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11105693 TDA |
1 | /* |
2 | * Microchip / Atmel ECC (I2C) driver. | |
3 | * | |
4 | * Copyright (c) 2017, Microchip Technology Inc. | |
5 | * Author: Tudor Ambarus <tudor.ambarus@microchip.com> | |
6 | * | |
7 | * This software is licensed under the terms of the GNU General Public | |
8 | * License version 2, as published by the Free Software Foundation, and | |
9 | * may be copied, distributed, and modified under those terms. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | */ | |
17 | ||
18 | #include <linux/bitrev.h> | |
19 | #include <linux/crc16.h> | |
20 | #include <linux/delay.h> | |
21 | #include <linux/device.h> | |
22 | #include <linux/err.h> | |
23 | #include <linux/errno.h> | |
24 | #include <linux/i2c.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/kernel.h> | |
27 | #include <linux/module.h> | |
28 | #include <linux/of_device.h> | |
29 | #include <linux/scatterlist.h> | |
30 | #include <linux/slab.h> | |
31 | #include <linux/workqueue.h> | |
32 | #include <crypto/internal/kpp.h> | |
33 | #include <crypto/ecdh.h> | |
34 | #include <crypto/kpp.h> | |
35 | #include "atmel-ecc.h" | |
36 | ||
37 | /* Used for binding tfm objects to i2c clients. */ | |
38 | struct atmel_ecc_driver_data { | |
39 | struct list_head i2c_client_list; | |
40 | spinlock_t i2c_list_lock; | |
41 | } ____cacheline_aligned; | |
42 | ||
43 | static struct atmel_ecc_driver_data driver_data; | |
44 | ||
45 | /** | |
46 | * atmel_ecc_i2c_client_priv - i2c_client private data | |
47 | * @client : pointer to i2c client device | |
48 | * @i2c_client_list_node: part of i2c_client_list | |
49 | * @lock : lock for sending i2c commands | |
50 | * @wake_token : wake token array of zeros | |
51 | * @wake_token_sz : size in bytes of the wake_token | |
52 | * @tfm_count : number of active crypto transformations on i2c client | |
53 | * | |
54 | * Reads and writes from/to the i2c client are sequential. The first byte | |
55 | * transmitted to the device is treated as the byte size. Any attempt to send | |
56 | * more than this number of bytes will cause the device to not ACK those bytes. | |
57 | * After the host writes a single command byte to the input buffer, reads are | |
58 | * prohibited until after the device completes command execution. Use a mutex | |
59 | * when sending i2c commands. | |
60 | */ | |
61 | struct atmel_ecc_i2c_client_priv { | |
62 | struct i2c_client *client; | |
63 | struct list_head i2c_client_list_node; | |
64 | struct mutex lock; | |
65 | u8 wake_token[WAKE_TOKEN_MAX_SIZE]; | |
66 | size_t wake_token_sz; | |
67 | atomic_t tfm_count ____cacheline_aligned; | |
68 | }; | |
69 | ||
70 | /** | |
71 | * atmel_ecdh_ctx - transformation context | |
72 | * @client : pointer to i2c client device | |
73 | * @fallback : used for unsupported curves or when user wants to use its own | |
74 | * private key. | |
75 | * @public_key : generated when calling set_secret(). It's the responsibility | |
76 | * of the user to not call set_secret() while | |
77 | * generate_public_key() or compute_shared_secret() are in flight. | |
78 | * @curve_id : elliptic curve id | |
79 | * @n_sz : size in bytes of the n prime | |
80 | * @do_fallback: true when the device doesn't support the curve or when the user | |
81 | * wants to use its own private key. | |
82 | */ | |
83 | struct atmel_ecdh_ctx { | |
84 | struct i2c_client *client; | |
85 | struct crypto_kpp *fallback; | |
