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 */
25struct 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 */
39struct ec_host_response_i2c {
40 uint8_t result;
41 uint8_t packet_length;
42 struct ec_host_response ec_response;
43} __packed;
44
45static 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
52static 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(adap: client->adapter, msgs: i2c_msg, num: 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
181done:
182 if (msg->command == EC_CMD_REBOOT_EC)
183 msleep(EC_REBOOT_DELAY_MS);
184
185 return ret;
186}
187
188static 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(adap: client->adapter, msgs: i2c_msg, num: 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;
280done:
281 kfree(objp: in_buf);
282 kfree(objp: out_buf);
283 if (msg->command == EC_CMD_REBOOT_EC)
284 msleep(EC_REBOOT_DELAY_MS);
285
286 return ret;
287}
288
289static int cros_ec_i2c_probe(struct i2c_client *client)
290{
291 struct device *dev = &client->dev;
292 struct cros_ec_device *ec_dev;
293 int err;
294
295 ec_dev = cros_ec_device_alloc(dev);
296 if (!ec_dev)
297 return -ENOMEM;
298
299 i2c_set_clientdata(client, data: ec_dev);
300 ec_dev->priv = client;
301 ec_dev->irq = client->irq;
302 ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
303 ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
304 ec_dev->phys_name = client->adapter->name;
305
306 err = cros_ec_register(ec_dev);
307 if (err) {
308 dev_err(dev, "cannot register EC\n");
309 return err;
310 }
311
312 return 0;
313}
314
315static void cros_ec_i2c_remove(struct i2c_client *client)
316{
317 struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
318
319 cros_ec_unregister(ec_dev);
320}
321
322#ifdef CONFIG_PM_SLEEP
323static int cros_ec_i2c_suspend(struct device *dev)
324{
325 struct cros_ec_device *ec_dev = to_ec_dev(dev);
326
327 return cros_ec_suspend(ec_dev);
328}
329
330static int cros_ec_i2c_resume(struct device *dev)
331{
332 struct cros_ec_device *ec_dev = to_ec_dev(dev);
333
334 return cros_ec_resume(ec_dev);
335}
336#endif
337
338static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
339 SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
340};
341
342#ifdef CONFIG_OF
343static const struct of_device_id cros_ec_i2c_of_match[] = {
344 { .compatible = "google,cros-ec-i2c", },
345 { /* sentinel */ },
346};
347MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
348#endif
349
350static const struct i2c_device_id cros_ec_i2c_id[] = {
351 { "cros-ec-i2c" },
352 { }
353};
354MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
355
356#ifdef CONFIG_ACPI
357static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
358 { "GOOG0008", 0 },
359 { /* sentinel */ }
360};
361MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
362#endif
363
364static struct i2c_driver cros_ec_driver = {
365 .driver = {
366 .name = "cros-ec-i2c",
367 .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
368 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
369 .pm = &cros_ec_i2c_pm_ops,
370 },
371 .probe = cros_ec_i2c_probe,
372 .remove = cros_ec_i2c_remove,
373 .id_table = cros_ec_i2c_id,
374};
375
376module_i2c_driver(cros_ec_driver);
377
378MODULE_LICENSE("GPL v2");
379MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");
380

source code of linux/drivers/platform/chrome/cros_ec_i2c.c