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crypto: atmel-ecc - factor out code that can be shared 

In preparation of adding support for the random number generator in
Atmel atsha204a devices, refactor the existing atmel-ecc driver (which
drives hardware that is closely related) so we can share the basic
I2C and command queuing routines.

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 18:26:48 +02:00 committed by Herbert Xu
parent 3c756aa346
commit c34a320176
5 changed files with 451 additions and 389 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/crypto/Kconfig
View File

@ -519,9 +519,13 @@ config CRYPTO_DEV_ATMEL_SHA
To compile this driver as a module, choose M here: the module
will be called atmel-sha.
config CRYPTO_DEV_ATMEL_I2C
tristate
config CRYPTO_DEV_ATMEL_ECC
tristate "Support for Microchip / Atmel ECC hw accelerator"
depends on I2C
select CRYPTO_DEV_ATMEL_I2C
select CRYPTO_ECDH
select CRC16
help

1
drivers/crypto/Makefile
View File

@ -2,6 +2,7 @@
obj-$(CONFIG_CRYPTO_DEV_ATMEL_AES) += atmel-aes.o
obj-$(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_CAVIUM_ZIP) += cavium/
obj-$(CONFIG_CRYPTO_DEV_CCP) += ccp/

406
drivers/crypto/atmel-ecc.c
View File

@ -6,8 +6,6 @@
* Author: Tudor Ambarus <tudor.ambarus@microchip.com>
*/
#include <linux/bitrev.h>
#include <linux/crc16.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
@ -23,41 +21,10 @@
#include <crypto/internal/kpp.h>
#include <crypto/ecdh.h>
#include <crypto/kpp.h>
#include "atmel-ecc.h"
/* Used for binding tfm objects to i2c clients. */
struct atmel_ecc_driver_data {
struct list_head i2c_client_list;
spinlock_t i2c_list_lock;
} ____cacheline_aligned;
#include "atmel-i2c.h"
static struct atmel_ecc_driver_data driver_data;
/**
* atmel_ecc_i2c_client_priv - i2c_client private data
* @client : pointer to i2c client device
* @i2c_client_list_node: part of i2c_client_list
* @lock : lock for sending i2c commands
* @wake_token : wake token array of zeros
* @wake_token_sz : size in bytes of the wake_token
* @tfm_count : number of active crypto transformations on i2c client
*
* Reads and writes from/to the i2c client are sequential. The first byte
* transmitted to the device is treated as the byte size. Any attempt to send
* more than this number of bytes will cause the device to not ACK those bytes.
* After the host writes a single command byte to the input buffer, reads are
* prohibited until after the device completes command execution. Use a mutex
* when sending i2c commands.
*/
struct atmel_ecc_i2c_client_priv {
struct i2c_client *client;
struct list_head i2c_client_list_node;
struct mutex lock;
u8 wake_token[WAKE_TOKEN_MAX_SIZE];
size_t wake_token_sz;
atomic_t tfm_count ____cacheline_aligned;
};
/**
* atmel_ecdh_ctx - transformation context
* @client : pointer to i2c client device
@ -80,188 +47,12 @@ struct atmel_ecdh_ctx {
bool do_fallback;
};
/**
* atmel_ecc_work_data - data structure representing the work
* @ctx : transformation context.
* @cbk : pointer to a callback function to be invoked upon completion of this
* request. This has the form:
* callback(struct atmel_ecc_work_data *work_data, void *areq, u8 status)
* where:
* @work_data: data structure representing the work
* @areq : optional pointer to an argument passed with the original
* request.
* @status : status returned from the i2c client device or i2c error.
* @areq: optional pointer to a user argument for use at callback time.
* @work: describes the task to be executed.
* @cmd : structure used for communicating with the device.
*/
struct atmel_ecc_work_data {
struct atmel_ecdh_ctx *ctx;
void (*cbk)(struct atmel_ecc_work_data *work_data, void *areq,
int status);
void *areq;
struct work_struct work;
struct atmel_ecc_cmd cmd;
};
static u16 atmel_ecc_crc16(u16 crc, const u8 *buffer, size_t len)
{
return cpu_to_le16(bitrev16(crc16(crc, buffer, len)));
}
/**
* atmel_ecc_checksum() - Generate 16-bit CRC as required by ATMEL ECC.