86 | const u8 *public_key; | |
87 | unsigned int curve_id; | |
88 | size_t n_sz; | |
89 | bool do_fallback; | |
90 | }; | |
91 | ||
92 | /** | |
93 | * atmel_ecc_work_data - data structure representing the work | |
94 | * @ctx : transformation context. | |
95 | * @cbk : pointer to a callback function to be invoked upon completion of this | |
96 | * request. This has the form: | |
97 | * callback(struct atmel_ecc_work_data *work_data, void *areq, u8 status) | |
98 | * where: | |
99 | * @work_data: data structure representing the work | |
100 | * @areq : optional pointer to an argument passed with the original | |
101 | * request. | |
6d2bce6a | 102 | * @status : status returned from the i2c client device or i2c error. |
11105693 TDA |
103 | * @areq: optional pointer to a user argument for use at callback time. |
104 | * @work: describes the task to be executed. | |
105 | * @cmd : structure used for communicating with the device. | |
106 | */ | |
107 | struct atmel_ecc_work_data { | |
108 | struct atmel_ecdh_ctx *ctx; | |
109 | void (*cbk)(struct atmel_ecc_work_data *work_data, void *areq, | |
6d2bce6a | 110 | int status); |
11105693 TDA |
111 | void *areq; |
112 | struct work_struct work; | |
113 | struct atmel_ecc_cmd cmd; | |
114 | }; | |
115 | ||
116 | static u16 atmel_ecc_crc16(u16 crc, const u8 *buffer, size_t len) | |
117 | { | |
118 | return cpu_to_le16(bitrev16(crc16(crc, buffer, len))); | |
119 | } | |
120 | ||
121 | /** | |
122 | * atmel_ecc_checksum() - Generate 16-bit CRC as required by ATMEL ECC. | |
123 | * CRC16 verification of the count, opcode, param1, param2 and data bytes. | |
124 | * The checksum is saved in little-endian format in the least significant | |
125 | * two bytes of the command. CRC polynomial is 0x8005 and the initial register | |
126 | * value should be zero. | |
127 | * | |
128 | * @cmd : structure used for communicating with the device. | |
129 | */ | |
130 | static void atmel_ecc_checksum(struct atmel_ecc_cmd *cmd) | |
131 | { | |
132 | u8 *data = &cmd->count; | |
133 | size_t len = cmd->count - CRC_SIZE; | |
134 | u16 *crc16 = (u16 *)(data + len); | |
135 | ||
136 | *crc16 = atmel_ecc_crc16(0, data, len); | |
137 | } | |
138 | ||
139 | static void atmel_ecc_init_read_cmd(struct atmel_ecc_cmd *cmd) | |
140 | { | |
141 | cmd->word_addr = COMMAND; | |
142 | cmd->opcode = OPCODE_READ; | |
143 | /* | |
144 | * Read the word from Configuration zone that contains the lock bytes | |
145 | * (UserExtra, Selector, LockValue, LockConfig). | |
146 | */ | |
147 | cmd->param1 = CONFIG_ZONE; | |
148 | cmd->param2 = DEVICE_LOCK_ADDR; | |
149 | cmd->count = READ_COUNT; | |
150 | ||
151 | atmel_ecc_checksum(cmd); | |
152 | ||
153 | cmd->msecs = MAX_EXEC_TIME_READ; | |
154 | cmd->rxsize = READ_RSP_SIZE; | |
155 | } | |
156 | ||
157 | static void atmel_ecc_init_genkey_cmd(struct atmel_ecc_cmd *cmd, u16 keyid) | |
158 | { | |
159 | cmd->word_addr = COMMAND; | |
160 | cmd->count = GENKEY_COUNT; | |
161 | cmd->opcode = OPCODE_GENKEY; | |
162 | cmd->param1 = GENKEY_MODE_PRIVATE; | |
163 | /* a random private key will be generated and stored in slot keyID */ | |
164 | cmd->param2 = cpu_to_le16(keyid); | |
165 | ||
166 | atmel_ecc_checksum(cmd); | |
167 | ||
168 | cmd->msecs = MAX_EXEC_TIME_GENKEY; | |
169 | cmd->rxsize = GENKEY_RSP_SIZE; | |
170 | } | |
171 | ||
172 | static int atmel_ecc_init_ecdh_cmd(struct atmel_ecc_cmd *cmd, | |
173 | struct scatterlist *pubkey) | |
174 | { | |
175 | size_t copied; | |
176 | ||
