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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#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 BUG_ON(packet_len > ec_dev->din_size);
76 in_buf = ec_dev->din;
77 i2c_msg[1].len = packet_len;
78 i2c_msg[1].buf = (char *) in_buf;
79
80 packet_len = msg->outsize + request_header_size;
81 BUG_ON(packet_len > ec_dev->dout_size);
82 out_buf = ec_dev->dout;
83 i2c_msg[0].len = packet_len;
84 i2c_msg[0].buf = (char *) out_buf;
85
86 /* create request data */
87 ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
88 ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
89
90 ec_dev->dout++;
91 ret = cros_ec_prepare_tx(ec_dev, msg);
92 ec_dev->dout--;
93
94 /* send command to EC and read answer */
95 ret = i2c_transfer(client->adapter, i2c_msg, 2);
96 if (ret < 0) {
97 dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
98 goto done;
99 } else if (ret != 2) {
100 dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
101 ret = -EIO;
102 goto done;
103 }
104
105 ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
106 msg->result = ec_response_i2c->result;
107 ec_response = &ec_response_i2c->ec_response;
108
109 switch (msg->result) {
110 case EC_RES_SUCCESS:
111 break;
112 case EC_RES_IN_PROGRESS:
113 ret = -EAGAIN;
114 dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
115 msg->command);
116 goto done;
117
118 default:
119 dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
120 msg->command, msg->result);
121 /*
122 * When we send v3 request to v2 ec, ec won't recognize the
123 * 0xda (EC_COMMAND_PROTOCOL_3) and will return with status
124 * EC_RES_INVALID_COMMAND with zero data length.
125 *
126 * In case of invalid command for v3 protocol the data length
127 * will be at least sizeof(struct ec_host_response)
128 */
129 if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
130 ec_response_i2c->packet_length == 0) {
131 ret = -EPROTONOSUPPORT;
132 goto done;
133 }
134 }
135
136 if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
137 dev_err(ec_dev->dev,
138 "response of %u bytes too short; not a full header\n",
139 ec_response_i2c->packet_length);
140 ret = -EBADMSG;
141 goto done;
142 }
143
144 if (msg->insize < ec_response->data_len) {
145 dev_err(ec_dev->dev,
146 "response data size is too large: expected %u, got %u\n",
147 msg->insize,
148 ec_response->data_len);
149 ret = -EMSGSIZE;
150 goto done;
151 }
152
153 /* copy response packet payload and compute checksum */
154 sum = 0;
155 for (i = 0; i < sizeof(struct ec_host_response); i++)
156 sum += ((u8 *)ec_response)[i];
157
158 memcpy(msg->data,
159 in_buf + response_header_size,
160 ec_response->data_len);
161 for (i = 0; i < ec_response->data_len; i++)
162 sum += msg->data[i];
163
164 /* All bytes should sum to zero */
165 if (sum) {
166 dev_err(ec_dev->dev, "bad packet checksum\n");
167 ret = -EBADMSG;
168 goto done;
169 }
170
171 ret = ec_response->data_len;
172
173done:
174 if (msg->command == EC_CMD_REBOOT_EC)
175 msleep(EC_REBOOT_DELAY_MS);
176
177 return ret;
178}
179
180static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
181 struct cros_ec_command *msg)
182{
183 struct i2c_client *client = ec_dev->priv;
184 int ret = -ENOMEM;
185 int i;
186 int len;
187 int packet_len;
188 u8 *out_buf = NULL;
189 u8 *in_buf = NULL;
190 u8 sum;
191 struct i2c_msg i2c_msg[2];
192
193 i2c_msg[0].addr = client->addr;
194 i2c_msg[0].flags = 0;
195 i2c_msg[1].addr = client->addr;
196 i2c_msg[1].flags = I2C_M_RD;
197
198 /*
199 * allocate larger packet (one byte for checksum, one byte for
200 * length, and one for result code)
201 */
202 packet_len = msg->insize + 3;
203 in_buf = kzalloc(packet_len, GFP_KERNEL);
204 if (!in_buf)
205 goto done;
206 i2c_msg[1].len = packet_len;
207 i2c_msg[1].buf = (char *)in_buf;
208
209 /*
210 * allocate larger packet (one byte for checksum, one for
211 * command code, one for length, and one for command version)
212 */
213 packet_len = msg->outsize + 4;
214 out_buf = kzalloc(packet_len, GFP_KERNEL);
215 if (!out_buf)
216 goto done;
217 i2c_msg[0].len = packet_len;
218 i2c_msg[0].buf = (char *)out_buf;
219
220 out_buf[0] = EC_CMD_VERSION0 + msg->version;
