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Ard Biesheuvelherbertx
Ard Biesheuvel
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herbertx
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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: Linus Walleij <[email protected]> Signed-off-by: Ard Biesheuvel <[email protected]> Signed-off-by: Herbert Xu <[email protected]>
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‎drivers/crypto/Kconfig

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@@ -536,6 +536,20 @@ config CRYPTO_DEV_ATMEL_ECC
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To compile this driver as a module, choose M here: the module
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will be called atmel-ecc.
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config CRYPTO_DEV_ATMEL_SHA204A
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tristate "Support for Microchip / Atmel SHA accelerator and RNG"
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depends on I2C
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select CRYPTO_DEV_ATMEL_I2C
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select HW_RANDOM
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help
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Microhip / Atmel SHA accelerator and RNG.
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Select this if you want to use the Microchip / Atmel SHA204A
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module as a random number generator. (Other functions of the
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chip are currently not exposed by this driver)
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To compile this driver as a module, choose M here: the module
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will be called atmel-sha204a.
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config CRYPTO_DEV_CCP
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bool "Support for AMD Secure Processor"
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depends on ((X86 && PCI) || (ARM64 && (OF_ADDRESS || ACPI))) && HAS_IOMEM

‎drivers/crypto/Makefile

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

‎drivers/crypto/atmel-i2c.c

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

‎drivers/crypto/atmel-i2c.h

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

‎drivers/crypto/atmel-sha204a.c

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@@ -0,0 +1,171 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Microchip / Atmel SHA204A (I2C) driver.
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*
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* Copyright (c) 2019 Linaro, Ltd. <[email protected]>
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*/
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/i2c.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <linux/slab.h>
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#include <linux/workqueue.h>
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#include "atmel-i2c.h"
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static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data,
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void *areq, int status)
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{
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struct atmel_i2c_client_priv *i2c_priv = work_data->ctx;
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struct hwrng *rng = areq;
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if (status)
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dev_warn_ratelimited(&i2c_priv->client->dev,
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"i2c transaction failed (%d)\n",
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status);
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rng->priv = (unsigned long)work_data;
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atomic_dec(&i2c_priv->tfm_count);
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}
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static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data,
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size_t max)
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{
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struct atmel_i2c_client_priv *i2c_priv;
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struct atmel_i2c_work_data *work_data;
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i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
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/* keep maximum 1 asynchronous read in flight at any time */
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if (!atomic_add_unless(&i2c_priv->tfm_count, 1, 1))
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return 0;
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if (rng->priv) {
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work_data = (struct atmel_i2c_work_data *)rng->priv;
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max = min(sizeof(work_data->cmd.data), max);
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memcpy(data, &work_data->cmd.data, max);
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rng->priv = 0;
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} else {
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work_data = kmalloc(sizeof(*work_data), GFP_ATOMIC);
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if (!work_data)
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return -ENOMEM;
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work_data->ctx = i2c_priv;
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work_data->client = i2c_priv->client;
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max = 0;
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}
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atmel_i2c_init_random_cmd(&work_data->cmd);
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atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng);
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return max;
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}
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static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max,
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bool wait)
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{
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struct atmel_i2c_client_priv *i2c_priv;
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struct atmel_i2c_cmd cmd;
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int ret;
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if (!wait)
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return atmel_sha204a_rng_read_nonblocking(rng, data, max);
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i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
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atmel_i2c_init_random_cmd(&cmd);
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ret = atmel_i2c_send_receive(i2c_priv->client, &cmd);
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if (ret)
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return ret;
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max = min(sizeof(cmd.data), max);
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memcpy(data, cmd.data, max);
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return max;
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}
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static int atmel_sha204a_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct atmel_i2c_client_priv *i2c_priv;
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int ret;
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ret = atmel_i2c_probe(client, id);
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if (ret)
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return ret;
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i2c_priv = i2c_get_clientdata(client);
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memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng));
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i2c_priv->hwrng.name = dev_name(&client->dev);
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i2c_priv->hwrng.read = atmel_sha204a_rng_read;
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i2c_priv->hwrng.quality = 1024;
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ret = hwrng_register(&i2c_priv->hwrng);
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if (ret)
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dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
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return ret;
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}
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static int atmel_sha204a_remove(struct i2c_client *client)
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{
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struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
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if (atomic_read(&i2c_priv->tfm_count)) {
124+
dev_err(&client->dev, "Device is busy\n");
125+
return -EBUSY;
126+
}
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128+
if (i2c_priv->hwrng.priv)
129+
kfree((void *)i2c_priv->hwrng.priv);
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hwrng_unregister(&i2c_priv->hwrng);
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return 0;
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}
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static const struct of_device_id atmel_sha204a_dt_ids[] = {
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{ .compatible = "atmel,atsha204a", },
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{ /* sentinel */ }
138+
};
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MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
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static const struct i2c_device_id atmel_sha204a_id[] = {
142+
{ "atsha204a", 0 },
143+
{ /* sentinel */ }
144+
};
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MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);
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147+
static struct i2c_driver atmel_sha204a_driver = {
148+
.probe = atmel_sha204a_probe,
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.remove = atmel_sha204a_remove,
150+
.id_table = atmel_sha204a_id,
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152+
.driver.name = "atmel-sha204a",
153+
.driver.of_match_table = of_match_ptr(atmel_sha204a_dt_ids),
154+
};
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static int __init atmel_sha204a_init(void)
157+
{
158+
return i2c_add_driver(&atmel_sha204a_driver);
159+
}
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static void __exit atmel_sha204a_exit(void)
162+
{
163+
flush_scheduled_work();
164+
i2c_del_driver(&atmel_sha204a_driver);
165+
}
166+
167+
module_init(atmel_sha204a_init);
168+
module_exit(atmel_sha204a_exit);
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MODULE_AUTHOR("Ard Biesheuvel <[email protected]>");
171+
MODULE_LICENSE("GPL v2");

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