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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ltc2485.c (3419B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * ltc2485.c - Driver for Linear Technology LTC2485 ADC
      4 *
      5 * Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com>
      6 *
      7 * Datasheet: http://cds.linear.com/docs/en/datasheet/2485fd.pdf
      8 */
      9
     10#include <linux/delay.h>
     11#include <linux/i2c.h>
     12#include <linux/module.h>
     13
     14#include <linux/iio/iio.h>
     15#include <linux/iio/sysfs.h>
     16
     17/* Power-on configuration: rejects both 50/60Hz, operates at 1x speed */
     18#define LTC2485_CONFIG_DEFAULT		0
     19
     20struct ltc2485_data {
     21	struct i2c_client	*client;
     22	ktime_t			time_prev;	/* last conversion */
     23};
     24
     25static void ltc2485_wait_conv(struct ltc2485_data *data)
     26{
     27	const unsigned int conv_time = 147;	/* conversion time ms */
     28	unsigned int time_elapsed;
     29
     30	/* delay if conversion time not passed since last read or write */
     31	time_elapsed = ktime_ms_delta(ktime_get(), data->time_prev);
     32
     33	if (time_elapsed < conv_time)
     34		msleep(conv_time - time_elapsed);
     35}
     36
     37static int ltc2485_read(struct ltc2485_data *data, int *val)
     38{
     39	struct i2c_client *client = data->client;
     40	__be32 buf = 0;
     41	int ret;
     42
     43	ltc2485_wait_conv(data);
     44
     45	ret = i2c_master_recv(client, (char *)&buf, 4);
     46	if (ret < 0)  {
     47		dev_err(&client->dev, "i2c_master_recv failed\n");
     48		return ret;
     49	}
     50	data->time_prev = ktime_get();
     51	*val = sign_extend32(be32_to_cpu(buf) >> 6, 24);
     52
     53	return ret;
     54}
     55
     56static int ltc2485_read_raw(struct iio_dev *indio_dev,
     57			    struct iio_chan_spec const *chan,
     58			    int *val, int *val2, long mask)
     59{
     60	struct ltc2485_data *data = iio_priv(indio_dev);
     61	int ret;
     62
     63	if (mask == IIO_CHAN_INFO_RAW) {
     64		ret = ltc2485_read(data, val);
     65		if (ret < 0)
     66			return ret;
     67
     68		return IIO_VAL_INT;
     69
     70	} else if (mask == IIO_CHAN_INFO_SCALE) {
     71		*val = 5000;			/* on board vref millivolts */
     72		*val2 = 25;			/* 25 (24 + sign) data bits */
     73		return IIO_VAL_FRACTIONAL_LOG2;
     74
     75	} else {
     76		return -EINVAL;
     77	}
     78}
     79
     80static const struct iio_chan_spec ltc2485_channel[] = {
     81	{
     82		.type = IIO_VOLTAGE,
     83		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
     84		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)
     85	},
     86};
     87
     88static const struct iio_info ltc2485_info = {
     89	.read_raw = ltc2485_read_raw,
     90};
     91
     92static int ltc2485_probe(struct i2c_client *client,
     93			 const struct i2c_device_id *id)
     94{
     95	struct iio_dev *indio_dev;
     96	struct ltc2485_data *data;
     97	int ret;
     98
     99	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
    100				     I2C_FUNC_SMBUS_WRITE_BYTE))
    101		return -EOPNOTSUPP;
    102
    103	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
    104	if (!indio_dev)
    105		return -ENOMEM;
    106
    107	data = iio_priv(indio_dev);
    108	i2c_set_clientdata(client, indio_dev);
    109	data->client = client;
    110
    111	indio_dev->name = id->name;
    112	indio_dev->info = &ltc2485_info;
    113	indio_dev->modes = INDIO_DIRECT_MODE;
    114	indio_dev->channels = ltc2485_channel;
    115	indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel);
    116
    117	ret = i2c_smbus_write_byte(data->client, LTC2485_CONFIG_DEFAULT);
    118	if (ret < 0)
    119		return ret;
    120
    121	data->time_prev = ktime_get();
    122
    123	return devm_iio_device_register(&client->dev, indio_dev);
    124}
    125
    126static const struct i2c_device_id ltc2485_id[] = {
    127	{ "ltc2485", 0 },
    128	{ }
    129};
    130MODULE_DEVICE_TABLE(i2c, ltc2485_id);
    131
    132static struct i2c_driver ltc2485_driver = {
    133	.driver = {
    134		.name = "ltc2485",
    135	},
    136	.probe = ltc2485_probe,
    137	.id_table = ltc2485_id,
    138};
    139module_i2c_driver(ltc2485_driver);
    140
    141MODULE_AUTHOR("Alison Schofield <amsfield22@gmail.com>");
    142MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver");
    143MODULE_LICENSE("GPL v2");