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. */
 24static 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 */
 30static bool userspace_control;
 31
 32static 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 scnprintf(buf, PAGE_SIZE, "%lu\n", msec);
 38}
 39
 40static 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
 54static DEFINE_MUTEX(lb_mutex);
 55/* Return 0 if able to throttle correctly, error otherwise */
 56static 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;
 80out:
 81	mutex_unlock(&lb_mutex);
 82
 83	return ret;
 84}
 85
 86static 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
106static 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;
152exit:
153	kfree(msg);
154	return ret;
155}
156
157static 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 scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
173}
174
175static 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;
204exit:
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 */
217static 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
273exit:
274	kfree(msg);
275	return (ok && i == 0) ? count : -EINVAL;
276}
277
278static char const *seqname[] = {
279	"ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
280	"S0S3", "S3S5", "STOP", "RUN", "KONAMI",
281	"TAP", "PROGRAM",
282};
283
284static 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 = scnprintf(buf, PAGE_SIZE, "XFER / EC ERROR %d / %d\n",
306				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 = scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
313	else
314		ret = scnprintf(buf, PAGE_SIZE, "%s\n",
315				seqname[resp->get_seq.num]);
316
317exit:
318	kfree(msg);
319	return ret;
320}
321
322static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
323{
324	struct ec_params_lightbar *param;
325	struct cros_ec_command *msg;
326	int ret;
327
328	msg = alloc_lightbar_cmd_msg(ec);
329	if (!msg)
330		return -ENOMEM;
331
332	param = (struct ec_params_lightbar *)msg->data;
333	param->cmd = cmd;
334
335	ret = lb_throttle();
336	if (ret)
337		goto error;
338
339	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
340	if (ret < 0)
341		goto error;
342
343	ret = 0;
344error:
345	kfree(msg);
346
347	return ret;
348}
349
350static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
351{
352	struct ec_params_lightbar *param;
353	struct cros_ec_command *msg;
354	int ret;
355
356	msg = alloc_lightbar_cmd_msg(ec);
357	if (!msg)
358		return -ENOMEM;
359
360	param = (struct ec_params_lightbar *)msg->data;
361
362	param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
363	param->manual_suspend_ctrl.enable = enable;
364
365	ret = lb_throttle();
366	if (ret)
367		goto error;
368
369	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
370	if (ret < 0)
371		goto error;
372
373	ret = 0;
374error:
375	kfree(msg);
376
377	return ret;
378}
379
380static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
381			      const char *buf, size_t count)
382{
383	struct ec_params_lightbar *param;
384	struct cros_ec_command *msg;
385	unsigned int num;
386	int ret, len;
387	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
388
389	for (len = 0; len < count; len++)
390		if (!isalnum(buf[len]))
391			break;
392
393	for (num = 0; num < ARRAY_SIZE(seqname); num++)
394		if (!strncasecmp(seqname[num], buf, len))
395			break;
396
397	if (num >= ARRAY_SIZE(seqname)) {
398		ret = kstrtouint(buf, 0, &num);
399		if (ret)
400			return ret;
401	}
402
403	msg = alloc_lightbar_cmd_msg(ec);
404	if (!msg)
405		return -ENOMEM;
406
407	param = (struct ec_params_lightbar *)msg->data;
408	param->cmd = LIGHTBAR_CMD_SEQ;
409	param->seq.num = num;
410	ret = lb_throttle();
411	if (ret)
412		goto exit;
413
414	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
415	if (ret < 0)
416		goto exit;
417
418	ret = count;
419exit:
420	kfree(msg);
421	return ret;
422}
423
424static ssize_t program_store(struct device *dev, struct device_attribute *attr,
425			     const char *buf, size_t count)
426{
427	int extra_bytes, max_size, ret;
428	struct ec_params_lightbar *param;
429	struct cros_ec_command *msg;
430	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
431
432	/*
433	 * We might need to reject the program for size reasons. The EC
434	 * enforces a maximum program size, but we also don't want to try
435	 * and send a program that is too big for the protocol. In order
436	 * to ensure the latter, we also need to ensure we have extra bytes
437	 * to represent the rest of the packet.
