1 // SPDX-License-Identifier: GPL-2.0+ 2 // Expose the Chromebook Pixel lightbar to userspace 3 // 4 // Copyright (C) 2014 Google, Inc. 5 6 #include <linux/ctype.h> 7 #include <linux/delay.h> 8 #include <linux/device.h> 9 #include <linux/fs.h> 10 #include <linux/kobject.h> 11 #include <linux/module.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/sched.h> 16 #include <linux/types.h> 17 #include <linux/uaccess.h> 18 #include <linux/slab.h> 19 20 #define DRV_NAME "cros-ec-lightbar" 21 22 /* Rate-limit the lightbar interface to prevent DoS. */ 23 static unsigned long lb_interval_jiffies = 50 * HZ / 1000; 24 25 /* 26 * Whether or not we have given userspace control of the lightbar. 27 * If this is true, we won't do anything during suspend/resume. 28 */ 29 static bool userspace_control; 30 31 static ssize_t interval_msec_show(struct device *dev, 32 struct device_attribute *attr, char *buf) 33 { 34 unsigned long msec = lb_interval_jiffies * 1000 / HZ; 35 36 return scnprintf(buf, PAGE_SIZE, "%lu\n", msec); 37 } 38 39 static ssize_t interval_msec_store(struct device *dev, 40 struct device_attribute *attr, 41 const char *buf, size_t count) 42 { 43 unsigned long msec; 44 45 if (kstrtoul(buf, 0, &msec)) 46 return -EINVAL; 47 48 lb_interval_jiffies = msec * HZ / 1000; 49 50 return count; 51 } 52 53 static DEFINE_MUTEX(lb_mutex); 54 /* Return 0 if able to throttle correctly, error otherwise */ 55 static int lb_throttle(void) 56 { 57 static unsigned long last_access; 58 unsigned long now, next_timeslot; 59 long delay; 60 int ret = 0; 61 62 mutex_lock(&lb_mutex); 63 64 now = jiffies; 65 next_timeslot = last_access + lb_interval_jiffies; 66 67 if (time_before(now, next_timeslot)) { 68 delay = (long)(next_timeslot) - (long)now; 69 set_current_state(TASK_INTERRUPTIBLE); 70 if (schedule_timeout(delay) > 0) { 71 /* interrupted - just abort */ 72 ret = -EINTR; 73 goto out; 74 } 75 now = jiffies; 76 } 77 78 last_access = now; 79 out: 80 mutex_unlock(&lb_mutex); 81 82 return ret; 83 } 84 85 static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec) 86 { 87 struct cros_ec_command *msg; 88 int len; 89 90 len = max(sizeof(struct ec_params_lightbar), 91 sizeof(struct ec_response_lightbar)); 92 93 msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL); 94 if (!msg) 95 return NULL; 96 97 msg->version = 0; 98 msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset; 99 msg->outsize = sizeof(struct ec_params_lightbar); 100 msg->insize = sizeof(struct ec_response_lightbar); 101 102 return msg; 103 } 104 105 static int get_lightbar_version(struct cros_ec_dev *ec, 106 uint32_t *ver_ptr, uint32_t *flg_ptr) 107 { 108 struct ec_params_lightbar *param; 109 struct ec_response_lightbar *resp; 110 struct cros_ec_command *msg; 111 int ret; 112 113 msg = alloc_lightbar_cmd_msg(ec); 114 if (!msg) 115 return 0; 116 117 param = (struct ec_params_lightbar *)msg->data; 118 param->cmd = LIGHTBAR_CMD_VERSION; 119 msg->outsize = sizeof(param->cmd); 120 msg->result = sizeof(resp->version); 121 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 122 if (ret < 0 && ret != -EINVAL) { 123 ret = 0; 124 goto exit; 125 } 126 127 switch (msg->result) { 128 case EC_RES_INVALID_PARAM: 129 /* Pixel had no version command. */ 130 if (ver_ptr) 131 *ver_ptr = 0; 132 if (flg_ptr) 133 *flg_ptr = 0; 134 ret = 1; 135 goto exit; 136 137 case EC_RES_SUCCESS: 138 resp = (struct ec_response_lightbar *)msg->data; 139 140 /* Future devices w/lightbars should implement this command */ 141 if (ver_ptr) 142 *ver_ptr = resp->version.num; 143 if (flg_ptr) 144 *flg_ptr = resp->version.flags; 145 ret = 1; 146 goto exit; 147 } 148 149 /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */ 150 ret = 0; 151 exit: 152 kfree(msg); 153 return ret; 154 } 155 156 static ssize_t version_show(struct device *dev, 157 struct device_attribute *attr, char *buf) 158 { 159 uint32_t