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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/**
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 */
23struct 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 */
37struct ec_host_response_i2c {
38 uint8_t result;
39 uint8_t packet_length;
40 struct ec_host_response ec_response;
41} __packed;
42
43static 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
50static 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
171done:
172 if (msg->command == EC_CMD_REBOOT_EC)
173 msleep(EC_REBOOT_DELAY_MS);
174
175 return ret;
176}
177
178static 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;
270done:
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
279static 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
310static int cros_ec_i2c_remove(struct i2c_client *client)
311{
312 struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
313
314 return cros_ec_unregister(ec_dev);
315}
316
317#ifdef CONFIG_PM_SLEEP
318static int cros_ec_i2c_suspend(struct device *dev)
319{
320 struct cros_ec_device *ec_dev = to_ec_dev(dev);
321
322 return cros_ec_suspend(ec_dev);
323}
324
325static int cros_ec_i2c_resume(struct device *dev)
326{
327 struct cros_ec_device *ec_dev = to_ec_dev(dev);
328
329 return cros_ec_resume(ec_dev);
330}
331#endif
332
333static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
334 SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
335};
336
337#ifdef CONFIG_OF
338static const struct of_device_id cros_ec_i2c_of_match[] = {
339 { .compatible = "google,cros-ec-i2c", },
340 { /* sentinel */ },
341};
342MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
343#endif
344
345static const struct i2c_device_id cros_ec_i2c_id[] = {
346 { "cros-ec-i2c", 0 },
347 { }
348};
349MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
350
351#ifdef CONFIG_ACPI
352static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
353 { "GOOG0008", 0 },
354 { /* sentinel */ }
355};
356MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
357#endif
358
359static struct i2c_driver cros_ec_driver = {
360 .driver = {
361 .name = "cros-ec-i2c",
362 .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
363 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
364 .pm = &cros_ec_i2c_pm_ops,
365 },
366 .probe = cros_ec_i2c_probe,
367 .remove = cros_ec_i2c_remove,
368 .id_table = cros_ec_i2c_id,
369};
370
371module_i2c_driver(cros_ec_driver);
372
373MODULE_LICENSE("GPL v2");
374MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");