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/mfd/cros_ec.h> 13 #include <linux/mfd/cros_ec_commands.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 */ 23 struct 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 */ 37 struct ec_host_response_i2c { 38 uint8_t result; 39 uint8_t packet_length; 40 struct ec_host_response ec_response; 41 } __packed; 42 43 static 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 50 static 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; 170 171 done: 172 if (msg->command == EC_CMD_REBOOT_EC) 173 msleep(EC_REBOOT_DELAY_MS); 174 175 return ret; 176 } 177 178 static 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; 270 done: 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 } 278 279 static 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 } 309 310 #ifdef CONFIG_PM_SLEEP 311 static int cros_ec_i2c_suspend(struct device *dev) 312 { 313 struct cros_ec_device *ec_dev = to_ec_dev(dev); 314 315 return cros_ec_suspend(ec_dev); 316 } 317 318 static int cros_ec_i2c_resume(struct device *dev) 319 { 320 struct cros_ec_device *ec_dev = to_ec_dev(dev); 321 322 return cros_ec_resume(ec_dev); 323 } 324 #endif 325 326 static const struct dev_pm_ops cros_ec_i2c_pm_ops = { 327 SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume) 328 }; 329 330 #ifdef CONFIG_OF 331 static const struct of_device_id cros_ec_i2c_of_match[] = { 332 { .compatible = "google,cros-ec-i2c", }, 333 { /* sentinel */ }, 334 }; 335 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match); 336 #endif 337 338 static const struct i2c_device_id cros_ec_i2c_id[] = { 339 { "cros-ec-i2c", 0 }, 340 { } 341 }; 342 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id); 343 344 #ifdef CONFIG_ACPI 345 static const struct acpi_device_id cros_ec_i2c_acpi_id[] = { 346 { "GOOG0008", 0 }, 347 { /* sentinel */ } 348 }; 349 MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id); 350 #endif 351 352 static struct i2c_driver cros_ec_driver = { 353 .driver = { 354 .name = "cros-ec-i2c", 355 .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id), 356 .of_match_table = of_match_ptr(cros_ec_i2c_of_match), 357 .pm = &cros_ec_i2c_pm_ops, 358 }, 359 .probe = cros_ec_i2c_probe, 360 .id_table = cros_ec_i2c_id, 361 }; 362 363 module_i2c_driver(cros_ec_driver); 364 365 MODULE_LICENSE("GPL v2"); 366 MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller"); 367