177 | cmd->word_addr = COMMAND; | |
178 | cmd->count = ECDH_COUNT; | |
179 | cmd->opcode = OPCODE_ECDH; | |
180 | cmd->param1 = ECDH_PREFIX_MODE; | |
181 | /* private key slot */ | |
182 | cmd->param2 = cpu_to_le16(DATA_SLOT_2); | |
183 | ||
184 | /* | |
185 | * The device only supports NIST P256 ECC keys. The public key size will | |
186 | * always be the same. Use a macro for the key size to avoid unnecessary | |
187 | * computations. | |
188 | */ | |
189 | copied = sg_copy_to_buffer(pubkey, 1, cmd->data, ATMEL_ECC_PUBKEY_SIZE); | |
190 | if (copied != ATMEL_ECC_PUBKEY_SIZE) | |
191 | return -EINVAL; | |
192 | ||
193 | atmel_ecc_checksum(cmd); | |
194 | ||
195 | cmd->msecs = MAX_EXEC_TIME_ECDH; | |
196 | cmd->rxsize = ECDH_RSP_SIZE; | |
197 | ||
198 | return 0; | |
199 | } | |
200 | ||
201 | /* | |
202 | * After wake and after execution of a command, there will be error, status, or | |
203 | * result bytes in the device's output register that can be retrieved by the | |
204 | * system. When the length of that group is four bytes, the codes returned are | |
205 | * detailed in error_list. | |
206 | */ | |
207 | static int atmel_ecc_status(struct device *dev, u8 *status) | |
208 | { | |
209 | size_t err_list_len = ARRAY_SIZE(error_list); | |
210 | int i; | |
211 | u8 err_id = status[1]; | |
212 | ||
213 | if (*status != STATUS_SIZE) | |
214 | return 0; | |
215 | ||
216 | if (err_id == STATUS_WAKE_SUCCESSFUL || err_id == STATUS_NOERR) | |
217 | return 0; | |
218 | ||
219 | for (i = 0; i < err_list_len; i++) | |
220 | if (error_list[i].value == err_id) | |
221 | break; | |
222 | ||
223 | /* if err_id is not in the error_list then ignore it */ | |
224 | if (i != err_list_len) { | |
225 | dev_err(dev, "%02x: %s:\n", err_id, error_list[i].error_text); | |
226 | return err_id; | |
227 | } | |
228 | ||
229 | return 0; | |
230 | } | |
231 | ||
232 | static int atmel_ecc_wakeup(struct i2c_client *client) | |
233 | { | |
234 | struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); | |
235 | u8 status[STATUS_RSP_SIZE]; | |
236 | int ret; | |
237 | ||
238 | /* | |
239 | * The device ignores any levels or transitions on the SCL pin when the | |
240 | * device is idle, asleep or during waking up. Don't check for error | |
241 | * when waking up the device. | |
242 | */ | |
243 | i2c_master_send(client, i2c_priv->wake_token, i2c_priv->wake_token_sz); | |
244 | ||
245 | /* | |
246 | * Wait to wake the device. Typical execution times for ecdh and genkey | |
247 | * are around tens of milliseconds. Delta is chosen to 50 microseconds. | |
248 | */ | |
249 | usleep_range(TWHI_MIN, TWHI_MAX); | |
250 | ||
251 | ret = i2c_master_recv(client, status, STATUS_SIZE); | |
252 | if (ret < 0) | |
253 | return ret; | |
254 | ||
255 | return atmel_ecc_status(&client->dev, status); | |
256 | } | |
257 | ||
258 | static int atmel_ecc_sleep(struct i2c_client *client) | |
259 | { | |
260 | u8 sleep = SLEEP_TOKEN; | |
261 | ||
262 | return i2c_master_send(client, &sleep, 1); | |
263 | } | |
264 | ||
265 | static void atmel_ecdh_done(struct atmel_ecc_work_data *work_data, void *areq, | |
6d2bce6a | 266 | int status) |
11105693 TDA |
267 | { |
268 | struct kpp_request *req = areq; | |
269 | struct atmel_ecdh_ctx *ctx = work_data->ctx; | |
270 | struct atmel_ecc_cmd *cmd = &work_data->cmd; | |
271 | size_t copied; | |
272 | size_t n_sz = ctx->n_sz; | |
273 | ||
274 | if (status) | |
275 | goto free_work_data; | |
276 | ||
277 | /* copy the shared secret */ | |
