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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_otp_read(struct i2c_client *client, u16 addr, u8 *otp)
{
struct atmel_i2c_cmd cmd;
int ret = -1;
if (atmel_i2c_init_read_otp_cmd(&cmd, addr) < 0) {
dev_err(&client->dev, "failed, invalid otp address %04X\n",
addr);
return ret;
}
ret = atmel_i2c_send_receive(client, &cmd);
if (cmd.data[0] == 0xff) {
dev_err(&client->dev, "failed, device not ready\n");
return -EINVAL;
}
memcpy(otp, cmd.data+1, 4);
return ret;
}
static ssize_t otp_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
u16 addr;
u8 otp[OTP_ZONE_SIZE];
char *str = buf;
struct i2c_client *client = to_i2c_client(dev);
int i;
for (addr = 0; addr < OTP_ZONE_SIZE/4; addr++) {
if (atmel_sha204a_otp_read(client, addr, otp + addr * 4) < 0) {
dev_err(dev, "failed to read otp zone\n");
break;
}
}
for (i = 0; i < addr*2; i++)
str += sprintf(str, "%02X", otp[i]);
str += sprintf(str, "\n");
return str - buf;
}
static DEVICE_ATTR_RO(otp);
static struct attribute *atmel_sha204a_attrs[] = {
&dev_attr_otp.attr,
NULL
};
static const struct attribute_group atmel_sha204a_groups = {
.name = "atsha204a",
.attrs = atmel_sha204a_attrs,
};
static int atmel_sha204a_probe(struct i2c_client *client)
{
struct atmel_i2c_client_priv *i2c_priv;
int ret;
ret = atmel_i2c_probe(client);
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;
ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);
if (ret)
dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
/* otp read out */
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
ret = sysfs_create_group(&client->dev.kobj, &atmel_sha204a_groups);
if (ret) {
dev_err(&client->dev, "failed to register sysfs entry\n");
return ret;
}
return ret;
}
static void 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_emerg(&client->dev, "Device is busy, will remove it anyhow\n");
return;
}
sysfs_remove_group(&client->dev.kobj, &atmel_sha204a_groups);
kfree((void *)i2c_priv->hwrng.priv);
}
static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = {
{ .compatible = "atmel,atsha204", },
{ .compatible = "atmel,atsha204a", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
static const struct i2c_device_id atmel_sha204a_id[] = {
{ "atsha204", 0 },
{ "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)
{
atmel_i2c_flush_queue();
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_DESCRIPTION("Microchip / Atmel SHA204A (I2C) driver");
MODULE_LICENSE("GPL v2");
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