* CRC16 verification of the count, opcode, param1, param2 and data bytes.
* The checksum is saved in little-endian format in the least significant
* two bytes of the command. CRC polynomial is 0x8005 and the initial register
* value should be zero.
*
* @cmd : structure used for communicating with the device.
*/
static void atmel_ecc_checksum(struct atmel_ecc_cmd *cmd)
{
u8 *data = &cmd->count;
size_t len = cmd->count - CRC_SIZE;
u16 *crc16 = (u16 *)(data + len);
*crc16 = atmel_ecc_crc16(0, data, len);
}
static void atmel_ecc_init_read_cmd(struct atmel_ecc_cmd *cmd)
{
cmd->word_addr = COMMAND;
cmd->opcode = OPCODE_READ;
/*
* Read the word from Configuration zone that contains the lock bytes
* (UserExtra, Selector, LockValue, LockConfig).
*/
cmd->param1 = CONFIG_ZONE;
cmd->param2 = DEVICE_LOCK_ADDR;
cmd->count = READ_COUNT;
atmel_ecc_checksum(cmd);
cmd->msecs = MAX_EXEC_TIME_READ;
cmd->rxsize = READ_RSP_SIZE;
}
static void atmel_ecc_init_genkey_cmd(struct atmel_ecc_cmd *cmd, u16 keyid)
{
cmd->word_addr = COMMAND;
cmd->count = GENKEY_COUNT;
cmd->opcode = OPCODE_GENKEY;
cmd->param1 = GENKEY_MODE_PRIVATE;
/* a random private key will be generated and stored in slot keyID */
cmd->param2 = cpu_to_le16(keyid);
atmel_ecc_checksum(cmd);
cmd->msecs = MAX_EXEC_TIME_GENKEY;
cmd->rxsize = GENKEY_RSP_SIZE;
}
static int atmel_ecc_init_ecdh_cmd(struct atmel_ecc_cmd *cmd,
struct scatterlist *pubkey)
{
size_t copied;
cmd->word_addr = COMMAND;
cmd->count = ECDH_COUNT;
cmd->opcode = OPCODE_ECDH;
cmd->param1 = ECDH_PREFIX_MODE;
/* private key slot */
cmd->param2 = cpu_to_le16(DATA_SLOT_2);
/*
* The device only supports NIST P256 ECC keys. The public key size will
* always be the same. Use a macro for the key size to avoid unnecessary
* computations.
*/
copied = sg_copy_to_buffer(pubkey,
sg_nents_for_len(pubkey,
ATMEL_ECC_PUBKEY_SIZE),
cmd->data, ATMEL_ECC_PUBKEY_SIZE);
if (copied != ATMEL_ECC_PUBKEY_SIZE)
return -EINVAL;
atmel_ecc_checksum(cmd);
cmd->msecs = MAX_EXEC_TIME_ECDH;
cmd->rxsize = ECDH_RSP_SIZE;
return 0;
}
/*
* After wake and after execution of a command, there will be error, status, or
* result bytes in the device's output register that can be retrieved by the
* system. When the length of that group is four bytes, the codes returned are
* detailed in error_list.
*/
static int atmel_ecc_status(struct device *dev, u8 *status)
{
size_t err_list_len = ARRAY_SIZE(error_list);
int i;
u8 err_id = status[1];
if (*status != STATUS_SIZE)
return 0;
if (err_id == STATUS_WAKE_SUCCESSFUL || err_id == STATUS_NOERR)
return 0;
for (i = 0; i < err_list_len; i++)
if (error_list[i].value == err_id)
break;
/* if err_id is not in the error_list then ignore it */
if (i != err_list_len) {
dev_err(dev, "%02x: %s:\n", err_id, error_list[i].error_text);
return err_id;
}
return 0;
}
static int atmel_ecc_wakeup(struct i2c_client *client)
{
struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
u8 status[STATUS_RSP_SIZE];
int ret;
/*
* The device ignores any levels or transitions on the SCL pin when the
* device is idle, asleep or during waking up. Don't check for error
* when waking up the device.
