[PATCH v3 6/7] iio:dac:ad5686: Refactor the driver

[Stefan Popa <stefan.popa@analog.com>]

In this patch restructures the existing ad5686 driver by adding a module
for SPI and a header file, while the baseline module deals with the
chip-logic.

This is a necessary step, as this driver should support in the future
similar devices which differ only in the type of interface used (I2C
instead of SPI).

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
---
Changes in v2:
	- Refactored the patch
	- Use st->write directly instead of the ad5686_write() wrapper
	- Use st->read directly instead of the ad5686_read() wrapper
Changes in v3:
	- Indented the the help text from the Konfig file with 2
	  additional spaces.
	- Changed the license description to use an SPDX tag.

 MAINTAINERS                  |   7 ++
 drivers/iio/dac/Kconfig      |  13 ++-
 drivers/iio/dac/Makefile     |   1 +
 drivers/iio/dac/ad5686-spi.c |  92 +++++++++++++++++++++
 drivers/iio/dac/ad5686.c     | 190 +++++++------------------------------------
 drivers/iio/dac/ad5686.h     | 114 ++++++++++++++++++++++++++
 6 files changed, 252 insertions(+), 165 deletions(-)
 create mode 100644 drivers/iio/dac/ad5686-spi.c
 create mode 100644 drivers/iio/dac/ad5686.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 473ac00..637e62d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -791,6 +791,13 @@ M:	Michael Hanselmann <linux-kernel@hansmi.ch>
 S:	Supported
 F:	drivers/macintosh/ams/
 
+ANALOG DEVICES INC AD5686 DRIVER
+M:	Stefan Popa <stefan.popa@analog.com>
+L:	linux-pm@vger.kernel.org
+W:	http://ez.analog.com/community/linux-device-drivers
+S:	Supported
+F:	drivers/iio/dac/ad5686*
+
 ANALOG DEVICES INC AD9389B DRIVER
 M:	Hans Verkuil <hans.verkuil@cisco.com>
 L:	linux-media@vger.kernel.org
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 965d5c0..7a81f1e 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -131,16 +131,21 @@ config LTC2632
 	  module will be called ltc2632.
 
 config AD5686
-	tristate "Analog Devices AD5686R/AD5685R/AD5684R DAC SPI driver"
+	tristate
+
+config AD5686_SPI
+	tristate "Analog Devices AD5686 and similar multi-channel DACs (SPI)"
 	depends on SPI
+	select AD5686
 	help
-	  Say yes here to build support for Analog Devices AD5686R, AD5685R,
-	  AD5684R, AD5791 Voltage Output Digital to
-	  Analog Converter.
+	  Say yes here to build support for Analog Devices AD5672R, AD5676,
+	  AD5676R, AD5684, AD5684R, AD5684R, AD5685R, AD5686, AD5686R.
+	  Voltage Output Digital to Analog Converter.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad5686.
 
