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1// SPDX-License-Identifier: GPL-2.02/*3 * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S904 *5 * Copyright (c) 2010-2010 Analog Devices Inc.6 */7#include <linux/types.h>8#include <linux/mutex.h>9#include <linux/device.h>10#include <linux/spi/spi.h>11#include <linux/slab.h>12#include <linux/sysfs.h>13#include <linux/module.h>14 15#include <linux/iio/iio.h>16#include <linux/iio/sysfs.h>17 18/*19 * Although chip's max frequency is 2Mhz, it needs 600ns between CS and the20 * first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7)21 */22#define AD2S90_MAX_SPI_FREQ_HZ 83000023 24struct ad2s90_state {25 struct mutex lock; /* lock to protect rx buffer */26 struct spi_device *sdev;27 u8 rx[2] __aligned(IIO_DMA_MINALIGN);28};29 30static int ad2s90_read_raw(struct iio_dev *indio_dev,31 struct iio_chan_spec const *chan,32 int *val,33 int *val2,34 long m)35{36 int ret;37 struct ad2s90_state *st = iio_priv(indio_dev);38 39 if (chan->type != IIO_ANGL)40 return -EINVAL;41 42 switch (m) {43 case IIO_CHAN_INFO_SCALE:44 /* 2 * Pi / 2^12 */45 *val = 6283; /* mV */46 *val2 = 12;47 return IIO_VAL_FRACTIONAL_LOG2;48 case IIO_CHAN_INFO_RAW:49 mutex_lock(&st->lock);50 ret = spi_read(st->sdev, st->rx, 2);51 if (ret < 0) {52 mutex_unlock(&st->lock);53 return ret;54 }55 *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);56 57 mutex_unlock(&st->lock);58 59 return IIO_VAL_INT;60 default:61 break;62 }63 64 return -EINVAL;65}66 67static const struct iio_info ad2s90_info = {68 .read_raw = ad2s90_read_raw,69};70 71static const struct iio_chan_spec ad2s90_chan = {72 .type = IIO_ANGL,73 .indexed = 1,74 .channel = 0,75 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),76};77 78static int ad2s90_probe(struct spi_device *spi)79{80 struct iio_dev *indio_dev;81 struct ad2s90_state *st;82 83 if (spi->max_speed_hz > AD2S90_MAX_SPI_FREQ_HZ) {84 dev_err(&spi->dev, "SPI CLK, %d Hz exceeds %d Hz\n",85 spi->max_speed_hz, AD2S90_MAX_SPI_FREQ_HZ);86 return -EINVAL;87 }88 89 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));90 if (!indio_dev)91 return -ENOMEM;92 st = iio_priv(indio_dev);93 spi_set_drvdata(spi, indio_dev);94 95 mutex_init(&st->lock);96 st->sdev = spi;97 indio_dev->info = &ad2s90_info;98 indio_dev->modes = INDIO_DIRECT_MODE;99 indio_dev->channels = &ad2s90_chan;100 indio_dev->num_channels = 1;101 indio_dev->name = spi_get_device_id(spi)->name;102 103 return devm_iio_device_register(indio_dev->dev.parent, indio_dev);104}105 106static const struct of_device_id ad2s90_of_match[] = {107 { .compatible = "adi,ad2s90", },108 {}109};110MODULE_DEVICE_TABLE(of, ad2s90_of_match);111 112static const struct spi_device_id ad2s90_id[] = {113 { "ad2s90" },114 {}115};116MODULE_DEVICE_TABLE(spi, ad2s90_id);117 118static struct spi_driver ad2s90_driver = {119 .driver = {120 .name = "ad2s90",121 .of_match_table = ad2s90_of_match,122 },123 .probe = ad2s90_probe,124 .id_table = ad2s90_id,125};126module_spi_driver(ad2s90_driver);127 128MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");129MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");130MODULE_LICENSE("GPL v2");131