*/
i2c_master_send(client, i2c_priv->wake_token, i2c_priv->wake_token_sz);
/*
* Wait to wake the device. Typical execution times for ecdh and genkey
* are around tens of milliseconds. Delta is chosen to 50 microseconds.
*/
usleep_range(TWHI_MIN, TWHI_MAX);
ret = i2c_master_recv(client, status, STATUS_SIZE);
if (ret < 0)
return ret;
return atmel_ecc_status(&client->dev, status);
}
static int atmel_ecc_sleep(struct i2c_client *client)
{
u8 sleep = SLEEP_TOKEN;
return i2c_master_send(client, &sleep, 1);
}
static void atmel_ecdh_done(struct atmel_ecc_work_data *work_data, void *areq,
static void atmel_ecdh_done(struct atmel_i2c_work_data *work_data, void *areq,
int status)
{
struct kpp_request *req = areq;
struct atmel_ecdh_ctx *ctx = work_data->ctx;
struct atmel_ecc_cmd *cmd = &work_data->cmd;
struct atmel_i2c_cmd *cmd = &work_data->cmd;
size_t copied, n_sz;
if (status)
@ -282,82 +73,6 @@ free_work_data:
kpp_request_complete(req, status);
}
/*
* atmel_ecc_send_receive() - send a command to the device and receive its
* response.
* @client: i2c client device
* @cmd : structure used to communicate with the device
*
* After the device receives a Wake token, a watchdog counter starts within the
* device. After the watchdog timer expires, the device enters sleep mode
* regardless of whether some I/O transmission or command execution is in
* progress. If a command is attempted when insufficient time remains prior to
* watchdog timer execution, the device will return the watchdog timeout error
* code without attempting to execute the command. There is no way to reset the
* counter other than to put the device into sleep or idle mode and then
* wake it up again.
*/
static int atmel_ecc_send_receive(struct i2c_client *client,
struct atmel_ecc_cmd *cmd)
{
struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
int ret;
mutex_lock(&i2c_priv->lock);
ret = atmel_ecc_wakeup(client);
if (ret)
goto err;
/* send the command */
ret = i2c_master_send(client, (u8 *)cmd, cmd->count + WORD_ADDR_SIZE);
if (ret < 0)
goto err;
/* delay the appropriate amount of time for command to execute */
msleep(cmd->msecs);
/* receive the response */
ret = i2c_master_recv(client, cmd->data, cmd->rxsize);
if (ret < 0)
goto err;
/* put the device into low-power mode */
ret = atmel_ecc_sleep(client);
if (ret < 0)
goto err;
mutex_unlock(&i2c_priv->lock);
return atmel_ecc_status(&client->dev, cmd->data);
err:
mutex_unlock(&i2c_priv->lock);
return ret;
}
static void atmel_ecc_work_handler(struct work_struct *work)
{
struct atmel_ecc_work_data *work_data =
container_of(work, struct atmel_ecc_work_data, work);
struct atmel_ecc_cmd *cmd = &work_data->cmd;
struct i2c_client *client = work_data->ctx->client;
int status;
status = atmel_ecc_send_receive(client, cmd);
work_data->cbk(work_data, work_data->areq, status);
}
static void atmel_ecc_enqueue(struct atmel_ecc_work_data *work_data,
void (*cbk)(struct atmel_ecc_work_data *work_data,
void *areq, int status),
void *areq)
{
work_data->cbk = (void *)cbk;
work_data->areq = areq;
INIT_WORK(&work_data->work, atmel_ecc_work_handler);
schedule_work(&work_data->work);
}
static unsigned int atmel_ecdh_supported_curve(unsigned int curve_id)
{
if (curve_id == ECC_CURVE_NIST_P256)
@ -374,7 +89,7 @@ static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
unsigned int len)
{
struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
struct atmel_ecc_cmd *cmd;
struct atmel_i2c_cmd *cmd;
void *public_key;
struct ecdh params;
int ret = -ENOMEM;
@ -412,9 +127,9 @@ static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
ctx->do_fallback = false;
ctx->curve_id = params.curve_id;
atmel_ecc_init_genkey_cmd(cmd, DATA_SLOT_2);
atmel_i2c_init_genkey_cmd(cmd, DATA_SLOT_2);
