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1 /*
2  * ChromeOS EC communication protocol helper functions
3  *
4  * Copyright (C) 2015 Google, Inc
5  *
6  * This software is licensed under the terms of the GNU General Public
7  * License version 2, as published by the Free Software Foundation, and
8  * may be copied, distributed, and modified under those terms.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  */
16 
17 #include <linux/mfd/cros_ec.h>
18 #include <linux/delay.h>
19 #include <linux/device.h>
20 #include <linux/module.h>
21 #include <linux/slab.h>
22 #include <asm/unaligned.h>
23 
24 #define EC_COMMAND_RETRIES	50
25 
prepare_packet(struct cros_ec_device * ec_dev,struct cros_ec_command * msg)26 static int prepare_packet(struct cros_ec_device *ec_dev,
27 			  struct cros_ec_command *msg)
28 {
29 	struct ec_host_request *request;
30 	u8 *out;
31 	int i;
32 	u8 csum = 0;
33 
34 	BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
35 	BUG_ON(msg->outsize + sizeof(*request) > ec_dev->dout_size);
36 
37 	out = ec_dev->dout;
38 	request = (struct ec_host_request *)out;
39 	request->struct_version = EC_HOST_REQUEST_VERSION;
40 	request->checksum = 0;
41 	request->command = msg->command;
42 	request->command_version = msg->version;
43 	request->reserved = 0;
44 	request->data_len = msg->outsize;
45 
46 	for (i = 0; i < sizeof(*request); i++)
47 		csum += out[i];
48 
49 	/* Copy data and update checksum */
50 	memcpy(out + sizeof(*request), msg->data, msg->outsize);
51 	for (i = 0; i < msg->outsize; i++)
52 		csum += msg->data[i];
53 
54 	request->checksum = -csum;
55 
56 	return sizeof(*request) + msg->outsize;
57 }
58 
send_command(struct cros_ec_device * ec_dev,struct cros_ec_command * msg)59 static int send_command(struct cros_ec_device *ec_dev,
60 			struct cros_ec_command *msg)
61 {
62 	int ret;
63 	int (*xfer_fxn)(struct cros_ec_device *ec, struct cros_ec_command *msg);
64 
65 	if (ec_dev->proto_version > 2)
66 		xfer_fxn = ec_dev->pkt_xfer;
67 	else
68 		xfer_fxn = ec_dev->cmd_xfer;
69 
70 	ret = (*xfer_fxn)(ec_dev, msg);
71 	if (msg->result == EC_RES_IN_PROGRESS) {
72 		int i;
73 		struct cros_ec_command *status_msg;
74 		struct ec_response_get_comms_status *status;
75 
76 		status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
77 				     GFP_KERNEL);
78 		if (!status_msg)
79 			return -ENOMEM;
80 
81 		status_msg->version = 0;
82 		status_msg->command = EC_CMD_GET_COMMS_STATUS;
83 		status_msg->insize = sizeof(*status);
84 		status_msg->outsize = 0;
85 
86 		/*
87 		 * Query the EC's status until it's no longer busy or
88 		 * we encounter an error.
89 		 */
90 		for (i = 0; i < EC_COMMAND_RETRIES; i++) {
91 			usleep_range(10000, 11000);
92 
93 			ret = (*xfer_fxn)(ec_dev, status_msg);
94 			if (ret < 0)
95 				break;
96 
97 			msg->result = status_msg->result;
98 			if (status_msg->result != EC_RES_SUCCESS)
99 				break;
100 
101 			status = (struct ec_response_get_comms_status *)
102 				 status_msg->data;
103 			if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
104 				break;
105 		}
106 
107 		kfree(status_msg);
108 	}
109 
110 	return ret;
111 }
112 
cros_ec_prepare_tx(struct cros_ec_device * ec_dev,struct cros_ec_command * msg)113 int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
114 		       struct cros_ec_command *msg)
115 {
116 	u8 *out;
117 	u8 csum;
118 	int i;
119 
120 	if (ec_dev->proto_version > 2)
121 		return prepare_packet(ec_dev, msg);
122 
123 	BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
124 	out = ec_dev->dout;
125 	out[0] = EC_CMD_VERSION0 + msg->version;
126 	out[1] = msg->command;
127 	out[2] = msg->outsize;
128 	csum = out[0] + out[1] + out[2];
129 	for (i = 0; i < msg->outsize; i++)
130 		csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
131 	out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;
132 
133 	return EC_MSG_TX_PROTO_BYTES + msg->outsize;
134 }
135 EXPORT_SYMBOL(cros_ec_prepare_tx);
136 
cros_ec_check_result(struct cros_ec_device * ec_dev,struct cros_ec_command * msg)137 int cros_ec_check_result(struct cros_ec_device *ec_dev,
138 			 struct cros_ec_command *msg)
139 {
140 	switch (msg->result) {
141 	case EC_RES_SUCCESS:
142 		return 0;
143 	case EC_RES_IN_PROGRESS:
144 		dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
145 			msg->command);
146 		return -EAGAIN;
147 	default:
148 		dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
149 			msg->command, msg->result);
150 		return 0;
151 	}
152 }
153 EXPORT_SYMBOL(cros_ec_check_result);
154 
cros_ec_host_command_proto_query(struct cros_ec_device * ec_dev,int devidx,struct cros_ec_command * msg)155 static int cros_ec_host_command_proto_query(struct cros_ec_device *ec_dev,
156 					    int devidx,
157 					    struct cros_ec_command *msg)
158 {
159 	/*
160 	 * Try using v3+ to query for supported protocols. If this
161 	 * command fails, fall back to v2. Returns the highest protocol
162 	 * supported by the EC.
