1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (c) 2017, Microchip Technology Inc.
4  * Author: Tudor Ambarus
5  */
6 
7 #ifndef __ATMEL_I2C_H__
8 #define __ATMEL_I2C_H__
9 
10 #include <linux/hw_random.h>
11 #include <linux/types.h>
12 
13 #define ATMEL_ECC_PRIORITY		300
14 
15 #define COMMAND				0x03 /* packet function */
16 #define SLEEP_TOKEN			0x01
17 #define WAKE_TOKEN_MAX_SIZE		8
18 
19 /* Definitions of Data and Command sizes */
20 #define WORD_ADDR_SIZE			1
21 #define COUNT_SIZE			1
22 #define CRC_SIZE			2
23 #define CMD_OVERHEAD_SIZE		(COUNT_SIZE + CRC_SIZE)
24 
25 /* size in bytes of the n prime */
26 #define ATMEL_ECC_NIST_P256_N_SIZE	32
27 #define ATMEL_ECC_PUBKEY_SIZE		(2 * ATMEL_ECC_NIST_P256_N_SIZE)
28 
29 #define STATUS_RSP_SIZE			4
30 #define ECDH_RSP_SIZE			(32 + CMD_OVERHEAD_SIZE)
31 #define GENKEY_RSP_SIZE			(ATMEL_ECC_PUBKEY_SIZE + \
32 					 CMD_OVERHEAD_SIZE)
33 #define READ_RSP_SIZE			(4 + CMD_OVERHEAD_SIZE)
34 #define RANDOM_RSP_SIZE			(32 + CMD_OVERHEAD_SIZE)
35 #define MAX_RSP_SIZE			GENKEY_RSP_SIZE
36 
37 /**
38  * atmel_i2c_cmd - structure used for communicating with the device.
39  * @word_addr: indicates the function of the packet sent to the device. This
40  *             byte should have a value of COMMAND for normal operation.
41  * @count    : number of bytes to be transferred to (or from) the device.
42  * @opcode   : the command code.
43  * @param1   : the first parameter; always present.
44  * @param2   : the second parameter; always present.
45  * @data     : optional remaining input data. Includes a 2-byte CRC.
46  * @rxsize   : size of the data received from i2c client.
47  * @msecs    : command execution time in milliseconds
48  */
49 struct atmel_i2c_cmd {
50 	u8 word_addr;
51 	u8 count;
52 	u8 opcode;
53 	u8 param1;
54 	__le16 param2;
55 	u8 data[MAX_RSP_SIZE];
56 	u8 msecs;
57 	u16 rxsize;
58 } __packed;
59 
60 /* Status/Error codes */
61 #define STATUS_SIZE			0x04
62 #define STATUS_NOERR			0x00
63 #define STATUS_WAKE_SUCCESSFUL		0x11
64 
65 /* Definitions for eeprom organization */
66 #define CONFIGURATION_ZONE		0
67 
68 /* Definitions for Indexes common to all commands */
69 #define RSP_DATA_IDX			1 /* buffer index of data in response */
70 #define DATA_SLOT_2			2 /* used for ECDH private key */
71 
72 /* Definitions for the device lock state */
73 #define DEVICE_LOCK_ADDR		0x15
74 #define LOCK_VALUE_IDX			(RSP_DATA_IDX + 2)
75 #define LOCK_CONFIG_IDX			(RSP_DATA_IDX + 3)
76 
77 /*
78  * Wake High delay to data communication (microseconds). SDA should be stable
79  * high for this entire duration.