ret = atmel_ecc_send_receive(ctx->client, cmd);
ret = atmel_i2c_send_receive(ctx->client, cmd);
if (ret)
goto free_public_key;
@ -444,6 +159,9 @@ static int atmel_ecdh_generate_public_key(struct kpp_request *req)
return crypto_kpp_generate_public_key(req);
}
if (!ctx->public_key)
return -EINVAL;
/* might want less than we've got */
nbytes = min_t(size_t, ATMEL_ECC_PUBKEY_SIZE, req->dst_len);
@ -461,7 +179,7 @@ static int atmel_ecdh_compute_shared_secret(struct kpp_request *req)
{
struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
struct atmel_ecc_work_data *work_data;
struct atmel_i2c_work_data *work_data;
gfp_t gfp;
int ret;
@ -482,12 +200,13 @@ static int atmel_ecdh_compute_shared_secret(struct kpp_request *req)
return -ENOMEM;
work_data->ctx = ctx;
work_data->client = ctx->client;
ret = atmel_ecc_init_ecdh_cmd(&work_data->cmd, req->src);
ret = atmel_i2c_init_ecdh_cmd(&work_data->cmd, req->src);
if (ret)
goto free_work_data;
atmel_ecc_enqueue(work_data, atmel_ecdh_done, req);
atmel_i2c_enqueue(work_data, atmel_ecdh_done, req);
return -EINPROGRESS;
@ -498,7 +217,7 @@ free_work_data:
static struct i2c_client *atmel_ecc_i2c_client_alloc(void)
{
struct atmel_ecc_i2c_client_priv *i2c_priv, *min_i2c_priv = NULL;
struct atmel_i2c_client_priv *i2c_priv, *min_i2c_priv = NULL;
struct i2c_client *client = ERR_PTR(-ENODEV);
int min_tfm_cnt = INT_MAX;
int tfm_cnt;
@ -533,7 +252,7 @@ static struct i2c_client *atmel_ecc_i2c_client_alloc(void)
static void atmel_ecc_i2c_client_free(struct i2c_client *client)
{
struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
atomic_dec(&i2c_priv->tfm_count);
}
@ -604,99 +323,18 @@ static struct kpp_alg atmel_ecdh = {
},
};
static inline size_t atmel_ecc_wake_token_sz(u32 bus_clk_rate)
{
u32 no_of_bits = DIV_ROUND_UP(TWLO_USEC * bus_clk_rate, USEC_PER_SEC);
/* return the size of the wake_token in bytes */
return DIV_ROUND_UP(no_of_bits, 8);
}
static int device_sanity_check(struct i2c_client *client)
{
struct atmel_ecc_cmd *cmd;
int ret;
cmd = kmalloc(sizeof(*cmd), GFP_KERNEL);
if (!cmd)
return -ENOMEM;
atmel_ecc_init_read_cmd(cmd);
ret = atmel_ecc_send_receive(client, cmd);
if (ret)
goto free_cmd;
/*
* It is vital that the Configuration, Data and OTP zones be locked
* prior to release into the field of the system containing the device.
* Failure to lock these zones may permit modification of any secret
* keys and may lead to other security problems.
*/
if (cmd->data[LOCK_CONFIG_IDX] || cmd->data[LOCK_VALUE_IDX]) {
dev_err(&client->dev, "Configuration or Data and OTP zones are unlocked!\n");
ret = -ENOTSUPP;
}
/* fall through */
free_cmd:
kfree(cmd);
return ret;
}
static int atmel_ecc_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct atmel_ecc_i2c_client_priv *i2c_priv;
struct device *dev = &client->dev;
struct atmel_i2c_client_priv *i2c_priv;
int ret;
u32 bus_clk_rate;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
dev_err(dev, "I2C_FUNC_I2C not supported\n");
return -ENODEV;
}
clk_rate = i2c_acpi_find_bus_speed(&client->adapter->dev);
if (!clk_rate) {
ret = device_property_read_u32(&client->adapter->dev,
"clock-frequency", &bus_clk_rate);
if (ret) {
dev_err(dev, "failed to read clock-frequency property\n");
return ret;
}
}
if (bus_clk_rate > 1000000L) {
dev_err(dev, "%d exceeds maximum supported clock frequency (1MHz)\n",
bus_clk_rate);
return -EINVAL;
}
i2c_priv = devm_kmalloc(dev, sizeof(*i2c_priv), GFP_KERNEL);
if (!i2c_priv)
return -ENOMEM;
i2c_priv->client = client;
mutex_init(&i2c_priv->lock);
/*
* WAKE_TOKEN_MAX_SIZE was calculated for the maximum bus_clk_rate -
* 1MHz. The previous bus_clk_rate check ensures us that wake_token_sz
* will always be smaller than or equal to WAKE_TOKEN_MAX_SIZE.
