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-rw-r--r--drivers/iio/resolver/ad2s90.c130
1 files changed, 130 insertions, 0 deletions
diff --git a/drivers/iio/resolver/ad2s90.c b/drivers/iio/resolver/ad2s90.c
new file mode 100644
index 000000000..be6836e55
--- /dev/null
+++ b/drivers/iio/resolver/ad2s90.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90
+ *
+ * Copyright (c) 2010-2010 Analog Devices Inc.
+ */
+#include <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/device.h>
+#include <linux/spi/spi.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+/*
+ * Although chip's max frequency is 2Mhz, it needs 600ns between CS and the
+ * first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7)
+ */
+#define AD2S90_MAX_SPI_FREQ_HZ 830000
+
+struct ad2s90_state {
+ struct mutex lock; /* lock to protect rx buffer */
+ struct spi_device *sdev;
+ u8 rx[2] __aligned(IIO_DMA_MINALIGN);
+};
+
+static int ad2s90_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long m)
+{
+ int ret;
+ struct ad2s90_state *st = iio_priv(indio_dev);
+
+ if (chan->type != IIO_ANGL)
+ return -EINVAL;
+
+ switch (m) {
+ case IIO_CHAN_INFO_SCALE:
+ /* 2 * Pi / 2^12 */
+ *val = 6283; /* mV */
+ *val2 = 12;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ case IIO_CHAN_INFO_RAW:
+ mutex_lock(&st->lock);
+ ret = spi_read(st->sdev, st->rx, 2);
+ if (ret < 0) {
+ mutex_unlock(&st->lock);
+ return ret;
+ }
+ *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
+
+ mutex_unlock(&st->lock);
+
+ return IIO_VAL_INT;
+ default:
+ break;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_info ad2s90_info = {
+ .read_raw = ad2s90_read_raw,
+};
+
+static const struct iio_chan_spec ad2s90_chan = {
+ .type = IIO_ANGL,
+ .indexed = 1,
+ .channel = 0,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+};
+
+static int ad2s90_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct ad2s90_state *st;
+
+ if (spi->max_speed_hz > AD2S90_MAX_SPI_FREQ_HZ) {
+ dev_err(&spi->dev, "SPI CLK, %d Hz exceeds %d Hz\n",
+ spi->max_speed_hz, AD2S90_MAX_SPI_FREQ_HZ);
+ return -EINVAL;
+ }
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+ st = iio_priv(indio_dev);
+ spi_set_drvdata(spi, indio_dev);
+
+ mutex_init(&st->lock);
+ st->sdev = spi;
+ indio_dev->info = &ad2s90_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = &ad2s90_chan;
+ indio_dev->num_channels = 1;
+ indio_dev->name = spi_get_device_id(spi)->name;
+
+ return devm_iio_device_register(indio_dev->dev.parent, indio_dev);
+}
+
+static const struct of_device_id ad2s90_of_match[] = {
+ { .compatible = "adi,ad2s90", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, ad2s90_of_match);
+
+static const struct spi_device_id ad2s90_id[] = {
+ { "ad2s90" },
+ {}
+};
+MODULE_DEVICE_TABLE(spi, ad2s90_id);
+
+static struct spi_driver ad2s90_driver = {
+ .driver = {
+ .name = "ad2s90",
+ .of_match_table = ad2s90_of_match,
+ },
+ .probe = ad2s90_probe,
+ .id_table = ad2s90_id,
+};
+module_spi_driver(ad2s90_driver);
+
+MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
+MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
+MODULE_LICENSE("GPL v2");