version = 0, flags = 0; 160 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 161 int ret; 162 163 ret = lb_throttle(); 164 if (ret) 165 return ret; 166 167 /* This should always succeed, because we check during init. */ 168 if (!get_lightbar_version(ec, &version, &flags)) 169 return -EIO; 170 171 return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags); 172 } 173 174 static ssize_t brightness_store(struct device *dev, 175 struct device_attribute *attr, 176 const char *buf, size_t count) 177 { 178 struct ec_params_lightbar *param; 179 struct cros_ec_command *msg; 180 int ret; 181 unsigned int val; 182 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 183 184 if (kstrtouint(buf, 0, &val)) 185 return -EINVAL; 186 187 msg = alloc_lightbar_cmd_msg(ec); 188 if (!msg) 189 return -ENOMEM; 190 191 param = (struct ec_params_lightbar *)msg->data; 192 param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS; 193 param->set_brightness.num = val; 194 ret = lb_throttle(); 195 if (ret) 196 goto exit; 197 198 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 199 if (ret < 0) 200 goto exit; 201 202 ret = count; 203 exit: 204 kfree(msg); 205 return ret; 206 } 207 208 209 /* 210 * We expect numbers, and we'll keep reading until we find them, skipping over 211 * any whitespace (sysfs guarantees that the input is null-terminated). Every 212 * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first 213 * parsing error, if we don't parse any numbers, or if we have numbers left 214 * over. 215 */ 216 static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr, 217 const char *buf, size_t count) 218 { 219 struct ec_params_lightbar *param; 220 struct cros_ec_command *msg; 221 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 222 unsigned int val[4]; 223 int ret, i = 0, j = 0, ok = 0; 224 225 msg = alloc_lightbar_cmd_msg(ec); 226 if (!msg) 227 return -ENOMEM; 228 229 do { 230 /* Skip any whitespace */ 231 while (*buf && isspace(*buf)) 232 buf++; 233 234 if (!*buf) 235 break; 236 237 ret = sscanf(buf, "%i", &val[i++]); 238 if (ret == 0) 239 goto exit; 240 241 if (i == 4) { 242 param = (struct ec_params_lightbar *)msg->data; 243 param->cmd = LIGHTBAR_CMD_SET_RGB; 244 param->set_rgb.led = val[0]; 245 param->set_rgb.red = val[1]; 246 param->set_rgb.green = val[2]; 247 param->set_rgb.blue = val[3]; 248 /* 249 * Throttle only the first of every four transactions, 250 * so that the user can update all four LEDs at once. 251 */ 252 if ((j++ % 4) == 0) { 253 ret = lb_throttle(); 254 if (ret) 255 goto exit; 256 } 257 258 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 259 if (ret < 0) 260 goto exit; 261 262 i = 0; 263 ok = 1; 264 } 265 266 /* Skip over the number we just read */ 267 while (*buf && !isspace(*buf)) 268 buf++; 269 270 } while (*buf); 271 272 exit: 273 kfree(msg); 274 return (ok && i == 0) ? count : -EINVAL; 275 } 276 277 static char const *seqname[] = { 278 "ERROR", "S5", "S3", "S0", "S5S3", "S3S0", 279 "S0S3", "S3S5", "STOP", "RUN", "KONAMI", 280 "TAP", "PROGRAM", 281 }; 282 283 static ssize_t sequence_show(struct device *dev, 284 struct device_attribute *attr, char *buf) 285 { 286 struct ec_params_lightbar *param; 287 struct ec_response_lightbar *resp; 288 struct cros_ec_command *msg; 289 int ret; 290 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 291 292 msg = alloc_lightbar_cmd_msg(ec); 293 if (!msg) 294 return -ENOMEM; 295 296 param = (struct ec_params_lightbar *)msg->data; 297 param->cmd = LIGHTBAR_CMD_GET_SEQ; 298 ret = lb_throttle(); 299 if (ret) 300 goto exit; 301 302 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 303 if (ret < 0) { 304 ret = scnprintf(buf, PAGE_SIZE, "XFER / EC ERROR %d / %d\n", 305 ret, msg->result); 306 goto exit; 307 } 308 309 resp = (struct ec_response_lightbar *)msg->data; 310 if (resp->get_seq.num >= ARRAY_SIZE(seqname)) 311 ret = scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num); 312 else 313 ret = scnprintf(buf, PAGE_SIZE, "%s\n", 314 seqname[resp->get_seq.num]); 315 316 exit: 317 kfree(msg); 318 return ret; 319 } 320 321 static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd) 322 { 323 struct ec_params_lightbar *param; 324 struct cros_ec_command *msg; 325 int ret; 326 327 msg = alloc_lightbar_cmd_msg(ec); 328 if (!msg) 329 return -ENOMEM; 330 331 param = (struct ec_params_lightbar *)msg->data; 332 param->cmd = cmd; 333 334 ret = lb_throttle(); 335 if (ret) 336 goto error; 337 338 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 339 if (ret < 0) 340 goto error; 341 342 ret = 0; 343 error: 344 kfree(msg); 345 346 return ret; 347 } 348 349 static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable) 350 { 351 struct ec_params_lightbar *param; 352 struct cros_ec_command *msg; 353 int ret; 354 355 msg = alloc_lightbar_cmd_msg(ec); 356 if (!msg) 357 return -ENOMEM; 358 359 param = (struct ec_params_lightbar *)msg->data; 360 361 param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL; 362 param->manual_suspend_ctrl.enable = enable; 363 364 ret = lb_throttle(); 365 if (ret) 366 goto error; 367 368 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 369 if (ret < 0) 370 goto error; 371 372 ret = 0; 373 error: 374 kfree(msg); 375 376 return ret; 377 } 378 379 static ssize_t sequence_store(struct device *dev, struct device_attribute *attr, 380 const char *buf, size_t count) 381 { 382 struct ec_params_lightbar *param; 383 struct cros_ec_command *msg; 384 unsigned int num; 385 int ret, len; 386 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 387 388 for (len = 0; len < count; len++) 389 if (!isalnum(buf[len])) 390 break; 391 392 for (num = 0; num < ARRAY_SIZE(seqname); num++) 393 if (!strncasecmp(seqname[num], buf, len)) 394 break; 395 396 if (num >= ARRAY_SIZE(seqname)) { 397 ret = kstrtouint(buf, 0, &num); 398 if (ret) 399 return ret; 400 } 401 402 msg = alloc_lightbar_cmd_msg(ec); 403 if (!msg) 404 return -ENOMEM; 405 406 param = (struct ec_params_lightbar *)msg->data; 407 param->cmd = LIGHTBAR_CMD_SEQ; 408 param->seq.num = num; 409 ret = lb_throttle(); 410 if (ret) 411 goto exit; 412 413 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 414 if (ret < 0) 415 goto exit; 416 417 ret = count; 418 exit: 419 kfree(msg); 420 return ret; 421 } 422 423 static ssize_t program_store(struct device *dev, struct device_attribute *attr, 424 const char *buf, size_t count) 425 { 426 int extra_bytes, max_size, ret; 427 struct ec_params_lightbar *param; 428 struct cros_ec_command *msg; 429 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 430 431 /* 432 * We might need to reject the program for size reasons. The EC 433 * enforces a maximum program size, but we also don't want to try 434 * and send a program that is too big for the protocol. In order 435 * to ensure the latter, we also need to ensure we have extra bytes 436 * to represent the rest of the packet. 437 */ 438 extra_bytes = sizeof(*param) - sizeof(param->set_program.data); 439 max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes); 440 if (count > max_size) { 441 dev_err(dev, "Program is %u bytes, too long to send (max: %u)", 442 (unsigned int)count, max_size); 443 444 return -EINVAL; 445 } 446 447 msg = alloc_lightbar_cmd_msg(ec); 448 if (!msg) 449 return -ENOMEM; 450 451 ret = lb_throttle(); 452 if (ret) 453 goto exit; 454 455 dev_info(dev, "Copying %zu byte program to EC", count); 456 457 param = (struct ec_params_lightbar *)msg->data; 458 param->cmd = LIGHTBAR_CMD_SET_PROGRAM; 459 460 param->set_program.size = count; 461 memcpy(param->set_program.data, buf, count); 462 463 /* 464 * We need to set the message size manually or else it will use 465 * EC_LB_PROG_LEN. This might be too long, and the program 466 * is unlikely to use all of the space. 