278 | copied = sg_copy_from_buffer(req->dst, 1, &cmd->data[RSP_DATA_IDX], | |
279 | n_sz); | |
280 | if (copied != n_sz) | |
281 | status = -EINVAL; | |
282 | ||
283 | /* fall through */ | |
284 | free_work_data: | |
285 | kzfree(work_data); | |
286 | kpp_request_complete(req, status); | |
287 | } | |
288 | ||
289 | /* | |
290 | * atmel_ecc_send_receive() - send a command to the device and receive its | |
291 | * response. | |
292 | * @client: i2c client device | |
293 | * @cmd : structure used to communicate with the device | |
294 | * | |
295 | * After the device receives a Wake token, a watchdog counter starts within the | |
296 | * device. After the watchdog timer expires, the device enters sleep mode | |
297 | * regardless of whether some I/O transmission or command execution is in | |
298 | * progress. If a command is attempted when insufficient time remains prior to | |
299 | * watchdog timer execution, the device will return the watchdog timeout error | |
300 | * code without attempting to execute the command. There is no way to reset the | |
301 | * counter other than to put the device into sleep or idle mode and then | |
302 | * wake it up again. | |
303 | */ | |
304 | static int atmel_ecc_send_receive(struct i2c_client *client, | |
305 | struct atmel_ecc_cmd *cmd) | |
306 | { | |
307 | struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); | |
308 | int ret; | |
309 | ||
310 | mutex_lock(&i2c_priv->lock); | |
311 | ||
312 | ret = atmel_ecc_wakeup(client); | |
313 | if (ret) | |
314 | goto err; | |
315 | ||
316 | /* send the command */ | |
317 | ret = i2c_master_send(client, (u8 *)cmd, cmd->count + WORD_ADDR_SIZE); | |
318 | if (ret < 0) | |
319 | goto err; | |
320 | ||
321 | /* delay the appropriate amount of time for command to execute */ | |
322 | msleep(cmd->msecs); | |
323 | ||
324 | /* receive the response */ | |
325 | ret = i2c_master_recv(client, cmd->data, cmd->rxsize); | |
326 | if (ret < 0) | |
327 | goto err; | |
328 | ||
329 | /* put the device into low-power mode */ | |
330 | ret = atmel_ecc_sleep(client); | |
331 | if (ret < 0) | |
332 | goto err; | |
333 | ||
334 | mutex_unlock(&i2c_priv->lock); | |
335 | return atmel_ecc_status(&client->dev, cmd->data); | |
336 | err: | |
337 | mutex_unlock(&i2c_priv->lock); | |
338 | return ret; | |
339 | } | |
340 | ||
341 | static void atmel_ecc_work_handler(struct work_struct *work) | |
342 | { | |
343 | struct atmel_ecc_work_data *work_data = | |
344 | container_of(work, struct atmel_ecc_work_data, work); | |
345 | struct atmel_ecc_cmd *cmd = &work_data->cmd; | |
346 | struct i2c_client *client = work_data->ctx->client; | |
6d2bce6a | 347 | int status; |
11105693 TDA |
348 | |
349 | status = atmel_ecc_send_receive(client, cmd); | |
350 | work_data->cbk(work_data, work_data->areq, status); | |
351 | } | |
352 | ||
353 | static void atmel_ecc_enqueue(struct atmel_ecc_work_data *work_data, | |
354 | void (*cbk)(struct atmel_ecc_work_data *work_data, | |
6d2bce6a | 355 | void *areq, int status), |
11105693 TDA |
356 | void *areq) |
357 | { | |
358 | work_data->cbk = (void *)cbk; | |
359 | work_data->areq = areq; | |
360 | ||
361 | INIT_WORK(&work_data->work, atmel_ecc_work_handler); | |
362 | schedule_work(&work_data->work); | |
363 | } | |
364 | ||
365 | static unsigned int atmel_ecdh_supported_curve(unsigned int curve_id) | |
366 | { | |
367 | if (curve_id == ECC_CURVE_NIST_P256) | |
368 | return ATMEL_ECC_NIST_P256_N_SIZE; | |
