[PATCH 2/2] iio: dac: Introduce the TI DAC8771 DAC driver

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Adding the Texas Instruments single channel 16 bit DAC driver.
This device has configurable voltage and current output with 16 bit
resolution for offset and gain.

Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
---
 drivers/iio/dac/Kconfig      |   7 +
 drivers/iio/dac/Makefile     |   1 +
 drivers/iio/dac/ti-dac8771.c | 499 +++++++++++++++++++++++++++++++++++
 3 files changed, 507 insertions(+)
 create mode 100644 drivers/iio/dac/ti-dac8771.c

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 979070196da9..df7793113415 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -386,6 +386,13 @@ config TI_DAC7612
 
 	  If compiled as a module, it will be called ti-dac7612.
 
+config TI_DAC8771
+	tristate "Texas Instruments 16-bit single channel DAC driver"
+	depends on SPI_MASTER && GPIOLIB
+	help
+	  Driver for the Texas Instruments DAC8771.
+	  If compiled as a module, it will be called ti-dac8771.
+
 config VF610_DAC
 	tristate "Vybrid vf610 DAC driver"
 	depends on OF
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 1369fa1d2f0e..4aa6e35348cf 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -42,4 +42,5 @@ obj-$(CONFIG_TI_DAC082S085) += ti-dac082s085.o
 obj-$(CONFIG_TI_DAC5571) += ti-dac5571.o
 obj-$(CONFIG_TI_DAC7311) += ti-dac7311.o
 obj-$(CONFIG_TI_DAC7612) += ti-dac7612.o
+obj-$(CONFIG_TI_DAC8771) += ti-dac8771.o
 obj-$(CONFIG_VF610_DAC) += vf610_dac.o
diff --git a/drivers/iio/dac/ti-dac8771.c b/drivers/iio/dac/ti-dac8771.c
new file mode 100644
index 000000000000..309728212a07
--- /dev/null
+++ b/drivers/iio/dac/ti-dac8771.c
@@ -0,0 +1,499 @@
+// SPDX-License-Identifier: GPL-2.0
+// DAC8771 DAC
+// Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of_gpio.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/events.h>
+
+#define DAC8771_RESET		0x01
+#define DAC8771_RESET_CFG	0x02
+#define DAC8771_DAC_SELECT	0x03
+#define DAC8771_DAC_CFG		0x04
+#define DAC8771_DAC_DATA	0x05
+#define DAC8771_BUCK_BOOST_SEL	0x06
+#define DAC8771_BUCK_BOOST_CFG	0x07
+#define DAC8771_CH_CAL_EN	0x08
+#define DAC8771_CH_GAIN_CAL	0x09
+#define DAC8771_CH_OFF_CAL	0x0a
+#define DAC8771_STATUS		0x0b
+#define DAC8771_STATUS_MSK	0x0c
+#define DAC8771_ALARM_ACTION	0x0d
+#define DAC8771_ALARM_CODE	0x0e
+#define DAC8771_WDOG_RESET	0x10
+#define DAC8771_DEV_ID		0x11
+
+#define DAC8771_RESOLUTION	16
+
+/* Status register */
+#define DAC8771_OVERTEMP	BIT(4)
+#define DAC8771_DAC_FAULT	BIT(0)
+#define DAC8771_STATUS_MASK	(DAC8771_OVERTEMP | DAC8771_DAC_FAULT)
+
+#define DAC8771_READ_EN		BIT(7)
+
+#define DAC8771_SW_RESET	BIT(0)
+#define DAC8771_SPI_ENABLE	0
+#define DAC8771_SPI_DISABLE	1
+
+#define DAC8771_CHA_SEL		BIT(5)
+#define DAC8771_OUT_RANGE_MSK	GENMASK(3, 0)
+#define DAC8771_MAX_GAIN_OFF	65535
+
+#define DAC8771_OUT_RANGE_DEF	0x0
+#define DAC8771_OUT_RANGE_CURR_LOW	4
+#define DAC8771_OUT_RANGE_CURR_HIGH	7
+#define DAC8771_OUT_RANGE_MAX	12
+
+#define DAC8771_SELECT_A	BIT(0)
+
+/**
+ * struct dac8771_chip - TI DAC chip
+ * @lock: protects write sequences
+ * @vref: regulator generating Vref
+ * @spi: SPI device to send data to the device
+ * @ldac: load DAC GPIO
+ * @reset: reset GPIO
+ * @chan_type: Type of IIO channel either VOLTAGE or CURRENT
+ * @output_range: output range of the device
