cros_ec_lightbar.c

  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. */
 25static 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 */
 31static bool userspace_control;
 32
 33/*
 34 * Whether or not the lightbar supports the manual suspend commands.
 35 * The Pixel 2013 (Link) does not while all other devices with a
 36 * lightbar do.
 37 */
 38static bool has_manual_suspend;
 39
 40static ssize_t interval_msec_show(struct device *dev,
 41				  struct device_attribute *attr, char *buf)
 42{
 43	unsigned long msec = lb_interval_jiffies * 1000 / HZ;
 44
 45	return sysfs_emit(buf, "%lu\n", msec);
 46}
 47
 48static ssize_t interval_msec_store(struct device *dev,
 49				   struct device_attribute *attr,
 50				   const char *buf, size_t count)
 51{
 52	unsigned long msec;
 53
 54	if (kstrtoul(buf, 0, &msec))
 55		return -EINVAL;
 56
 57	lb_interval_jiffies = msec * HZ / 1000;
 58
 59	return count;
 60}
 61
 62static DEFINE_MUTEX(lb_mutex);
 63/* Return 0 if able to throttle correctly, error otherwise */
 64static int lb_throttle(void)
 65{
 66	static unsigned long last_access;
 67	unsigned long now, next_timeslot;
 68	long delay;
 69	int ret = 0;
 70
 71	mutex_lock(&lb_mutex);
 72
 73	now = jiffies;
 74	next_timeslot = last_access + lb_interval_jiffies;
 75
 76	if (time_before(now, next_timeslot)) {
 77		delay = (long)(next_timeslot) - (long)now;
 78		set_current_state(TASK_INTERRUPTIBLE);
 79		if (schedule_timeout(delay) > 0) {
 80			/* interrupted - just abort */
 81			ret = -EINTR;
 82			goto out;
 83		}
 84		now = jiffies;
 85	}
 86
 87	last_access = now;
 88out:
 89	mutex_unlock(&lb_mutex);
 90
 91	return ret;
 92}
 93
 94static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
 95{
 96	struct cros_ec_command *msg;
 97	int len;
 98
 99	len = max(sizeof(struct ec_params_lightbar),
100		  sizeof(struct ec_response_lightbar));
101
102	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
103	if (!msg)
104		return NULL;
105
106	msg->version = 0;
107	msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
108	msg->outsize = sizeof(struct ec_params_lightbar);
109	msg->insize = sizeof(struct ec_response_lightbar);
110
111	return msg;
112}
113
114static int get_lightbar_version(struct cros_ec_dev *ec,
115				uint32_t *ver_ptr, uint32_t *flg_ptr)
116{
117	struct ec_params_lightbar *param;
118	struct ec_response_lightbar *resp;
119	struct cros_ec_command *msg;
120	int ret;
121
122	msg = alloc_lightbar_cmd_msg(ec);
123	if (!msg)
124		return 0;
125
126	param = (struct ec_params_lightbar *)msg->data;
127	param->cmd = LIGHTBAR_CMD_VERSION;
128	msg->outsize = sizeof(param->cmd);
129	msg->insize = sizeof(resp->version);
130	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
131	if (ret < 0 && ret != -EINVAL) {
132		ret = 0;
133		goto exit;
134	}
135
136	switch (msg->result) {
137	case EC_RES_INVALID_PARAM:
138		/* Pixel had no version command. */
139		if (ver_ptr)
140			*ver_ptr = 0;
141		if (flg_ptr)
142			*flg_ptr = 0;
143		ret = 1;
144		goto exit;
145
146	case EC_RES_SUCCESS:
147		resp = (struct ec_response_lightbar *)msg->data;
148
149		/* Future devices w/lightbars should implement this command */
150		if (ver_ptr)
151			*ver_ptr = resp->version.num;
152		if (flg_ptr)
153			*flg_ptr = resp->version.flags;
154		ret = 1;
155		goto exit;
156	}
157
158	/* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
159	ret = 0;
160exit:
161	kfree(msg);
162	return ret;
163}
164
165static ssize_t version_show(struct device *dev,
166			    struct device_attribute *attr, char *buf)
167{
168	uint32_t version = 0, flags = 0;
169	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
170	int ret;
171
172	ret = lb_throttle();
173	if (ret)
174		return ret;
175
176	/* This should always succeed, because we check during init. */
