iio: add ad5761 DAC driver

ad5761 is a 1-channel DAC with configurable output range.
The driver uses the regulator interface for its voltage ref.

It shares its register layout with ad5761r, ad5721 and ad5721r.

Differences:
ad5761* are 16 bit, ad5721* are 12 bits.
ad57*1r have an internal reference.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

CREDITS

@@ -3035,6 +3035,7 @@ D: PLX USB338x driver
 D: PCA9634 driver
 D: Option GTM671WFS
 D: Fintek F81216A
+D: AD5761 iio driver
 D: Various kernel hacks
 S: Qtechnology A/S
 S: Valby Langgade 142

drivers/iio/dac/Kconfig

@@ -111,6 +111,16 @@ config AD5755
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad5755.
 
+config AD5761
+	tristate "Analog Devices AD5761/61R/21/21R DAC driver"
+	depends on SPI_MASTER
+	help
+	  Say yes here to build support for Analog Devices AD5761, AD5761R, AD5721,
+	  AD5721R Digital to Analog Converter.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad5761.
+
 config AD5764
 	tristate "Analog Devices AD5764/64R/44/44R DAC driver"
 	depends on SPI_MASTER

drivers/iio/dac/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_AD5504) += ad5504.o
 obj-$(CONFIG_AD5446) += ad5446.o
 obj-$(CONFIG_AD5449) += ad5449.o
 obj-$(CONFIG_AD5755) += ad5755.o
+obj-$(CONFIG_AD5761) += ad5761.o
 obj-$(CONFIG_AD5764) += ad5764.o
 obj-$(CONFIG_AD5791) += ad5791.o
 obj-$(CONFIG_AD5686) += ad5686.o

