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