*/
i2c_priv->wake_token_sz = atmel_ecc_wake_token_sz(bus_clk_rate);
memset(i2c_priv->wake_token, 0, sizeof(i2c_priv->wake_token));
atomic_set(&i2c_priv->tfm_count, 0);
i2c_set_clientdata(client, i2c_priv);
ret = device_sanity_check(client);
ret = atmel_i2c_probe(client, id);
if (ret)
return ret;
i2c_priv = i2c_get_clientdata(client);
spin_lock(&driver_data.i2c_list_lock);
list_add_tail(&i2c_priv->i2c_client_list_node,
&driver_data.i2c_client_list);
@ -708,10 +346,10 @@ static int atmel_ecc_probe(struct i2c_client *client,
list_del(&i2c_priv->i2c_client_list_node);
spin_unlock(&driver_data.i2c_list_lock);
dev_err(dev, "%s alg registration failed\n",
dev_err(&client->dev, "%s alg registration failed\n",
atmel_ecdh.base.cra_driver_name);
} else {
dev_info(dev, "atmel ecc algorithms registered in /proc/crypto\n");
dev_info(&client->dev, "atmel ecc algorithms registered in /proc/crypto\n");
}
return ret;
@ -719,7 +357,7 @@ static int atmel_ecc_probe(struct i2c_client *client,
static int atmel_ecc_remove(struct i2c_client *client)
{
struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
/* Return EBUSY if i2c client already allocated. */
if (atomic_read(&i2c_priv->tfm_count)) {

349
drivers/crypto/atmel-i2c.c Normal file
View File

@ -0,0 +1,349 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Microchip / Atmel ECC (I2C) driver.
*
* Copyright (c) 2017, Microchip Technology Inc.
* Author: Tudor Ambarus <tudor.ambarus@microchip.com>
*/
#include <linux/bitrev.h>
#include <linux/crc16.h>
#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"
/**
* atmel_i2c_checksum() - Generate 16-bit CRC as required by ATMEL ECC.
* CRC16 verification of the count, opcode, param1, param2 and data bytes.
* The checksum is saved in little-endian format in the least significant
* two bytes of the command. CRC polynomial is 0x8005 and the initial register
* value should be zero.
*
* @cmd : structure used for communicating with the device.
*/
static void atmel_i2c_checksum(struct atmel_i2c_cmd *cmd)
{
u8 *data = &cmd->count;
size_t len = cmd->count - CRC_SIZE;
u16 *__crc16 = (u16 *)(data + len);
*__crc16 = cpu_to_le16(bitrev16(crc16(0, data, len)));
}
void atmel_i2c_init_read_cmd(struct atmel_i2c_cmd *cmd)
{
cmd->word_addr = COMMAND;
cmd->opcode = OPCODE_READ;
/*
* Read the word from Configuration zone that contains the lock bytes
* (UserExtra, Selector, LockValue, LockConfig).
*/
cmd->param1 = CONFIG_ZONE;
cmd->param2 = DEVICE_LOCK_ADDR;
cmd->count = READ_COUNT;
atmel_i2c_checksum(cmd);
cmd->msecs = MAX_EXEC_TIME_READ;
cmd->rxsize = READ_RSP_SIZE;
}
EXPORT_SYMBOL(atmel_i2c_init_read_cmd);
void atmel_i2c_init_genkey_cmd(struct atmel_i2c_cmd *cmd, u16 keyid)
{
cmd->word_addr = COMMAND;
cmd->count = GENKEY_COUNT;
cmd->opcode = OPCODE_GENKEY;
cmd->param1 = GENKEY_MODE_PRIVATE;
/* a random private key will be generated and stored in slot keyID */
cmd->param2 = cpu_to_le16(keyid);
atmel_i2c_checksum(cmd);
cmd->msecs = MAX_EXEC_TIME_GENKEY;
cmd->rxsize = GENKEY_RSP_SIZE;
}
EXPORT_SYMBOL(atmel_i2c_init_genkey_cmd);
int atmel_i2c_init_ecdh_cmd(struct atmel_i2c_cmd *cmd,
struct scatterlist *pubkey)
{
size_t copied;
cmd->word_addr = COMMAND;
cmd->count = ECDH_COUNT;
cmd->opcode = OPCODE_ECDH;
cmd->param1 = ECDH_PREFIX_MODE;
/* private key slot */
cmd->param2 = cpu_to_le16(DATA_SLOT_2);
/*
* The device only supports NIST P256 ECC keys. The public key size will
* always be the same. Use a macro for the key size to avoid unnecessary
* computations.