438	 */
439	extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
440	max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
441	if (count > max_size) {
442		dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
443			(unsigned int)count, max_size);
444
445		return -EINVAL;
446	}
447
448	msg = alloc_lightbar_cmd_msg(ec);
449	if (!msg)
450		return -ENOMEM;
451
452	ret = lb_throttle();
453	if (ret)
454		goto exit;
455
456	dev_info(dev, "Copying %zu byte program to EC", count);
457
458	param = (struct ec_params_lightbar *)msg->data;
459	param->cmd = LIGHTBAR_CMD_SET_PROGRAM;
460
461	param->set_program.size = count;
462	memcpy(param->set_program.data, buf, count);
463
464	/*
465	 * We need to set the message size manually or else it will use
466	 * EC_LB_PROG_LEN. This might be too long, and the program
467	 * is unlikely to use all of the space.
468	 */
469	msg->outsize = count + extra_bytes;
470
471	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
472	if (ret < 0)
473		goto exit;
474
475	ret = count;
476exit:
477	kfree(msg);
478
479	return ret;
480}
481
482static ssize_t userspace_control_show(struct device *dev,
483				      struct device_attribute *attr,
484				      char *buf)
485{
486	return scnprintf(buf, PAGE_SIZE, "%d\n", userspace_control);
487}
488
489static ssize_t userspace_control_store(struct device *dev,
490				       struct device_attribute *attr,
491				       const char *buf,
492				       size_t count)
493{
494	bool enable;
495	int ret;
496
497	ret = kstrtobool(buf, &enable);
498	if (ret < 0)
499		return ret;
500
501	userspace_control = enable;
502
503	return count;
504}
505
506/* Module initialization */
507
508static DEVICE_ATTR_RW(interval_msec);
509static DEVICE_ATTR_RO(version);
510static DEVICE_ATTR_WO(brightness);
511static DEVICE_ATTR_WO(led_rgb);
512static DEVICE_ATTR_RW(sequence);
513static DEVICE_ATTR_WO(program);
514static DEVICE_ATTR_RW(userspace_control);
515
516static struct attribute *__lb_cmds_attrs[] = {
517	&dev_attr_interval_msec.attr,
518	&dev_attr_version.attr,
519	&dev_attr_brightness.attr,
520	&dev_attr_led_rgb.attr,
521	&dev_attr_sequence.attr,
522	&dev_attr_program.attr,
523	&dev_attr_userspace_control.attr,
524	NULL,
525};
526
527static const struct attribute_group cros_ec_lightbar_attr_group = {
528	.name = "lightbar",
529	.attrs = __lb_cmds_attrs,
530};
531
532static int cros_ec_lightbar_probe(struct platform_device *pd)
533{
534	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
535	struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
536	struct device *dev = &pd->dev;
537	int ret;
538
539	/*
540	 * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
541	 * devices like 'cros_pd' doesn't have a lightbar.
542	 */
543	if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
544		return -ENODEV;
545
546	/*
547	 * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
548	 * doesn't have a lightbar.
549	 */
550	if (!get_lightbar_version(ec_dev, NULL, NULL))
551		return -ENODEV;
552
553	/* Take control of the lightbar from the EC. */
554	lb_manual_suspend_ctrl(ec_dev, 1);
555
556	ret = sysfs_create_group(&ec_dev->class_dev.kobj,
557				 &cros_ec_lightbar_attr_group);
558	if (ret < 0)
559		dev_err(dev, "failed to create %s attributes. err=%d\n",
560			cros_ec_lightbar_attr_group.name, ret);
561
562	return ret;
563}
564
565static int cros_ec_lightbar_remove(struct platform_device *pd)
566{
567	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
568
569	sysfs_remove_group(&ec_dev->class_dev.kobj,
570			   &cros_ec_lightbar_attr_group);
571
572	/* Let the EC take over the lightbar again. */
573	lb_manual_suspend_ctrl(ec_dev, 0);
574
575	return 0;
576}
577
578static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
579{
580	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
581
582	if (userspace_control)
583		return 0;
584
585	return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME);
586}
587
588static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
589{
590	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
591
592	if (userspace_control)
593		return 0;
594
595	return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND);
596}
597
598static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
599			 cros_ec_lightbar_suspend, cros_ec_lightbar_resume);
600
601static struct platform_driver cros_ec_lightbar_driver = {
602	.driver = {
603		.name = DRV_NAME,
604		.pm = &cros_ec_lightbar_pm_ops,
605		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
606	},
607	.probe = cros_ec_lightbar_probe,
608	.remove = cros_ec_lightbar_remove,
609};
610
611module_platform_driver(cros_ec_lightbar_driver);
612
613MODULE_LICENSE("GPL");
614MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");
615MODULE_ALIAS("platform:" DRV_NAME);