[PATCH v2 1/3] iio: dac: add support for ltc1660

Marcus Folkesson
2018-08-21T19:55:34Z

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

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---

Notes:
v2:
- rename all instances of ltc166x to ltc1660
- read regulator value "in-place" instead of cache voltage
- fix error handling in ltc1660_write_raw

drivers/iio/dac/Kconfig | 10 ++
drivers/iio/dac/Makefile | 1 +
drivers/iio/dac/ltc1660.c | 250 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 261 insertions(+)
create mode 100644 drivers/iio/dac/ltc1660.c

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 76db0768e454..cbee80bd111e 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 LTC1660
+ 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 ltc1660.
+
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..e446eeb09c85 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-$(CONFIG_LTC1660) += ltc1660.o
obj-$(CONFIG_LTC2632) += ltc2632.o
obj-$(CONFIG_M62332) += m62332.o
obj-$(CONFIG_MAX517) += max517.o
diff --git a/drivers/iio/dac/ltc1660.c b/drivers/iio/dac/ltc1660.c
new file mode 100644
index 000000000000..10866838c72a
--- /dev/null
+++ b/drivers/iio/dac/ltc1660.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Linear Technology LTC1665/LTC1660, 8 channels DAC
+ *
+ * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@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 LTC1660_REG_WAKE 0x0
+#define LTC1660_REG_DAC_A 0x1
+#define LTC1660_REG_DAC_B 0x2
+#define LTC1660_REG_DAC_C 0x3
+#define LTC1660_REG_DAC_D 0x4
+#define LTC1660_REG_DAC_E 0x5
+#define LTC1660_REG_DAC_F 0x6
+#define LTC1660_REG_DAC_G 0x7
+#define LTC1660_REG_DAC_H 0x8
+#define LTC1660_REG_SLEEP 0xe
+
+#define LTC1660_NUM_CHANNELS 8
+
+static const struct regmap_config ltc1660_regmap_config = {
+ .reg_bits = 4,
+ .val_bits = 12,
+};
+
+enum ltc1660_supported_device_ids {
+ ID_LTC1660,
+ ID_LTC1665,
+};
+
+struct ltc1660_priv {
+ struct spi_device *spi;
+ struct regmap *regmap;
+ struct regulator *vref_reg;
+ unsigned int value[LTC1660_NUM_CHANNELS];
+ unsigned int vref_mv;
+};
+
+static int ltc1660_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long mask)
+{
+ struct ltc1660_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 = regulator_get_voltage(priv->vref_reg);
+ if (*val < 0) {
+ dev_err(&priv->spi->dev, "failed to read vref regulator: %d\n",
+ *val);
+ return *val;
+ }
+
+ /* Convert to mV */
+ *val /= 1000;
+ *val2 = chan->scan_type.realbits;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ltc1660_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val,
+ int val2,
+ long mask)
+{
+ struct ltc1660_priv *priv = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (val2 != 0)
+ return -EINVAL;
+
+ if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
+ return -EINVAL;
+
+ ret = regmap_write(priv->regmap, chan->channel,
+ (val << chan->scan_type.shift));
+ if (!ret)
+ priv->value[chan->channel] = val;
+
+ return ret;
+ default:
+ return -EINVAL;
+ }
+}
+
+#define LTC1660_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 LTC1660_OCTAL_CHANNELS(bits) { \
+ LTC1660_CHAN(LTC1660_REG_DAC_A, bits), \
+ LTC1660_CHAN(LTC1660_REG_DAC_B, bits), \
+ LTC1660_CHAN(LTC1660_REG_DAC_C, bits), \
+ LTC1660_CHAN(LTC1660_REG_DAC_D, bits), \
+ LTC1660_CHAN(LTC1660_REG_DAC_E, bits), \
+ LTC1660_CHAN(LTC1660_REG_DAC_F, bits), \
+ LTC1660_CHAN(LTC1660_REG_DAC_G, bits), \
+ LTC1660_CHAN(LTC1660_REG_DAC_H, bits), \
+}
+
+static const struct iio_chan_spec ltc1660_channels[][LTC1660_NUM_CHANNELS] = {
+ [ID_LTC1660] = LTC1660_OCTAL_CHANNELS(10),
+ [ID_LTC1665] = LTC1660_OCTAL_CHANNELS(8),
+};
+
+static const struct iio_info ltc1660_info = {
+ .read_raw = &ltc1660_read_raw,
+ .write_raw = &ltc1660_write_raw,
+};
+
+static int __maybe_unused ltc1660_suspend(struct device *dev)
+{
+ struct ltc1660_priv *priv = iio_priv(spi_get_drvdata(
+ to_spi_device(dev)));
+ return regmap_write(priv->regmap, LTC1660_REG_SLEEP, 0x00);
+}
+
+static int __maybe_unused ltc1660_resume(struct device *dev)
+{
+ struct ltc1660_priv *priv = iio_priv(spi_get_drvdata(
+ to_spi_device(dev)));
+ return regmap_write(priv->regmap, LTC1660_REG_WAKE, 0x00);
+}
+static SIMPLE_DEV_PM_OPS(ltc1660_pm_ops, ltc1660_suspend, ltc1660_resume);
+
+static int ltc1660_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct ltc1660_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, &ltc1660_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;
+ }
+
+ priv->spi = spi;
+ spi_set_drvdata(spi, indio_dev);
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->info = &ltc1660_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = ltc1660_channels[id->driver_data];
+ indio_dev->num_channels = LTC1660_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 ltc1660_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct ltc1660_priv *priv = iio_priv(indio_dev);
+
+ iio_device_unregister(indio_dev);
+ regulator_disable(priv->vref_reg);
+
+ return 0;
+}
+
+static const struct of_device_id ltc1660_dt_ids[] = {
+ { .compatible = "lltc,ltc1660", .data = (void *)ID_LTC1660 },
+ { .compatible = "lltc,ltc1665", .data = (void *)ID_LTC1665 },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ltc1660_dt_ids);
+
+static const struct spi_device_id ltc1660_id[] = {
+ {"ltc1660", ID_LTC1660},
+ {"ltc1665", ID_LTC1665},
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(spi, ltc1660_id);
+
+static struct spi_driver ltc1660_driver = {
+ .driver = {
+ .name = "ltc1660",
+ .of_match_table = ltc1660_dt_ids,
+ .pm = &ltc1660_pm_ops,
+ },
+ .probe = ltc1660_probe,
+ .remove = ltc1660_remove,
+ .id_table = ltc1660_id,
+};
+module_spi_driver(ltc1660_driver);
+
+MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
+MODULE_DESCRIPTION("Linear Technology LTC1660/LTC1665 DAC");
+MODULE_LICENSE("GPL v2");
--
2.11.0.rc2