*/
copied = sg_copy_to_buffer(pubkey,
sg_nents_for_len(pubkey,
ATMEL_ECC_PUBKEY_SIZE),
cmd->data, ATMEL_ECC_PUBKEY_SIZE);
if (copied != ATMEL_ECC_PUBKEY_SIZE)
return -EINVAL;
atmel_i2c_checksum(cmd);
cmd->msecs = MAX_EXEC_TIME_ECDH;
cmd->rxsize = ECDH_RSP_SIZE;
return 0;
}
EXPORT_SYMBOL(atmel_i2c_init_ecdh_cmd);
/*
* After wake and after execution of a command, there will be error, status, or
* result bytes in the device's output register that can be retrieved by the
* system. When the length of that group is four bytes, the codes returned are
* detailed in error_list.
*/
static int atmel_i2c_status(struct device *dev, u8 *status)
{
size_t err_list_len = ARRAY_SIZE(error_list);
int i;
u8 err_id = status[1];
if (*status != STATUS_SIZE)
return 0;
if (err_id == STATUS_WAKE_SUCCESSFUL || err_id == STATUS_NOERR)
return 0;
for (i = 0; i < err_list_len; i++)
if (error_list[i].value == err_id)
break;
/* if err_id is not in the error_list then ignore it */
if (i != err_list_len) {
dev_err(dev, "%02x: %s:\n", err_id, error_list[i].error_text);
return err_id;
}
return 0;
}
static int atmel_i2c_wakeup(struct i2c_client *client)
{
struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
u8 status[STATUS_RSP_SIZE];
int ret;
/*
* The device ignores any levels or transitions on the SCL pin when the
* device is idle, asleep or during waking up. Don't check for error
* when waking up the device.
*/
i2c_master_send(client, i2c_priv->wake_token, i2c_priv->wake_token_sz);
/*
* Wait to wake the device. Typical execution times for ecdh and genkey
* are around tens of milliseconds. Delta is chosen to 50 microseconds.
*/
usleep_range(TWHI_MIN, TWHI_MAX);
ret = i2c_master_recv(client, status, STATUS_SIZE);
if (ret < 0)
return ret;
return atmel_i2c_status(&client->dev, status);
}
static int atmel_i2c_sleep(struct i2c_client *client)
{
u8 sleep = SLEEP_TOKEN;
return i2c_master_send(client, &sleep, 1);
}
/*
* atmel_i2c_send_receive() - send a command to the device and receive its
* response.
* @client: i2c client device
* @cmd : structure used to communicate with the device
*
* After the device receives a Wake token, a watchdog counter starts within the
* device. After the watchdog timer expires, the device enters sleep mode
* regardless of whether some I/O transmission or command execution is in
* progress. If a command is attempted when insufficient time remains prior to
* watchdog timer execution, the device will return the watchdog timeout error
* code without attempting to execute the command. There is no way to reset the
* counter other than to put the device into sleep or idle mode and then
* wake it up again.
