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/kstrtox.h>
12 #include <linux/mod_devicetable.h>
13 #include <linux/module.h>
14 #include <linux/platform_data/cros_ec_commands.h>
15 #include <linux/platform_data/cros_ec_proto.h>
16 #include <linux/platform_device.h>
17 #include <linux/sched.h>
18 #include <linux/types.h>
19 #include <linux/uaccess.h>
20 #include <linux/slab.h>
21
22 #define DRV_NAME "cros-ec-lightbar"
23
24 /* Rate-limit the lightbar interface to prevent DoS. */
25 static unsigned long lb_interval_jiffies = 50 * HZ / 1000;
26
27 /*
28 * Whether or not we have given userspace control of the lightbar.
29 * If this is true, we won't do anything during suspend/resume.
30 */
31 static bool userspace_control;
32
interval_msec_show(struct device * dev,struct device_attribute * attr,char * buf)33 static ssize_t interval_msec_show(struct device *dev,
34 struct device_attribute *attr, char *buf)
35 {
36 unsigned long msec = lb_interval_jiffies * 1000 / HZ;
37
38 return sysfs_emit(buf, "%lu\n", msec);
39 }
40
interval_msec_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)41 static ssize_t interval_msec_store(struct device *dev,
42 struct device_attribute *attr,
43 const char *buf, size_t count)
44 {
45 unsigned long msec;
46
47 if (kstrtoul(buf, 0, &msec))
48 return -EINVAL;
49
50 lb_interval_jiffies = msec * HZ / 1000;
51
52 return count;
53 }
54
55 static DEFINE_MUTEX(lb_mutex);
56 /* Return 0 if able to throttle correctly, error otherwise */
lb_throttle(void)57 static int lb_throttle(void)
58 {
59 static unsigned long last_access;
60 unsigned long now, next_timeslot;
61 long delay;
62 int ret = 0;
63
64 mutex_lock(&lb_mutex);
65
66 now = jiffies;
67 next_timeslot = last_access + lb_interval_jiffies;
68
69 if (time_before(now, next_timeslot)) {
70 delay = (long)(next_timeslot) - (long)now;
71 set_current_state(TASK_INTERRUPTIBLE);
72 if (schedule_timeout(delay) > 0) {
73 /* interrupted - just abort */
74 ret = -EINTR;
75 goto out;
76 }
77 now = jiffies;
78 }
79
80 last_access = now;
81 out:
82 mutex_unlock(&lb_mutex);
83
84 return ret;
85 }
86
alloc_lightbar_cmd_msg(struct cros_ec_dev * ec)87 static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
88 {
89 struct cros_ec_command *msg;
90 int len;
91
92 len = max(sizeof(struct ec_params_lightbar),
93 sizeof(struct ec_response_lightbar));
94
95 msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
96 if (!msg)
97 return NULL;
98
99 msg->version = 0;
100 msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
101 msg->outsize = sizeof(struct ec_params_lightbar);
102 msg->insize = sizeof(struct ec_response_lightbar);
103
104 return msg;
105 }
106
get_lightbar_version(struct cros_ec_dev * ec,uint32_t * ver_ptr,uint32_t * flg_ptr)107 static int get_lightbar_version(struct cros_ec_dev *ec,
108 uint32_t *ver_ptr, uint32_t *flg_ptr)
109 {
110 struct ec_params_lightbar *param;
111 struct ec_response_lightbar *resp;
112 struct cros_ec_command *msg;
113 int ret;
114
115 msg = alloc_lightbar_cmd_msg(ec);
116 if (!msg)
117 return 0;
118
119 param = (struct ec_params_lightbar *)msg->data;
120 param->cmd = LIGHTBAR_CMD_VERSION;
121 msg->outsize = sizeof(param->cmd);
122 msg->result = sizeof(resp->version);
123 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
124 if (ret < 0 && ret != -EINVAL) {
125 ret = 0;
126 goto exit;
127 }
128
129 switch (msg->result) {
130 case EC_RES_INVALID_PARAM:
131 /* Pixel had no version command. */
132 if (ver_ptr)
133 *ver_ptr = 0;
134 if (flg_ptr)
135 *flg_ptr = 0;
136 ret = 1;
137 goto exit;
138
139 case EC_RES_SUCCESS:
140 resp = (struct ec_response_lightbar *)msg->data;
141
142 /* Future devices w/lightbars should implement this command */
143 if (ver_ptr)
144 *ver_ptr = resp->version.num;
145 if (flg_ptr)
146 *flg_ptr = resp->version.flags;
147 ret = 1;
148 goto exit;
149 }
150
151 /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
152 ret = 0;
153 exit:
154 kfree(msg);
155 return ret;
156 }
157
version_show(struct device * dev,struct device_attribute * attr,char * buf)158 static ssize_t version_show(struct device *dev,
159 struct device_attribute *attr, char *buf)
160 {
161 uint32_t version = 0, flags = 0;
162 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
163 int ret;
164
165 ret = lb_throttle();
166 if (ret)
167 return ret;
168
169 /* This should always succeed, because we check during init. */
170 if (!get_lightbar_version(ec, &version, &flags))
171 return -EIO;
172
173 return sysfs_emit(buf, "%d %d\n", version, flags);
174 }
175
brightness_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)176 static ssize_t brightness_store(struct device *dev,
177 struct device_attribute *attr,
178 const char *buf, size_t count)
179 {
180 struct ec_params_lightbar *param;
181 struct cros_ec_command *msg;
182 int ret;
183 unsigned int val;
184 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
185
186 if (kstrtouint(buf, 0, &val))
187 return -EINVAL;
188
189 msg = alloc_lightbar_cmd_msg(ec);
190 if (!msg)
191 return -ENOMEM;
192
193 param = (struct ec_params_lightbar *)msg->data;
194 param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
195 param->set_brightness.num = val;
196 ret = lb_throttle();
197 if (ret)
198 goto exit;
199
200 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
201 if (ret < 0)
202 goto exit;
203
204 ret = count;
205 exit:
206 kfree(msg);
207 return ret;
208 }
209
210
211 /*
212 * We expect numbers, and we'll keep reading until we find them, skipping over
213 * any whitespace (sysfs guarantees that the input is null-terminated). Every
214 * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
215 * parsing error, if we don't parse any numbers, or if we have numbers left
216 * over.
