, should be 0\n", __func__, ret);
+			break;
+		}
+	}
+	return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int ds4424_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ds4424_data *data = iio_priv(indio_dev);
+	int ret = 0;
+	u32 i;
+
+	for (i = 0; i < indio_dev->num_channels; i++) {
+		data->save[i] = data->raw[i];
+		ret = ds4424_set_value(indio_dev, 0,
+				&(indio_dev->channels[i]));
+		if (ret < 0)
+			return ret;
+	}
+	return ret;
+}
+
+static int ds4424_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ds4424_data *data = iio_priv(indio_dev);
+	int ret = 0;
+	u32 i;
+
+	for (i = 0; i < indio_dev->num_channels; i++) {
+		ret = ds4424_set_value(indio_dev, data->save[i],
+				&(indio_dev->channels[i]));
+		if (ret < 0)
+			return ret;
+	}
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(ds4424_pm_ops, ds4424_suspend, ds4424_resume);
+#define DS4424_PM_OPS (&ds4424_pm_ops)
+#else
+#define DS4424_PM_OPS NULL
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct iio_info ds4424_info = {
+	.read_raw = ds4424_read_raw,
+	.write_raw = ds4424_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+#ifdef CONFIG_OF
+static int ds4424_parse_dt(struct iio_dev *indio_dev)
+{
+	int ret;
+	int len;
+	int num_ch;
+	int i;
+	int count;
+	struct property *prop;
+	struct ds4424_data *data = iio_priv(indio_dev);
+	struct device_node *node = indio_dev->dev.parent->of_node;
+
+	if (!node) {
+		pr_info("%s:%d ds4424 dts not found\n", __func__, __LINE__);
+		return -ENODEV;
+	}
+
+	prop = of_find_property(node, "rfs-resistors", &len);
+	if (!prop) {
+		pr_err("Invalid rfs-resistor in dt. len: %d\n", len);
+		return -EINVAL;
+	}
+
+	if (len != (DS442X_MAX_DAC_CHANNELS * sizeof(uint32_t))) {
+		pr_err("Invalid rfs-resistor length in dt. len: %d\n", len);
+		return -EINVAL;
+	}
+
+	ret = of_property_read_u32_array(node, "rfs-resistors",
+				 data->rfs_res, DS442X_MAX_DAC_CHANNELS);
+	if (ret < 0) {
+		pr_err("Reading rfs-resistors from dt failed. ret: %d\n", ret);
+		return ret;
+	}
+
+	pr_info("ds4424 rfs-resistors: %d, %d, %d, %d\n",
+			data->rfs_res[0], data->rfs_res[1],
+			data->rfs_res[2], data->rfs_res[3]);
+
+	ret = of_property_read_u32(node, "max-rfs",
+				   &data->max_rfs);
+	if (ret < 0) {
+		pr_err("Reading max-rfs from dt failed. ret: %d\n", ret);
+		return ret;
+	}
+
+	ret = of_property_read_u32(node, "min-rfs",
+				  (u32 *)&data->min_rfs);
+	if (ret < 0) {
+		pr_err("Reading min-rfs from dt failed. ret: %d\n", ret);
+		return ret;
+	}
+
+	pr_info("ds4424 max-rfs: %d, min-rfs: %d\n",
+			data->max_rfs, data->min_rfs);
+
+	ret = of_property_read_u32(node, "max-picoamp",
+				  (u32 *)&data->max_picoamp);
+	if (ret < 0) {
+		pr_err("Reading max-picoamp from dt failed. ret: %d\n", ret);
+		return ret;
+	}
+
+	ret = of_property_read_u32(node, "ifs-scale",
+				  (u32 *)&data->ifs_scale);
+	if (ret < 0) {
+		pr_err("Reading ifs-scale from dt failed. ret: %d\n", ret);
+		return ret;
+	}
+
+	pr_info("ds4424 max-picoamp: %d, ifs-scale: %d\n",
+			data->max_picoamp, data->ifs_scale);
+
+	count = of_property_count_strings(node, "dac-iio-map");