221 out_buf[1] = msg->command;
222 out_buf[2] = msg->outsize;
223
224 /* copy message payload and compute checksum */
225 sum = out_buf[0] + out_buf[1] + out_buf[2];
226 for (i = 0; i < msg->outsize; i++) {
227 out_buf[3 + i] = msg->data[i];
228 sum += out_buf[3 + i];
229 }
230 out_buf[3 + msg->outsize] = sum;
231
232 /* send command to EC and read answer */
233 ret = i2c_transfer(client->adapter, i2c_msg, 2);
234 if (ret < 0) {
235 dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
236 goto done;
237 } else if (ret != 2) {
238 dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
239 ret = -EIO;
240 goto done;
241 }
242
243 /* check response error code */
244 msg->result = i2c_msg[1].buf[0];
245 ret = cros_ec_check_result(ec_dev, msg);
246 if (ret)
247 goto done;
248
249 len = in_buf[1];
250 if (len > msg->insize) {
251 dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
252 len, msg->insize);
253 ret = -ENOSPC;
254 goto done;
255 }
256
257 /* copy response packet payload and compute checksum */
258 sum = in_buf[0] + in_buf[1];
259 for (i = 0; i < len; i++) {
260 msg->data[i] = in_buf[2 + i];
261 sum += in_buf[2 + i];
262 }
263 dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
264 i2c_msg[1].len, in_buf, sum);
265 if (sum != in_buf[2 + len]) {
266 dev_err(ec_dev->dev, "bad packet checksum\n");
267 ret = -EBADMSG;
268 goto done;
269 }
270
271 ret = len;
272done:
273 kfree(in_buf);
274 kfree(out_buf);
275 if (msg->command == EC_CMD_REBOOT_EC)
276 msleep(EC_REBOOT_DELAY_MS);
277
278 return ret;
279}
280
281static int cros_ec_i2c_probe(struct i2c_client *client,
282 const struct i2c_device_id *dev_id)
283{
284 struct device *dev = &client->dev;
285 struct cros_ec_device *ec_dev = NULL;
286 int err;
287
288 ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
289 if (!ec_dev)
290 return -ENOMEM;
291
292 i2c_set_clientdata(client, ec_dev);
293 ec_dev->dev = dev;
294 ec_dev->priv = client;
295 ec_dev->irq = client->irq;
296 ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
297 ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
298 ec_dev->phys_name = client->adapter->name;
299 ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
300 sizeof(struct ec_response_get_protocol_info);
301 ec_dev->dout_size = sizeof(struct ec_host_request_i2c);
302
303 err = cros_ec_register(ec_dev);
304 if (err) {
305 dev_err(dev, "cannot register EC\n");
306 return err;
307 }
308
309 return 0;
310}
311
312static int cros_ec_i2c_remove(struct i2c_client *client)
313{
314 struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
315
316 return cros_ec_unregister(ec_dev);
317}
318
319#ifdef CONFIG_PM_SLEEP
320static int cros_ec_i2c_suspend(struct device *dev)
321{
322 struct cros_ec_device *ec_dev = to_ec_dev(dev);
323
324 return cros_ec_suspend(ec_dev);
325}
326
327static int cros_ec_i2c_resume(struct device *dev)
328{
329 struct cros_ec_device *ec_dev = to_ec_dev(dev);
330
331 return cros_ec_resume(ec_dev);
332}
333#endif
334
335static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
336 SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
337};
338
339#ifdef CONFIG_OF
340static const struct of_device_id cros_ec_i2c_of_match[] = {
341 { .compatible = "google,cros-ec-i2c", },
342 { /* sentinel */ },
343};
344MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
345#endif
346
347static const struct i2c_device_id cros_ec_i2c_id[] = {
348 { "cros-ec-i2c", 0 },
349 { }
350};
351MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
352
353#ifdef CONFIG_ACPI
354static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
355 { "GOOG0008", 0 },
356 { /* sentinel */ }
357};
358MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
359#endif
360
361static struct i2c_driver cros_ec_driver = {
362 .driver = {
363 .name = "cros-ec-i2c",
364 .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
365 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
366 .pm = &cros_ec_i2c_pm_ops,
367 },
368 .probe = cros_ec_i2c_probe,
369 .remove = cros_ec_i2c_remove,
370 .id_table = cros_ec_i2c_id,
371};
372
373module_i2c_driver(cros_ec_driver);
374
375MODULE_LICENSE("GPL v2");
376MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");