+
 config AD5755
 	tristate "Analog Devices AD5755/AD5755-1/AD5757/AD5735/AD5737 DAC driver"
 	depends on SPI_MASTER
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 81e710e..07db92e 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_AD5761) += ad5761.o
 obj-$(CONFIG_AD5764) += ad5764.o
 obj-$(CONFIG_AD5791) += ad5791.o
 obj-$(CONFIG_AD5686) += ad5686.o
+obj-$(CONFIG_AD5686_SPI) += ad5686-spi.o
 obj-$(CONFIG_AD7303) += ad7303.o
 obj-$(CONFIG_AD8801) += ad8801.o
 obj-$(CONFIG_CIO_DAC) += cio-dac.o
diff --git a/drivers/iio/dac/ad5686-spi.c b/drivers/iio/dac/ad5686-spi.c
new file mode 100644
index 0000000..1cc807b
--- /dev/null
+++ b/drivers/iio/dac/ad5686-spi.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * AD5672R, AD5676, AD5676R, AD5684, AD5684R, AD5684R, AD5685R, AD5686, AD5686R
+ * Digital to analog converters driver
+ *
+ * Copyright 2018 Analog Devices Inc.
+ */
+
+#include "ad5686.h"
+
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+static int ad5686_spi_write(struct ad5686_state *st,
+			    u8 cmd, u8 addr, u16 val)
+{
+	struct spi_device *spi = to_spi_device(st->dev);
+
+	st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) |
+				      AD5686_ADDR(addr) |
+				      val);
+
+	return spi_write(spi, &st->data[0].d8[1], 3);
+}
+
+static int ad5686_spi_read(struct ad5686_state *st, u8 addr)
+{
+	struct spi_transfer t[] = {
+		{
+			.tx_buf = &st->data[0].d8[1],
+			.len = 3,
+			.cs_change = 1,
+		}, {
+			.tx_buf = &st->data[1].d8[1],
+			.rx_buf = &st->data[2].d8[1],
+			.len = 3,
+		},
+	};
+	struct spi_device *spi = to_spi_device(st->dev);
+	int ret;
+
+	st->data[0].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_READBACK_ENABLE) |
+				      AD5686_ADDR(addr));
+	st->data[1].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_NOOP));
+
+	ret = spi_sync_transfer(spi, t, ARRAY_SIZE(t));
+	if (ret < 0)
+		return ret;
+
+	return be32_to_cpu(st->data[2].d32);
+}
+
+static int ad5686_spi_probe(struct spi_device *spi)
+{
+	const struct spi_device_id *id = spi_get_device_id(spi);
+
+	return ad5686_probe(&spi->dev, id->driver_data, id->name,
+			    ad5686_spi_write, ad5686_spi_read);
+}
+
+static int ad5686_spi_remove(struct spi_device *spi)
+{
+	return ad5686_remove(&spi->dev);
+}
+
+static const struct spi_device_id ad5686_spi_id[] = {
+	{"ad5672r", ID_AD5672R},
+	{"ad5676", ID_AD5676},
+	{"ad5676r", ID_AD5676R},
+	{"ad5684", ID_AD5684},
+	{"ad5684r", ID_AD5684R},
+	{"ad5685r", ID_AD5685R},
+	{"ad5686", ID_AD5686},
+	{"ad5686r", ID_AD5686R},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, ad5686_spi_id);
+
+static struct spi_driver ad5686_spi_driver = {
+	.driver = {
+		.name = "ad5686",
+	},
+	.probe = ad5686_spi_probe,
+	.remove = ad5686_spi_remove,
+	.id_table = ad5686_spi_id,
+};
+
+module_spi_driver(ad5686_spi_driver);
+
+MODULE_AUTHOR("Stefan Popa <stefan.popa@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD5686 and similar multi-channel DACs");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index 54f67d5..79abff5 100644
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -10,7 +10,6 @@
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
-#include <linux/spi/spi.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/regulator/consumer.h>
@@ -18,121 +17,7 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 
-#define AD5686_ADDR(x)				((x) << 16)
-#define AD5686_CMD(x)				((x) << 20)
-
-#define AD5686_ADDR_DAC(chan)			(0x1 << (chan))
-#define AD5686_ADDR_ALL_DAC			0xF
-
-#define AD5686_CMD_NOOP				0x0
-#define AD5686_CMD_WRITE_INPUT_N		0x1
-#define AD5686_CMD_UPDATE_DAC_N			0x2
-#define AD5686_CMD_WRITE_INPUT_N_UPDATE_N	0x3
-#define AD5686_CMD_POWERDOWN_DAC		0x4
-#define AD5686_CMD_LDAC_MASK			0x5
-#define AD5686_CMD_RESET			0x6
-#define AD5686_CMD_INTERNAL_REFER_SETUP		0x7
-#define AD5686_CMD_DAISY_CHAIN_ENABLE		0x8
-#define AD5686_CMD_READBACK_ENABLE		0x9
-
-#define AD5686_LDAC_PWRDN_NONE			0x0
-#define AD5686_LDAC_PWRDN_1K			0x1
-#define AD5686_LDAC_PWRDN_100K			0x2
-#define AD5686_LDAC_PWRDN_3STATE		0x3
-
-/**
- * struct ad5686_chip_info - chip specific information
- * @int_vref_mv:	AD5620/40/60: the internal reference voltage
- * @num_channels:	number of channels
- * @channel:		channel specification
-*/
-
-struct ad5686_chip_info {
-	u16				int_vref_mv;
-	unsigned int			num_channels;
-	struct iio_chan_spec		*channels;
-};
-
-/**
- * struct ad5446_state - driver instance specific data
- * @spi:		spi_device
- * @chip_info:		chip model specific constants, available modes etc
- * @reg:		supply regulator
- * @vref_mv:		actual reference voltage used
- * @pwr_down_mask:	power down mask
- * @pwr_down_mode:	current power down mode
- * @data:		spi transfer buffers
- */
-
-struct ad5686_state {
-	struct spi_device		*spi;
-	const struct ad5686_chip_info	*chip_info;
-	struct regulator		*reg;
-	unsigned short			vref_mv;
-	unsigned			pwr_down_mask;
-	unsigned			pwr_down_mode;
-	/*
-	 * DMA (thus cache coherency maintenance) requires the
-	 * transfer buffers to live in their own cache lines.
-	 */
-
-	union {
-		__be32 d32;
-		u8 d8[4];
-	} data[3] ____cacheline_aligned;
-};
-
-/**
- * ad5686_supported_device_ids:
- */
-
-enum ad5686_supported_device_ids {
-	ID_AD5672R,
-	ID_AD5676,
-	ID_AD5676R,
-	ID_AD5684,
-	ID_AD5684R,
-	ID_AD5685R,
-	ID_AD5686,
-	ID_AD5686R
-};
-static int ad5686_spi_write(struct ad5686_state *st,
-			     u8 cmd, u8 addr, u16 val, u8 shift)
-{
-	val <<= shift;
-
-	st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) |
-			      AD5686_ADDR(addr) |
-			      val);
-
-	return spi_write(st->spi, &st->data[0].d8[1], 3);
-}
-
-static int ad5686_spi_read(struct ad5686_state *st, u8 addr)
-{
-	struct spi_transfer t[] = {
-		{
-			.tx_buf = &st->data[0].d8[1],
-			.len = 3,
-			.cs_change = 1,
-		}, {
-			.tx_buf = &st->data[1].d8[1],
-			.rx_buf = &st->data[2].d8[1],
-			.len = 3,
-		},
-	};
-	int ret;
-
-	st->data[0].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_READBACK_ENABLE) |
-			      AD5686_ADDR(addr));
-	st->data[1].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_NOOP));
-
-	ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
-	if (ret < 0)
-		return ret;
-
-	return be32_to_cpu(st->data[2].d32);
-}
+#include "ad5686.h"
 