369 | ||
370 | return 0; | |
371 | } | |
372 | ||
373 | /* | |
374 | * A random private key is generated and stored in the device. The device | |
375 | * returns the pair public key. | |
376 | */ | |
377 | static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf, | |
378 | unsigned int len) | |
379 | { | |
380 | struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm); | |
381 | struct atmel_ecc_cmd *cmd; | |
382 | void *public_key; | |
383 | struct ecdh params; | |
384 | int ret = -ENOMEM; | |
385 | ||
386 | /* free the old public key, if any */ | |
387 | kfree(ctx->public_key); | |
388 | /* make sure you don't free the old public key twice */ | |
389 | ctx->public_key = NULL; | |
390 | ||
391 | if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0) { | |
392 | dev_err(&ctx->client->dev, "crypto_ecdh_decode_key failed\n"); | |
393 | return -EINVAL; | |
394 | } | |
395 | ||
396 | ctx->n_sz = atmel_ecdh_supported_curve(params.curve_id); | |
397 | if (!ctx->n_sz || params.key_size) { | |
398 | /* fallback to ecdh software implementation */ | |
399 | ctx->do_fallback = true; | |
400 | return crypto_kpp_set_secret(ctx->fallback, buf, len); | |
401 | } | |
402 | ||
403 | cmd = kmalloc(sizeof(*cmd), GFP_KERNEL); | |
404 | if (!cmd) | |
405 | return -ENOMEM; | |
406 | ||
407 | /* | |
408 | * The device only supports NIST P256 ECC keys. The public key size will | |
409 | * always be the same. Use a macro for the key size to avoid unnecessary | |
410 | * computations. | |
411 | */ | |
412 | public_key = kmalloc(ATMEL_ECC_PUBKEY_SIZE, GFP_KERNEL); | |
413 | if (!public_key) | |
414 | goto free_cmd; | |
415 | ||
416 | ctx->do_fallback = false; | |
417 | ctx->curve_id = params.curve_id; | |
418 | ||
419 | atmel_ecc_init_genkey_cmd(cmd, DATA_SLOT_2); | |
420 | ||
421 | ret = atmel_ecc_send_receive(ctx->client, cmd); | |
422 | if (ret) | |
423 | goto free_public_key; | |
424 | ||
425 | /* save the public key */ | |
426 | memcpy(public_key, &cmd->data[RSP_DATA_IDX], ATMEL_ECC_PUBKEY_SIZE); | |
427 | ctx->public_key = public_key; | |
428 | ||
429 | kfree(cmd); | |
430 | return 0; | |
431 | ||
432 | free_public_key: | |
433 | kfree(public_key); | |
434 | free_cmd: | |
435 | kfree(cmd); | |
436 | return ret; | |
437 | } | |
438 | ||
439 | static int atmel_ecdh_generate_public_key(struct kpp_request *req) | |
440 | { | |
441 | struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); | |
442 | struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm); | |
443 | size_t copied; | |
444 | int ret = 0; | |
445 | ||
446 | if (ctx->do_fallback) { | |
447 | kpp_request_set_tfm(req, ctx->fallback); | |
448 | return crypto_kpp_generate_public_key(req); | |
449 | } | |
450 | ||
451 | /* public key was saved at private key generation */ | |
452 | copied = sg_copy_from_buffer(req->dst, 1, ctx->public_key, | |
453 | ATMEL_ECC_PUBKEY_SIZE); | |
454 | if (copied != ATMEL_ECC_PUBKEY_SIZE) | |
455 | ret = -EINVAL; | |
456 | ||
457 | return ret; | |
458 | } | |
459 | ||
460 | static int atmel_ecdh_compute_shared_secret(struct kpp_request *req) | |
461 | { | |
462 | struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); | |
463 | struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm); | |
464 | struct atmel_ecc_work_data *work_data; | |
465 | gfp_t gfp; | |
466 | int ret; | |
467 | ||
468 | if (ctx->do_fallback) { | |
469 | kpp_request_set_tfm(req, ctx->fallback); | |
470 | return crypto_kpp_compute_shared_secret(req); | |
