[RFC PATCH] one-bit-adc-dac: Add initial version of one bit ADC, DAC

[Cristian Pop <cristian.pop@analog.com>]

Implementation for 1-bit ADC (comparator) and a 1-bit DAC (switch)

Signed-off-by: Cristian Pop <cristian.pop@analog.com>
---
 drivers/iio/addac/one-bit-adc-dac.c | 229 ++++++++++++++++++++++++++++
 1 file changed, 229 insertions(+)
 create mode 100644 drivers/iio/addac/one-bit-adc-dac.c

diff --git a/drivers/iio/addac/one-bit-adc-dac.c b/drivers/iio/addac/one-bit-adc-dac.c
new file mode 100644
index 000000000000..8e2a8a09fedb
--- /dev/null
+++ b/drivers/iio/addac/one-bit-adc-dac.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices ONE_BIT_ADC_DAC
+ * Digital to Analog Converters driver
+ *
+ * Copyright 2019 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/platform_device.h>
+#include <linux/gpio/consumer.h>
+
+enum ch_direction {
+	CH_IN,
+	CH_OUT,
+};
+
+struct one_bit_adc_dac_state {
+	struct platform_device  *pdev;
+	struct gpio_descs       *in_gpio_descs;
+	struct gpio_descs       *out_gpio_descs;
+};
+
+ #define ONE_BIT_ADC_DAC_CHANNEL(idx, direction)			\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.indexed = 1,						\
+		.channel = idx,						\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.output = direction,					\
+	}
+
+static int one_bit_adc_dac_read_raw(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan, int *val, int *val2, long info)
+{
+	struct one_bit_adc_dac_state *st = iio_priv(indio_dev);
+	int in_num_ch = 0, out_num_ch = 0;
+	int channel = chan->channel;
+
+	if (st->in_gpio_descs)
+		in_num_ch = st->in_gpio_descs->ndescs;
+
+	if (st->out_gpio_descs)
+		out_num_ch = st->out_gpio_descs->ndescs;
+
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+		if (channel < in_num_ch) {
+			*val = gpiod_get_value_cansleep(
+				st->in_gpio_descs->desc[channel]);
+		} else {
+			channel -= in_num_ch;
+			*val = gpiod_get_value_cansleep(
+				st->out_gpio_descs->desc[channel]);
+		}
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int one_bit_adc_dac_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val,
+			    int val2,
+			    long info)
+{
+	struct one_bit_adc_dac_state *st = iio_priv(indio_dev);
+	int in_num_ch = 0, out_num_ch = 0;
+	int channel = chan->channel;
+
+	if (st->in_gpio_descs)
+		in_num_ch = st->in_gpio_descs->ndescs;
+
+	if (st->out_gpio_descs)
+		out_num_ch = st->out_gpio_descs->ndescs;
+
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+		if (channel < in_num_ch) {
+			gpiod_set_value_cansleep(
+				st->in_gpio_descs->desc[channel], val);
+		} else {
+			channel -= in_num_ch;
+			gpiod_set_value_cansleep(
+				st->out_gpio_descs->desc[channel], val);
+		}
+
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info one_bit_adc_dac_info = {
+	.read_raw = &one_bit_adc_dac_read_raw,
+	.write_raw = &one_bit_adc_dac_write_raw,
+};
+
+static int one_bit_adc_dac_set_ch(struct iio_dev *indio_dev,
+					struct iio_chan_spec *channels,
+					const char *propname,
+					int num_ch,
+					enum ch_direction direction,
+					int offset)
+{
+	struct one_bit_adc_dac_state *st = iio_priv(indio_dev);
+	const char **gpio_names;
+	int ret, i;
+
+	if (num_ch <= 0)
+		return 0;
+
+	gpio_names = devm_kcalloc(indio_dev->dev.parent,
+					num_ch,
+					sizeof(char *),
+					GFP_KERNEL);
+	if (!gpio_names)
+		return -ENOMEM;
+
+	ret = device_property_read_string_array(&st->pdev->dev,
+					propname,
+					gpio_names,
+					num_ch);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < num_ch; i++) {
+		channels[i] = (struct iio_chan_spec)ONE_BIT_ADC_DAC_CHANNEL(i +
+							offset,
+							direction);
+		channels[i].extend_name = gpio_names[i];
+	}
+
+	return 0;
+}
+
+static int one_bit_adc_dac_parse_dt(struct iio_dev *indio_dev)
+{
+	struct one_bit_adc_dac_state *st = iio_priv(indio_dev);
+	struct iio_chan_spec *channels;
+	int ret, in_num_ch = 0, out_num_ch = 0;
+
+	st->in_gpio_descs = devm_gpiod_get_array_optional(&st->pdev->dev,
+						"in", GPIOD_IN);
+	if (IS_ERR(st->in_gpio_descs))
+		return PTR_ERR(st->in_gpio_descs);
+
+	if (st->in_gpio_descs)
+		in_num_ch = st->in_gpio_descs->ndescs;
+
+	st->out_gpio_descs = devm_gpiod_get_array_optional(&st->pdev->dev,
+						"out", GPIOD_OUT_HIGH);
+	if (IS_ERR(st->out_gpio_descs))
+		return PTR_ERR(st->out_gpio_descs);
+
+	if (st->out_gpio_descs)
+		out_num_ch = st->out_gpio_descs->ndescs;
+
+	channels = devm_kcalloc(indio_dev->dev.parent, (in_num_ch + out_num_ch),
+				sizeof(struct iio_chan_spec), GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	ret = one_bit_adc_dac_set_ch(indio_dev, &channels[0],
+					"in-gpio-names", in_num_ch,
+					CH_IN, 0);
+	if (ret < 0)
+		return ret;
+
+	ret = one_bit_adc_dac_set_ch(indio_dev, &channels[in_num_ch],
+					"out-gpio-names", out_num_ch,
+					CH_OUT, in_num_ch);
+	if (ret < 0)
+		return ret;
+
+	indio_dev->channels = channels;
+	indio_dev->num_channels = in_num_ch + out_num_ch;
+
+	return 0;
+}
+
+static int one_bit_adc_dac_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct one_bit_adc_dac_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->pdev = pdev;
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->name = "one-bit-adc-dac";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &one_bit_adc_dac_info;
+
+	ret = one_bit_adc_dac_parse_dt(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	platform_set_drvdata(pdev, indio_dev);
+	return devm_iio_device_register(indio_dev->dev.parent, indio_dev);
+}
+
+static const struct of_device_id one_bit_adc_dac_dt_match[] = {
+	{ .compatible = "adi,one-bit-adc-dac" },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, one_bit_adc_dac_dt_match);
+
+static struct platform_driver one_bit_adc_dac_driver = {
+	.driver = {
+		.name = "one-bit-adc-dac",
+		.of_match_table = one_bit_adc_dac_dt_match,
+	},
+	.probe = one_bit_adc_dac_probe,
+};
+
+module_platform_driver(one_bit_adc_dac_driver);
+
+MODULE_AUTHOR("Cristian Pop <cristian.pop@analog.com>");
+MODULE_DESCRIPTION("Analog Devices ONE_BIT_ADC_DAC");
+MODULE_LICENSE("GPL v2");
-- 
2.17.1