177	if (!get_lightbar_version(ec, &version, &flags))
178		return -EIO;
179
180	return sysfs_emit(buf, "%d %d\n", version, flags);
181}
182
183static ssize_t brightness_store(struct device *dev,
184				struct device_attribute *attr,
185				const char *buf, size_t count)
186{
187	struct ec_params_lightbar *param;
188	struct cros_ec_command *msg;
189	int ret;
190	unsigned int val;
191	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
192
193	if (kstrtouint(buf, 0, &val))
194		return -EINVAL;
195
196	msg = alloc_lightbar_cmd_msg(ec);
197	if (!msg)
198		return -ENOMEM;
199
200	param = (struct ec_params_lightbar *)msg->data;
201	param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
202	param->set_brightness.num = val;
203	ret = lb_throttle();
204	if (ret)
205		goto exit;
206
207	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
208	if (ret < 0)
209		goto exit;
210
211	ret = count;
212exit:
213	kfree(msg);
214	return ret;
215}
216
217
218/*
219 * We expect numbers, and we'll keep reading until we find them, skipping over
220 * any whitespace (sysfs guarantees that the input is null-terminated). Every
221 * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
222 * parsing error, if we don't parse any numbers, or if we have numbers left
223 * over.
224 */
225static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
226			     const char *buf, size_t count)
227{
228	struct ec_params_lightbar *param;
229	struct cros_ec_command *msg;
230	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
231	unsigned int val[4];
232	int ret, i = 0, j = 0, ok = 0;
233
234	msg = alloc_lightbar_cmd_msg(ec);
235	if (!msg)
236		return -ENOMEM;
237
238	do {
239		/* Skip any whitespace */
240		while (*buf && isspace(*buf))
241			buf++;
242
243		if (!*buf)
244			break;
245
246		ret = sscanf(buf, "%i", &val[i++]);
247		if (ret == 0)
248			goto exit;
249
250		if (i == 4) {
251			param = (struct ec_params_lightbar *)msg->data;
252			param->cmd = LIGHTBAR_CMD_SET_RGB;
253			param->set_rgb.led = val[0];
254			param->set_rgb.red = val[1];
255			param->set_rgb.green = val[2];
256			param->set_rgb.blue = val[3];
257			/*
258			 * Throttle only the first of every four transactions,
259			 * so that the user can update all four LEDs at once.
260			 */
261			if ((j++ % 4) == 0) {
262				ret = lb_throttle();
263				if (ret)
264					goto exit;
265			}
266
267			ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
268			if (ret < 0)
269				goto exit;
270
271			i = 0;
272			ok = 1;
273		}
274
275		/* Skip over the number we just read */
276		while (*buf && !isspace(*buf))
277			buf++;
278
279	} while (*buf);
280
281exit:
282	kfree(msg);
283	return (ok && i == 0) ? count : -EINVAL;
284}
285
286static char const *seqname[] = {
287	"ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
288	"S0S3", "S3S5", "STOP", "RUN", "KONAMI",
289	"TAP", "PROGRAM",
290};
291
292static ssize_t sequence_show(struct device *dev,
293			     struct device_attribute *attr, char *buf)
294{
295	struct ec_params_lightbar *param;
296	struct ec_response_lightbar *resp;
297	struct cros_ec_command *msg;
298	int ret;
299	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
300
301	msg = alloc_lightbar_cmd_msg(ec);
302	if (!msg)
303		return -ENOMEM;
304
305	param = (struct ec_params_lightbar *)msg->data;
306	param->cmd = LIGHTBAR_CMD_GET_SEQ;
307	ret = lb_throttle();
308	if (ret)
309		goto exit;
310
311	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
312	if (ret < 0) {
313		ret = sysfs_emit(buf, "XFER / EC ERROR %d / %d\n", ret, msg->result);
314		goto exit;
315	}
316
317	resp = (struct ec_response_lightbar *)msg->data;
318	if (resp->get_seq.num >= ARRAY_SIZE(seqname))
319		ret = sysfs_emit(buf, "%d\n", resp->get_seq.num);
320	else
