cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ad2s90.c (3040B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90
      4 *
      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 the
     20 * first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7)
     21 */
     22#define AD2S90_MAX_SPI_FREQ_HZ  830000
     23
     24struct ad2s90_state {
     25	struct mutex lock; /* lock to protect rx buffer */
     26	struct spi_device *sdev;
     27	u8 rx[2] ____cacheline_aligned;
     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");