Date:   Thu, 14 Sep 2017 13:24:49 -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, mike.looijmans@...ic.nl,
        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: ds4422/ds4424 dac driver

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

This patch provides an iio device driver for DS4422/DS4424 chips that support
two/four channel 7-bit Sink/Source Current DAC.

The driver supports device tree and platform 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>
---
 drivers/iio/dac/Kconfig        |   9 +
 drivers/iio/dac/Makefile       |   1 +
 drivers/iio/dac/ds4424.c       | 476 +++++++++++++++++++++++++++++++++++++++++
 include/linux/iio/dac/ds4424.h |  24 +++
 4 files changed, 510 insertions(+)
 create mode 100644 drivers/iio/dac/ds4424.c
 create mode 100644 include/linux/iio/dac/ds4424.h

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 25bed2d7d2b9..db6ceba1c76f 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -310,4 +310,13 @@ config VF610_DAC
 	  This driver can also be built as a module. If so, the module will
 	  be called vf610_dac.
 
+config DS4424
+	tristate "Maxim Integrated DS4422/DS4424 DAC driver"
+	depends on I2C
+	help
+	  If you say yes here you get support for Maxim chips DS4422, DS4424.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ds4424.
+
 endmenu
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 603587cc2f07..f29f929a0587 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_DS4424) += ds4424.o
diff --git a/drivers/iio/dac/ds4424.c b/drivers/iio/dac/ds4424.c
new file mode 100644
index 000000000000..8765bf20ab62
--- /dev/null
+++ b/drivers/iio/dac/ds4424.c
@@ -0,0 +1,476 @@
+/*
+ * 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/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/consumer.h>
+#include <linux/iio/dac/ds4424.h>
+
+#define DS4424_DAC_ADDR(chan)   ((chan) + 0xf8)
+#define DS4424_SOURCE_I		1
+#define DS4424_SINK_I		0
+
+#define DS4424_CHANNEL(chan) { \
+	.type = IIO_CURRENT, \
+	.indexed = 1, \
+	.output = 1, \
+	.channel = chan, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET), \
+	.address = DS4424_DAC_ADDR(chan), \
+	.scan_type = { \
+		.sign = 'u', \
+		.realbits = 8, \
+		.storagebits = 8, \
+		}, \
+}
+
+union ds4424_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[DS4424_MAX_DAC_CHANNELS];
+	__maybe_unused uint16_t save[DS4424_MAX_DAC_CHANNELS];
+	uint32_t rfs_res[DS4424_MAX_DAC_CHANNELS];
+	struct regulator *vcc_reg;
+};
+
+static struct iio_map ds4424_iio_maps[] = {
+	{	.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 ds4424_pdata ds4424_pdata = {
+	.rfs_res = {400, 800, 1000, 1600},
+	.dac_iio_map = ds4424_iio_maps,
+};
+
+static const struct iio_chan_spec ds4424_channels[] = {
+	DS4424_CHANNEL(0),
+	DS4424_CHANNEL(1),
+	DS4424_CHANNEL(2),
+	DS4424_CHANNEL(3),
+};
+
+static int ds4424_get_value(struct iio_dev *indio_dev,
+			     int *val, int channel)
+{
+	struct ds4424_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = i2c_smbus_write_byte_data(data->client,
+			DS4424_DAC_ADDR(channel), 1);
+	if (ret < 0)
+		goto fail;
+
+	ret = i2c_smbus_read_byte_data(data->client, 1);
+	if (ret < 0)
+		goto fail;
+
+	*val = ret;
+	mutex_unlock(&data->lock);
+	return 0;
+
+fail:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+/*
+ * DS4424 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);
+	int ret;
+
+	if (val < 0 || val > U8_MAX)
+		return -EINVAL;
+
+	mutex_lock(&data->lock);
+	ret = i2c_smbus_write_byte_data(data->client,
+			DS4424_DAC_ADDR(chan->channel), val);
+	if (ret < 0) {
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	data->raw[chan->channel] = val;
+	mutex_unlock(&data->lock);
+
+	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 ds4424_raw_data raw;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		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 == DS4424_SINK_I)
+			*val = -*val;
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ds4424_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	union ds4424_raw_data raw;
+
+	if (val2 != 0)
+		return -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+
+		if (val > S8_MAX || val < S8_MIN)
+			return -EINVAL;
+
+		if (val > 0) {
+			raw.source_bit = DS4424_SOURCE_I;
+			raw.dx = val;
+		} else {
+			raw.source_bit = DS4424_SINK_I;