163 	 * Also sets the max request/response/passthru size.
164 	 */
165 	int ret;
166 
167 	if (!ec_dev->pkt_xfer)
168 		return -EPROTONOSUPPORT;
169 
170 	memset(msg, 0, sizeof(*msg));
171 	msg->command = EC_CMD_PASSTHRU_OFFSET(devidx) | EC_CMD_GET_PROTOCOL_INFO;
172 	msg->insize = sizeof(struct ec_response_get_protocol_info);
173 
174 	ret = send_command(ec_dev, msg);
175 
176 	if (ret < 0) {
177 		dev_dbg(ec_dev->dev,
178 			"failed to check for EC[%d] protocol version: %d\n",
179 			devidx, ret);
180 		return ret;
181 	}
182 
183 	if (devidx > 0 && msg->result == EC_RES_INVALID_COMMAND)
184 		return -ENODEV;
185 	else if (msg->result != EC_RES_SUCCESS)
186 		return msg->result;
187 
188 	return 0;
189 }
190 
cros_ec_host_command_proto_query_v2(struct cros_ec_device * ec_dev)191 static int cros_ec_host_command_proto_query_v2(struct cros_ec_device *ec_dev)
192 {
193 	struct cros_ec_command *msg;
194 	struct ec_params_hello *hello_params;
195 	struct ec_response_hello *hello_response;
196 	int ret;
197 	int len = max(sizeof(*hello_params), sizeof(*hello_response));
198 
199 	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
200 	if (!msg)
201 		return -ENOMEM;
202 
203 	msg->version = 0;
204 	msg->command = EC_CMD_HELLO;
205 	hello_params = (struct ec_params_hello *)msg->data;
206 	msg->outsize = sizeof(*hello_params);
207 	hello_response = (struct ec_response_hello *)msg->data;
208 	msg->insize = sizeof(*hello_response);
209 
210 	hello_params->in_data = 0xa0b0c0d0;
211 
212 	ret = send_command(ec_dev, msg);
213 
214 	if (ret < 0) {
215 		dev_dbg(ec_dev->dev,
216 			"EC failed to respond to v2 hello: %d\n",
217 			ret);
218 		goto exit;
219 	} else if (msg->result != EC_RES_SUCCESS) {
220 		dev_err(ec_dev->dev,
221 			"EC responded to v2 hello with error: %d\n",
222 			msg->result);
223 		ret = msg->result;
224 		goto exit;
225 	} else if (hello_response->out_data != 0xa1b2c3d4) {
226 		dev_err(ec_dev->dev,
227 			"EC responded to v2 hello with bad result: %u\n",
228 			hello_response->out_data);
229 		ret = -EBADMSG;
230 		goto exit;
231 	}
232 
233 	ret = 0;
234 
235  exit:
236 	kfree(msg);
237 	return ret;
238 }
239 
cros_ec_get_host_command_version_mask(struct cros_ec_device * ec_dev,u16 cmd,u32 * mask)240 static int cros_ec_get_host_command_version_mask(struct cros_ec_device *ec_dev,
241 	u16 cmd, u32 *mask)
242 {
243 	struct ec_params_get_cmd_versions *pver;
244 	struct ec_response_get_cmd_versions *rver;
245 	struct cros_ec_command *msg;
246 	int ret;
247 
248 	msg = kmalloc(sizeof(*msg) + max(sizeof(*rver), sizeof(*pver)),
249 		      GFP_KERNEL);
250 	if (!msg)
251 		return -ENOMEM;
252 
253 	msg->version = 0;
254 	msg->command = EC_CMD_GET_CMD_VERSIONS;
255 	msg->insize = sizeof(*rver);
256 	msg->outsize = sizeof(*pver);
257 
