1/*
  2 * ChromeOS EC multi-function device (I2C)
  3 *
  4 * Copyright (C) 2012 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#include <linux/delay.h>
 17#include <linux/kernel.h>
 18#include <linux/module.h>
 19#include <linux/i2c.h>
 20#include <linux/interrupt.h>
 21#include <linux/mfd/cros_ec.h>
 22#include <linux/mfd/cros_ec_commands.h>
 23#include <linux/platform_device.h>
 24#include <linux/slab.h>
 25
 26/**
 27 * Request format for protocol v3
 28 * byte 0	0xda (EC_COMMAND_PROTOCOL_3)
 29 * byte 1-8	struct ec_host_request
 30 * byte 10-	response data
 31 */
 32struct ec_host_request_i2c {
 33	/* Always 0xda to backward compatible with v2 struct */
 34	uint8_t  command_protocol;
 35	struct ec_host_request ec_request;
 36} __packed;
 37
 38
 39/*
 40 * Response format for protocol v3
 41 * byte 0	result code
 42 * byte 1	packet_length
 43 * byte 2-9	struct ec_host_response
 44 * byte 10-	response data
 45 */
 46struct ec_host_response_i2c {
 47	uint8_t result;
 48	uint8_t packet_length;
 49	struct ec_host_response ec_response;
 50} __packed;
 51
 52static inline struct cros_ec_device *to_ec_dev(struct device *dev)
 53{
 54	struct i2c_client *client = to_i2c_client(dev);
 55
 56	return i2c_get_clientdata(client);
 57}
 58
 59static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
 60				struct cros_ec_command *msg)
 61{
 62	struct i2c_client *client = ec_dev->priv;
 63	int ret = -ENOMEM;
 64	int i;
 65	int packet_len;
 66	u8 *out_buf = NULL;
 67	u8 *in_buf = NULL;
 68	u8 sum;
 69	struct i2c_msg i2c_msg[2];
 70	struct ec_host_response *ec_response;
 71	struct ec_host_request_i2c *ec_request_i2c;
 72	struct ec_host_response_i2c *ec_response_i2c;
 73	int request_header_size = sizeof(struct ec_host_request_i2c);
 74	int response_header_size = sizeof(struct ec_host_response_i2c);
 75
 76	i2c_msg[0].addr = client->addr;
 77	i2c_msg[0].flags = 0;
 78	i2c_msg[1].addr = client->addr;
 79	i2c_msg[1].flags = I2C_M_RD;
 80
 81	packet_len = msg->insize + response_header_size;
 82	BUG_ON(packet_len > ec_dev->din_size);
 83	in_buf = ec_dev->din;
 84	i2c_msg[1].len = packet_len;
 85	i2c_msg[1].buf = (char *) in_buf;
 86
 87	packet_len = msg->outsize + request_header_size;
 88	BUG_ON(packet_len > ec_dev->dout_size);
 89	out_buf = ec_dev->dout;
 90	i2c_msg[0].len = packet_len;
 91	i2c_msg[0].buf = (char *) out_buf;
 92
 93	/* create request data */
 94	ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
 95	ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
 96
 97	ec_dev->dout++;
 98	ret = cros_ec_prepare_tx(ec_dev, msg);
 99	ec_dev->dout--;
100
101	/* send command to EC and read answer */
102	ret = i2c_transfer(client->adapter, i2c_msg, 2);
103	if (ret < 0) {
104		dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
105		goto done;
106	} else if (ret != 2) {
107		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
108		ret = -EIO;
109		goto done;
110	}
111
112	ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
113	msg->result = ec_response_i2c->result;
114	ec_response = &ec_response_i2c->ec_response;
115
116	switch (msg->result) {
117	case EC_RES_SUCCESS:
118		break;
119	case EC_RES_IN_PROGRESS:
120		ret = -EAGAIN;
121		dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
122			msg->command);
123		goto done;
124
125	default:
126		dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
127			msg->command, msg->result);
128		/*
129		 * When we send v3 request to v2 ec, ec won't recognize the
130		 * 0xda (EC_COMMAND_PROTOCOL_3) and will return with status
131		 * EC_RES_INVALID_COMMAND with zero data length.