321		ret = sysfs_emit(buf, "%s\n", seqname[resp->get_seq.num]);
322
323exit:
324	kfree(msg);
325	return ret;
326}
327
328static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
329{
330	struct ec_params_lightbar *param;
331	struct cros_ec_command *msg;
332	int ret;
333
334	msg = alloc_lightbar_cmd_msg(ec);
335	if (!msg)
336		return -ENOMEM;
337
338	param = (struct ec_params_lightbar *)msg->data;
339	param->cmd = cmd;
340
341	ret = lb_throttle();
342	if (ret)
343		goto error;
344
345	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
346	if (ret < 0)
347		goto error;
348
349	ret = 0;
350error:
351	kfree(msg);
352
353	return ret;
354}
355
356static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
357{
358	struct ec_params_lightbar *param;
359	struct cros_ec_command *msg;
360	int ret;
361
362	msg = alloc_lightbar_cmd_msg(ec);
363	if (!msg)
364		return -ENOMEM;
365
366	param = (struct ec_params_lightbar *)msg->data;
367
368	param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
369	param->manual_suspend_ctrl.enable = enable;
370
371	ret = lb_throttle();
372	if (ret)
373		goto error;
374
375	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
376	if (ret < 0)
377		goto error;
378
379	ret = 0;
380error:
381	kfree(msg);
382
383	return ret;
384}
385
386static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
387			      const char *buf, size_t count)
388{
389	struct ec_params_lightbar *param;
390	struct cros_ec_command *msg;
391	unsigned int num;
392	int ret, len;
393	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
394
395	for (len = 0; len < count; len++)
396		if (!isalnum(buf[len]))
397			break;
398
399	for (num = 0; num < ARRAY_SIZE(seqname); num++)
400		if (!strncasecmp(seqname[num], buf, len))
401			break;
402
403	if (num >= ARRAY_SIZE(seqname)) {
404		ret = kstrtouint(buf, 0, &num);
405		if (ret)
406			return ret;
407	}
408
409	msg = alloc_lightbar_cmd_msg(ec);
410	if (!msg)
411		return -ENOMEM;
412
413	param = (struct ec_params_lightbar *)msg->data;
414	param->cmd = LIGHTBAR_CMD_SEQ;
415	param->seq.num = num;
416	ret = lb_throttle();
417	if (ret)
418		goto exit;
419
420	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
421	if (ret < 0)
422		goto exit;
423
424	ret = count;
425exit:
426	kfree(msg);
427	return ret;
428}
429
430static ssize_t program_store(struct device *dev, struct device_attribute *attr,
431			     const char *buf, size_t count)
432{
433	int extra_bytes, max_size, ret;
434	struct ec_params_lightbar *param;
435	struct cros_ec_command *msg;
436	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
437
438	/*
439	 * We might need to reject the program for size reasons. The EC
440	 * enforces a maximum program size, but we also don't want to try
441	 * and send a program that is too big for the protocol. In order
442	 * to ensure the latter, we also need to ensure we have extra bytes
443	 * to represent the rest of the packet.
444	 */
445	extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
446	max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
447	if (count > max_size) {
448		dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
449			(unsigned int)count, max_size);
450
451		return -EINVAL;
452	}
453
454	msg = alloc_lightbar_cmd_msg(ec);
455	if (!msg)
456		return -ENOMEM;
457
458	ret = lb_throttle();
459	if (ret)
460		goto exit;
461
462	dev_info(dev, "Copying %zu byte program to EC", count);
463
464	param = (struct ec_params_lightbar *)msg->data;
465	param->cmd = LIGHTBAR_CMD_SET_PROGRAM;
466
467	param->set_program.size = count;
468	memcpy(param->set_program.data, buf, count);
469
470	/*
471	 * We need to set the message size manually or else it will use
472	 * EC_LB_PROG_LEN. This might be too long, and the program
473	 * is unlikely to use all of the space.