 static const char * const ad5686_powerdown_modes[] = {
 	"1kohm_to_gnd",
@@ -195,8 +80,9 @@ static ssize_t ad5686_write_dac_powerdown(struct iio_dev *indio_dev,
 	else
 		st->pwr_down_mask &= ~(0x3 << (chan->channel * 2));
 
-	ret = ad5686_spi_write(st, AD5686_CMD_POWERDOWN_DAC, 0,
-			       st->pwr_down_mask & st->pwr_down_mode, 0);
+	ret = st->write(st, AD5686_CMD_POWERDOWN_DAC, 0,
+			st->pwr_down_mask & st->pwr_down_mode);
+
 
 	return ret ? ret : len;
 }
@@ -213,7 +99,7 @@ static int ad5686_read_raw(struct iio_dev *indio_dev,
 	switch (m) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&indio_dev->mlock);
-		ret = ad5686_spi_read(st, chan->address);
+		ret = st->read(st, chan->address);
 		mutex_unlock(&indio_dev->mlock);
 		if (ret < 0)
 			return ret;
@@ -242,11 +128,10 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
 			return -EINVAL;
 
 		mutex_lock(&indio_dev->mlock);
-		ret = ad5686_spi_write(st,
-				 AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
-				 chan->address,
-				 val,
-				 chan->scan_type.shift);
+		ret = st->write(st,
+				AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
+				chan->address,
+				val << chan->scan_type.shift);
 		mutex_unlock(&indio_dev->mlock);
 		break;
 	default:
@@ -356,20 +241,27 @@ static const struct ad5686_chip_info ad5686_chip_info_tbl[] = {
 	},
 };
 