471 | } | |
472 | ||
473 | gfp = (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ? GFP_KERNEL : | |
474 | GFP_ATOMIC; | |
475 | ||
476 | work_data = kmalloc(sizeof(*work_data), gfp); | |
477 | if (!work_data) | |
478 | return -ENOMEM; | |
479 | ||
480 | work_data->ctx = ctx; | |
481 | ||
482 | ret = atmel_ecc_init_ecdh_cmd(&work_data->cmd, req->src); | |
483 | if (ret) | |
484 | goto free_work_data; | |
485 | ||
486 | atmel_ecc_enqueue(work_data, atmel_ecdh_done, req); | |
487 | ||
488 | return -EINPROGRESS; | |
489 | ||
490 | free_work_data: | |
491 | kfree(work_data); | |
492 | return ret; | |
493 | } | |
494 | ||
0138d32f | 495 | static struct i2c_client *atmel_ecc_i2c_client_alloc(void) |
11105693 TDA |
496 | { |
497 | struct atmel_ecc_i2c_client_priv *i2c_priv, *min_i2c_priv = NULL; | |
498 | struct i2c_client *client = ERR_PTR(-ENODEV); | |
499 | int min_tfm_cnt = INT_MAX; | |
500 | int tfm_cnt; | |
501 | ||
502 | spin_lock(&driver_data.i2c_list_lock); | |
503 | ||
504 | if (list_empty(&driver_data.i2c_client_list)) { | |
505 | spin_unlock(&driver_data.i2c_list_lock); | |
506 | return ERR_PTR(-ENODEV); | |
507 | } | |
508 | ||
509 | list_for_each_entry(i2c_priv, &driver_data.i2c_client_list, | |
510 | i2c_client_list_node) { | |
511 | tfm_cnt = atomic_read(&i2c_priv->tfm_count); | |
512 | if (tfm_cnt < min_tfm_cnt) { | |
513 | min_tfm_cnt = tfm_cnt; | |
514 | min_i2c_priv = i2c_priv; | |
515 | } | |
516 | if (!min_tfm_cnt) | |
517 | break; | |
518 | } | |
519 | ||
520 | if (min_i2c_priv) { | |
521 | atomic_inc(&min_i2c_priv->tfm_count); | |
522 | client = min_i2c_priv->client; | |
523 | } | |
524 | ||
525 | spin_unlock(&driver_data.i2c_list_lock); | |
526 | ||
527 | return client; | |
528 | } | |
529 | ||
0138d32f | 530 | static void atmel_ecc_i2c_client_free(struct i2c_client *client) |
11105693 TDA |
531 | { |
532 | struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); | |
533 | ||
534 | atomic_dec(&i2c_priv->tfm_count); | |
535 | } | |
536 | ||
537 | static int atmel_ecdh_init_tfm(struct crypto_kpp *tfm) | |
538 | { | |
539 | const char *alg = kpp_alg_name(tfm); | |
540 | struct crypto_kpp *fallback; | |
541 | struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm); | |
542 | ||
543 | ctx->client = atmel_ecc_i2c_client_alloc(); | |
544 | if (IS_ERR(ctx->client)) { | |
545 | pr_err("tfm - i2c_client binding failed\n"); | |
546 | return PTR_ERR(ctx->client); | |
547 | } | |
548 | ||
549 | fallback = crypto_alloc_kpp(alg, 0, CRYPTO_ALG_NEED_FALLBACK); | |
550 | if (IS_ERR(fallback)) { | |
551 | dev_err(&ctx->client->dev, "Failed to allocate transformation for '%s': %ld\n", | |
552 | alg, PTR_ERR(fallback)); | |
553 | return PTR_ERR(fallback); | |
554 | } | |
555 | ||
556 | crypto_kpp_set_flags(fallback, crypto_kpp_get_flags(tfm)); | |
557 | ||
558 | dev_info(&ctx->client->dev, "Using '%s' as fallback implementation.\n", | |
559 | crypto_tfm_alg_driver_name(crypto_kpp_tfm(fallback))); | |
560 | ||
561 | ctx->fallback = fallback; | |
562 | ||
563 | return 0; | |
564 | } | |
565 | ||
566 | static void atmel_ecdh_exit_tfm(struct crypto_kpp *tfm) | |
567 | { | |
568 | struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm); | |
569 | ||
570 | kfree(ctx->public_key); | |
571 | crypto_free_kpp(ctx->fallback); | |
572 | atmel_ecc_i2c_client_free(ctx->client); | |
573 | } | |
574 | ||
575 | static unsigned int atmel_ecdh_max_size(struct crypto_kpp *tfm) | |
576 | { | |
