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// SPDX-License-Identifier: GPL-2.0
/*
* Microchip / Atmel SHA204A (I2C) driver.
*
* Copyright (c) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
*/
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include "atmel-i2c.h"
static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data,
void *areq, int status)
{
struct atmel_i2c_client_priv *i2c_priv = work_data->ctx;
struct hwrng *rng = areq;
if (status)
dev_warn_ratelimited(&i2c_priv->client->dev,
"i2c transaction failed (%d)\n",
status);
rng->priv = (unsigned long)work_data;
atomic_dec(&i2c_priv->tfm_count);
}
static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data,
size_t max)
{
struct atmel_i2c_client_priv *i2c_priv;
struct atmel_i2c_work_data *work_data;
i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
/* keep maximum 1 asynchronous read in flight at any time */
if (!atomic_add_unless(&i2c_priv->tfm_count, 1, 1))
return 0;
if (rng->priv) {
work_data = (struct atmel_i2c_work_data *)rng->priv;
max = min(sizeof(work_data->cmd.data), max);
memcpy(data, &work_data->cmd.data, max);
rng->priv = 0;
} else {
work_data = kmalloc(sizeof(*work_data), GFP_ATOMIC);
if (!work_data)
return -ENOMEM;
work_data->ctx = i2c_priv;
work_data->client = i2c_priv->client;
max = 0;
}
atmel_i2c_init_random_cmd(&work_data->cmd);
atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng);
return max;
}
static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max,
bool wait)
{
struct atmel_i2c_client_priv *i2c_priv;
struct atmel_i2c_cmd cmd;
int ret;
if (!wait)
return atmel_sha204a_rng_read_nonblocking(rng, data, max);
i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
atmel_i2c_init_random_cmd(&cmd);
ret = atmel_i2c_send_receive(i2c_priv->client, &cmd);
if (ret)
return ret;
max = min(sizeof(cmd.data), max);
memcpy(data, cmd.data, max);
return max;
}
static int atmel_sha204a_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct atmel_i2c_client_priv *i2c_priv;
int ret;
ret = atmel_i2c_probe(client, id);
if (ret)
return ret;
i2c_priv = i2c_get_clientdata(client);
memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng));
i2c_priv->hwrng.name = dev_name(&client->dev);
i2c_priv->hwrng.read = atmel_sha204a_rng_read;
i2c_priv->hwrng.quality = 1024;
ret = hwrng_register(&i2c_priv->hwrng);
if (ret)
dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
return ret;
}
static int atmel_sha204a_remove(struct i2c_client *client)
{
struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
if (atomic_read(&i2c_priv->tfm_count)) {
dev_err(&client->dev, "Device is busy\n");
return -EBUSY;
}
if (i2c_priv->hwrng.priv)
kfree((void *)i2c_priv->hwrng.priv);
hwrng_unregister(&i2c_priv->hwrng);
return 0;
}
static const struct of_device_id atmel_sha204a_dt_ids[] = {
{ .compatible = "atmel,atsha204a", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
static const struct i2c_device_id atmel_sha204a_id[] = {
{ "atsha204a", 0 },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);
static struct i2c_driver atmel_sha204a_driver = {
.probe = atmel_sha204a_probe,
.remove = atmel_sha204a_remove,
.id_table = atmel_sha204a_id,
.driver.name = "atmel-sha204a",
.driver.of_match_table = of_match_ptr(atmel_sha204a_dt_ids),
};
static int __init atmel_sha204a_init(void)
{
return i2c_add_driver(&atmel_sha204a_driver);
}
static void __exit atmel_sha204a_exit(void)
{
flush_scheduled_work();
i2c_del_driver(&atmel_sha204a_driver);
}
module_init(atmel_sha204a_init);
module_exit(atmel_sha204a_exit);
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
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