474	 */
475	msg->outsize = count + extra_bytes;
476
477	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
478	if (ret < 0)
479		goto exit;
480
481	ret = count;
482exit:
483	kfree(msg);
484
485	return ret;
486}
487
488static ssize_t userspace_control_show(struct device *dev,
489				      struct device_attribute *attr,
490				      char *buf)
491{
492	return sysfs_emit(buf, "%d\n", userspace_control);
493}
494
495static ssize_t userspace_control_store(struct device *dev,
496				       struct device_attribute *attr,
497				       const char *buf,
498				       size_t count)
499{
500	bool enable;
501	int ret;
502
503	ret = kstrtobool(buf, &enable);
504	if (ret < 0)
505		return ret;
506
507	userspace_control = enable;
508
509	return count;
510}
511
512/* Module initialization */
513
514static DEVICE_ATTR_RW(interval_msec);
515static DEVICE_ATTR_RO(version);
516static DEVICE_ATTR_WO(brightness);
517static DEVICE_ATTR_WO(led_rgb);
518static DEVICE_ATTR_RW(sequence);
519static DEVICE_ATTR_WO(program);
520static DEVICE_ATTR_RW(userspace_control);
521
522static struct attribute *__lb_cmds_attrs[] = {
523	&dev_attr_interval_msec.attr,
524	&dev_attr_version.attr,
525	&dev_attr_brightness.attr,
526	&dev_attr_led_rgb.attr,
527	&dev_attr_sequence.attr,
528	&dev_attr_program.attr,
529	&dev_attr_userspace_control.attr,
530	NULL,
531};
532
533static const struct attribute_group cros_ec_lightbar_attr_group = {
534	.name = "lightbar",
535	.attrs = __lb_cmds_attrs,
536};
537
538static int cros_ec_lightbar_probe(struct platform_device *pd)
539{
540	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
541	struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
542	struct device *dev = &pd->dev;
543	int ret;
544
545	/*
546	 * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
547	 * devices like 'cros_pd' doesn't have a lightbar.
548	 */
549	if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
550		return -ENODEV;
551
552	/*
553	 * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
554	 * doesn't have a lightbar.
555	 */
556	if (!get_lightbar_version(ec_dev, NULL, NULL))
557		return -ENODEV;
558
559	/* Take control of the lightbar from the EC. */
560	has_manual_suspend = (lb_manual_suspend_ctrl(ec_dev, 1) != -EINVAL);
561
562	ret = sysfs_create_group(&ec_dev->class_dev.kobj,
563				 &cros_ec_lightbar_attr_group);
564	if (ret < 0)
565		dev_err(dev, "failed to create %s attributes. err=%d\n",
566			cros_ec_lightbar_attr_group.name, ret);
567
568	return ret;
569}
570
571static void cros_ec_lightbar_remove(struct platform_device *pd)
572{
573	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
574
575	sysfs_remove_group(&ec_dev->class_dev.kobj,
576			   &cros_ec_lightbar_attr_group);
577
578	/* Let the EC take over the lightbar again. */
579	if (has_manual_suspend)
580		lb_manual_suspend_ctrl(ec_dev, 0);
581}
582
583static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
584{
585	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
586
587	if (userspace_control || !has_manual_suspend)
588		return 0;
589
590	return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME);
591}
592
593static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
594{
595	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
596
597	if (userspace_control || !has_manual_suspend)
598		return 0;
599
600	return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND);
601}
602
603static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
604			 cros_ec_lightbar_suspend, cros_ec_lightbar_resume);
605
606static const struct platform_device_id cros_ec_lightbar_id[] = {
607	{ DRV_NAME, 0 },
608	{}
609};
610MODULE_DEVICE_TABLE(platform, cros_ec_lightbar_id);
611
612static struct platform_driver cros_ec_lightbar_driver = {
613	.driver = {
614		.name = DRV_NAME,
615		.pm = &cros_ec_lightbar_pm_ops,
616		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
617	},
618	.probe = cros_ec_lightbar_probe,
619	.remove = cros_ec_lightbar_remove,
620	.id_table = cros_ec_lightbar_id,
621};
622
623module_platform_driver(cros_ec_lightbar_driver);
624
625MODULE_LICENSE("GPL");
626MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");