1 // SPDX-License-Identifier: GPL-2.0
2 // I2C interface for ChromeOS Embedded Controller
3 //
4 // Copyright (C) 2012 Google, Inc
5 
6 #include <linux/acpi.h>
7 #include <linux/delay.h>
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/i2c.h>
11 #include <linux/interrupt.h>
12 #include <linux/mfd/cros_ec.h>
13 #include <linux/mfd/cros_ec_commands.h>
14 #include <linux/platform_device.h>
15 #include <linux/slab.h>
16 
17 /**
18  * Request format for protocol v3
19  * byte 0	0xda (EC_COMMAND_PROTOCOL_3)
20  * byte 1-8	struct ec_host_request
21  * byte 10-	response data
22  */
23 struct ec_host_request_i2c {
24 	/* Always 0xda to backward compatible with v2 struct */
25 	uint8_t  command_protocol;
26 	struct ec_host_request ec_request;
27 } __packed;
28 
29 
30 /*
31  * Response format for protocol v3
32  * byte 0	result code
33  * byte 1	packet_length
34  * byte 2-9	struct ec_host_response
35  * byte 10-	response data
36  */
37 struct ec_host_response_i2c {
38 	uint8_t result;
39 	uint8_t packet_length;
40 	struct ec_host_response ec_response;
41 } __packed;
42 
43 static inline struct cros_ec_device *to_ec_dev(struct device *dev)
44 {
45 	struct i2c_client *client = to_i2c_client(dev);
46 
47 	return i2c_get_clientdata(client);
48 }
49 
50 static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
51 				struct cros_ec_command *msg)
52 {
53 	struct i2c_client *client = ec_dev->priv;
54 	int ret = -ENOMEM;
55 	int i;
56 	int packet_len;
57 	u8 *out_buf = NULL;
58 	u8 *in_buf = NULL;
59 	u8 sum;
60 	struct i2c_msg i2c_msg[2];
61 	struct ec_host_response *ec_response;
62 	struct ec_host_request_i2c *ec_request_i2c;
63 	struct ec_host_response_i2c *ec_response_i2c;
64 	int request_header_size = sizeof(struct ec_host_request_i2c);
65 	int response_header_size = sizeof(struct ec_host_response_i2c);
66 
67 	i2c_msg[0].addr = client->addr;
68 	i2c_msg[0].flags = 0;
69 	i2c_msg[1].addr = client->addr;
70 	i2c_msg[1].flags = I2C_M_RD;
71 
72 	packet_len = msg->insize + response_header_size;
73 	BUG_ON(packet_len > ec_dev->din_size);
74 	in_buf = ec_dev->din;
75 	i2c_msg[1].len = packet_len;
76 	i2c_msg[1].buf = (char *) in_buf;
77 
78 	packet_len = msg->outsize + request_header_size;
79 	BUG_ON(packet_len > ec_dev->dout_size);
80 	out_buf = ec_dev->dout;
81 	i2c_msg[0].len = packet_len;
82 	i2c_msg[0].buf = (char *) out_buf;
83 
84 	/* create request data */
85 	ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
86 	ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
87 
88 	ec_dev->dout++;
89 	ret = cros_ec_prepare_tx(ec_dev, msg);
90 	ec_dev->dout--;
91 
92 	/* send command to EC and read answer */
93 	ret = i2c_transfer(client->adapter, i2c_msg, 2);
94 	if (ret < 0) {
95 		dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
96 		goto done;
97 	} else if (ret != 2) {
98 		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
99 		ret = -EIO;
100 		goto done;
101 	}
102 
103 	ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
104 	msg->result = ec_response_i2c->result;
105 	ec_response = &ec_response_i2c->ec_response;
106 
107 	switch (msg->result) {
108 	case EC_RES_SUCCESS:
109 		break;
110 	case EC_RES_IN_PROGRESS:
111 		ret = -EAGAIN;
112 		dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
113 			msg->command);
114 		goto done;
115 
116 	default:
117 		dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
118 			msg->command, msg->result);
119 		/*
120 		 * When we send v3 request to v2 ec, ec won't recognize the
121 		 * 0xda (EC_COMMAND_PROTOCOL_3) and will return with status
122 		 * EC_RES_INVALID_COMMAND with zero data length.