-static int ad5686_probe(struct spi_device *spi)
+int ad5686_probe(struct device *dev,
+		 enum ad5686_supported_device_ids chip_type,
+		 const char *name, ad5686_write_func write,
+		 ad5686_read_func read)
 {
 	struct ad5686_state *st;
 	struct iio_dev *indio_dev;
 	int ret, voltage_uv = 0;
 
-	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
 	if (indio_dev == NULL)
 		return  -ENOMEM;
 
 	st = iio_priv(indio_dev);
-	spi_set_drvdata(spi, indio_dev);
+	dev_set_drvdata(dev, indio_dev);
+
+	st->dev = dev;
+	st->write = write;
+	st->read = read;
 
-	st->reg = devm_regulator_get_optional(&spi->dev, "vcc");
+	st->reg = devm_regulator_get_optional(dev, "vcc");
 	if (!IS_ERR(st->reg)) {
 		ret = regulator_enable(st->reg);
 		if (ret)
@@ -382,28 +274,25 @@ static int ad5686_probe(struct spi_device *spi)
 		voltage_uv = ret;
 	}
 
-	st->chip_info =
-		&ad5686_chip_info_tbl[spi_get_device_id(spi)->driver_data];
+	st->chip_info = &ad5686_chip_info_tbl[chip_type];
 
 	if (voltage_uv)
 		st->vref_mv = voltage_uv / 1000;
 	else
 		st->vref_mv = st->chip_info->int_vref_mv;
 
-	st->spi = spi;
-
 	/* Set all the power down mode for all channels to 1K pulldown */
 	st->pwr_down_mode = 0x55;
 
-	indio_dev->dev.parent = &spi->dev;
-	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->dev.parent = dev;
+	indio_dev->name = name;
 	indio_dev->info = &ad5686_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = st->chip_info->channels;
 	indio_dev->num_channels = st->chip_info->num_channels;
 
-	ret = ad5686_spi_write(st, AD5686_CMD_INTERNAL_REFER_SETUP, 0,
-				!!voltage_uv, 0);
+	ret = st->write(st, AD5686_CMD_INTERNAL_REFER_SETUP,
+			0, !!voltage_uv);
 	if (ret)
 		goto error_disable_reg;
 
@@ -418,10 +307,11 @@ static int ad5686_probe(struct spi_device *spi)
 		regulator_disable(st->reg);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(ad5686_probe);
 
-static int ad5686_remove(struct spi_device *spi)
+int ad5686_remove(struct device *dev)
 {
-	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct ad5686_state *st = iio_priv(indio_dev);
 
 	iio_device_unregister(indio_dev);
@@ -430,29 +320,7 @@ static int ad5686_remove(struct spi_device *spi)
 
 	return 0;
 }
-
-static const struct spi_device_id ad5686_id[] = {
-	{"ad5672r", ID_AD5672R},
-	{"ad5676", ID_AD5676},
-	{"ad5676r", ID_AD5676R},
-	{"ad5684", ID_AD5684},
-	{"ad5684r", ID_AD5684R},
-	{"ad5685r", ID_AD5685R},
-	{"ad5686", ID_AD5686},
-	{"ad5686r", ID_AD5686R},
-	{}
-};
-MODULE_DEVICE_TABLE(spi, ad5686_id);
-
-static struct spi_driver ad5686_driver = {
-	.driver = {
-		   .name = "ad5686",
-		   },
-	.probe = ad5686_probe,
-	.remove = ad5686_remove,
-	.id_table = ad5686_id,
-};
-module_spi_driver(ad5686_driver);
+EXPORT_SYMBOL_GPL(ad5686_remove);
 