drivers/iio/dac/ad5761.c

@@ -0,0 +1,430 @@
+/*
+ * AD5721, AD5721R, AD5761, AD5761R, Voltage Output Digital to Analog Converter
+ *
+ * Copyright 2016 Qtechnology A/S
+ * 2016 Ricardo Ribalda <ricardo.ribalda@gmail.com>
+ *
+ * Licensed under the GPL-2.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/bitops.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/regulator/consumer.h>
+#include <linux/platform_data/ad5761.h>
+
+#define AD5761_ADDR(addr)		((addr & 0xf) << 16)
+#define AD5761_ADDR_NOOP		0x0
+#define AD5761_ADDR_DAC_WRITE		0x3
+#define AD5761_ADDR_CTRL_WRITE_REG	0x4
+#define AD5761_ADDR_SW_DATA_RESET	0x7
+#define AD5761_ADDR_DAC_READ		0xb
+#define AD5761_ADDR_CTRL_READ_REG	0xc
+#define AD5761_ADDR_SW_FULL_RESET	0xf
+
+#define AD5761_CTRL_USE_INTVREF		BIT(5)
+#define AD5761_CTRL_ETS			BIT(6)
+
+/**
+ * struct ad5761_chip_info - chip specific information
+ * @int_vref:	Value of the internal reference voltage in mV - 0 if external
+ *		reference voltage is used
+ * @channel:	channel specification
+*/
+
+struct ad5761_chip_info {
+	unsigned long int_vref;
+	const struct iio_chan_spec channel;
+};
+
+struct ad5761_range_params {
+	int m;
+	int c;
+};
+
+enum ad5761_supported_device_ids {
+	ID_AD5721,
+	ID_AD5721R,
+	ID_AD5761,
+	ID_AD5761R,
+};
+
+/**
+ * struct ad5761_state - driver instance specific data
+ * @spi:		spi_device
+ * @vref_reg:		reference voltage regulator
+ * @use_intref:		true when the internal voltage reference is used
+ * @vref:		actual voltage reference in mVolts
+ * @range:		output range mode used
+ * @data:		cache aligned spi buffer
+ */
+struct ad5761_state {
+	struct spi_device		*spi;
+	struct regulator		*vref_reg;
+
+	bool use_intref;
+	int vref;
+	enum ad5761_voltage_range range;
+
+	/*
+	 * 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;
+};
+
+static const struct ad5761_range_params ad5761_range_params[] = {
+	[AD5761_VOLTAGE_RANGE_M10V_10V] = {
+		.m = 80,
+		.c = 40,
+	},
+	[AD5761_VOLTAGE_RANGE_0V_10V] = {
+		.m = 40,
+		.c = 0,
+	},
+	[AD5761_VOLTAGE_RANGE_M5V_5V] = {
+		.m = 40,
+		.c = 20,
+	},
+	[AD5761_VOLTAGE_RANGE_0V_5V] = {
+		.m = 20,
+		.c = 0,
+	},
+	[AD5761_VOLTAGE_RANGE_M2V5_7V5] = {
+		.m = 40,
+		.c = 10,
+	},
+	[AD5761_VOLTAGE_RANGE_M3V_3V] = {
+		.m = 24,
+		.c = 12,
+	},
+	[AD5761_VOLTAGE_RANGE_0V_16V] = {
+		.m = 64,
+		.c = 0,
+	},
+	[AD5761_VOLTAGE_RANGE_0V_20V] = {
+		.m = 80,
+		.c = 0,
+	},
+};
+
+static int _ad5761_spi_write(struct ad5761_state *st, u8 addr, u16 val)
+{
+	st->data[0].d32 = cpu_to_be32(AD5761_ADDR(addr) | val);
+
+	return spi_write(st->spi, &st->data[0].d8[1], 3);
+}
+
+static int ad5761_spi_write(struct iio_dev *indio_dev, u8 addr, u16 val)
+{
+	struct ad5761_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&indio_dev->mlock);
+	ret = _ad5761_spi_write(st, addr, val);
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret;
+}
+
+static int _ad5761_spi_read(struct ad5761_state *st, u8 addr, u16 *val)
+{
+	int ret;
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = &st->data[0].d8[1],
+			.bits_per_word = 8,
+			.len = 3,
+			.cs_change = true,
+		}, {
+			.tx_buf = &st->data[1].d8[1],
+			.rx_buf = &st->data[2].d8[1],
+			.bits_per_word = 8,
+			.len = 3,
+		},
+	};
+
+	st->data[0].d32 = cpu_to_be32(AD5761_ADDR(addr));
+	st->data[1].d32 = cpu_to_be32(AD5761_ADDR(AD5761_ADDR_NOOP));
+
+	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
+
+	*val = be32_to_cpu(st->data[2].d32);
+
+	return ret;
+}
+
+static int ad5761_spi_read(struct iio_dev *indio_dev, u8 addr, u16 *val)
+{
+	struct ad5761_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&indio_dev->mlock);
+	ret = _ad5761_spi_read(st, addr, val);
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret;
+}
+
+static int ad5761_spi_set_range(struct ad5761_state *st,
+				enum ad5761_voltage_range range)
+{
+	u16 aux;
+	int ret;
+
+	aux = (range & 0x7) | AD5761_CTRL_ETS;
+
+	if (st->use_intref)
+		aux |= AD5761_CTRL_USE_INTVREF;
+
+	ret = _ad5761_spi_write(st, AD5761_ADDR_SW_FULL_RESET, 0);
+	if (ret)
+		return ret;
+
+	ret = _ad5761_spi_write(st, AD5761_ADDR_CTRL_WRITE_REG, aux);
+	if (ret)
+		return ret;
+
+	st->range = range;
+
+	return 0;
+}
+
+static int ad5761_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val,
+			   int *val2,
+			   long mask)
+{
+	struct ad5761_state *st;
+	int ret;
+	u16 aux;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = ad5761_spi_read(indio_dev, AD5761_ADDR_DAC_READ, &aux);
+		if (ret)
+			return ret;
+		*val = aux >> chan->scan_type.shift;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		st = iio_priv(indio_dev);
+		*val = st->vref * ad5761_range_params[st->range].m;
+		*val /= 10;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	case IIO_CHAN_INFO_OFFSET:
+		st = iio_priv(indio_dev);
+		*val = -(1 << chan->scan_type.realbits);
+		*val *=	ad5761_range_params[st->range].c;
+		*val /=	ad5761_range_params[st->range].m;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad5761_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val,
+			    int val2,
+			    long mask)
+{
+	u16 aux;
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	if (val2 || (val << chan->scan_type.shift) > 0xffff || val < 0)
+		return -EINVAL;
+
+	aux = val << chan->scan_type.shift;
+
+	return ad5761_spi_write(indio_dev, AD5761_ADDR_DAC_WRITE, aux);
+}
+
+static const struct iio_info ad5761_info = {
+	.read_raw = &ad5761_read_raw,
+	.write_raw = &ad5761_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+#define AD5761_CHAN(_bits) {				\
+	.type = IIO_VOLTAGE,				\
+	.output = 1,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |	\
+		BIT(IIO_CHAN_INFO_OFFSET),		\
+	.scan_type = {					\
+		.sign = 'u',				\
+		.realbits = (_bits),			\
+		.storagebits = 16,			\
+		.shift = 16 - (_bits),			\
+	},						\
+}
+
+static const struct ad5761_chip_info ad5761_chip_infos[] = {
+	[ID_AD5721] = {
+		.int_vref = 0,
+		.channel = AD5761_CHAN(12),
+	},
+	[ID_AD5721R] = {
+		.int_vref = 2500,
+		.channel = AD5761_CHAN(12),
+	},
+	[ID_AD5761] = {
+		.int_vref = 0,
+		.channel = AD5761_CHAN(16),
+	},
+	[ID_AD5761R] = {
+		.int_vref = 2500,
+		.channel = AD5761_CHAN(16),
+	},
+};
+
+static int ad5761_get_vref(struct ad5761_state *st,
+			   const struct ad5761_chip_info *chip_info)
+{
+	int ret;
+
+	st->vref_reg = devm_regulator_get_optional(&st->spi->dev, "vref");
+	if (PTR_ERR(st->vref_reg) == -ENODEV) {
+		/* Use Internal regulator */
+		if (!chip_info->int_vref) {
+			dev_err(&st->spi->dev,
+				"Voltage reference not found\n");
+			return -EIO;
+		}
+
+		st->use_intref = true;
+		st->vref = chip_info->int_vref;
+		return 0;
+	}
+
+	if (IS_ERR(st->vref_reg)) {
+		dev_err(&st->spi->dev,
+			"Error getting voltage reference regulator\n");
+		return PTR_ERR(st->vref_reg);
+	}
+
+	ret = regulator_enable(st->vref_reg);
+	if (ret) {
+		dev_err(&st->spi->dev,
+			 "Failed to enable voltage reference\n");
+		return ret;
+	}
+
+	ret = regulator_get_voltage(st->vref_reg);
+	if (ret < 0) {
+		dev_err(&st->spi->dev,
+			 "Failed to get voltage reference value\n");
+		goto disable_regulator_vref;
+	}
+
+	if (ret < 2000000 || ret > 3000000) {
+		dev_warn(&st->spi->dev,
+			 "Invalid external voltage ref. value %d uV\n", ret);
+		ret = -EIO;
+		goto disable_regulator_vref;
+	}
+
+	st->vref = ret / 1000;
+	st->use_intref = false;
+
+	return 0;
+
+disable_regulator_vref:
+	regulator_disable(st->vref_reg);
+	st->vref_reg = NULL;
+	return ret;
+}
+
+static int ad5761_probe(struct spi_device *spi)
+{
+	struct iio_dev *iio_dev;
+	struct ad5761_state *st;
+	int ret;
+	const struct ad5761_chip_info *chip_info =
+		&ad5761_chip_infos[spi_get_device_id(spi)->driver_data];
+	enum ad5761_voltage_range voltage_range = AD5761_VOLTAGE_RANGE_0V_5V;
+	struct ad5761_platform_data *pdata = dev_get_platdata(&spi->dev);
+
+	iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(iio_dev);
+
+	st->spi = spi;
+	spi_set_drvdata(spi, iio_dev);
+
+	ret = ad5761_get_vref(st, chip_info);
+	if (ret)
+		return ret;
+
+	if (pdata)
+		voltage_range = pdata->voltage_range;
+
+	ret = ad5761_spi_set_range(st, voltage_range);
+	if (ret)
+		goto disable_regulator_err;
+
+	iio_dev->dev.parent = &spi->dev;
+	iio_dev->info = &ad5761_info;
+	iio_dev->modes = INDIO_DIRECT_MODE;
+	iio_dev->channels = &chip_info->channel;
+	iio_dev->num_channels = 1;
+	iio_dev->name = spi_get_device_id(st->spi)->name;
+	ret = iio_device_register(iio_dev);
+	if (ret)
+		goto disable_regulator_err;
+
+	return 0;
+
+disable_regulator_err:
+	if (!IS_ERR_OR_NULL(st->vref_reg))
+		regulator_disable(st->vref_reg);
+
+	return ret;
+}
+
+static int ad5761_remove(struct spi_device *spi)
+{
+	struct iio_dev *iio_dev = spi_get_drvdata(spi);
+	struct ad5761_state *st = iio_priv(iio_dev);
+
+	iio_device_unregister(iio_dev);
+
+	if (!IS_ERR_OR_NULL(st->vref_reg))
+		regulator_disable(st->vref_reg);
+
+	return 0;
+}
+
+static const struct spi_device_id ad5761_id[] = {
+	{"ad5721", ID_AD5721},
+	{"ad5721r", ID_AD5721R},
+	{"ad5761", ID_AD5761},
+	{"ad5761r", ID_AD5761R},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, ad5761_id);
+
+static struct spi_driver ad5761_driver = {
+	.driver = {
+		   .name = "ad5761",
+		   },
+	.probe = ad5761_probe,
+	.remove = ad5761_remove,
+	.id_table = ad5761_id,
+};
+module_spi_driver(ad5761_driver);
+
+MODULE_AUTHOR("Ricardo Ribalda <ricardo.ribalda@gmail.com>");
+MODULE_DESCRIPTION("Analog Devices AD5721, AD5721R, AD5761, AD5761R driver");
+MODULE_LICENSE("GPL v2");