123 		 *
124 		 * In case of invalid command for v3 protocol the data length
125 		 * will be at least sizeof(struct ec_host_response)
126 		 */
127 		if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
128 		    ec_response_i2c->packet_length == 0) {
129 			ret = -EPROTONOSUPPORT;
130 			goto done;
131 		}
132 	}
133 
134 	if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
135 		dev_err(ec_dev->dev,
136 			"response of %u bytes too short; not a full header\n",
137 			ec_response_i2c->packet_length);
138 		ret = -EBADMSG;
139 		goto done;
140 	}
141 
142 	if (msg->insize < ec_response->data_len) {
143 		dev_err(ec_dev->dev,
144 			"response data size is too large: expected %u, got %u\n",
145 			msg->insize,
146 			ec_response->data_len);
147 		ret = -EMSGSIZE;
148 		goto done;
149 	}
150 
151 	/* copy response packet payload and compute checksum */
152 	sum = 0;
153 	for (i = 0; i < sizeof(struct ec_host_response); i++)
154 		sum += ((u8 *)ec_response)[i];
155 
156 	memcpy(msg->data,
157 	       in_buf + response_header_size,
158 	       ec_response->data_len);
159 	for (i = 0; i < ec_response->data_len; i++)
160 		sum += msg->data[i];
161 
162 	/* All bytes should sum to zero */
163 	if (sum) {
164 		dev_err(ec_dev->dev, "bad packet checksum\n");
165 		ret = -EBADMSG;
166 		goto done;
167 	}
168 
169 	ret = ec_response->data_len;
170 
171 done:
172 	if (msg->command == EC_CMD_REBOOT_EC)
173 		msleep(EC_REBOOT_DELAY_MS);
174 
175 	return ret;
176 }
177 
178 static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
179 				struct cros_ec_command *msg)
180 {
181 	struct i2c_client *client = ec_dev->priv;
182 	int ret = -ENOMEM;
183 	int i;
184 	int len;
185 	int packet_len;
186 	u8 *out_buf = NULL;
187 	u8 *in_buf = NULL;
188 	u8 sum;
189 	struct i2c_msg i2c_msg[2];
190 
191 	i2c_msg[0].addr = client->addr;
192 	i2c_msg[0].flags = 0;
193 	i2c_msg[1].addr = client->addr;
194 	i2c_msg[1].flags = I2C_M_RD;
195 
196 	/*
197 	 * allocate larger packet (one byte for checksum, one byte for
198 	 * length, and one for result code)
199 	 */
200 	packet_len = msg->insize + 3;
201 	in_buf = kzalloc(packet_len, GFP_KERNEL);
202 	if (!in_buf)
203 		goto done;
204 	i2c_msg[1].len = packet_len;
205 	i2c_msg[1].buf = (char *)in_buf;
206 
207 	/*
208 	 * allocate larger packet (one byte for checksum, one for
209 	 * command code, one for length, and one for command version)
210 	 */
211 	packet_len = msg->outsize + 4;
212 	out_buf = kzalloc(packet_len, GFP_KERNEL);
213 	if (!out_buf)
214 		goto done;
215 	i2c_msg[0].len = packet_len;
216 	i2c_msg[0].buf = (char *)out_buf;
217 
218 	out_buf[0] = EC_CMD_VERSION0 + msg->version;
219 	out_buf[1] = msg->command;
220 	out_buf[2] = msg->outsize;
221 
222 	/* copy message payload and compute checksum */
223 	sum = out_buf[0] + out_buf[1] + out_buf[2];
224 	for (i = 0; i < msg->outsize; i++) {
225 		out_buf[3 + i] = msg->data[i];
226 		sum += out_buf[3 + i];
227 	}
228 	out_buf[3 + msg->outsize] = sum;
229 
230 	/* send command to EC and read answer */
231 	ret = i2c_transfer(client->adapter, i2c_msg, 2);
232 	if (ret < 0) {
233 		dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
234 		goto done;
235 	} else if (ret != 2) {
236 		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
237 		ret = -EIO;
238 		goto done;
239 	}
240 
241 	/* check response error code */
242 	msg->result = i2c_msg[1].buf[0];