80  */
81 #define TWHI_MIN			1500
82 #define TWHI_MAX			1550
83 
84 /* Wake Low duration */
85 #define TWLO_USEC			60
86 
87 /* Command execution time (milliseconds) */
88 #define MAX_EXEC_TIME_ECDH		58
89 #define MAX_EXEC_TIME_GENKEY		115
90 #define MAX_EXEC_TIME_READ		1
91 #define MAX_EXEC_TIME_RANDOM		50
92 
93 /* Command opcode */
94 #define OPCODE_ECDH			0x43
95 #define OPCODE_GENKEY			0x40
96 #define OPCODE_READ			0x02
97 #define OPCODE_RANDOM			0x1b
98 
99 /* Definitions for the READ Command */
100 #define READ_COUNT			7
101 
102 /* Definitions for the RANDOM Command */
103 #define RANDOM_COUNT			7
104 
105 /* Definitions for the GenKey Command */
106 #define GENKEY_COUNT			7
107 #define GENKEY_MODE_PRIVATE		0x04
108 
109 /* Definitions for the ECDH Command */
110 #define ECDH_COUNT			71
111 #define ECDH_PREFIX_MODE		0x00
112 
113 /* Used for binding tfm objects to i2c clients. */
114 struct atmel_ecc_driver_data {
115 	struct list_head i2c_client_list;
116 	spinlock_t i2c_list_lock;
117 } ____cacheline_aligned;
118 
119 /**
120  * atmel_i2c_client_priv - i2c_client private data
121  * @client              : pointer to i2c client device
122  * @i2c_client_list_node: part of i2c_client_list
123  * @lock                : lock for sending i2c commands
124  * @wake_token          : wake token array of zeros
125  * @wake_token_sz       : size in bytes of the wake_token
126  * @tfm_count           : number of active crypto transformations on i2c client
127  *
128  * Reads and writes from/to the i2c client are sequential. The first byte
129  * transmitted to the device is treated as the byte size. Any attempt to send
130  * more than this number of bytes will cause the device to not ACK those bytes.
131  * After the host writes a single command byte to the input buffer, reads are
132  * prohibited until after the device completes command execution. Use a mutex
133  * when sending i2c commands.
134  */
135 struct atmel_i2c_client_priv {
136 	struct i2c_client *client;
137 	struct list_head i2c_client_list_node;
138 	struct mutex lock;
139 	u8 wake_token[WAKE_TOKEN_MAX_SIZE];
140 	size_t wake_token_sz;
141 	atomic_t tfm_count ____cacheline_aligned;
142 	struct hwrng hwrng;
143 };
144 
145 /**
146  * atmel_i2c_work_data - data structure representing the work
147  * @ctx : transformation context.
148  * @cbk : pointer to a callback function to be invoked upon completion of this
149  *        request. This has the form:
150  *        callback(struct atmel_i2c_work_data *work_data, void *areq, u8 status)
151  *        where:
152  *        @work_data: data structure representing the work
153  *        @areq     : optional pointer to an argument passed with the original
154  *                    request.
155  *        @status   : status returned from the i2c client device or i2c error.
156  * @areq: optional pointer to a user argument for use at callback time.
157  * @work: describes the task to be executed.
158  * @cmd : structure used for communicating with the device.
159  */
160 struct atmel_i2c_work_data {
161 	void *ctx;
162 	struct i2c_client *client;
163 	void (*cbk)(struct atmel_i2c_work_data *work_data, void *areq,
164 		    int status);
165 	void *areq;
166 	struct work_struct work;
167 	struct atmel_i2c_cmd cmd;
168 };
169 
170 int atmel_i2c_probe(struct i2c_client *client);
171 
172 void atmel_i2c_enqueue(struct atmel_i2c_work_data *work_data,
173 		       void (*cbk)(struct atmel_i2c_work_data *work_data,
174 				   void *areq, int status),
175 		       void *areq);
176 void atmel_i2c_flush_queue(void);
177 
178 int atmel_i2c_send_receive(struct i2c_client *client, struct atmel_i2c_cmd *cmd);
179 
180 void atmel_i2c_init_read_cmd(struct atmel_i2c_cmd *cmd);
181 void atmel_i2c_init_random_cmd(struct atmel_i2c_cmd *cmd);
182 void atmel_i2c_init_genkey_cmd(struct atmel_i2c_cmd *cmd, u16 keyid);
183 int atmel_i2c_init_ecdh_cmd(struct atmel_i2c_cmd *cmd,
184 			    struct scatterlist *pubkey);
185 
186 #endif /* __ATMEL_I2C_H__ */
187