LTC1665/LTC1660 is a 8/10-bit Digital-to-Analog Converter
(DAC) with eight individual channels.

Signed-off-by: Marcus Folkesson <marcus.folkes...@gmail.com>
---
 drivers/iio/dac/Kconfig   |  10 ++
 drivers/iio/dac/Makefile  |   1 +
 drivers/iio/dac/ltc166x.c | 244 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 255 insertions(+)
 create mode 100644 drivers/iio/dac/ltc166x.c

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 76db0768e454..04cfa6bb9dc1 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -120,6 +120,16 @@ config AD5624R_SPI
          Say yes here to build support for Analog Devices AD5624R, AD5644R and
          AD5664R converters (DAC). This driver uses the common SPI interface.
 
+config LTC166X
+       tristate "Linear Technology LTC1660/LTC1665 DAC SPI driver"
+       depends on SPI
+       help
+         Say yes here to build support for Linear Technology
+         LTC1660 and LTC1665 Digital to Analog Converters.
+
+         To compile this driver as a module, choose M here: the
+         module will be called ltc166x.
+
 config LTC2632
        tristate "Linear Technology LTC2632-12/10/8 DAC spi driver"
        depends on SPI
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 81e710ed7491..380749c87c26 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_CIO_DAC) += cio-dac.o
 obj-$(CONFIG_DPOT_DAC) += dpot-dac.o
 obj-$(CONFIG_DS4424) += ds4424.o
 obj-$(CONFIG_LPC18XX_DAC) += lpc18xx_dac.o
+obj-$(CONFIG_LTC166X) += ltc166x.o
 obj-$(CONFIG_LTC2632) += ltc2632.o
 obj-$(CONFIG_M62332) += m62332.o
 obj-$(CONFIG_MAX517) += max517.o
diff --git a/drivers/iio/dac/ltc166x.c b/drivers/iio/dac/ltc166x.c
new file mode 100644
index 000000000000..0031f2b50f14
--- /dev/null
+++ b/drivers/iio/dac/ltc166x.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Linear Technology LTC1665/LTC1660, 8 channels DAC
+ *
+ * Copyright (C) 2018 Marcus Folkesson <marcus.folkes...@gmail.com>
+ */
+#include <linux/bitops.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+#define LTC166X_REG_WAKE       0x0
+#define LTC166X_REG_DAC_A      0x1
+#define LTC166X_REG_DAC_B      0x2
+#define LTC166X_REG_DAC_C      0x3
+#define LTC166X_REG_DAC_D      0x4
+#define LTC166X_REG_DAC_E      0x5
+#define LTC166X_REG_DAC_F      0x6
+#define LTC166X_REG_DAC_G      0x7
+#define LTC166X_REG_DAC_H      0x8
+#define LTC166X_REG_SLEEP      0xe
+
+#define LTC166X_NUM_CHANNELS   8
+
+static const struct regmap_config ltc166x_regmap_config = {
+       .reg_bits = 4,
+       .val_bits = 12,
+};
+
+enum ltc166x_supported_device_ids {
+       ID_LTC1660,
+       ID_LTC1665,
+};
+
+struct ltc166x_priv {
+       struct spi_device *spi;
+       struct regmap *regmap;
+       struct regulator *vref_reg;
+       unsigned int value[LTC166X_NUM_CHANNELS];
+       unsigned int vref_mv;
+};
+
+static int ltc166x_read_raw(struct iio_dev *indio_dev,
+               struct iio_chan_spec const *chan,
+               int *val,
+               int *val2,
+               long mask)
+{
+       struct ltc166x_priv *priv = iio_priv(indio_dev);
+
+       switch (mask) {
+       case IIO_CHAN_INFO_RAW:
+               *val = priv->value[chan->channel];
+               return IIO_VAL_INT;
+       case IIO_CHAN_INFO_SCALE:
+               *val = priv->vref_mv;
+               *val2 = chan->scan_type.realbits;
+               return IIO_VAL_FRACTIONAL_LOG2;
+       default:
+               return -EINVAL;
+       }
+}
+
+static int ltc166x_write_raw(struct iio_dev *indio_dev,
+               struct iio_chan_spec const *chan,
+               int val,
+               int val2,
+               long mask)
+{
+       struct ltc166x_priv *priv = iio_priv(indio_dev);
+
+       switch (mask) {
+       case IIO_CHAN_INFO_RAW:
+               if (val2 != 0)
+                       return -EINVAL;
+               if (val > GENMASK(chan->scan_type.realbits-1, 0))
+                       return -EINVAL;
+               priv->value[chan->channel] = val;
+               val <<= chan->scan_type.shift;
+               return regmap_write(priv->regmap, chan->channel, val);
+       default:
+               return -EINVAL;
+       }
+}
+
+#define LTC166X_CHAN(chan, bits) {                     \
+       .type = IIO_VOLTAGE,                            \
+       .indexed = 1,                                   \
+       .output = 1,                                    \
+       .channel = chan,                                \
+       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
+       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
+       .scan_type = {                                  \
+               .sign = 'u',                            \
+               .realbits = (bits),                     \
+               .storagebits = 16,                      \
+               .shift = 12 - (bits),                   \
+       },                                              \