+ * @val: cached value
+ * @buf: buffer for transfer data
+ */
+struct dac8771_chip {
+	struct mutex lock;
+	struct regulator *vref;
+	struct spi_device *spi;
+	struct gpio_desc *ldac;
+	struct gpio_desc *reset;
+	enum iio_chan_type chan_type;
+	u8 output_range;
+	u16 val;
+	union {
+		__be32 d32;
+		__be16 d16;
+		u8 d8[3];
+	} data[3] ____cacheline_aligned;
+};
+
+static int dac8771_write(struct dac8771_chip *dac8771,
+			 unsigned int reg, int val)
+{
+	u8 data[3];
+
+	data[0] = reg;
+	data[1] = val >> 8;
+	data[2] = val & 0xff;
+
+	return spi_write(dac8771->spi, &data, sizeof(data));
+}
+
+static int dac8771_read(struct dac8771_chip *dac8771, unsigned int reg)
+{
+	int ret;
+	struct spi_transfer t[] = {
+		{
+			.tx_buf = &dac8771->data[0].d8[0],
+			.len = 3,
+			.cs_change = 1,
+		}, {
+			.tx_buf = &dac8771->data[1].d8[0],
+			.rx_buf = &dac8771->data[2].d8[0],
+			.len = 3,
+		},
+	};
+
+	dac8771->data[0].d8[0] = (DAC8771_READ_EN | reg);
+
+	ret = spi_sync_transfer(dac8771->spi, t, ARRAY_SIZE(t));
+	if (ret < 0)
+		return ret;
+
+	return (dac8771->data[2].d8[1] << 8 | dac8771->data[2].d8[2]);
+}
+
+static int dac8771_sync_write(struct dac8771_chip *dac8771,
+			      unsigned int reg, int val)
+{
+	int ret;
+
+	ret = dac8771_write(dac8771, reg, val);
+	if (ret)
+		return ret;
+
+	if (dac8771->ldac) {
+		gpiod_set_value(dac8771->ldac, 1);
+		gpiod_set_value(dac8771->ldac, 0);
+	}
+
+	return ret;
+}
+
+static int dac8771_reset(struct dac8771_chip *dac8771)
+{
+	if (dac8771->reset) {
+		gpiod_set_value(dac8771->reset, 0);
+		gpiod_set_value(dac8771->reset, 1);
+	} else {
+		return dac8771_sync_write(dac8771, DAC8771_RESET,
+					  DAC8771_SW_RESET);
+	}
+
+	return 0;
+}
+
+static int dac8771_update_bits(struct dac8771_chip *dac8771, unsigned int reg,
+			       int mask, int val)
+{
+	int write_val;
+	int tmp;
+
+	tmp = dac8771_read(dac8771, reg);
+	if (tmp < 0)
+		return tmp;
+
+	write_val = (tmp & ~mask);
+	write_val |= val & mask;
+
+	return dac8771_write(dac8771, reg, write_val);
+}
+
+static int dac8771_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct dac8771_chip *dac8771 = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		*val = dac8771->val;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		ret = regulator_get_voltage(dac8771->vref);
+		if (ret < 0)
+			return ret;
+
+		*val = ret / 1000;
+		*val2 = DAC8771_RESOLUTION;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	case IIO_CHAN_INFO_OFFSET:
+		mutex_lock(&dac8771->lock);
+		ret = dac8771_read(dac8771, DAC8771_CH_OFF_CAL);
+		mutex_unlock(&dac8771->lock);
+
+		if (ret < 0)
+			return ret;
+
+		*val = ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		mutex_lock(&dac8771->lock);
+		ret = dac8771_read(dac8771, DAC8771_CH_GAIN_CAL);
+		mutex_unlock(&dac8771->lock);
+
+		if (ret < 0)
+			return ret;
+
+		*val = ret;
+		return IIO_VAL_INT;
+	default:
+		ret = -EINVAL;
+	}
+
+	return -EINVAL;
+}
+
+static int dac8771_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long mask)
+{
+	struct dac8771_chip *dac8771 = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&dac8771->lock);
+		ret = dac8771_sync_write(dac8771, DAC8771_DAC_DATA, val);
+		if (!ret)
+			dac8771->val = val;
+		break;
+	case IIO_CHAN_INFO_ENABLE:
+		if (val)
+			val = DAC8771_CHA_SEL;
+		else
+			val = 0;
+
+		mutex_lock(&dac8771->lock);