132		 *
133		 * In case of invalid command for v3 protocol the data length
134		 * will be at least sizeof(struct ec_host_response)
135		 */
136		if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
137		    ec_response_i2c->packet_length == 0) {
138			ret = -EPROTONOSUPPORT;
139			goto done;
140		}
141	}
142
143	if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
144		dev_err(ec_dev->dev,
145			"response of %u bytes too short; not a full header\n",
146			ec_response_i2c->packet_length);
147		ret = -EBADMSG;
148		goto done;
149	}
150
151	if (msg->insize < ec_response->data_len) {
152		dev_err(ec_dev->dev,
153			"response data size is too large: expected %u, got %u\n",
154			msg->insize,
155			ec_response->data_len);
156		ret = -EMSGSIZE;
157		goto done;
158	}
159
160	/* copy response packet payload and compute checksum */
161	sum = 0;
162	for (i = 0; i < sizeof(struct ec_host_response); i++)
163		sum += ((u8 *)ec_response)[i];
164
165	memcpy(msg->data,
166	       in_buf + response_header_size,
167	       ec_response->data_len);
168	for (i = 0; i < ec_response->data_len; i++)
169		sum += msg->data[i];
170
171	/* All bytes should sum to zero */
172	if (sum) {
173		dev_err(ec_dev->dev, "bad packet checksum\n");
174		ret = -EBADMSG;
175		goto done;
176	}
177
178	ret = ec_response->data_len;
179
180done:
181	if (msg->command == EC_CMD_REBOOT_EC)
182		msleep(EC_REBOOT_DELAY_MS);
183
184	return ret;
185}
186
187static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
188				struct cros_ec_command *msg)
189{
190	struct i2c_client *client = ec_dev->priv;
191	int ret = -ENOMEM;
192	int i;
193	int len;
194	int packet_len;
195	u8 *out_buf = NULL;
196	u8 *in_buf = NULL;
197	u8 sum;
198	struct i2c_msg i2c_msg[2];
199
200	i2c_msg[0].addr = client->addr;
201	i2c_msg[0].flags = 0;
202	i2c_msg[1].addr = client->addr;
203	i2c_msg[1].flags = I2C_M_RD;
204
205	/*
206	 * allocate larger packet (one byte for checksum, one byte for
207	 * length, and one for result code)
208	 */
209	packet_len = msg->insize + 3;
210	in_buf = kzalloc(packet_len, GFP_KERNEL);
211	if (!in_buf)
212		goto done;
213	i2c_msg[1].len = packet_len;
214	i2c_msg[1].buf = (char *)in_buf;
215
216	/*
217	 * allocate larger packet (one byte for checksum, one for
218	 * command code, one for length, and one for command version)
219	 */
220	packet_len = msg->outsize + 4;
221	out_buf = kzalloc(packet_len, GFP_KERNEL);
222	if (!out_buf)
223		goto done;
224	i2c_msg[0].len = packet_len;
225	i2c_msg[0].buf = (char *)out_buf;
226
227	out_buf[0] = EC_CMD_VERSION0 + msg->version;
228	out_buf[1] = msg->command;
229	out_buf[2] = msg->outsize;
230
231	/* copy message payload and compute checksum */
232	sum = out_buf[0] + out_buf[1] + out_buf[2];
233	for (i = 0; i < msg->outsize; i++) {
234		out_buf[3 + i] = msg->data[i];
235		sum += out_buf[3 + i];
236	}
237	out_buf[3 + msg->outsize] = sum;
238
239	/* send command to EC and read answer */
240	ret = i2c_transfer(client->adapter, i2c_msg, 2);
241	if (ret < 0) {
242		dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
243		goto done;
244	} else if (ret != 2) {
245		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
246		ret = -EIO;
247		goto done;
248	}
249
250	/* check response error code */