+	if (count < 0) {
+		pr_info("dac-iio-map not found in dts\n");
+		return count;
+	}
+
+	ret = of_property_read_string(node, "vcc-supply", &data->vcc_reg_name);
+	if (ret < 0) {
+		pr_info("DAC vcc-supply is not available in dts\n");
+		data->vcc_reg_name = NULL;
+	}
+
+	if (count != DS4424_MAX_DAC_CHANNELS * 3 &&
+		count != DS4424_MAX_DAC_CHANNELS * 3) {
+		pr_info("Incorrect dac-iio-map in dts. count: %d\n", count);
+		return -EINVAL;
+	}
+
+	num_ch = count / 3;
+	for (i = 0; i < num_ch; i++) {
+		ret = of_property_read_string_index(node,
+				"dac-iio-map", i * 3,
+				&data->dac_iio_map[i].consumer_dev_name);
+		if (ret < 0) {
+			pr_info("%s:%d\n", __func__, __LINE__);
+			return ret;
+		}
+
+		ret = of_property_read_string_index(node, "dac-iio-map",
+			i * 3 + 1,
+			&data->dac_iio_map[i].consumer_channel);
+		if (ret < 0) {
+			pr_info("%s:%d\n", __func__, __LINE__);
+			return ret;
+		}
+
+		ret = of_property_read_string_index(node, "dac-iio-map",
+				i * 3 + 2,
+				&data->dac_iio_map[i].adc_channel_label);
+		if (ret < 0) {
+			pr_info("%s:%d\n", __func__, __LINE__);
+			return ret;
+		}
+
+		pr_info("ds4424 iio-map[%d]: %s, %s, %s\n", i,
+				data->dac_iio_map[i].consumer_dev_name,
+				data->dac_iio_map[i].consumer_channel,
+				data->dac_iio_map[i].adc_channel_label);
+	}
+
+	return 0;
+}
+#else
+static int ds4424_parse_dt(struct iio_dev *indio_dev)
+{
+	return -ENODEV;
+}
+#endif
+
+static int ds4424_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	const struct ds4424_pdata *pdata;
+	struct ds4424_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev, "I2C is not supported\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev) {
+		pr_err("%s:%d\n", __func__, __LINE__);
+		return -ENOMEM;
+	}
+
+	data = iio_priv(indio_dev);
+	memset(data, 0, sizeof(*data));
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	indio_dev->name = id->name;
+	indio_dev->dev.parent = &client->dev;
+
+	ret = ds4424_verify_chip(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "%s failed. ret:%d\n", __func__, ret);
+		return -ENXIO;
+	}
+
+	if (client->dev.of_node) {
+		ret = ds4424_parse_dt(indio_dev);
+		if (ret < 0) {
+			dev_err(&client->dev,
+					"%s - of_node error\n", __func__);
+			ret = -EINVAL;
+		}
+	} else {
+		pdata =  client->dev.platform_data;
+		if (!pdata) {
+			dev_err(&client->dev,
+				"dts/platform data not found.\n");
+			/* Use default driver settings */
+			pdata = &ds4424_pdata_default;
+		}
+
+		pdata = client->dev.platform_data;
+		data->min_rfs = pdata->min_rfs;
+		data->max_rfs = pdata->max_rfs;
+		data->ifs_scale = pdata->ifs_scale;
+		data->max_picoamp = pdata->max_picoamp;
+		data->vcc_reg_name = pdata->vcc_supply_name;
+		memcpy(data->rfs_res, pdata->rfs_res,
+			sizeof(uint32_t) * DS442X_MAX_DAC_CHANNELS);
+		memcpy(data->dac_iio_map, pdata->dac_iio_map,
+			sizeof(struct iio_map) * DS442X_MAX_DAC_CHANNELS);
+	}
+
+	if (data->vcc_reg_name) {
+		data->vcc_reg = devm_regulator_get(&client->dev,
+			data->vcc_reg_name);
+		if (IS_ERR(data->vcc_reg)) {
+			ret = PTR_ERR(data->vcc_reg);
+			dev_err(&client->dev,
