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 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; 172 173 done: 174 if (msg->command == EC_CMD_REBOOT_EC) 175 msleep(EC_REBOOT_DELAY_MS); 176 177 return ret; 178 } 179 180 static 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; 272 done: 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 } 280 281 static 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 } 311 312 static 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 320 static 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 } 326 327 static 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 334 335 static 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 340 static const struct of_device_id cros_ec_i2c_of_match[] = { 341 { .compatible = "google,cros-ec-i2c", }, 342 { /* sentinel */ }, 343 }; 344 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match); 345 #endif 346 347 static const struct i2c_device_id cros_ec_i2c_id[] = { 348 { "cros-ec-i2c", 0 }, 349 { } 350 }; 351 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id); 352 353 #ifdef CONFIG_ACPI 354 static const struct acpi_device_id cros_ec_i2c_acpi_id[] = { 355 { "GOOG0008", 0 }, 356 { /* sentinel */ } 357 }; 358 MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id); 359 #endif 360 361 static 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 }; 372 373 module_i2c_driver(cros_ec_driver); 374 375 MODULE_LICENSE("GPL v2"); 376 MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller"); 377