From da001fb651b00e1deeaf24767dd691ae8152a4f5 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 24 May 2019 18:26:49 +0200 Subject: [PATCH] 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 Signed-off-by: Ard Biesheuvel Signed-off-by: Herbert Xu --- drivers/crypto/Kconfig | 14 +++ drivers/crypto/Makefile | 1 + drivers/crypto/atmel-i2c.c | 15 +++ drivers/crypto/atmel-i2c.h | 10 ++ drivers/crypto/atmel-sha204a.c | 171 +++++++++++++++++++++++++++++++++ 5 files changed, 211 insertions(+) create mode 100644 drivers/crypto/atmel-sha204a.c diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig index 20674842261e..bc7abad9fdff 100644 --- a/drivers/crypto/Kconfig +++ b/drivers/crypto/Kconfig @@ -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 diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile index 394e84089924..afc4753b5d28 100644 --- a/drivers/crypto/Makefile +++ b/drivers/crypto/Makefile @@ -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/ diff --git a/drivers/crypto/atmel-i2c.c b/drivers/crypto/atmel-i2c.c index 5e099368d120..be49ab7f4338 100644 --- a/drivers/crypto/atmel-i2c.c +++ b/drivers/crypto/atmel-i2c.c @@ -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; diff --git a/drivers/crypto/atmel-i2c.h b/drivers/crypto/atmel-i2c.h index 82de5166acfa..c6bd43b78f33 100644 --- a/drivers/crypto/atmel-i2c.h +++ b/drivers/crypto/atmel-i2c.h @@ -7,6 +7,8 @@ #ifndef __ATMEL_I2C_H__ #define __ATMEL_I2C_H__ +#include + #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); diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c new file mode 100644 index 000000000000..ea0d2068ea4f --- /dev/null +++ b/drivers/crypto/atmel-sha204a.c @@ -0,0 +1,171 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Microchip / Atmel SHA204A (I2C) driver. + * + * Copyright (c) 2019 Linaro, Ltd. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#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 "); +MODULE_LICENSE("GPL v2");