+			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;
+
+	ret = ds4424_get_value(indio_dev, &val, DS4424_DAC_ADDR(0));
+	if (ret < 0)
+		dev_err(&indio_dev->dev,
+				"ds4424 i2c read failed. ret: %d\n", ret);
+
+	return ret;
+}
+
+static int __maybe_unused 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 __maybe_unused 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);
+
+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 count;
+	struct property *prop;
+	struct ds4424_data *data = iio_priv(indio_dev);
+	struct device_node *node = indio_dev->dev.of_node;
+
+	if (!node) {
+		pr_info("%s:%d ds4424 DT not found\n", __func__, __LINE__);
+		return -ENODEV;
+	}
+
+	prop = of_find_property(node, "maxim,rfs-resistors-ohms", &len);
+	if (!prop) {
+		pr_err("ds4424 maxim,rfs-resistor not found in DT.\n");
+		return -EINVAL;
+	}
+
+	if (len != (DS4424_MAX_DAC_CHANNELS * sizeof(uint32_t))) {
+		pr_err("ds4424 maxim,rfs-resistor length in DT not valid.\n");
+		return -EINVAL;
+	}
+
+	ret = of_property_read_u32_array(node, "maxim,rfs-resistors-ohms",
+				 data->rfs_res, DS4424_MAX_DAC_CHANNELS);
+	if (ret < 0) {
+		pr_err("ds4424 reading maxim,rfs-resistors from DT failed.\n");
+		return ret;
+	}
+
+	pr_info("ds4424 maxim,rfs-resistors: %d, %d, %d, %d\n",
+			data->rfs_res[0], data->rfs_res[1],
+			data->rfs_res[2], data->rfs_res[3]);
+
+	count = of_property_count_strings(node, "maxim,dac-iio-map");
+	if (count < 0) {
+		pr_info("ds4424 maxim,dac-iio-map not found in DT\n");
+		return count;
+	}
+
+	if (count != DS4424_MAX_DAC_CHANNELS * 3 &&
+		count != DS4424_MAX_DAC_CHANNELS * 3) {
+		pr_info("ds4424 maxim,dac-iio-map in DT not valid.\n");
+		return -EINVAL;
+	}
+
+	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;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev) {
+		dev_err(&client->dev, "iio dev alloc failed.\n");
+		return -ENOMEM;
+	}
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	indio_dev->name = id->name;
+	indio_dev->dev.of_node = client->dev.of_node;
+	indio_dev->dev.parent = &client->dev;
+
+	if (client->dev.of_node) {
+		indio_dev->dev.of_node = client->dev.of_node;
+		ret = ds4424_parse_dt(indio_dev);
+		if (ret < 0) {
+			dev_err(&client->dev,
+					"%s - of_node error\n", __func__);
+			return -EINVAL;
+		}
+	} else {
+		pdata = client->dev.platform_data;
+		if (!pdata) {
+			dev_err(&client->dev,
+				"dts/platform data not found.\n");
+			pdata = &ds4424_pdata;
+		}
+
+		pdata = client->dev.platform_data;
+		memcpy(data->rfs_res, pdata->rfs_res,
+			sizeof(uint32_t) * DS4424_MAX_DAC_CHANNELS);
+	}
+
+	data->vcc_reg = devm_regulator_get(&client->dev, "vcc");
+	if (IS_ERR(data->vcc_reg)) {
+		ret = PTR_ERR(data->vcc_reg);
+		dev_err(&client->dev,
+			"Failed to get vcc-supply regulator: %d\n", ret);
+		return ret;
+	}
+
+	mutex_init(&data->lock);
+	ret = regulator_enable(data->vcc_reg);
+	if (ret < 0) {
+		dev_err(&client->dev,
+				"Unable to enable the regulator.\n");
+		return ret;
+	}
+
+	usleep_range(1000, 1200);
+	ret = ds4424_verify_chip(indio_dev);
+	if (ret < 0)
+		return -ENXIO;
+
+	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:
+		dev_err(&client->dev,
+				"ds4424: Invalid chip id.\n");
+		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, ds4424_pdata.dac_iio_map);
+	if (ret < 0)
+		goto err_iio_map_register;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev,
+				"iio_device_register failed. ret: %d\n", ret);
+		goto err_iio_dev_register;
+	}
+
+	return ret;
+
+err_iio_map_register:
+	regulator_disable(data->vcc_reg);
+
+err_iio_dev_register:
+	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);
+	struct ds4424_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_map_array_unregister(indio_dev);
+	regulator_disable(data->vcc_reg);
+
+	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",
+		.of_match_table = ds4424_of_match,
+		.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..2c814118df38
--- /dev/null
+++ b/include/linux/iio/dac/ds4424.h
@@ -0,0 +1,24 @@
+/*
+ * 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
+
+struct ds4424_pdata {
+	const char *vcc_supply_name;
+	uint32_t rfs_res[DS4424_MAX_DAC_CHANNELS];
+	struct iio_map *dac_iio_map;
+};
+#endif /* IIO_DAC_DS4424_H_ */
-- 
2.11.0

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