243 	ret = cros_ec_check_result(ec_dev, msg);
244 	if (ret)
245 		goto done;
246 
247 	len = in_buf[1];
248 	if (len > msg->insize) {
249 		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
250 			len, msg->insize);
251 		ret = -ENOSPC;
252 		goto done;
253 	}
254 
255 	/* copy response packet payload and compute checksum */
256 	sum = in_buf[0] + in_buf[1];
257 	for (i = 0; i < len; i++) {
258 		msg->data[i] = in_buf[2 + i];
259 		sum += in_buf[2 + i];
260 	}
261 	dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
262 		i2c_msg[1].len, in_buf, sum);
263 	if (sum != in_buf[2 + len]) {
264 		dev_err(ec_dev->dev, "bad packet checksum\n");
265 		ret = -EBADMSG;
266 		goto done;
267 	}
268 
269 	ret = len;
270 done:
271 	kfree(in_buf);
272 	kfree(out_buf);
273 	if (msg->command == EC_CMD_REBOOT_EC)
274 		msleep(EC_REBOOT_DELAY_MS);
275 
276 	return ret;
277 }
278 
279 static int cros_ec_i2c_probe(struct i2c_client *client,
280 			     const struct i2c_device_id *dev_id)
281 {
282 	struct device *dev = &client->dev;
283 	struct cros_ec_device *ec_dev = NULL;
284 	int err;
285 
286 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
287 	if (!ec_dev)
288 		return -ENOMEM;
289 
290 	i2c_set_clientdata(client, ec_dev);
291 	ec_dev->dev = dev;
292 	ec_dev->priv = client;
293 	ec_dev->irq = client->irq;
294 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
295 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
296 	ec_dev->phys_name = client->adapter->name;
297 	ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
298 			   sizeof(struct ec_response_get_protocol_info);
299 	ec_dev->dout_size = sizeof(struct ec_host_request_i2c);
300 
301 	err = cros_ec_register(ec_dev);
302 	if (err) {
303 		dev_err(dev, "cannot register EC\n");
304 		return err;
305 	}
306 
307 	return 0;
308 }
309 
310 #ifdef CONFIG_PM_SLEEP
311 static int cros_ec_i2c_suspend(struct device *dev)
312 {
313 	struct cros_ec_device *ec_dev = to_ec_dev(dev);
314 
315 	return cros_ec_suspend(ec_dev);
316 }
317 
318 static int cros_ec_i2c_resume(struct device *dev)
319 {
320 	struct cros_ec_device *ec_dev = to_ec_dev(dev);
321 
322 	return cros_ec_resume(ec_dev);
323 }
324 #endif
325 
326 static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
327 	SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
328 };
329 
330 #ifdef CONFIG_OF
331 static const struct of_device_id cros_ec_i2c_of_match[] = {
332 	{ .compatible = "google,cros-ec-i2c", },
333 	{ /* sentinel */ },
334 };
335 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
336 #endif
337 
338 static const struct i2c_device_id cros_ec_i2c_id[] = {
339 	{ "cros-ec-i2c", 0 },
340 	{ }
341 };
342 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
343 
344 #ifdef CONFIG_ACPI
345 static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
346 	{ "GOOG0008", 0 },
347 	{ /* sentinel */ }
348 };
349 MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
350 #endif
351 
352 static struct i2c_driver cros_ec_driver = {
353 	.driver	= {
354 		.name	= "cros-ec-i2c",
355 		.acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
356 		.of_match_table = of_match_ptr(cros_ec_i2c_of_match),
357 		.pm	= &cros_ec_i2c_pm_ops,
358 	},
359 	.probe		= cros_ec_i2c_probe,
360 	.id_table	= cros_ec_i2c_id,
361 };
362 
363 module_i2c_driver(cros_ec_driver);
364 
365 MODULE_LICENSE("GPL v2");
366 MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");
367