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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atmel-sha204a.c (4131B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Microchip / Atmel SHA204A (I2C) driver.
      4 *
      5 * Copyright (c) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
      6 */
      7
      8#include <linux/delay.h>
      9#include <linux/device.h>
     10#include <linux/err.h>
     11#include <linux/errno.h>
     12#include <linux/i2c.h>
     13#include <linux/init.h>
     14#include <linux/kernel.h>
     15#include <linux/module.h>
     16#include <linux/scatterlist.h>
     17#include <linux/slab.h>
     18#include <linux/workqueue.h>
     19#include "atmel-i2c.h"
     20
     21static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data,
     22				   void *areq, int status)
     23{
     24	struct atmel_i2c_client_priv *i2c_priv = work_data->ctx;
     25	struct hwrng *rng = areq;
     26
     27	if (status)
     28		dev_warn_ratelimited(&i2c_priv->client->dev,
     29				     "i2c transaction failed (%d)\n",
     30				     status);
     31
     32	rng->priv = (unsigned long)work_data;
     33	atomic_dec(&i2c_priv->tfm_count);
     34}
     35
     36static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data,
     37					      size_t max)
     38{
     39	struct atmel_i2c_client_priv *i2c_priv;
     40	struct atmel_i2c_work_data *work_data;
     41
     42	i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
     43
     44	/* keep maximum 1 asynchronous read in flight at any time */
     45	if (!atomic_add_unless(&i2c_priv->tfm_count, 1, 1))
     46		return 0;
     47
     48	if (rng->priv) {
     49		work_data = (struct atmel_i2c_work_data *)rng->priv;
     50		max = min(sizeof(work_data->cmd.data), max);
     51		memcpy(data, &work_data->cmd.data, max);
     52		rng->priv = 0;
     53	} else {
     54		work_data = kmalloc(sizeof(*work_data), GFP_ATOMIC);
     55		if (!work_data)
     56			return -ENOMEM;
     57
     58		work_data->ctx = i2c_priv;
     59		work_data->client = i2c_priv->client;
     60
     61		max = 0;
     62	}
     63
     64	atmel_i2c_init_random_cmd(&work_data->cmd);
     65	atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng);
     66
     67	return max;
     68}
     69
     70static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max,
     71				  bool wait)
     72{
     73	struct atmel_i2c_client_priv *i2c_priv;
     74	struct atmel_i2c_cmd cmd;
     75	int ret;
     76
     77	if (!wait)
     78		return atmel_sha204a_rng_read_nonblocking(rng, data, max);
     79
     80	i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
     81
     82	atmel_i2c_init_random_cmd(&cmd);
     83
     84	ret = atmel_i2c_send_receive(i2c_priv->client, &cmd);
     85	if (ret)
     86		return ret;
     87
     88	max = min(sizeof(cmd.data), max);
     89	memcpy(data, cmd.data, max);
     90
     91	return max;
     92}
     93
     94static int atmel_sha204a_probe(struct i2c_client *client,
     95			       const struct i2c_device_id *id)
     96{
     97	struct atmel_i2c_client_priv *i2c_priv;
     98	int ret;
     99
    100	ret = atmel_i2c_probe(client, id);
    101	if (ret)
    102		return ret;
    103
    104	i2c_priv = i2c_get_clientdata(client);
    105
    106	memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng));
    107
    108	i2c_priv->hwrng.name = dev_name(&client->dev);
    109	i2c_priv->hwrng.read = atmel_sha204a_rng_read;
    110	i2c_priv->hwrng.quality = 1024;
    111
    112	ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);
    113	if (ret)
    114		dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
    115
    116	return ret;
    117}
    118
    119static int atmel_sha204a_remove(struct i2c_client *client)
    120{
    121	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
    122
    123	if (atomic_read(&i2c_priv->tfm_count)) {
    124		dev_emerg(&client->dev, "Device is busy, will remove it anyhow\n");
    125		return 0;
    126	}
    127
    128	kfree((void *)i2c_priv->hwrng.priv);
    129
    130	return 0;
    131}
    132
    133static const struct of_device_id atmel_sha204a_dt_ids[] = {
    134	{ .compatible = "atmel,atsha204", },
    135	{ .compatible = "atmel,atsha204a", },
    136	{ /* sentinel */ }
    137};
    138MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
    139
    140static const struct i2c_device_id atmel_sha204a_id[] = {
    141	{ "atsha204", 0 },
    142	{ "atsha204a", 0 },
    143	{ /* sentinel */ }
    144};
    145MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);
    146
    147static struct i2c_driver atmel_sha204a_driver = {
    148	.probe			= atmel_sha204a_probe,
    149	.remove			= atmel_sha204a_remove,
    150	.id_table		= atmel_sha204a_id,
    151
    152	.driver.name		= "atmel-sha204a",
    153	.driver.of_match_table	= of_match_ptr(atmel_sha204a_dt_ids),
    154};
    155
    156static int __init atmel_sha204a_init(void)
    157{
    158	return i2c_add_driver(&atmel_sha204a_driver);
    159}
    160
    161static void __exit atmel_sha204a_exit(void)
    162{
    163	atmel_i2c_flush_queue();
    164	i2c_del_driver(&atmel_sha204a_driver);
    165}
    166
    167module_init(atmel_sha204a_init);
    168module_exit(atmel_sha204a_exit);
    169
    170MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
    171MODULE_LICENSE("GPL v2");