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 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