251	msg->result = i2c_msg[1].buf[0];
252	ret = cros_ec_check_result(ec_dev, msg);
253	if (ret)
254		goto done;
255
256	len = in_buf[1];
257	if (len > msg->insize) {
258		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
259			len, msg->insize);
260		ret = -ENOSPC;
261		goto done;
262	}
263
264	/* copy response packet payload and compute checksum */
265	sum = in_buf[0] + in_buf[1];
266	for (i = 0; i < len; i++) {
267		msg->data[i] = in_buf[2 + i];
268		sum += in_buf[2 + i];
269	}
270	dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
271		i2c_msg[1].len, in_buf, sum);
272	if (sum != in_buf[2 + len]) {
273		dev_err(ec_dev->dev, "bad packet checksum\n");
274		ret = -EBADMSG;
275		goto done;
276	}
277
278	ret = len;
279done:
280	kfree(in_buf);
281	kfree(out_buf);
282	if (msg->command == EC_CMD_REBOOT_EC)
283		msleep(EC_REBOOT_DELAY_MS);
284
285	return ret;
286}
287
288static int cros_ec_i2c_probe(struct i2c_client *client,
289			     const struct i2c_device_id *dev_id)
290{
291	struct device *dev = &client->dev;
292	struct cros_ec_device *ec_dev = NULL;
293	int err;
294
295	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
296	if (!ec_dev)
297		return -ENOMEM;
298
299	i2c_set_clientdata(client, ec_dev);
300	ec_dev->dev = dev;
301	ec_dev->priv = client;
302	ec_dev->irq = client->irq;
303	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
304	ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
305	ec_dev->phys_name = client->adapter->name;
306	ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
307			   sizeof(struct ec_response_get_protocol_info);
308	ec_dev->dout_size = sizeof(struct ec_host_request_i2c);
309
310	err = cros_ec_register(ec_dev);
311	if (err) {
312		dev_err(dev, "cannot register EC\n");
313		return err;
314	}
315
316	return 0;
317}
318
319static int cros_ec_i2c_remove(struct i2c_client *client)
320{
321	struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
322
323	cros_ec_remove(ec_dev);
324
325	return 0;
326}
327
328#ifdef CONFIG_PM_SLEEP
329static int cros_ec_i2c_suspend(struct device *dev)
330{
331	struct cros_ec_device *ec_dev = to_ec_dev(dev);
332
333	return cros_ec_suspend(ec_dev);
334}
335
336static int cros_ec_i2c_resume(struct device *dev)
337{
338	struct cros_ec_device *ec_dev = to_ec_dev(dev);
339
340	return cros_ec_resume(ec_dev);
341}
342#endif
343
344static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend,
345			  cros_ec_i2c_resume);
346
347static const struct of_device_id cros_ec_i2c_of_match[] = {
348	{ .compatible = "google,cros-ec-i2c", },
349	{ /* sentinel */ },
350};
351MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
352
353static const struct i2c_device_id cros_ec_i2c_id[] = {
354	{ "cros-ec-i2c", 0 },
355	{ }
356};
357MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
358
359static struct i2c_driver cros_ec_driver = {
360	.driver	= {
361		.name	= "cros-ec-i2c",
362		.of_match_table = of_match_ptr(cros_ec_i2c_of_match),
363		.pm	= &cros_ec_i2c_pm_ops,
364	},
365	.probe		= cros_ec_i2c_probe,
366	.remove		= cros_ec_i2c_remove,
367	.id_table	= cros_ec_i2c_id,
368};
369
370module_i2c_driver(cros_ec_driver);
371
372MODULE_LICENSE("GPL");
373MODULE_DESCRIPTION("ChromeOS EC multi function device");