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