iio:dac:ad5686: Add AD5671R/75R/94/94R/95R/96/96R support

The AD5694/AD5694R/AD5695R/AD5696/AD5696R are a family of 4 channel DACs
with 12-bit, 14-bit and 16-bit precision respectively. The devices have
either no built-in reference, or built-in 2.5V reference.

The AD5671R/AD5675R are similar, except that they have 8 instead of 4
channels.

These devices are similar to AD5672R/AD5676/AD5676R and
AD5684/AD5684R/AD5684/AD5685R/AD5686/AD5686R, except that they use i2c
instead of spi.

Datasheets:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD5671R_5675R.pdf
http://www.analog.com/media/en/technical-documentation/data-sheets/AD5696R_5695R_5694R.pdf

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -797,6 +797,7 @@ L:	linux-pm@vger.kernel.org
 W:	http://ez.analog.com/community/linux-device-drivers
 S:	Supported
 F:	drivers/iio/dac/ad5686*
+F:	drivers/iio/dac/ad5696*
 
 ANALOG DEVICES INC AD9389B DRIVER
 M:	Hans Verkuil <hans.verkuil@cisco.com>

drivers/iio/dac/Kconfig

@@ -145,6 +145,16 @@ config AD5686_SPI
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad5686.
 
+config AD5696_I2C
+	tristate "Analog Devices AD5696 and similar multi-channel DACs (I2C)"
+	depends on I2C
+	select AD5686
+	help
+	  Say yes here to build support for Analog Devices AD5671R, AD5675R,
+	  AD5694, AD5694R, AD5695R, AD5696, AD5696R Voltage Output Digital to
+	  Analog Converter.
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad5696.
 
 config AD5755
 	tristate "Analog Devices AD5755/AD5755-1/AD5757/AD5735/AD5737 DAC driver"

drivers/iio/dac/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_AD5764) += ad5764.o
 obj-$(CONFIG_AD5791) += ad5791.o
 obj-$(CONFIG_AD5686) += ad5686.o
 obj-$(CONFIG_AD5686_SPI) += ad5686-spi.o
+obj-$(CONFIG_AD5696_I2C) += ad5696-i2c.o
 obj-$(CONFIG_AD7303) += ad7303.o
 obj-$(CONFIG_AD8801) += ad8801.o
 obj-$(CONFIG_CIO_DAC) += cio-dac.o

drivers/iio/dac/ad5686.c

@@ -202,11 +202,21 @@ DECLARE_AD5686_CHANNELS(ad5685r_channels, 14, 2);
 DECLARE_AD5686_CHANNELS(ad5686_channels, 16, 0);
 
 static const struct ad5686_chip_info ad5686_chip_info_tbl[] = {
+	[ID_AD5671R] = {
+		.channels = ad5672_channels,
+		.int_vref_mv = 2500,
+		.num_channels = 8,
+	},
 	[ID_AD5672R] = {
 		.channels = ad5672_channels,
 		.int_vref_mv = 2500,
 		.num_channels = 8,
 	},
+	[ID_AD5675R] = {
+		.channels = ad5676_channels,
+		.int_vref_mv = 2500,
+		.num_channels = 8,
+	},
 	[ID_AD5676] = {
 		.channels = ad5676_channels,
 		.num_channels = 8,
@@ -239,6 +249,24 @@ static const struct ad5686_chip_info ad5686_chip_info_tbl[] = {
 		.int_vref_mv = 2500,
 		.num_channels = 4,
 	},
+	[ID_AD5694] = {
+		.channels = ad5684_channels,
+		.num_channels = 4,
+	},
+	[ID_AD5694R] = {
+		.channels = ad5684_channels,
+		.int_vref_mv = 2500,
+		.num_channels = 4,
+	},
+	[ID_AD5696] = {
+		.channels = ad5686_channels,
+		.num_channels = 4,
+	},
+	[ID_AD5696R] = {
+		.channels = ad5686_channels,
+		.int_vref_mv = 2500,
+		.num_channels = 4,
+	},
 };
 