 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 MODULE_DESCRIPTION("Analog Devices AD5686/85/84 DAC");
diff --git a/drivers/iio/dac/ad5686.h b/drivers/iio/dac/ad5686.h
new file mode 100644
index 0000000..c8e1565
--- /dev/null
+++ b/drivers/iio/dac/ad5686.h
@@ -0,0 +1,114 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * This file is part of AD5686 DAC driver
+ *
+ * Copyright 2018 Analog Devices Inc.
+ */
+
+#ifndef __DRIVERS_IIO_DAC_AD5686_H__
+#define __DRIVERS_IIO_DAC_AD5686_H__
+
+#include <linux/types.h>
+#include <linux/cache.h>
+#include <linux/mutex.h>
+#include <linux/kernel.h>
+
+#define AD5686_ADDR(x)				((x) << 16)
+#define AD5686_CMD(x)				((x) << 20)
+
+#define AD5686_ADDR_DAC(chan)			(0x1 << (chan))
+#define AD5686_ADDR_ALL_DAC			0xF
+
+#define AD5686_CMD_NOOP				0x0
+#define AD5686_CMD_WRITE_INPUT_N		0x1
+#define AD5686_CMD_UPDATE_DAC_N			0x2
+#define AD5686_CMD_WRITE_INPUT_N_UPDATE_N	0x3
+#define AD5686_CMD_POWERDOWN_DAC		0x4
+#define AD5686_CMD_LDAC_MASK			0x5
+#define AD5686_CMD_RESET			0x6
+#define AD5686_CMD_INTERNAL_REFER_SETUP		0x7
+#define AD5686_CMD_DAISY_CHAIN_ENABLE		0x8
+#define AD5686_CMD_READBACK_ENABLE		0x9
+
+#define AD5686_LDAC_PWRDN_NONE			0x0
+#define AD5686_LDAC_PWRDN_1K			0x1
+#define AD5686_LDAC_PWRDN_100K			0x2
+#define AD5686_LDAC_PWRDN_3STATE		0x3
+
+/**
+ * ad5686_supported_device_ids:
+ */
+enum ad5686_supported_device_ids {
+	ID_AD5672R,
+	ID_AD5676,
+	ID_AD5676R,
+	ID_AD5684,
+	ID_AD5684R,
+	ID_AD5685R,
+	ID_AD5686,
+	ID_AD5686R,
+};
+
+struct ad5686_state;
+
+typedef int (*ad5686_write_func)(struct ad5686_state *st,
+				 u8 cmd, u8 addr, u16 val);
+
+typedef int (*ad5686_read_func)(struct ad5686_state *st, u8 addr);
+
+/**
+ * struct ad5686_chip_info - chip specific information
+ * @int_vref_mv:	AD5620/40/60: the internal reference voltage
+ * @num_channels:	number of channels
+ * @channel:		channel specification
+ */
+
+struct ad5686_chip_info {
+	u16				int_vref_mv;
+	unsigned int			num_channels;
+	struct iio_chan_spec		*channels;
+};
+
+/**
+ * struct ad5446_state - driver instance specific data
+ * @spi:		spi_device
+ * @chip_info:		chip model specific constants, available modes etc
+ * @reg:		supply regulator
+ * @vref_mv:		actual reference voltage used
+ * @pwr_down_mask:	power down mask
+ * @pwr_down_mode:	current power down mode
+ * @data:		spi transfer buffers
+ */
+
+struct ad5686_state {
+	struct device			*dev;
+	const struct ad5686_chip_info	*chip_info;
+	struct regulator		*reg;
+	unsigned short			vref_mv;
+	unsigned int			pwr_down_mask;
+	unsigned int			pwr_down_mode;
+	ad5686_write_func		write;
+	ad5686_read_func		read;
+
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 */
+
+	union {
+		__be32 d32;
+		__be16 d16;
+		u8 d8[4];
+	} data[3] ____cacheline_aligned;
+};
+
+
+int ad5686_probe(struct device *dev,
+		 enum ad5686_supported_device_ids chip_type,
+		 const char *name, ad5686_write_func write,
+		 ad5686_read_func read);
+
+int ad5686_remove(struct device *dev);
+
+
+#endif /* __DRIVERS_IIO_DAC_AD5686_H__ */
-- 
2.7.4