577 | struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm); | |
578 | ||
579 | if (ctx->fallback) | |
580 | return crypto_kpp_maxsize(ctx->fallback); | |
581 | ||
582 | /* | |
583 | * The device only supports NIST P256 ECC keys. The public key size will | |
584 | * always be the same. Use a macro for the key size to avoid unnecessary | |
585 | * computations. | |
586 | */ | |
587 | return ATMEL_ECC_PUBKEY_SIZE; | |
588 | } | |
589 | ||
590 | static struct kpp_alg atmel_ecdh = { | |
591 | .set_secret = atmel_ecdh_set_secret, | |
592 | .generate_public_key = atmel_ecdh_generate_public_key, | |
593 | .compute_shared_secret = atmel_ecdh_compute_shared_secret, | |
594 | .init = atmel_ecdh_init_tfm, | |
595 | .exit = atmel_ecdh_exit_tfm, | |
596 | .max_size = atmel_ecdh_max_size, | |
597 | .base = { | |
598 | .cra_flags = CRYPTO_ALG_NEED_FALLBACK, | |
599 | .cra_name = "ecdh", | |
600 | .cra_driver_name = "atmel-ecdh", | |
601 | .cra_priority = ATMEL_ECC_PRIORITY, | |
602 | .cra_module = THIS_MODULE, | |
603 | .cra_ctxsize = sizeof(struct atmel_ecdh_ctx), | |
604 | }, | |
605 | }; | |
606 | ||
607 | static inline size_t atmel_ecc_wake_token_sz(u32 bus_clk_rate) | |
608 | { | |
609 | u32 no_of_bits = DIV_ROUND_UP(TWLO_USEC * bus_clk_rate, USEC_PER_SEC); | |
610 | ||
611 | /* return the size of the wake_token in bytes */ | |
612 | return DIV_ROUND_UP(no_of_bits, 8); | |
613 | } | |
614 | ||
615 | static int device_sanity_check(struct i2c_client *client) | |
616 | { | |
617 | struct atmel_ecc_cmd *cmd; | |
618 | int ret; | |
619 | ||
620 | cmd = kmalloc(sizeof(*cmd), GFP_KERNEL); | |
621 | if (!cmd) | |
622 | return -ENOMEM; | |
623 | ||
624 | atmel_ecc_init_read_cmd(cmd); | |
625 | ||
626 | ret = atmel_ecc_send_receive(client, cmd); | |
627 | if (ret) | |
628 | goto free_cmd; | |
629 | ||
630 | /* | |
631 | * It is vital that the Configuration, Data and OTP zones be locked | |
632 | * prior to release into the field of the system containing the device. | |
633 | * Failure to lock these zones may permit modification of any secret | |
634 | * keys and may lead to other security problems. | |
635 | */ | |
636 | if (cmd->data[LOCK_CONFIG_IDX] || cmd->data[LOCK_VALUE_IDX]) { | |
637 | dev_err(&client->dev, "Configuration or Data and OTP zones are unlocked!\n"); | |
638 | ret = -ENOTSUPP; | |
639 | } | |
640 | ||
641 | /* fall through */ | |
642 | free_cmd: | |
643 | kfree(cmd); | |
644 | return ret; | |
645 | } | |
646 | ||
647 | static int atmel_ecc_probe(struct i2c_client *client, | |
648 | const struct i2c_device_id *id) | |
649 | { | |
650 | struct atmel_ecc_i2c_client_priv *i2c_priv; | |
651 | struct device *dev = &client->dev; | |
652 | int ret; | |
653 | u32 bus_clk_rate; | |
654 | ||
655 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { | |
656 | dev_err(dev, "I2C_FUNC_I2C not supported\n"); | |
657 | return -ENODEV; | |
658 | } | |
659 | ||
660 | ret = of_property_read_u32(client->adapter->dev.of_node, | |
661 | "clock-frequency", &bus_clk_rate); | |
662 | if (ret) { | |
663 | dev_err(dev, "of: failed to read clock-frequency property\n"); | |
664 | return ret; | |
665 | } | |
666 | ||
667 | if (bus_clk_rate > 1000000L) { | |
668 | dev_err(dev, "%d exceeds maximum supported clock frequency (1MHz)\n", | |
669 | bus_clk_rate); | |
670 | return -EINVAL; | |
671 | } | |
672 | ||
673 | i2c_priv = devm_kmalloc(dev, sizeof(*i2c_priv), GFP_KERNEL); | |
674 | if (!i2c_priv) | |
675 | return -ENOMEM; | |
676 | ||
677 | i2c_priv->client = client; | |