 int ad5686_probe(struct device *dev,

drivers/iio/dac/ad5686.h

@@ -39,7 +39,9 @@
  * ad5686_supported_device_ids:
  */
 enum ad5686_supported_device_ids {
+	ID_AD5671R,
 	ID_AD5672R,
+	ID_AD5675R,
 	ID_AD5676,
 	ID_AD5676R,
 	ID_AD5684,
@@ -47,6 +49,11 @@ enum ad5686_supported_device_ids {
 	ID_AD5685R,
 	ID_AD5686,
 	ID_AD5686R,
+	ID_AD5694,
+	ID_AD5694R,
+	ID_AD5695R,
+	ID_AD5696,
+	ID_AD5696R,
 };
 
 struct ad5686_state;

drivers/iio/dac/ad5696-i2c.c

@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * AD5671R, AD5675R, AD5694, AD5694R, AD5695R, AD5696, AD5696R
+ * Digital to analog converters driver
+ *
+ * Copyright 2018 Analog Devices Inc.
+ */
+
+#include "ad5686.h"
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+
+static int ad5686_i2c_read(struct ad5686_state *st, u8 addr)
+{
+	struct i2c_client *i2c = to_i2c_client(st->dev);
+	struct i2c_msg msg[2] = {
+		{
+			.addr = i2c->addr,
+			.flags = i2c->flags,
+			.len = 3,
+			.buf = &st->data[0].d8[1],
+		},
+		{
+			.addr = i2c->addr,
+			.flags = i2c->flags | I2C_M_RD,
+			.len = 2,
+			.buf = (char *)&st->data[0].d16,
+		},
+	};
+	int ret;
+
+	st->data[0].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_NOOP) |
+				      AD5686_ADDR(addr) |
+				      0x00);
+
+	ret = i2c_transfer(i2c->adapter, msg, 2);
+	if (ret < 0)
+		return ret;
+
+	return be16_to_cpu(st->data[0].d16);
+}
+
+static int ad5686_i2c_write(struct ad5686_state *st,
+			    u8 cmd, u8 addr, u16 val)
+{
+	struct i2c_client *i2c = to_i2c_client(st->dev);
+	int ret;
+
+	st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) | AD5686_ADDR(addr)
+				      | val);
+
+	ret = i2c_master_send(i2c, &st->data[0].d8[1], 3);
+	if (ret < 0)
+		return ret;
+
+	return (ret != 3) ? -EIO : 0;
+}
+
+static int ad5686_i2c_probe(struct i2c_client *i2c,
+			    const struct i2c_device_id *id)
+{
+	return ad5686_probe(&i2c->dev, id->driver_data, id->name,
+			    ad5686_i2c_write, ad5686_i2c_read);
+}
+
+static int ad5686_i2c_remove(struct i2c_client *i2c)
+{
+	return ad5686_remove(&i2c->dev);
+}
+
+static const struct i2c_device_id ad5686_i2c_id[] = {
+	{"ad5671r", ID_AD5671R},
+	{"ad5675r", ID_AD5675R},
+	{"ad5694", ID_AD5694},
+	{"ad5694r", ID_AD5694R},
+	{"ad5695r", ID_AD5695R},
+	{"ad5696", ID_AD5696},
+	{"ad5696r", ID_AD5696R},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, ad5686_i2c_id);
+
+static struct i2c_driver ad5686_i2c_driver = {
+	.driver = {
+		.name = "ad5696",
+	},
+	.probe = ad5686_i2c_probe,
+	.remove = ad5686_i2c_remove,
+	.id_table = ad5686_i2c_id,
+};
+
+module_i2c_driver(ad5686_i2c_driver);
+
+MODULE_AUTHOR("Stefan Popa <stefan.popa@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD5686 and similar multi-channel DACs");
+MODULE_LICENSE("GPL v2");