467 */ 468 msg->outsize = count + extra_bytes; 469 470 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); 471 if (ret < 0) 472 goto exit; 473 474 ret = count; 475 exit: 476 kfree(msg); 477 478 return ret; 479 } 480 481 static ssize_t userspace_control_show(struct device *dev, 482 struct device_attribute *attr, 483 char *buf) 484 { 485 return scnprintf(buf, PAGE_SIZE, "%d\n", userspace_control); 486 } 487 488 static ssize_t userspace_control_store(struct device *dev, 489 struct device_attribute *attr, 490 const char *buf, 491 size_t count) 492 { 493 bool enable; 494 int ret; 495 496 ret = strtobool(buf, &enable); 497 if (ret < 0) 498 return ret; 499 500 userspace_control = enable; 501 502 return count; 503 } 504 505 /* Module initialization */ 506 507 static DEVICE_ATTR_RW(interval_msec); 508 static DEVICE_ATTR_RO(version); 509 static DEVICE_ATTR_WO(brightness); 510 static DEVICE_ATTR_WO(led_rgb); 511 static DEVICE_ATTR_RW(sequence); 512 static DEVICE_ATTR_WO(program); 513 static DEVICE_ATTR_RW(userspace_control); 514 515 static struct attribute *__lb_cmds_attrs[] = { 516 &dev_attr_interval_msec.attr, 517 &dev_attr_version.attr, 518 &dev_attr_brightness.attr, 519 &dev_attr_led_rgb.attr, 520 &dev_attr_sequence.attr, 521 &dev_attr_program.attr, 522 &dev_attr_userspace_control.attr, 523 NULL, 524 }; 525 526 static const struct attribute_group cros_ec_lightbar_attr_group = { 527 .name = "lightbar", 528 .attrs = __lb_cmds_attrs, 529 }; 530 531 static int cros_ec_lightbar_probe(struct platform_device *pd) 532 { 533 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 534 struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev); 535 struct device *dev = &pd->dev; 536 int ret; 537 538 /* 539 * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC 540 * devices like 'cros_pd' doesn't have a lightbar. 541 */ 542 if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0) 543 return -ENODEV; 544 545 /* 546 * Ask then for the lightbar version, if it's 0 then the 'cros_ec' 547 * doesn't have a lightbar. 548 */ 549 if (!get_lightbar_version(ec_dev, NULL, NULL)) 550 return -ENODEV; 551 552 /* Take control of the lightbar from the EC. */ 553 lb_manual_suspend_ctrl(ec_dev, 1); 554 555 ret = sysfs_create_group(&ec_dev->class_dev.kobj, 556 &cros_ec_lightbar_attr_group); 557 if (ret < 0) 558 dev_err(dev, "failed to create %s attributes. err=%d\n", 559 cros_ec_lightbar_attr_group.name, ret); 560 561 return ret; 562 } 563 564 static int cros_ec_lightbar_remove(struct platform_device *pd) 565 { 566 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 567 568 sysfs_remove_group(&ec_dev->class_dev.kobj, 569 &cros_ec_lightbar_attr_group); 570 571 /* Let the EC take over the lightbar again. */ 572 lb_manual_suspend_ctrl(ec_dev, 0); 573 574 return 0; 575 } 576 577 static int __maybe_unused cros_ec_lightbar_resume(struct device *dev) 578 { 579 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent); 580 581 if (userspace_control) 582 return 0; 583 584 return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME); 585 } 586 587 static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev) 588 { 589 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent); 590 591 if (userspace_control) 592 return 0; 593 594 return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND); 595 } 596 597 static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops, 598 cros_ec_lightbar_suspend, cros_ec_lightbar_resume); 599 600 static struct platform_driver cros_ec_lightbar_driver = { 601 .driver = { 602 .name = DRV_NAME, 603 .pm = &cros_ec_lightbar_pm_ops, 604 }, 605 .probe = cros_ec_lightbar_probe, 606 .remove = cros_ec_lightbar_remove, 607 }; 608 609 module_platform_driver(cros_ec_lightbar_driver); 610 611 MODULE_LICENSE("GPL"); 612 MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace"); 613 MODULE_ALIAS("platform:" DRV_NAME); 614