678 | mutex_init(&i2c_priv->lock); | |
679 | ||
680 | /* | |
681 | * WAKE_TOKEN_MAX_SIZE was calculated for the maximum bus_clk_rate - | |
682 | * 1MHz. The previous bus_clk_rate check ensures us that wake_token_sz | |
683 | * will always be smaller than or equal to WAKE_TOKEN_MAX_SIZE. | |
684 | */ | |
685 | i2c_priv->wake_token_sz = atmel_ecc_wake_token_sz(bus_clk_rate); | |
686 | ||
687 | memset(i2c_priv->wake_token, 0, sizeof(i2c_priv->wake_token)); | |
688 | ||
689 | atomic_set(&i2c_priv->tfm_count, 0); | |
690 | ||
691 | i2c_set_clientdata(client, i2c_priv); | |
692 | ||
693 | ret = device_sanity_check(client); | |
694 | if (ret) | |
695 | return ret; | |
696 | ||
697 | spin_lock(&driver_data.i2c_list_lock); | |
698 | list_add_tail(&i2c_priv->i2c_client_list_node, | |
699 | &driver_data.i2c_client_list); | |
700 | spin_unlock(&driver_data.i2c_list_lock); | |
701 | ||
702 | ret = crypto_register_kpp(&atmel_ecdh); | |
703 | if (ret) { | |
704 | spin_lock(&driver_data.i2c_list_lock); | |
705 | list_del(&i2c_priv->i2c_client_list_node); | |
706 | spin_unlock(&driver_data.i2c_list_lock); | |
707 | ||
708 | dev_err(dev, "%s alg registration failed\n", | |
709 | atmel_ecdh.base.cra_driver_name); | |
710 | } else { | |
711 | dev_info(dev, "atmel ecc algorithms registered in /proc/crypto\n"); | |
712 | } | |
713 | ||
714 | return ret; | |
715 | } | |
716 | ||
717 | static int atmel_ecc_remove(struct i2c_client *client) | |
718 | { | |
719 | struct atmel_ecc_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); | |
720 | ||
721 | /* Return EBUSY if i2c client already allocated. */ | |
722 | if (atomic_read(&i2c_priv->tfm_count)) { | |
723 | dev_err(&client->dev, "Device is busy\n"); | |
724 | return -EBUSY; | |
725 | } | |
726 | ||
727 | crypto_unregister_kpp(&atmel_ecdh); | |
728 | ||
729 | spin_lock(&driver_data.i2c_list_lock); | |
730 | list_del(&i2c_priv->i2c_client_list_node); | |
731 | spin_unlock(&driver_data.i2c_list_lock); | |
732 | ||
733 | return 0; | |
734 | } | |
735 | ||
736 | #ifdef CONFIG_OF | |
737 | static const struct of_device_id atmel_ecc_dt_ids[] = { | |
738 | { | |
739 | .compatible = "atmel,atecc508a", | |
740 | }, { | |
741 | /* sentinel */ | |
742 | } | |
743 | }; | |
744 | MODULE_DEVICE_TABLE(of, atmel_ecc_dt_ids); | |
745 | #endif | |
746 | ||
747 | static const struct i2c_device_id atmel_ecc_id[] = { | |
748 | { "atecc508a", 0 }, | |
749 | { } | |
750 | }; | |
751 | MODULE_DEVICE_TABLE(i2c, atmel_ecc_id); | |
752 | ||
753 | static struct i2c_driver atmel_ecc_driver = { | |
754 | .driver = { | |
755 | .name = "atmel-ecc", | |
756 | .of_match_table = of_match_ptr(atmel_ecc_dt_ids), | |
757 | }, | |
758 | .probe = atmel_ecc_probe, | |
759 | .remove = atmel_ecc_remove, | |
760 | .id_table = atmel_ecc_id, | |
761 | }; | |
762 | ||
763 | static int __init atmel_ecc_init(void) | |
764 | { | |
765 | spin_lock_init(&driver_data.i2c_list_lock); | |
766 | INIT_LIST_HEAD(&driver_data.i2c_client_list); | |
767 | return i2c_add_driver(&atmel_ecc_driver); | |
768 | } | |
769 | ||
770 | static void __exit atmel_ecc_exit(void) | |
771 | { | |
772 | flush_scheduled_work(); | |
773 | i2c_del_driver(&atmel_ecc_driver); | |
774 | } | |
775 | ||
776 | module_init(atmel_ecc_init); | |
777 | module_exit(atmel_ecc_exit); | |
778 | ||
779 | MODULE_AUTHOR("Tudor Ambarus <tudor.ambarus@microchip.com>"); | |
780 | MODULE_DESCRIPTION("Microchip / Atmel ECC (I2C) driver"); | |
781 | MODULE_LICENSE("GPL v2"); |