258 	pver = (struct ec_params_get_cmd_versions *)msg->data;
259 	pver->cmd = cmd;
260 
261 	ret = cros_ec_cmd_xfer(ec_dev, msg);
262 	if (ret > 0) {
263 		rver = (struct ec_response_get_cmd_versions *)msg->data;
264 		*mask = rver->version_mask;
265 	}
266 
267 	kfree(msg);
268 
269 	return ret;
270 }
271 
cros_ec_query_all(struct cros_ec_device * ec_dev)272 int cros_ec_query_all(struct cros_ec_device *ec_dev)
273 {
274 	struct device *dev = ec_dev->dev;
275 	struct cros_ec_command *proto_msg;
276 	struct ec_response_get_protocol_info *proto_info;
277 	u32 ver_mask = 0;
278 	int ret;
279 
280 	proto_msg = kzalloc(sizeof(*proto_msg) + sizeof(*proto_info),
281 			    GFP_KERNEL);
282 	if (!proto_msg)
283 		return -ENOMEM;
284 
285 	/* First try sending with proto v3. */
286 	ec_dev->proto_version = 3;
287 	ret = cros_ec_host_command_proto_query(ec_dev, 0, proto_msg);
288 
289 	if (ret == 0) {
290 		proto_info = (struct ec_response_get_protocol_info *)
291 			proto_msg->data;
292 		ec_dev->max_request = proto_info->max_request_packet_size -
293 			sizeof(struct ec_host_request);
294 		ec_dev->max_response = proto_info->max_response_packet_size -
295 			sizeof(struct ec_host_response);
296 		ec_dev->proto_version =
297 			min(EC_HOST_REQUEST_VERSION,
298 					fls(proto_info->protocol_versions) - 1);
299 		dev_dbg(ec_dev->dev,
300 			"using proto v%u\n",
301 			ec_dev->proto_version);
302 
303 		ec_dev->din_size = ec_dev->max_response +
304 			sizeof(struct ec_host_response) +
305 			EC_MAX_RESPONSE_OVERHEAD;
306 		ec_dev->dout_size = ec_dev->max_request +
307 			sizeof(struct ec_host_request) +
308 			EC_MAX_REQUEST_OVERHEAD;
309 
310 		/*
311 		 * Check for PD
312 		 */
313 		ret = cros_ec_host_command_proto_query(ec_dev, 1, proto_msg);
314 
315 		if (ret) {
316 			dev_dbg(ec_dev->dev, "no PD chip found: %d\n", ret);
317 			ec_dev->max_passthru = 0;
318 		} else {
319 			dev_dbg(ec_dev->dev, "found PD chip\n");
320 			ec_dev->max_passthru =
321 				proto_info->max_request_packet_size -
322 				sizeof(struct ec_host_request);
323 		}
324 	} else {
325 		/* Try querying with a v2 hello message. */
326 		ec_dev->proto_version = 2;
327 		ret = cros_ec_host_command_proto_query_v2(ec_dev);
328 
329 		if (ret == 0) {
330 			/* V2 hello succeeded. */
331 			dev_dbg(ec_dev->dev, "falling back to proto v2\n");
332 
333 			ec_dev->max_request = EC_PROTO2_MAX_PARAM_SIZE;
334 			ec_dev->max_response = EC_PROTO2_MAX_PARAM_SIZE;
335 			ec_dev->max_passthru = 0;
336 			ec_dev->pkt_xfer = NULL;
337 			ec_dev->din_size = EC_PROTO2_MSG_BYTES;
338 			ec_dev->dout_size = EC_PROTO2_MSG_BYTES;
339 		} else {
340 			/*
341 			 * It's possible for a test to occur too early when
342 			 * the EC isn't listening. If this happens, we'll
343 			 * test later when the first command is run.