+
+		ret = dac8771_update_bits(dac8771, DAC8771_DAC_SELECT,
+					  DAC8771_CHA_SEL, val);
+		if (ret)
+			goto io_err;
+
+		ret = dac8771_update_bits(dac8771, DAC8771_DAC_CFG,
+				   DAC8771_OUT_RANGE_MSK,
+				   dac8771->output_range);
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		if (val > DAC8771_MAX_GAIN_OFF)
+			return -EINVAL;
+
+		mutex_lock(&dac8771->lock);
+		ret = dac8771_sync_write(dac8771, DAC8771_CH_OFF_CAL, val);
+		break;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		if (val > DAC8771_MAX_GAIN_OFF)
+			return -EINVAL;
+
+		mutex_lock(&dac8771->lock);
+		ret = dac8771_sync_write(dac8771, DAC8771_CH_GAIN_CAL, val);
+		break;
+	default:
+		return -EINVAL;
+	}
+io_err:
+	mutex_unlock(&dac8771->lock);
+	return ret;
+}
+
+static int dac8771_write_raw_get_fmt(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan, long mask)
+{
+	return IIO_VAL_INT;
+}
+
+static irqreturn_t dac8771_event_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct dac8771_chip *dac8771 = iio_priv(indio_dev);
+	int clear_bits = 0;
+	int ret;
+
+	ret = dac8771_read(dac8771, DAC8771_STATUS);
+
+	if (ret & DAC8771_OVERTEMP) {
+		iio_push_event(private,
+			       IIO_UNMOD_EVENT_CODE(IIO_TEMP,
+			       0, IIO_EV_TYPE_THRESH, IIO_EV_DIR_RISING),
+			       iio_get_time_ns(private));
+		clear_bits = DAC8771_OVERTEMP;
+	}
+
+	if (ret & DAC8771_DAC_FAULT) {
+		iio_push_event(private,
+			       IIO_UNMOD_EVENT_CODE(dac8771->chan_type,
+			       0, IIO_EV_TYPE_CHANGE, IIO_EV_DIR_NONE),
+			       iio_get_time_ns(private));
+
+		clear_bits |= DAC8771_DAC_FAULT;
+	}
+
+	ret = dac8771_update_bits(dac8771, DAC8771_STATUS, DAC8771_STATUS_MASK,
+				  clear_bits);
+	if (ret)
+		dev_err(&dac8771->spi->dev,
+			"Failed to clear status register\n");
+
+	return IRQ_HANDLED;
+}
+
+static const struct iio_info dac8771_info = {
+	.read_raw	   = dac8771_read_raw,
+	.write_raw	   = dac8771_write_raw,
+	.write_raw_get_fmt = dac8771_write_raw_get_fmt,
+};
+
+static int dac8771_probe_dt(struct dac8771_chip *dac8771)
+{
+	u32 range;
+	int ret;
+
+	dac8771->ldac = devm_gpiod_get_optional(&dac8771->spi->dev, "loaddacs",
+						 GPIOD_OUT_HIGH);
+	if (IS_ERR(dac8771->ldac)) {
+		ret = PTR_ERR(dac8771->ldac);
+		if (ret != -ENODEV) {
+			if (ret != -EPROBE_DEFER)
+				dev_err(&dac8771->spi->dev,
+					"Failed to get loaddacs gpio: %d\n",
+					ret);
+			return ret;
+		}
+		dac8771->ldac = NULL;
+	}
+
+	dac8771->reset = devm_gpiod_get_optional(&dac8771->spi->dev, "reset",
+						 GPIOD_OUT_HIGH);
+	if (IS_ERR(dac8771->reset)) {
+		ret = PTR_ERR(dac8771->reset);
+		if (ret != -ENODEV) {
+			if (ret != -EPROBE_DEFER)
+				dev_err(&dac8771->spi->dev,
+					"Failed to get reset gpio: %d\n",
+					ret);
+			return ret;
+		}
+		dac8771->reset = NULL;
+	}
+
+	ret = device_property_read_u32(&dac8771->spi->dev, "ti,output-range",
+				      &range);
+	if (ret) {
+		dev_err(&dac8771->spi->dev,
+			"Output range is not set using default\n");
+		range = DAC8771_OUT_RANGE_DEF;
+	} else {
+		if (dac8771->output_range < DAC8771_OUT_RANGE_DEF ||
+		    dac8771->output_range > DAC8771_OUT_RANGE_MAX) {
+			dev_err(&dac8771->spi->dev,
+				"Output range is invalid\n");
+			return -EINVAL;
+		}
+	}
+
+	dac8771->output_range = range;
+	if ((dac8771->output_range >= DAC8771_OUT_RANGE_CURR_LOW &&
+	    dac8771->output_range <= DAC8771_OUT_RANGE_CURR_HIGH) ||
