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 <linus.walleij@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
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 ca7a5564e9ce..fe01a9905ab1 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -537,6 +537,20 @@ 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 <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@xxxxxxxxxx>
+ */
+
+#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@xxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
--
2.20.1