344 			 */
345 			ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
346 			dev_dbg(ec_dev->dev, "EC query failed: %d\n", ret);
347 			goto exit;
348 		}
349 	}
350 
351 	devm_kfree(dev, ec_dev->din);
352 	devm_kfree(dev, ec_dev->dout);
353 
354 	ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
355 	if (!ec_dev->din) {
356 		ret = -ENOMEM;
357 		goto exit;
358 	}
359 
360 	ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
361 	if (!ec_dev->dout) {
362 		devm_kfree(dev, ec_dev->din);
363 		ret = -ENOMEM;
364 		goto exit;
365 	}
366 
367 	/* Probe if MKBP event is supported */
368 	ret = cros_ec_get_host_command_version_mask(ec_dev,
369 						    EC_CMD_GET_NEXT_EVENT,
370 						    &ver_mask);
371 	if (ret < 0 || ver_mask == 0)
372 		ec_dev->mkbp_event_supported = 0;
373 	else
374 		ec_dev->mkbp_event_supported = 1;
375 
376 exit:
377 	kfree(proto_msg);
378 	return ret;
379 }
380 EXPORT_SYMBOL(cros_ec_query_all);
381 
cros_ec_cmd_xfer(struct cros_ec_device * ec_dev,struct cros_ec_command * msg)382 int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
383 		     struct cros_ec_command *msg)
384 {
385 	int ret;
386 
387 	mutex_lock(&ec_dev->lock);
388 	if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
389 		ret = cros_ec_query_all(ec_dev);
390 		if (ret) {
391 			dev_err(ec_dev->dev,
392 				"EC version unknown and query failed; aborting command\n");
393 			mutex_unlock(&ec_dev->lock);
394 			return ret;
395 		}
396 	}
397 
398 	if (msg->insize > ec_dev->max_response) {
399 		dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
400 		msg->insize = ec_dev->max_response;
401 	}
402 
403 	if (msg->command < EC_CMD_PASSTHRU_OFFSET(1)) {
404 		if (msg->outsize > ec_dev->max_request) {
405 			dev_err(ec_dev->dev,
406 				"request of size %u is too big (max: %u)\n",
407 				msg->outsize,
408 				ec_dev->max_request);
409 			mutex_unlock(&ec_dev->lock);
410 			return -EMSGSIZE;
411 		}
412 	} else {
413 		if (msg->outsize > ec_dev->max_passthru) {
414 			dev_err(ec_dev->dev,
415 				"passthru rq of size %u is too big (max: %u)\n",
416 				msg->outsize,
417 				ec_dev->max_passthru);
418 			mutex_unlock(&ec_dev->lock);
419 			return -EMSGSIZE;
420 		}
421 	}
422 	ret = send_command(ec_dev, msg);
423 	mutex_unlock(&ec_dev->lock);
424 
425 	return ret;
426 }
427 EXPORT_SYMBOL(cros_ec_cmd_xfer);
428 
cros_ec_cmd_xfer_status(struct cros_ec_device * ec_dev,struct cros_ec_command * msg)429 int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
430 			    struct cros_ec_command *msg)
431 {
432 	int ret;
433 
434 	ret = cros_ec_cmd_xfer(ec_dev, msg);
435 	if (ret < 0) {
436 		dev_err(ec_dev->dev, "Command xfer error (err:%d)\n", ret);
437 	} else if (msg->result != EC_RES_SUCCESS) {
438 		dev_dbg(ec_dev->dev, "Command result (err: %d)\n", msg->result);
439 		return -EPROTO;
440 	}
441 
442 	return ret;
443 }
444 EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
445 
get_next_event(struct cros_ec_device * ec_dev)446 static int get_next_event(struct cros_ec_device *ec_dev)
447 {
448 	u8 buffer[sizeof(struct cros_ec_command) + sizeof(ec_dev->event_data)];
449 	struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
450 	int ret;
451 
452 	msg->version = 0;
453 	msg->command = EC_CMD_GET_NEXT_EVENT;
454 	msg->insize = sizeof(ec_dev->event_data);
455 	msg->outsize = 0;
456 
457 	ret = cros_ec_cmd_xfer(ec_dev, msg);
458 	if (ret > 0) {
459 		ec_dev->event_size = ret - 1;
460 		memcpy(&ec_dev->event_data, msg->data,
461 		       sizeof(ec_dev->event_data));
462 	}
463 
464 	return ret;
465 }
466 
get_keyboard_state_event(struct cros_ec_device * ec_dev)467 static int get_keyboard_state_event(struct cros_ec_device *ec_dev)
468 {
469 	u8 buffer[sizeof(struct cros_ec_command) +
470 		  sizeof(ec_dev->event_data.data)];
471 	struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
472 
473 	msg->version = 0;
474 	msg->command = EC_CMD_MKBP_STATE;
475 	msg->insize = sizeof(ec_dev->event_data.data);
476 	msg->outsize = 0;
477 
478 	ec_dev->event_size = cros_ec_cmd_xfer(ec_dev, msg);
479 	ec_dev->event_data.event_type = EC_MKBP_EVENT_KEY_MATRIX;
480 	memcpy(&ec_dev->event_data.data, msg->data,
481 	       sizeof(ec_dev->event_data.data));
482 
483 	return ec_dev->event_size;
484 }
485 
cros_ec_get_next_event(struct cros_ec_device * ec_dev)486 int cros_ec_get_next_event(struct cros_ec_device *ec_dev)
487 {
488 	if (ec_dev->mkbp_event_supported)
489 		return get_next_event(ec_dev);
490 	else
491 		return get_keyboard_state_event(ec_dev);
492 }
493 EXPORT_SYMBOL(cros_ec_get_next_event);
494