*/
int atmel_i2c_send_receive(struct i2c_client *client, struct atmel_i2c_cmd *cmd)
{
struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
int ret;
mutex_lock(&i2c_priv->lock);
ret = atmel_i2c_wakeup(client);
if (ret)
goto err;
/* send the command */
ret = i2c_master_send(client, (u8 *)cmd, cmd->count + WORD_ADDR_SIZE);
if (ret < 0)
goto err;
/* delay the appropriate amount of time for command to execute */
msleep(cmd->msecs);
/* receive the response */
ret = i2c_master_recv(client, cmd->data, cmd->rxsize);
if (ret < 0)
goto err;
/* put the device into low-power mode */
ret = atmel_i2c_sleep(client);
if (ret < 0)
goto err;
mutex_unlock(&i2c_priv->lock);
return atmel_i2c_status(&client->dev, cmd->data);
err:
mutex_unlock(&i2c_priv->lock);
return ret;
}
EXPORT_SYMBOL(atmel_i2c_send_receive);
static void atmel_i2c_work_handler(struct work_struct *work)
{
struct atmel_i2c_work_data *work_data =
container_of(work, struct atmel_i2c_work_data, work);
struct atmel_i2c_cmd *cmd = &work_data->cmd;
struct i2c_client *client = work_data->client;
int status;
status = atmel_i2c_send_receive(client, cmd);
work_data->cbk(work_data, work_data->areq, status);
}
void atmel_i2c_enqueue(struct atmel_i2c_work_data *work_data,
void (*cbk)(struct atmel_i2c_work_data *work_data,
void *areq, int status),
void *areq)
{
work_data->cbk = (void *)cbk;
work_data->areq = areq;
INIT_WORK(&work_data->work, atmel_i2c_work_handler);
schedule_work(&work_data->work);
}
EXPORT_SYMBOL(atmel_i2c_enqueue);
static inline size_t atmel_i2c_wake_token_sz(u32 bus_clk_rate)
{
u32 no_of_bits = DIV_ROUND_UP(TWLO_USEC * bus_clk_rate, USEC_PER_SEC);
/* return the size of the wake_token in bytes */
return DIV_ROUND_UP(no_of_bits, 8);
}
static int device_sanity_check(struct i2c_client *client)
{
struct atmel_i2c_cmd *cmd;
int ret;
cmd = kmalloc(sizeof(*cmd), GFP_KERNEL);
if (!cmd)
return -ENOMEM;
atmel_i2c_init_read_cmd(cmd);
ret = atmel_i2c_send_receive(client, cmd);
if (ret)
goto free_cmd;
/*
* It is vital that the Configuration, Data and OTP zones be locked
* prior to release into the field of the system containing the device.
* Failure to lock these zones may permit modification of any secret
* keys and may lead to other security problems.
*/
if (cmd->data[LOCK_CONFIG_IDX] || cmd->data[LOCK_VALUE_IDX]) {
dev_err(&client->dev, "Configuration or Data and OTP zones are unlocked!\n");
ret = -ENOTSUPP;
}
/* fall through */
free_cmd:
kfree(cmd);
return ret;
}
int atmel_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
struct atmel_i2c_client_priv *i2c_priv;
struct device *dev = &client->dev;
int ret;
u32 bus_clk_rate;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
dev_err(dev, "I2C_FUNC_I2C not supported\n");
return -ENODEV;
}
bus_clk_rate = i2c_acpi_find_bus_speed(&client->adapter->dev);
if (!bus_clk_rate) {
ret = device_property_read_u32(&client->adapter->dev,
"clock-frequency", &bus_clk_rate);
if (ret) {
dev_err(dev, "failed to read clock-frequency property\n");
return ret;
}
}
if (bus_clk_rate > 1000000L) {
dev_err(dev, "%d exceeds maximum supported clock frequency (1MHz)\n",
bus_clk_rate);
return -EINVAL;
}
i2c_priv = devm_kmalloc(dev, sizeof(*i2c_priv), GFP_KERNEL);
if (!i2c_priv)
return -ENOMEM;
i2c_priv->client = client;
mutex_init(&i2c_priv->lock);
/*
* WAKE_TOKEN_MAX_SIZE was calculated for the maximum bus_clk_rate -
* 1MHz. The previous bus_clk_rate check ensures us that wake_token_sz
* will always be smaller than or equal to WAKE_TOKEN_MAX_SIZE.
