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>

1 files changed, 186 insertions, 0 deletions

diff --git a/drivers/crypto/atmel-i2c.h b/drivers/crypto/atmel-i2c.h
new file mode 100644
index 000000000000..82de5166acfa
--- /dev/null
+++ b/drivers/crypto/atmel-i2c.h
@@ -0,0 +1,186 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2017, Microchip Technology Inc.
+ * Author: Tudor Ambarus <tudor.ambarus@microchip.com>
+ */
+
+#ifndef __ATMEL_I2C_H__
+#define __ATMEL_I2C_H__
+
+#define ATMEL_ECC_PRIORITY		300
+
+#define COMMAND				0x03 /* packet function */
+#define SLEEP_TOKEN			0x01
+#define WAKE_TOKEN_MAX_SIZE		8
+
+/* Definitions of Data and Command sizes */
+#define WORD_ADDR_SIZE			1
+#define COUNT_SIZE			1
+#define CRC_SIZE			2
+#define CMD_OVERHEAD_SIZE		(COUNT_SIZE + CRC_SIZE)
+
+/* size in bytes of the n prime */
+#define ATMEL_ECC_NIST_P256_N_SIZE	32
+#define ATMEL_ECC_PUBKEY_SIZE		(2 * ATMEL_ECC_NIST_P256_N_SIZE)
+
+#define STATUS_RSP_SIZE			4
+#define ECDH_RSP_SIZE			(32 + CMD_OVERHEAD_SIZE)
+#define GENKEY_RSP_SIZE			(ATMEL_ECC_PUBKEY_SIZE + \
+					 CMD_OVERHEAD_SIZE)
+#define READ_RSP_SIZE			(4 + CMD_OVERHEAD_SIZE)
+#define MAX_RSP_SIZE			GENKEY_RSP_SIZE
+
+/**
+ * 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.
+ * @opcode   : the command code.
+ * @param1   : the first parameter; always present.
+ * @param2   : the second parameter; always present.
+ * @data     : optional remaining input data. Includes a 2-byte CRC.
+ * @rxsize   : size of the data received from i2c client.
+ * @msecs    : command execution time in milliseconds
+ */
+struct atmel_i2c_cmd {
+	u8 word_addr;
+	u8 count;
+	u8 opcode;
+	u8 param1;
+	u16 param2;
+	u8 data[MAX_RSP_SIZE];
+	u8 msecs;
+	u16 rxsize;
+} __packed;
+
+/* Status/Error codes */
+#define STATUS_SIZE			0x04
+#define STATUS_NOERR			0x00
+#define STATUS_WAKE_SUCCESSFUL		0x11
+
+static const struct {
+	u8 value;
+	const char *error_text;
+} error_list[] = {
+	{ 0x01, "CheckMac or Verify miscompare" },
+	{ 0x03, "Parse Error" },
+	{ 0x05, "ECC Fault" },
+	{ 0x0F, "Execution Error" },
+	{ 0xEE, "Watchdog about to expire" },
+	{ 0xFF, "CRC or other communication error" },
+};
+
+/* Definitions for eeprom organization */
+#define CONFIG_ZONE			0
+
+/* Definitions for Indexes common to all commands */
+#define RSP_DATA_IDX			1 /* buffer index of data in response */
+#define DATA_SLOT_2			2 /* used for ECDH private key */
+
+/* Definitions for the device lock state */
+#define DEVICE_LOCK_ADDR		0x15
+#define LOCK_VALUE_IDX			(RSP_DATA_IDX + 2)
+#define LOCK_CONFIG_IDX			(RSP_DATA_IDX + 3)
+
+/*
+ * Wake High delay to data communication (microseconds). SDA should be stable
+ * high for this entire duration.
+ */
+#define TWHI_MIN			1500
+#define TWHI_MAX			1550
+
+/* Wake Low duration */
+#define TWLO_USEC			60
+
+/* Command execution time (milliseconds) */
+#define MAX_EXEC_TIME_ECDH		58
+#define MAX_EXEC_TIME_GENKEY		115
+#define MAX_EXEC_TIME_READ		1
+
+/* Command opcode */
+#define OPCODE_ECDH			0x43
+#define OPCODE_GENKEY			0x40
+#define OPCODE_READ			0x02
+
+/* Definitions for the READ Command */
+#define READ_COUNT			7
+
+/* Definitions for the GenKey Command */
+#define GENKEY_COUNT			7
+#define GENKEY_MODE_PRIVATE		0x04
+
+/* Definitions for the ECDH Command */
+#define ECDH_COUNT			71
+#define ECDH_PREFIX_MODE		0x00
+
+/* 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__ */