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/platform_data/cros_ec_commands.h>
13 #include <linux/platform_data/cros_ec_proto.h>
14 #include <linux/platform_device.h>
15 #include <linux/slab.h>
16 
17 #include "cros_ec.h"
18 
19 /*
20  * Request format for protocol v3
21  * byte 0	0xda (EC_COMMAND_PROTOCOL_3)
22  * byte 1-8	struct ec_host_request
23  * byte 10-	response data
24  */
25 struct ec_host_request_i2c {
26 	/* Always 0xda to backward compatible with v2 struct */
27 	uint8_t  command_protocol;
28 	struct ec_host_request ec_request;
29 } __packed;
30 
31 
32 /*
33  * Response format for protocol v3
34  * byte 0	result code
35  * byte 1	packet_length
36  * byte 2-9	struct ec_host_response
37  * byte 10-	response data
38  */
39 struct ec_host_response_i2c {
40 	uint8_t result;
41 	uint8_t packet_length;
42 	struct ec_host_response ec_response;
43 } __packed;
44 
45 static inline struct cros_ec_device *to_ec_dev(struct device *dev)
46 {
47 	struct i2c_client *client = to_i2c_client(dev);
48 
49 	return i2c_get_clientdata(client);
50 }
51 
52 static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
53 				struct cros_ec_command *msg)
54 {
55 	struct i2c_client *client = ec_dev->priv;
56 	int ret = -ENOMEM;
57 	int i;
58 	int packet_len;
59 	u8 *out_buf = NULL;
60 	u8 *in_buf = NULL;
61 	u8 sum;
62 	struct i2c_msg i2c_msg[2];
63 	struct ec_host_response *ec_response;
64 	struct ec_host_request_i2c *ec_request_i2c;
65 	struct ec_host_response_i2c *ec_response_i2c;
66 	int request_header_size = sizeof(struct ec_host_request_i2c);
67 	int response_header_size = sizeof(struct ec_host_response_i2c);
68 
69 	i2c_msg[0].addr = client->addr;
70 	i2c_msg[0].flags = 0;
71 	i2c_msg[1].addr = client->addr;
72 	i2c_msg[1].flags = I2C_M_RD;
73 
74 	packet_len = msg->insize + response_header_size;
75 	if (packet_len > ec_dev->din_size) {
76 		ret = -EINVAL;
77 		goto done;
78 	}
79 	in_buf = ec_dev->din;
80 	i2c_msg[1].len = packet_len;
81 	i2c_msg[1].buf = (char *) in_buf;
82 
83 	packet_len = msg->outsize + request_header_size;
84 	if (packet_len > ec_dev->dout_size) {
85 		ret = -EINVAL;
86 		goto done;
87 	}
88 	out_buf = ec_dev->dout;
89 	i2c_msg[0].len = packet_len;
90 	i2c_msg[0].buf = (char *) out_buf;
91 
92 	/* create request data */
93 	ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
94 	ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
95 
96 	ec_dev->dout++;
97 	ret = cros_ec_prepare_tx(ec_dev, msg);
98 	if (ret < 0)
99 		goto done;
100 	ec_dev->dout--;
101 
102 	/* send command to EC and read answer */
103 	ret = i2c_transfer(client->adapter, i2c_msg, 2);
104 	if (ret < 0) {
105 		dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
106 		goto done;
107 	} else if (ret != 2) {
108 		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
109 		ret = -EIO;
110 		goto done;
111 	}
112 
113 	ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
114 	msg->result = ec_response_i2c->result;
115 	ec_response = &ec_response_i2c->ec_response;
116 
117 	switch (msg->result) {
118 	case EC_RES_SUCCESS:
119 		break;
120 	case EC_RES_IN_PROGRESS:
121 		ret = -EAGAIN;
122 		dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
123 			msg->command);
124 		goto done;
125 
126 	default:
127 		dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
128 			msg->command, msg->result);
129 		/*
130 		 * When we send v3 request to v2 ec, ec won't recognize the
131 		 * 0xda (EC_COMMAND_PROTOCOL_3) and will return with status
132 		 * EC_RES_INVALID_COMMAND with zero data length.