217 */
led_rgb_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)218 static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
219 const char *buf, size_t count)
220 {
221 struct ec_params_lightbar *param;
222 struct cros_ec_command *msg;
223 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
224 unsigned int val[4];
225 int ret, i = 0, j = 0, ok = 0;
226
227 msg = alloc_lightbar_cmd_msg(ec);
228 if (!msg)
229 return -ENOMEM;
230
231 do {
232 /* Skip any whitespace */
233 while (*buf && isspace(*buf))
234 buf++;
235
236 if (!*buf)
237 break;
238
239 ret = sscanf(buf, "%i", &val[i++]);
240 if (ret == 0)
241 goto exit;
242
243 if (i == 4) {
244 param = (struct ec_params_lightbar *)msg->data;
245 param->cmd = LIGHTBAR_CMD_SET_RGB;
246 param->set_rgb.led = val[0];
247 param->set_rgb.red = val[1];
248 param->set_rgb.green = val[2];
249 param->set_rgb.blue = val[3];
250 /*
251 * Throttle only the first of every four transactions,
252 * so that the user can update all four LEDs at once.
253 */
254 if ((j++ % 4) == 0) {
255 ret = lb_throttle();
256 if (ret)
257 goto exit;
258 }
259
260 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
261 if (ret < 0)
262 goto exit;
263
264 i = 0;
265 ok = 1;
266 }
267
268 /* Skip over the number we just read */
269 while (*buf && !isspace(*buf))
270 buf++;
271
272 } while (*buf);
273
274 exit:
275 kfree(msg);
276 return (ok && i == 0) ? count : -EINVAL;
277 }
278
279 static char const *seqname[] = {
280 "ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
281 "S0S3", "S3S5", "STOP", "RUN", "KONAMI",
282 "TAP", "PROGRAM",
283 };
284
sequence_show(struct device * dev,struct device_attribute * attr,char * buf)285 static ssize_t sequence_show(struct device *dev,
286 struct device_attribute *attr, char *buf)
287 {
288 struct ec_params_lightbar *param;
289 struct ec_response_lightbar *resp;
290 struct cros_ec_command *msg;
291 int ret;
292 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
293
294 msg = alloc_lightbar_cmd_msg(ec);
295 if (!msg)
296 return -ENOMEM;
297
298 param = (struct ec_params_lightbar *)msg->data;
299 param->cmd = LIGHTBAR_CMD_GET_SEQ;
300 ret = lb_throttle();
301 if (ret)
302 goto exit;
303
304 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
305 if (ret < 0) {
306 ret = sysfs_emit(buf, "XFER / EC ERROR %d / %d\n", ret, msg->result);
307 goto exit;
308 }
309
310 resp = (struct ec_response_lightbar *)msg->data;
311 if (resp->get_seq.num >= ARRAY_SIZE(seqname))
312 ret = sysfs_emit(buf, "%d\n", resp->get_seq.num);
313 else
314 ret = sysfs_emit(buf, "%s\n", seqname[resp->get_seq.num]);
315
316 exit:
317 kfree(msg);
318 return ret;
319 }
320
lb_send_empty_cmd(struct cros_ec_dev * ec,uint8_t cmd)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
lb_manual_suspend_ctrl(struct cros_ec_dev * ec,uint8_t enable)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
sequence_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
program_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
userspace_control_show(struct device * dev,struct device_attribute * attr,char * buf)481 static ssize_t userspace_control_show(struct device *dev,
482 struct device_attribute *attr,
483 char *buf)
484 {
485 return sysfs_emit(buf, "%d\n", userspace_control);
486 }
487
userspace_control_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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 = kstrtobool(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
cros_ec_lightbar_probe(struct platform_device * pd)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
cros_ec_lightbar_remove(struct platform_device * pd)564 static void 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
cros_ec_lightbar_resume(struct device * dev)575 static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
576 {
577 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
578
579 if (userspace_control)
580 return 0;
581
582 return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME);
583 }
584
cros_ec_lightbar_suspend(struct device * dev)585 static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
586 {
587 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
588
589 if (userspace_control)
590 return 0;
591
592 return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND);
593 }
594
595 static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
596 cros_ec_lightbar_suspend, cros_ec_lightbar_resume);
597
598 static const struct platform_device_id cros_ec_lightbar_id[] = {
599 { DRV_NAME, 0 },
600 {}
601 };
602 MODULE_DEVICE_TABLE(platform, cros_ec_lightbar_id);
603
604 static struct platform_driver cros_ec_lightbar_driver = {
605 .driver = {
606 .name = DRV_NAME,
607 .pm = &cros_ec_lightbar_pm_ops,
608 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
609 },
610 .probe = cros_ec_lightbar_probe,
611 .remove_new = cros_ec_lightbar_remove,
612 .id_table = cros_ec_lightbar_id,
613 };
614
615 module_platform_driver(cros_ec_lightbar_driver);
616
617 MODULE_LICENSE("GPL");
618 MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");
619