+				"Failed to get vcc_reg regulator: %d\n", ret);
+			return ret;
+		}
+	}
+
+	mutex_init(&data->lock);
+	ret = ds4424_regulator_onoff(indio_dev, PWR_ON);
+	if (ret < 0) {
+		pr_err("Unable to turn on the regulator. %s:%d, ret: %d\n",
+			__func__, __LINE__, ret);
+		return ret;
+	}
+
+	switch (id->driver_data) {
+	case ID_DS4422:
+		indio_dev->num_channels = DS4422_MAX_DAC_CHANNELS;
+		break;
+	case ID_DS4424:
+		indio_dev->num_channels = DS4424_MAX_DAC_CHANNELS;
+		break;
+	default:
+		indio_dev->num_channels = DS4424_MAX_DAC_CHANNELS;
+		break;
+	}
+
+	indio_dev->channels = ds4424_channels;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &ds4424_info;
+
+	ret = iio_map_array_register(indio_dev, data->dac_iio_map);
+	if (ret < 0)
+		goto err_iio_device_0;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		pr_err("iio_device_register failed . %s:%d, ret: %d\n",
+			__func__, __LINE__, ret);
+		goto err_iio_device_1;
+	}
+
+	return ret;
+
+err_iio_device_0:
+	ds4424_regulator_onoff(indio_dev, PWR_OFF);
+err_iio_device_1:
+	iio_map_array_unregister(indio_dev);
+	return ret;
+}
+
+static int ds4424_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+	iio_map_array_unregister(indio_dev);
+	ds4424_regulator_onoff(indio_dev, PWR_OFF);
+	return 0;
+}
+
+static const struct i2c_device_id ds4424_id[] = {
+	{ "ds4422", ID_DS4422 },
+	{ "ds4424", ID_DS4424 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ds4424_id);
+
+static const struct of_device_id ds4424_of_match[] = {
+	{ .compatible = "maxim,ds4422" },
+	{ .compatible = "maxim,ds4424" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, ds4424_of_match);
+
+static struct i2c_driver ds4424_driver = {
+	.driver = {
+		.name	= "ds4424",
+		.pm     = DS4424_PM_OPS,
+	},
+	.probe		= ds4424_probe,
+	.remove		= ds4424_remove,
+	.id_table	= ds4424_id,
+};
+module_i2c_driver(ds4424_driver);
+
+MODULE_DESCRIPTION("Maxim DS4424 DAC Driver");
+MODULE_AUTHOR("Ismail H. Kose <ismail.kose@...imintegrated.com>");
+MODULE_AUTHOR("Vishal Sood <vishal.sood@...imintegrated.com>");
+MODULE_AUTHOR("David Jung <david.jung@...imintegrated.com>");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/iio/dac/ds4424.h b/include/linux/iio/dac/ds4424.h
new file mode 100644
index 000000000000..09ff3d61797d
--- /dev/null
+++ b/include/linux/iio/dac/ds4424.h
@@ -0,0 +1,29 @@
+/*
+ * Maxim Integrated
+ * 7-bit, Multi-Channel Sink/Source Current DAC Driver
+ * Copyright (C) 2017 Maxim Integrated
+ *
+ * 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.
+ */
+
+#ifndef IIO_DAC_DS4424_H_
+#define IIO_DAC_DS4424_H_
+#include <linux/iio/iio.h>
+#include <linux/iio/machine.h>
+
+#define DS4422_MAX_DAC_CHANNELS		2
+#define DS4424_MAX_DAC_CHANNELS		4
+#define DS442X_MAX_DAC_CHANNELS		DS4424_MAX_DAC_CHANNELS
+
+struct ds4424_pdata {
+	const char *vcc_supply_name;
+	uint32_t max_rfs;
+	uint32_t min_rfs;
+	uint32_t ifs_scale;
+	uint32_t max_picoamp;
+	uint32_t rfs_res[DS442X_MAX_DAC_CHANNELS];
+	struct iio_map dac_iio_map[DS442X_MAX_DAC_CHANNELS + 1];
+};
+#endif /* IIO_DAC_DS4424_H_ */
-- 
2.11.0

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