3 files changed, 232 insertions, 0 deletions
diff --git a/drivers/iio/resolver/Kconfig b/drivers/iio/resolver/Kconfig
new file mode 100644
index 000000000000..2ced9f22aa70
--- /dev/null
+++ b/drivers/iio/resolver/Kconfig
@@ -0,0 +1,17 @@
+#
+# Resolver/Synchro drivers
+#
+menu "Resolver to digital converters"
+
+config AD2S1200
+	tristate "Analog Devices ad2s1200/ad2s1205 driver"
+	depends on SPI
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say yes here to build support for Analog Devices spi resolver
+	  to digital converters, ad2s1200 and ad2s1205, provides direct access
+	  via sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad2s1200.
+endmenu
diff --git a/drivers/iio/resolver/Makefile b/drivers/iio/resolver/Makefile
new file mode 100644
index 000000000000..4e1dccae07e7
--- /dev/null
+++ b/drivers/iio/resolver/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for Resolver/Synchro drivers
+#
+
+obj-$(CONFIG_AD2S1200) += ad2s1200.o
diff --git a/drivers/iio/resolver/ad2s1200.c b/drivers/iio/resolver/ad2s1200.c
new file mode 100644
index 000000000000..28e618af9939
--- /dev/null
+++ b/drivers/iio/resolver/ad2s1200.c
@@ -0,0 +1,210 @@
+/*
+ * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
+ * AD2S1200/1205
+ *
+ * Copyright (c) 2018-2018 David Veenstra <davidjulianveenstra@gmail.com>
+ * Copyright (c) 2010-2010 Analog Devices Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/spi/spi.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define DRV_NAME "ad2s1200"
+
+/* input clock on serial interface */
+#define AD2S1200_HZ	8192000
+/* clock period in nano second */
+#define AD2S1200_TSCLK	(1000000000 / AD2S1200_HZ)
+
+/**
+ * struct ad2s1200_state - driver instance specific data.
+ * @lock:	protects both the GPIO pins and the rx buffer.
+ * @sdev:	spi device.
+ * @sample:	GPIO pin SAMPLE.
+ * @rdvel:	GPIO pin RDVEL.
+ * @rx:		buffer for spi transfers.
+ */
+struct ad2s1200_state {
+	struct mutex lock;
+	struct spi_device *sdev;
+	struct gpio_desc *sample;
+	struct gpio_desc *rdvel;
+	__be16 rx ____cacheline_aligned;
+};
+
+static int ad2s1200_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val,
+			     int *val2,
+			     long m)
+{
+	struct ad2s1200_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (m) {
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_ANGL:
+			/* 2 * Pi / (2^12 - 1) ~= 0.001534355 */
+			*val = 0;
+			*val2 = 1534355;
+			return IIO_VAL_INT_PLUS_NANO;
+		case IIO_ANGL_VEL:
+			/* 2 * Pi ~= 6.283185 */
+			*val = 6;
+			*val2 = 283185;
+			return IIO_VAL_INT_PLUS_MICRO;
+		default:
+			return -EINVAL;
+		}
+		break;
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&st->lock);
+		gpiod_set_value(st->sample, 0);
+
+		/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
+		udelay(1);
+		gpiod_set_value(st->sample, 1);
+		gpiod_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
+
+		ret = spi_read(st->sdev, &st->rx, 2);
+		if (ret < 0) {
+			mutex_unlock(&st->lock);
+			return ret;
+		}
+
+		switch (chan->type) {
+		case IIO_ANGL:
+			*val = be16_to_cpup(&st->rx) >> 4;
+			break;
+		case IIO_ANGL_VEL:
+			*val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
+			break;
+		default:
+			mutex_unlock(&st->lock);
+			return -EINVAL;
+		}
+
+		/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
+		udelay(1);
+		mutex_unlock(&st->lock);
+
+		return IIO_VAL_INT;
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_chan_spec ad2s1200_channels[] = {
+	{
+		.type = IIO_ANGL,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+	}, {
+		.type = IIO_ANGL_VEL,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+	}
+};
+
+static const struct iio_info ad2s1200_info = {
+	.read_raw = ad2s1200_read_raw,
+};
+
+static int ad2s1200_probe(struct spi_device *spi)
+{
+	struct ad2s1200_state *st;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, indio_dev);
+	st = iio_priv(indio_dev);
+	mutex_init(&st->lock);
+	st->sdev = spi;
+
+	st->sample = devm_gpiod_get(&spi->dev, "adi,sample", GPIOD_OUT_LOW);
+	if (IS_ERR(st->sample)) {
+		dev_err(&spi->dev, "Failed to claim SAMPLE gpio: err=%ld\n",
+			PTR_ERR(st->sample));
+		return PTR_ERR(st->sample);
+	}
+
+	st->rdvel = devm_gpiod_get(&spi->dev, "adi,rdvel", GPIOD_OUT_LOW);
+	if (IS_ERR(st->rdvel)) {
+		dev_err(&spi->dev, "Failed to claim RDVEL gpio: err=%ld\n",
+			PTR_ERR(st->rdvel));
+		return PTR_ERR(st->rdvel);
+	}
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->info = &ad2s1200_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ad2s1200_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
+	indio_dev->name = spi_get_device_id(spi)->name;
+
+	spi->max_speed_hz = AD2S1200_HZ;
+	spi->mode = SPI_MODE_3;
+	ret = spi_setup(spi);
+
+	if (ret < 0) {
+		dev_err(&spi->dev, "spi_setup failed!\n");
+		return ret;
+	}
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct of_device_id ad2s1200_of_match[] = {
+	{ .compatible = "adi,ad2s1200", },
+	{ .compatible = "adi,ad2s1205", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ad2s1200_of_match);
+
+static const struct spi_device_id ad2s1200_id[] = {
+	{ "ad2s1200" },
+	{ "ad2s1205" },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, ad2s1200_id);
+
+static struct spi_driver ad2s1200_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.of_match_table = of_match_ptr(ad2s1200_of_match),
+	},
+	.probe = ad2s1200_probe,
+	.id_table = ad2s1200_id,
+};
+module_spi_driver(ad2s1200_driver);
+
+MODULE_AUTHOR("David Veenstra <davidjulianveenstra@gmail.com>");
+MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
+MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
+MODULE_LICENSE("GPL v2");