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Commit da001fb6 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Herbert Xu
Browse files

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



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: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent c34a3201

drivers/crypto/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -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

drivers/crypto/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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/

drivers/crypto/atmel-i2c.c

+15 −0
Original line number Diff line number Diff line
@@ -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;

drivers/crypto/atmel-i2c.h

+10 −0
Original line number Diff line number Diff line
@@ -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);

drivers/crypto/atmel-sha204a.c

0 → 100644
+171 −0
Original line number Diff line number Diff line 
// 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");