/*
 * include/uapi/linux/nvhvivc_mempool_ioctl.h 
 *
 * nvhvivc_mempool_ioctl.h- Access CPC storage blocks through i2c bus
 *
 * Copyright (c) 2016-2020, NVIDIA CORPORATION.  All rights reserved.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#ifndef __UAPI_TEGRA_CPC_H
#define __UAPI_TEGRA_CPC_H

#include <linux/ioctl.h>
#include <linux/types.h>

enum req_resp_t {
	CPC_READ_M_COUNT = 0x2,
	CPC_WRITE_FRAME,
	CPC_READ_FRAME,
	CPC_GET_RESULT = 0x5,
	CPC_GET_VERSION = 0x6,
};

enum result_t {
	CPC_RESULT_OK = 0x0,
	CPC_RESULT_GENERAL_FAILURE,
	CPC_RESULT_AUTH_FAILURE,
	CPC_RESULT_COUNTER_FAILURE,
	CPC_RESULT_ADDR_FAILURE,
	CPC_RESULT_WRITE_FAILURE = 0x5,
	CPC_RESULT_READ_FAILURE,
	CPC_RESULT_UNKNOWN_REQUEST,
	CPC_RESULT_KEY_PROG_SEQ_FAILURE,
	CPC_RESULT_KEY_PROG_PG_CORRUPT,
	CPC_RESULT_KEY_PROG_DONE_PRIOR = 0xA,
	CPC_RESULT_DATA_LENGTH_MISMATCH,
	CPC_RESULT_UNEXPECTED_CONDITION,
	CPC_RESULT_CONTROLLER_BUSY
};

#define CPC_MAX_DATA_SIZE	48
#define CPC_KEY_SIZE		32
#define CPC_HMAC_SIZE		32
#define CPC_DERIVATION_SIZE	28
#define CPC_NONCE_SIZE		4
#define CPC_COUNTER_SIZE	4
#define CPC_MAJOR_VER_SIZE	3
#define CPC_MINOR_VER_SIZE	1

/*
 * CPC field description
 *
 * req		is a command ID
 * result	is the status as returned by uC. If the communication to uC was
 *		not successful, this value will be set by the host
 * len		is the byte indicating how many bytes in data are valid data
 *		For read, this tells the kernel what is the expected size of
 *		data which will be returned by uC
 *		For write, this tells the kernel how many bytes in the data
 *		field are valid data.
 *		The range of this is 0 < n && n <= CPC_MAX_DATA_SIZE
 * nonce	is the counter which will be used for HMAC calculation. It is
 *		also used to correlate the response to the request. Host
 *		uses this value to match the response and the request
 * write_counter
 *		The counter which indicates how many successful commits have
 *		been made by uC for the life time of uC
 * data	is the field which the client of uC could use to send / receive
 *		data which will be stored permanently by uC.
 * derivation_value
 *		This field should be used to pass the unique data during
 *		read counter, which will be used for encryption later by
 *		both parties
 * HMAC	is the field which the client of uC could use to authenticate
 *		packets sent to and received from uC. If this field does not
 *		match uC's expectation, the packet will be rejected.
 *		HMAC is sent last tegra=>uC
 *		HMAC is sent first uC=>tegra
 */

/*
 * Structs used for serialization and deserialization. The implementation is
 * order sensitive. Any change to the struct would require a change to
 * oneshot serialization / deserialization
 *
 * Notation: "Used for *" applies to all fields below until the end of struct
 */

struct tegra_cpc_read_counter_data {
	/* Used for request */
	__u8 nonce[CPC_NONCE_SIZE];

	/* Used for response */
	__u8 write_counter[CPC_COUNTER_SIZE];
	/* Used for request */
	__u8 derivation_value[CPC_DERIVATION_SIZE];
	/* Used for response */
	__u8 hmac[CPC_HMAC_SIZE];
} __packed;

struct tegra_cpc_write_frame_data {
	/* Used for request */
	__u8 length;
	__u8 nonce[CPC_NONCE_SIZE];
	__u8 write_counter[CPC_COUNTER_SIZE];
	__u8 data[CPC_MAX_DATA_SIZE];
	__u8 hmac[CPC_HMAC_SIZE];
} __packed;

struct tegra_cpc_read_frame_data {
	/* Used for request */
	__u8 length;
	__u8 nonce[CPC_NONCE_SIZE];

	/* Not used by kernel or uC as of now */
	__u8 write_counter[CPC_COUNTER_SIZE];

	/* Used for response */
	__u8 data[CPC_MAX_DATA_SIZE];
	__u8 hmac[CPC_HMAC_SIZE];
} __packed;

struct tegra_cpc_get_version_data {
	/* Used for request */
	__u8 nonce[CPC_NONCE_SIZE];

	/* Used for response */
	__u8 minor_ver[CPC_MINOR_VER_SIZE];
	__u8 major_ver[CPC_MAJOR_VER_SIZE];
} __packed;

union tegra_cpc_cmd_data {
	struct tegra_cpc_read_counter_data read_counter;
	struct tegra_cpc_read_frame_data read_frame;
	struct tegra_cpc_write_frame_data write_frame;
	struct tegra_cpc_get_version_data get_version;
};

struct tegra_cpc_frame {
	/* Used for request */
	__u8 req;

	/* Used for both request and response */
	union tegra_cpc_cmd_data cmd_data;

	/* Used for response of GET_STATUS */
	__u8 hmac[CPC_HMAC_SIZE];
	__u8 result;
	__u8 nonce[CPC_NONCE_SIZE];
} __packed;

#define CPC_CMD_FIELD_SIZE(target_type, field) \
	sizeof(((struct target_type *) 0)->field)

#define CPC_FIELD_SIZE(field) \
	CPC_CMD_FIELD_SIZE(struct tegra_cpc_frame, field)

#define NVCPC_IOC_MAGIC 'C'

/*
 * Returns 0 if a communication with uC was successful, regardless of operation
 * pass or fail.
 */
#define NVCPC_IOCTL_DO_IO	_IOWR(NVCPC_IOC_MAGIC, 2, \
					struct tegra_cpc_frame)

#endif