*/
i2c_priv->wake_token_sz = atmel_i2c_wake_token_sz(bus_clk_rate);
memset(i2c_priv->wake_token, 0, sizeof(i2c_priv->wake_token));
atomic_set(&i2c_priv->tfm_count, 0);
i2c_set_clientdata(client, i2c_priv);
ret = device_sanity_check(client);
if (ret)
return ret;
return 0;
}
EXPORT_SYMBOL(atmel_i2c_probe);
MODULE_AUTHOR("Tudor Ambarus <tudor.ambarus@microchip.com>");
MODULE_DESCRIPTION("Microchip / Atmel ECC (I2C) driver");
MODULE_LICENSE("GPL v2");

80
drivers/crypto/atmel-ecc.h → drivers/crypto/atmel-i2c.h
View File

@ -4,8 +4,8 @@
* Author: Tudor Ambarus <tudor.ambarus@microchip.com>
*/
#ifndef __ATMEL_ECC_H__
#define __ATMEL_ECC_H__
#ifndef __ATMEL_I2C_H__
#define __ATMEL_I2C_H__
#define ATMEL_ECC_PRIORITY 300
@ -31,7 +31,7 @@
#define MAX_RSP_SIZE GENKEY_RSP_SIZE
/**
* atmel_ecc_cmd - structure used for communicating with the device.
* atmel_i2c_cmd - structure used for communicating with the device.
* @word_addr: indicates the function of the packet sent to the device. This
* byte should have a value of COMMAND for normal operation.
* @count : number of bytes to be transferred to (or from) the device.
@ -42,7 +42,7 @@
* @rxsize : size of the data received from i2c client.
* @msecs : command execution time in milliseconds
*/
struct atmel_ecc_cmd {
struct atmel_i2c_cmd {
u8 word_addr;
u8 count;
u8 opcode;
@ -113,4 +113,74 @@ static const struct {
#define ECDH_COUNT 71
#define ECDH_PREFIX_MODE 0x00
#endif /* __ATMEL_ECC_H__ */
/* Used for binding tfm objects to i2c clients. */
struct atmel_ecc_driver_data {
struct list_head i2c_client_list;
spinlock_t i2c_list_lock;
} ____cacheline_aligned;
/**
* atmel_i2c_client_priv - i2c_client private data
* @client : pointer to i2c client device
* @i2c_client_list_node: part of i2c_client_list
* @lock : lock for sending i2c commands
* @wake_token : wake token array of zeros
* @wake_token_sz : size in bytes of the wake_token
* @tfm_count : number of active crypto transformations on i2c client
*
* Reads and writes from/to the i2c client are sequential. The first byte
* transmitted to the device is treated as the byte size. Any attempt to send
* more than this number of bytes will cause the device to not ACK those bytes.
* After the host writes a single command byte to the input buffer, reads are
* prohibited until after the device completes command execution. Use a mutex
* when sending i2c commands.
*/
struct atmel_i2c_client_priv {
struct i2c_client *client;
struct list_head i2c_client_list_node;
struct mutex lock;
u8 wake_token[WAKE_TOKEN_MAX_SIZE];
size_t wake_token_sz;
atomic_t tfm_count ____cacheline_aligned;
};
/**
* atmel_i2c_work_data - data structure representing the work
* @ctx : transformation context.
* @cbk : pointer to a callback function to be invoked upon completion of this
* request. This has the form:
* callback(struct atmel_i2c_work_data *work_data, void *areq, u8 status)
* where:
* @work_data: data structure representing the work
* @areq : optional pointer to an argument passed with the original
* request.
* @status : status returned from the i2c client device or i2c error.
* @areq: optional pointer to a user argument for use at callback time.
* @work: describes the task to be executed.
* @cmd : structure used for communicating with the device.
*/
struct atmel_i2c_work_data {
void *ctx;
struct i2c_client *client;
void (*cbk)(struct atmel_i2c_work_data *work_data, void *areq,
int status);
void *areq;
struct work_struct work;
struct atmel_i2c_cmd cmd;
};
int atmel_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id);
void atmel_i2c_enqueue(struct atmel_i2c_work_data *work_data,
void (*cbk)(struct atmel_i2c_work_data *work_data,
void *areq, int status),
void *areq);
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_genkey_cmd(struct atmel_i2c_cmd *cmd, u16 keyid);
int atmel_i2c_init_ecdh_cmd(struct atmel_i2c_cmd *cmd,
struct scatterlist *pubkey);
#endif /* __ATMEL_I2C_H__ */