// 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] ____cacheline_aligned; }; 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->dev.parent = &spi->dev; 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");