133 		 *
134 		 * In case of invalid command for v3 protocol the data length
135 		 * will be at least sizeof(struct ec_host_response)
136 		 */
137 		if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
138 		    ec_response_i2c->packet_length == 0) {
139 			ret = -EPROTONOSUPPORT;
140 			goto done;
141 		}
142 	}
143 
144 	if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
145 		dev_err(ec_dev->dev,
146 			"response of %u bytes too short; not a full header\n",
147 			ec_response_i2c->packet_length);
148 		ret = -EBADMSG;
149 		goto done;
150 	}
151 
152 	if (msg->insize < ec_response->data_len) {
153 		dev_err(ec_dev->dev,
154 			"response data size is too large: expected %u, got %u\n",
155 			msg->insize,
156 			ec_response->data_len);
157 		ret = -EMSGSIZE;
158 		goto done;
159 	}
160 
161 	/* copy response packet payload and compute checksum */
162 	sum = 0;
163 	for (i = 0; i < sizeof(struct ec_host_response); i++)
164 		sum += ((u8 *)ec_response)[i];
165 
166 	memcpy(msg->data,
167 	       in_buf + response_header_size,
168 	       ec_response->data_len);
169 	for (i = 0; i < ec_response->data_len; i++)
170 		sum += msg->data[i];
171 
172 	/* All bytes should sum to zero */
173 	if (sum) {
174 		dev_err(ec_dev->dev, "bad packet checksum\n");
175 		ret = -EBADMSG;
176 		goto done;
177 	}
178 
179 	ret = ec_response->data_len;
180 
181 done:
182 	if (msg->command == EC_CMD_REBOOT_EC)
183 		msleep(EC_REBOOT_DELAY_MS);
184 
185 	return ret;
186 }
187 
188 static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
189 				struct cros_ec_command *msg)
190 {
191 	struct i2c_client *client = ec_dev->priv;
192 	int ret = -ENOMEM;
193 	int i;
194 	int len;
195 	int packet_len;
196 	u8 *out_buf = NULL;
197 	u8 *in_buf = NULL;
198 	u8 sum;
199 	struct i2c_msg i2c_msg[2];
200 
201 	i2c_msg[0].addr = client->addr;
202 	i2c_msg[0].flags = 0;
203 	i2c_msg[1].addr = client->addr;
204 	i2c_msg[1].flags = I2C_M_RD;
205 
206 	/*
207 	 * allocate larger packet (one byte for checksum, one byte for
208 	 * length, and one for result code)
209 	 */
210 	packet_len = msg->insize + 3;
211 	in_buf = kzalloc(packet_len, GFP_KERNEL);
212 	if (!in_buf)
213 		goto done;
214 	i2c_msg[1].len = packet_len;
215 	i2c_msg[1].buf = (char *)in_buf;
216 
217 	/*
218 	 * allocate larger packet (one byte for checksum, one for
219 	 * command code, one for length, and one for command version)
220 	 */
221 	packet_len = msg->outsize + 4;
222 	out_buf = kzalloc(packet_len, GFP_KERNEL);
223 	if (!out_buf)
224 		goto done;
225 	i2c_msg[0].len = packet_len;
226 	i2c_msg[0].buf = (char *)out_buf;
227 
228 	out_buf[0] = EC_CMD_VERSION0 + msg->version;
229 	out_buf[1] = msg->command;
230 	out_buf[2] = msg->outsize;
231 
232 	/* copy message payload and compute checksum */
233 	sum = out_buf[0] + out_buf[1] + out_buf[2];
234 	for (i = 0; i < msg->outsize; i++) {
235 		out_buf[3 + i] = msg->data[i];
236 		sum += out_buf[3 + i];
237 	}
238 	out_buf[3 + msg->outsize] = sum;
239 
240 	/* send command to EC and read answer */
241 	ret = i2c_transfer(client->adapter, i2c_msg, 2);
242 	if (ret < 0) {
243 		dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
244 		goto done;
245 	} else if (ret != 2) {
246 		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
247 		ret = -EIO;
248 		goto done;
249 	}
250 
251 	/* check response error code */
252 	msg->result = i2c_msg[1].buf[0];
253 	ret = cros_ec_check_result(ec_dev, msg);
254 	if (ret)
255 		goto done;
256 
257 	len = in_buf[1];
258 	if (len > msg->insize) {
259 		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
260 			len, msg->insize);
261 		ret = -ENOSPC;
262 		goto done;
263 	}
264 
265 	/* copy response packet payload and compute checksum */
266 	sum = in_buf[0] + in_buf[1];
267 	for (i = 0; i < len; i++) {
268 		msg->data[i] = in_buf[2 + i];
269 		sum += in_buf[2 + i];
270 	}
271 	dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
272 		i2c_msg[1].len, in_buf, sum);
273 	if (sum != in_buf[2 + len]) {
274 		dev_err(ec_dev->dev, "bad packet checksum\n");
275 		ret = -EBADMSG;
276 		goto done;
277 	}
278 
279 	ret = len;
280 done:
281 	kfree(in_buf);
282 	kfree(out_buf);
283 	if (msg->command == EC_CMD_REBOOT_EC)
284 		msleep(EC_REBOOT_DELAY_MS);
285 
286 	return ret;
287 }
288 
289 static int cros_ec_i2c_probe(struct i2c_client *client)
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 
319 static void cros_ec_i2c_remove(struct i2c_client *client)
320 {
321 	struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
322 
323 	cros_ec_unregister(ec_dev);
324 }
325 
326 #ifdef CONFIG_PM_SLEEP
327 static int cros_ec_i2c_suspend(struct device *dev)
328 {
329 	struct cros_ec_device *ec_dev = to_ec_dev(dev);
330 
331 	return cros_ec_suspend(ec_dev);
332 }
333 
334 static int cros_ec_i2c_resume(struct device *dev)
335 {
336 	struct cros_ec_device *ec_dev = to_ec_dev(dev);
337 
338 	return cros_ec_resume(ec_dev);
339 }
340 #endif
341 
342 static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
343 	SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
344 };
345 
346 #ifdef CONFIG_OF
347 static const struct of_device_id cros_ec_i2c_of_match[] = {
348 	{ .compatible = "google,cros-ec-i2c", },
349 	{ /* sentinel */ },
350 };
351 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
352 #endif
353 
354 static const struct i2c_device_id cros_ec_i2c_id[] = {
355 	{ "cros-ec-i2c", 0 },
356 	{ }
357 };
358 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
359 
360 #ifdef CONFIG_ACPI
361 static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
362 	{ "GOOG0008", 0 },
363 	{ /* sentinel */ }
364 };
365 MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
366 #endif
367 
368 static struct i2c_driver cros_ec_driver = {
369 	.driver	= {
370 		.name	= "cros-ec-i2c",
371 		.acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
372 		.of_match_table = of_match_ptr(cros_ec_i2c_of_match),
373 		.pm	= &cros_ec_i2c_pm_ops,
374 	},
375 	.probe		= cros_ec_i2c_probe,
376 	.remove		= cros_ec_i2c_remove,
377 	.id_table	= cros_ec_i2c_id,
378 };
379 
380 module_i2c_driver(cros_ec_driver);
381 
382 MODULE_LICENSE("GPL v2");
383 MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");
384