+}
+
+#define  LTC166X_OCTAL_CHANNELS(bits) {                        \
+               LTC166X_CHAN(LTC166X_REG_DAC_A, bits),  \
+               LTC166X_CHAN(LTC166X_REG_DAC_B, bits),  \
+               LTC166X_CHAN(LTC166X_REG_DAC_C, bits),  \
+               LTC166X_CHAN(LTC166X_REG_DAC_D, bits),  \
+               LTC166X_CHAN(LTC166X_REG_DAC_E, bits),  \
+               LTC166X_CHAN(LTC166X_REG_DAC_F, bits),  \
+               LTC166X_CHAN(LTC166X_REG_DAC_G, bits),  \
+               LTC166X_CHAN(LTC166X_REG_DAC_H, bits),  \
+}
+
+static const struct iio_chan_spec ltc166x_channels[][LTC166X_NUM_CHANNELS] = {
+       [ID_LTC1660] = LTC166X_OCTAL_CHANNELS(10),
+       [ID_LTC1665] = LTC166X_OCTAL_CHANNELS(8),
+};
+
+static const struct iio_info ltc166x_info = {
+       .read_raw = &ltc166x_read_raw,
+       .write_raw = &ltc166x_write_raw,
+};
+
+static int __maybe_unused ltc166x_suspend(struct device *dev)
+{
+       struct ltc166x_priv *priv = iio_priv(spi_get_drvdata(
+                                               to_spi_device(dev)));
+       return regmap_write(priv->regmap, LTC166X_REG_SLEEP, 0x00);
+}
+
+static int __maybe_unused ltc166x_resume(struct device *dev)
+{
+       struct ltc166x_priv *priv = iio_priv(spi_get_drvdata(
+                                               to_spi_device(dev)));
+       return regmap_write(priv->regmap, LTC166X_REG_WAKE, 0x00);
+}
+static SIMPLE_DEV_PM_OPS(ltc166x_pm_ops, ltc166x_suspend, ltc166x_resume);
+
+static int ltc166x_probe(struct spi_device *spi)
+{
+       struct iio_dev *indio_dev;
+       struct ltc166x_priv *priv;
+       const struct spi_device_id *id = spi_get_device_id(spi);
+       int ret;
+
+       indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
+       if (indio_dev == NULL)
+               return -ENOMEM;
+
+       priv = iio_priv(indio_dev);
+       priv->regmap = devm_regmap_init_spi(spi, &ltc166x_regmap_config);
+       if (IS_ERR(priv->regmap)) {
+               dev_err(&spi->dev, "failed to register spi regmap %ld\n",
+                       PTR_ERR(priv->regmap));
+               return PTR_ERR(priv->regmap);
+       }
+
+       priv->vref_reg = devm_regulator_get(&spi->dev, "vref");
+       if (IS_ERR(priv->vref_reg)) {
+               dev_err(&spi->dev, "vref regulator not specified\n");
+               return PTR_ERR(priv->vref_reg);
+       }
+
+       ret = regulator_enable(priv->vref_reg);
+       if (ret) {
+               dev_err(&spi->dev, "failed to enable vref regulator: %d\n",
+                               ret);
+               return ret;
+       }
+
+       ret = regulator_get_voltage(priv->vref_reg);
+       if (ret < 0) {
+               dev_err(&spi->dev, "failed to read vref regulator: %d\n",
+                               ret);
+               goto error_disable_reg;
+       }
+       priv->vref_mv = ret / 1000;
+
+       priv->spi = spi;
+       spi_set_drvdata(spi, indio_dev);
+       indio_dev->dev.parent = &spi->dev;
+       indio_dev->info = &ltc166x_info;
+       indio_dev->modes = INDIO_DIRECT_MODE;
+       indio_dev->channels = ltc166x_channels[id->driver_data];
+       indio_dev->num_channels = LTC166X_NUM_CHANNELS;
+       indio_dev->name = id->name;
+
+       ret = iio_device_register(indio_dev);
+       if (ret) {
+               dev_err(&spi->dev, "failed to register iio device: %d\n",
+                               ret);
+               goto error_disable_reg;
+       }
+
+       return 0;
+
+error_disable_reg:
+       regulator_disable(priv->vref_reg);
+
+       return ret;
+}
+
+static int ltc166x_remove(struct spi_device *spi)
+{
+       struct iio_dev *indio_dev = spi_get_drvdata(spi);
+       struct ltc166x_priv *priv = iio_priv(indio_dev);
+
+       iio_device_unregister(indio_dev);
+       regulator_disable(priv->vref_reg);
+
+       return 0;
+}
+
+static const struct of_device_id ltc166x_dt_ids[] = {
+       { .compatible = "lltc,ltc1660", .data = (void *)ID_LTC1660 },
+       { .compatible = "lltc,ltc1665", .data = (void *)ID_LTC1665 },
+       { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ltc166x_dt_ids);
+
+static const struct spi_device_id ltc166x_id[] = {
+       {"ltc1660", ID_LTC1660},
+       {"ltc1665", ID_LTC1665},
+       { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(spi, ltc166x_id);
+
+static struct spi_driver ltc166x_driver = {
+       .driver = {
+               .name = "ltc166x",
+               .of_match_table = ltc166x_dt_ids,
+               .pm = &ltc166x_pm_ops,
+       },
+       .probe  = ltc166x_probe,
+       .remove = ltc166x_remove,
+       .id_table = ltc166x_id,
+};
+module_spi_driver(ltc166x_driver);
+
+MODULE_AUTHOR("Marcus Folkesson <marcus.folkes...@gmail.com>");
+MODULE_DESCRIPTION("Linear Technology LTC166X DAC");
+MODULE_LICENSE("GPL v2");
-- 
2.11.0.rc2

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