include/linux/platform_data/ad5761.h

@@ -0,0 +1,44 @@
+/*
+ * AD5721, AD5721R, AD5761, AD5761R, Voltage Output Digital to Analog Converter
+ *
+ * Copyright 2016 Qtechnology A/S
+ * 2016 Ricardo Ribalda <ricardo.ribalda@gmail.com>
+ *
+ * Licensed under the GPL-2.
+ */
+#ifndef __LINUX_PLATFORM_DATA_AD5761_H__
+#define __LINUX_PLATFORM_DATA_AD5761_H__
+
+/**
+ * enum ad5761_voltage_range - Voltage range the AD5761 is configured for.
+ * @AD5761_VOLTAGE_RANGE_M10V_10V:  -10V to  10V
+ * @AD5761_VOLTAGE_RANGE_0V_10V:      0V to  10V
+ * @AD5761_VOLTAGE_RANGE_M5V_5V:     -5V to   5V
+ * @AD5761_VOLTAGE_RANGE_0V_5V:       0V to   5V
+ * @AD5761_VOLTAGE_RANGE_M2V5_7V5: -2.5V to 7.5V
+ * @AD5761_VOLTAGE_RANGE_M3V_3V:     -3V to   3V
+ * @AD5761_VOLTAGE_RANGE_0V_16V:      0V to  16V
+ * @AD5761_VOLTAGE_RANGE_0V_20V:      0V to  20V
+ */
+
+enum ad5761_voltage_range {
+	AD5761_VOLTAGE_RANGE_M10V_10V,
+	AD5761_VOLTAGE_RANGE_0V_10V,
+	AD5761_VOLTAGE_RANGE_M5V_5V,
+	AD5761_VOLTAGE_RANGE_0V_5V,
+	AD5761_VOLTAGE_RANGE_M2V5_7V5,
+	AD5761_VOLTAGE_RANGE_M3V_3V,
+	AD5761_VOLTAGE_RANGE_0V_16V,
+	AD5761_VOLTAGE_RANGE_0V_20V,
+};
+
+/**
+ * struct ad5761_platform_data - AD5761 DAC driver platform data
+ * @voltage_range: Voltage range the AD5761 is configured for
+ */
+
+struct ad5761_platform_data {
+	enum ad5761_voltage_range voltage_range;
+};
+
+#endif