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crypto: atmel-i2c - add support for SHA204A random number generator

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The Linaro/96boards Secure96 mezzanine contains (among other things)
an Atmel SHA204A symmetric crypto processor. This chip implements a
number of different functionalities, but one that is highly useful
for many different 96boards platforms is the random number generator.

So let's implement a driver for the SHA204A, and for the time being,
implement support for the random number generator only.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2019-05-24 18:26:49 +02:00 committed by Herbert Xu
parent c34a320176
commit da001fb651
5 changed files with 211 additions and 0 deletions
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14
drivers/crypto/Kconfig
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@ -536,6 +536,20 @@ config CRYPTO_DEV_ATMEL_ECC
To compile this driver as a module, choose M here: the module
will be called atmel-ecc.
config CRYPTO_DEV_ATMEL_SHA204A
tristate "Support for Microchip / Atmel SHA accelerator and RNG"
depends on I2C
select CRYPTO_DEV_ATMEL_I2C
select HW_RANDOM
help
Microhip / Atmel SHA accelerator and RNG.
Select this if you want to use the Microchip / Atmel SHA204A
module as a random number generator. (Other functions of the
chip are currently not exposed by this driver)
To compile this driver as a module, choose M here: the module
will be called atmel-sha204a.
config CRYPTO_DEV_CCP
bool "Support for AMD Secure Processor"
depends on ((X86 && PCI) || (ARM64 && (OF_ADDRESS || ACPI))) && HAS_IOMEM

1
drivers/crypto/Makefile
View File

@ -4,6 +4,7 @@ obj-$(CONFIG_CRYPTO_DEV_ATMEL_SHA) += atmel-sha.o
obj-$(CONFIG_CRYPTO_DEV_ATMEL_TDES) += atmel-tdes.o
obj-$(CONFIG_CRYPTO_DEV_ATMEL_I2C) += atmel-i2c.o
obj-$(CONFIG_CRYPTO_DEV_ATMEL_ECC) += atmel-ecc.o
obj-$(CONFIG_CRYPTO_DEV_ATMEL_SHA204A) += atmel-sha204a.o
obj-$(CONFIG_CRYPTO_DEV_CAVIUM_ZIP) += cavium/
obj-$(CONFIG_CRYPTO_DEV_CCP) += ccp/
obj-$(CONFIG_CRYPTO_DEV_CCREE) += ccree/

15
drivers/crypto/atmel-i2c.c
View File

@ -58,6 +58,21 @@ void atmel_i2c_init_read_cmd(struct atmel_i2c_cmd *cmd)
}
EXPORT_SYMBOL(atmel_i2c_init_read_cmd);
void atmel_i2c_init_random_cmd(struct atmel_i2c_cmd *cmd)
{
cmd->word_addr = COMMAND;
cmd->opcode = OPCODE_RANDOM;
cmd->param1 = 0;
cmd->param2 = 0;
cmd->count = RANDOM_COUNT;
atmel_i2c_checksum(cmd);
cmd->msecs = MAX_EXEC_TIME_RANDOM;
cmd->rxsize = RANDOM_RSP_SIZE;
}
EXPORT_SYMBOL(atmel_i2c_init_random_cmd);
void atmel_i2c_init_genkey_cmd(struct atmel_i2c_cmd *cmd, u16 keyid)
{
cmd->word_addr = COMMAND;

10
drivers/crypto/atmel-i2c.h
View File

@ -7,6 +7,8 @@
#ifndef __ATMEL_I2C_H__
#define __ATMEL_I2C_H__
#include <linux/hw_random.h>
#define ATMEL_ECC_PRIORITY 300
#define COMMAND 0x03 /* packet function */
@ -28,6 +30,7 @@
#define GENKEY_RSP_SIZE (ATMEL_ECC_PUBKEY_SIZE + \
CMD_OVERHEAD_SIZE)
#define READ_RSP_SIZE (4 + CMD_OVERHEAD_SIZE)
#define RANDOM_RSP_SIZE (32 + CMD_OVERHEAD_SIZE)
#define MAX_RSP_SIZE GENKEY_RSP_SIZE
/**
@ -96,15 +99,20 @@ static const struct {
#define MAX_EXEC_TIME_ECDH 58
#define MAX_EXEC_TIME_GENKEY 115
#define MAX_EXEC_TIME_READ 1
#define MAX_EXEC_TIME_RANDOM 50
/* Command opcode */
#define OPCODE_ECDH 0x43
#define OPCODE_GENKEY 0x40
#define OPCODE_READ 0x02
#define OPCODE_RANDOM 0x1b
/* Definitions for the READ Command */
#define READ_COUNT 7
/* Definitions for the RANDOM Command */
#define RANDOM_COUNT 7
/* Definitions for the GenKey Command */
#define GENKEY_COUNT 7
#define GENKEY_MODE_PRIVATE 0x04
@ -142,6 +150,7 @@ struct atmel_i2c_client_priv {
u8 wake_token[WAKE_TOKEN_MAX_SIZE];
size_t wake_token_sz;
atomic_t tfm_count ____cacheline_aligned;
struct hwrng hwrng;
};
/**
@ -179,6 +188,7 @@ void atmel_i2c_enqueue(struct atmel_i2c_work_data *work_data,
int atmel_i2c_send_receive(struct i2c_client *client, struct atmel_i2c_cmd *cmd);
void atmel_i2c_init_read_cmd(struct atmel_i2c_cmd *cmd);
void atmel_i2c_init_random_cmd(struct atmel_i2c_cmd *cmd);
void atmel_i2c_init_genkey_cmd(struct atmel_i2c_cmd *cmd, u16 keyid);
int atmel_i2c_init_ecdh_cmd(struct atmel_i2c_cmd *cmd,
struct scatterlist *pubkey);

171
drivers/crypto/atmel-sha204a.c Normal file
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@ -0,0 +1,171 @@
// 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");