* [PATCH 3/5] crypto: atmel-ecc: factor out code that can be shared
2019-04-30 16:29 [PATCH 0/5] synquacer - wire up Atmel SHA204A as RNG in DT and ACPI mode Ard Biesheuvel
2019-04-30 16:29 ` [PATCH 1/5] i2c: acpi: permit bus speed to be discovered after enumeration Ard Biesheuvel
2019-04-30 16:29 ` [PATCH 2/5] crypto: atmel-ecc: add support for ACPI probing on non-AT91 platforms Ard Biesheuvel
@ 2019-04-30 16:29 ` Ard Biesheuvel
2019-05-09 20:42 ` Linus Walleij
2019-04-30 16:29 ` [PATCH 4/5] crypto: atmel-i2c: add support for SHA204A random number generator Ard Biesheuvel
2019-04-30 16:29 ` [PATCH 5/5] dt-bindings: add Atmel SHA204A I2C crypto processor Ard Biesheuvel
4 siblings, 1 reply; 14+ messages in thread
From: Ard Biesheuvel @ 2019-04-30 16:29 UTC (permalink / raw)
To: linux-crypto; +Cc: linux-arm-kernel, linus.walleij, joakim.bech, Ard Biesheuvel
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.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
drivers/crypto/Kconfig | 4 +
drivers/crypto/Makefile | 1 +
drivers/crypto/atmel-ecc.c | 406 ++------------------
drivers/crypto/atmel-i2c.c | 349 +++++++++++++++++
drivers/crypto/{atmel-ecc.h => atmel-i2c.h} | 80 +++-
5 files changed, 451 insertions(+), 389 deletions(-)
diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index 4c95567e188f..11b0de15a99d 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -528,9 +528,13 @@ 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
diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile
index 8e7e225d2446..85be01afcc41 100644
--- a/drivers/crypto/Makefile
+++ b/drivers/crypto/Makefile
@@ -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/
diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c
index 5705348f540f..ff02cc05affb 100644
--- a/drivers/crypto/atmel-ecc.c
+++ b/drivers/crypto/atmel-ecc.c
@@ -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 @@ static void atmel_ecdh_done(struct atmel_ecc_work_data *work_data, void *areq,
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 @@ static int atmel_ecdh_compute_shared_secret(struct kpp_request *req)
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)) {
diff --git a/drivers/crypto/atmel-i2c.c b/drivers/crypto/atmel-i2c.c
new file mode 100644
index 000000000000..5e099368d120
--- /dev/null
+++ b/drivers/crypto/atmel-i2c.c
@@ -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");
diff --git a/drivers/crypto/atmel-ecc.h b/drivers/crypto/atmel-i2c.h
similarity index 51%
rename from drivers/crypto/atmel-ecc.h
rename to drivers/crypto/atmel-i2c.h
index 643a3b947338..82de5166acfa 100644
--- a/drivers/crypto/atmel-ecc.h
+++ b/drivers/crypto/atmel-i2c.h
@@ -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__ */
--
2.20.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH 4/5] crypto: atmel-i2c: add support for SHA204A random number generator
2019-04-30 16:29 [PATCH 0/5] synquacer - wire up Atmel SHA204A as RNG in DT and ACPI mode Ard Biesheuvel
` (2 preceding siblings ...)
2019-04-30 16:29 ` [PATCH 3/5] crypto: atmel-ecc: factor out code that can be shared Ard Biesheuvel
@ 2019-04-30 16:29 ` Ard Biesheuvel
2019-05-09 20:44 ` Linus Walleij
2019-04-30 16:29 ` [PATCH 5/5] dt-bindings: add Atmel SHA204A I2C crypto processor Ard Biesheuvel
4 siblings, 1 reply; 14+ messages in thread
From: Ard Biesheuvel @ 2019-04-30 16:29 UTC (permalink / raw)
To: linux-crypto; +Cc: linux-arm-kernel, linus.walleij, joakim.bech, Ard Biesheuvel
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.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
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(+)
diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index 11b0de15a99d..fe143d6c6050 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -545,6 +545,20 @@ 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 85be01afcc41..5d054ffa8814 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 <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);
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. <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");
--
2.20.1
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