+	    dac8771->output_range == DAC8771_OUT_RANGE_MAX)
+		dac8771->chan_type = IIO_CURRENT;
+	else
+		dac8771->chan_type = IIO_VOLTAGE;
+
+	return 0;
+}
+
+static int dac8771_init(struct dac8771_chip *dac8771)
+{
+	int ret;
+
+	ret = dac8771_reset(dac8771);
+	if (ret)
+		return ret;
+
+	return dac8771_write(dac8771, DAC8771_BUCK_BOOST_SEL, DAC8771_SELECT_A);
+}
+
+static int dac8771_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct dac8771_chip *dac8771;
+	struct iio_dev *indio_dev;
+	struct iio_chan_spec *chan;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*dac8771));
+	if (!indio_dev) {
+		dev_err(dev, "can not allocate iio device\n");
+		return -ENOMEM;
+	}
+
+	spi->mode = SPI_MODE_2;
+	spi_setup(spi);
+	spi_set_drvdata(spi, indio_dev);
+
+	dac8771 = iio_priv(indio_dev);
+	dac8771->spi = spi;
+
+	ret = dac8771_probe_dt(dac8771);
+	if (ret)
+		return ret;
+
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = spi->dev.of_node;
+	indio_dev->info = &dac8771_info;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->num_channels = 1;
+
+	chan = devm_kzalloc(&indio_dev->dev, sizeof(struct iio_chan_spec),
+			    GFP_KERNEL);
+
+	chan->type = dac8771->chan_type;
+	chan->channel = 0;
+	chan->output = true;
+	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
+	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			      BIT(IIO_CHAN_INFO_OFFSET) |
+			      BIT(IIO_CHAN_INFO_HARDWAREGAIN) |
+			      BIT(IIO_CHAN_INFO_ENABLE) |
+			      BIT(IIO_CHAN_INFO_SCALE);
+
+	indio_dev->channels = chan;
+
+	dac8771->vref = devm_regulator_get(&dac8771->spi->dev, "vref");
+	if (IS_ERR(dac8771->vref)) {
+		dev_err(&dac8771->spi->dev, "error to get regulator\n");
+		return PTR_ERR(dac8771->vref);
+	}
+
+	ret = regulator_enable(dac8771->vref);
+	if (ret < 0) {
+		dev_err(dev, "can not enable regulator\n");
+		return ret;
+	}
+
+	mutex_init(&dac8771->lock);
+
+	if (spi->irq) {
+		ret = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
+						&dac8771_event_handler,
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					  spi_get_device_id(dac8771->spi)->name,
+						indio_dev);
+		if (ret)
+			goto err;
+	}
+
+	ret = dac8771_init(dac8771);
+	if (ret)
+		goto err;
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+err:
+	mutex_destroy(&dac8771->lock);
+	regulator_disable(dac8771->vref);
+	return ret;
+}
+
+static int dac8771_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct dac8771_chip *dac8771 = iio_priv(indio_dev);
+
+	mutex_destroy(&dac8771->lock);
+	regulator_disable(dac8771->vref);
+	return 0;
+}
+
+static const struct of_device_id dac8771_of_id[] = {
+	{ .compatible = "ti,dac8771" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, dac8771_of_id);
+
+static const struct spi_device_id dac8771_spi_id[] = {
+	{ "dac8771", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, dac8771_spi_id);
+
+static struct spi_driver dac8771_driver = {
+	.driver = {
+		.name		= "ti-dac8771",
+		.of_match_table	= dac8771_of_id,
+	},
+	.probe	  = dac8771_probe,
+	.remove   = dac8771_remove,
+	.id_table = dac8771_spi_id,
+};
+module_spi_driver(dac8771_driver);
+
+MODULE_AUTHOR("Dan Murphy <dmurphy@xxxxxx>");
+MODULE_DESCRIPTION("Texas Instruments DAC8771 driver");
+MODULE_LICENSE("GPL v2");
-- 
2.23.0




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