summaryrefslogtreecommitdiff
path: root/drivers/platform/chrome/cros_ec_lightbar.c
blob: 469dfc7a4a0302bc5e7af4bd3fbd59a54c0f5ecf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
// SPDX-License-Identifier: GPL-2.0+
// Expose the Chromebook Pixel lightbar to userspace
//
// Copyright (C) 2014 Google, Inc.

#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/slab.h>

#define DRV_NAME "cros-ec-lightbar"

/* Rate-limit the lightbar interface to prevent DoS. */
static unsigned long lb_interval_jiffies = 50 * HZ / 1000;

/*
 * Whether or not we have given userspace control of the lightbar.
 * If this is true, we won't do anything during suspend/resume.
 */
static bool userspace_control;

static ssize_t interval_msec_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	unsigned long msec = lb_interval_jiffies * 1000 / HZ;

	return scnprintf(buf, PAGE_SIZE, "%lu\n", msec);
}

static ssize_t interval_msec_store(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf, size_t count)
{
	unsigned long msec;

	if (kstrtoul(buf, 0, &msec))
		return -EINVAL;

	lb_interval_jiffies = msec * HZ / 1000;

	return count;
}

static DEFINE_MUTEX(lb_mutex);
/* Return 0 if able to throttle correctly, error otherwise */
static int lb_throttle(void)
{
	static unsigned long last_access;
	unsigned long now, next_timeslot;
	long delay;
	int ret = 0;

	mutex_lock(&lb_mutex);

	now = jiffies;
	next_timeslot = last_access + lb_interval_jiffies;

	if (time_before(now, next_timeslot)) {
		delay = (long)(next_timeslot) - (long)now;
		set_current_state(TASK_INTERRUPTIBLE);
		if (schedule_timeout(delay) > 0) {
			/* interrupted - just abort */
			ret = -EINTR;
			goto out;
		}
		now = jiffies;
	}

	last_access = now;
out:
	mutex_unlock(&lb_mutex);

	return ret;
}

static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
{
	struct cros_ec_command *msg;
	int len;

	len = max(sizeof(struct ec_params_lightbar),
		  sizeof(struct ec_response_lightbar));

	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
	if (!msg)
		return NULL;

	msg->version = 0;
	msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
	msg->outsize = sizeof(struct ec_params_lightbar);
	msg->insize = sizeof(struct ec_response_lightbar);

	return msg;
}

static int get_lightbar_version(struct cros_ec_dev *ec,
				uint32_t *ver_ptr, uint32_t *flg_ptr)
{
	struct ec_params_lightbar *param;
	struct ec_response_lightbar *resp;
	struct cros_ec_command *msg;
	int ret;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return 0;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_VERSION;
	msg->outsize = sizeof(param->cmd);
	msg->result = sizeof(resp->version);
	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
	if (ret < 0 && ret != -EINVAL) {
		ret = 0;
		goto exit;
	}

	switch (msg->result) {
	case EC_RES_INVALID_PARAM:
		/* Pixel had no version command. */
		if (ver_ptr)
			*ver_ptr = 0;
		if (flg_ptr)
			*flg_ptr = 0;
		ret = 1;
		goto exit;

	case EC_RES_SUCCESS:
		resp = (struct ec_response_lightbar *)msg->data;

		/* Future devices w/lightbars should implement this command */
		if (ver_ptr)
			*ver_ptr = resp->version.num;
		if (flg_ptr)
			*flg_ptr = resp->version.flags;
		ret = 1;
		goto exit;
	}

	/* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
	ret = 0;
exit:
	kfree(msg);
	return ret;
}

static ssize_t version_show(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	uint32_t version = 0, flags = 0;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
	int ret;

	ret = lb_throttle();
	if (ret)
		return ret;

	/* This should always succeed, because we check during init. */
	if (!get_lightbar_version(ec, &version, &flags))
		return -EIO;

	return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
}

static ssize_t brightness_store(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t count)
{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	int ret;
	unsigned int val;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	if (kstrtouint(buf, 0, &val))
		return -EINVAL;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
	param->set_brightness.num = val;
	ret = lb_throttle();
	if (ret)
		goto exit;

	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
	if (ret < 0)
		goto exit;

	ret = count;
exit:
	kfree(msg);
	return ret;
}


/*
 * We expect numbers, and we'll keep reading until we find them, skipping over
 * any whitespace (sysfs guarantees that the input is null-terminated). Every
 * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
 * parsing error, if we don't parse any numbers, or if we have numbers left
 * over.
 */
static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
			     const char *buf, size_t count)
{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
	unsigned int val[4];
	int ret, i = 0, j = 0, ok = 0;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return -ENOMEM;

	do {
		/* Skip any whitespace */
		while (*buf && isspace(*buf))
			buf++;

		if (!*buf)
			break;

		ret = sscanf(buf, "%i", &val[i++]);
		if (ret == 0)
			goto exit;

		if (i == 4) {
			param = (struct ec_params_lightbar *)msg->data;
			param->cmd = LIGHTBAR_CMD_SET_RGB;
			param->set_rgb.led = val[0];
			param->set_rgb.red = val[1];
			param->set_rgb.green = val[2];
			param->set_rgb.blue = val[3];
			/*
			 * Throttle only the first of every four transactions,
			 * so that the user can update all four LEDs at once.
			 */
			if ((j++ % 4) == 0) {
				ret = lb_throttle();
				if (ret)
					goto exit;
			}

			ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
			if (ret < 0)
				goto exit;

			i = 0;
			ok = 1;
		}

		/* Skip over the number we just read */
		while (*buf && !isspace(*buf))
			buf++;

	} while (*buf);

exit:
	kfree(msg);
	return (ok && i == 0) ? count : -EINVAL;
}

static char const *seqname[] = {
	"ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
	"S0S3", "S3S5", "STOP", "RUN", "KONAMI",
	"TAP", "PROGRAM",
};

static ssize_t sequence_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct ec_params_lightbar *param;
	struct ec_response_lightbar *resp;
	struct cros_ec_command *msg;
	int ret;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_GET_SEQ;
	ret = lb_throttle();
	if (ret)
		goto exit;

	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
	if (ret < 0) {
		ret = scnprintf(buf, PAGE_SIZE, "XFER / EC ERROR %d / %d\n",
				ret, msg->result);
		goto exit;
	}

	resp = (struct ec_response_lightbar *)msg->data;
	if (resp->get_seq.num >= ARRAY_SIZE(seqname))
		ret = scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
	else
		ret = scnprintf(buf, PAGE_SIZE, "%s\n",
				seqname[resp->get_seq.num]);

exit:
	kfree(msg);
	return ret;
}

static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	int ret;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = cmd;

	ret = lb_throttle();
	if (ret)
		goto error;

	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
	if (ret < 0)
		goto error;

	ret = 0;
error:
	kfree(msg);

	return ret;
}

static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	int ret;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;

	param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
	param->manual_suspend_ctrl.enable = enable;

	ret = lb_throttle();
	if (ret)
		goto error;

	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
	if (ret < 0)
		goto error;

	ret = 0;
error:
	kfree(msg);

	return ret;
}

static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
			      const char *buf, size_t count)
{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	unsigned int num;
	int ret, len;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	for (len = 0; len < count; len++)
		if (!isalnum(buf[len]))
			break;

	for (num = 0; num < ARRAY_SIZE(seqname); num++)
		if (!strncasecmp(seqname[num], buf, len))
			break;

	if (num >= ARRAY_SIZE(seqname)) {
		ret = kstrtouint(buf, 0, &num);
		if (ret)
			return ret;
	}

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_SEQ;
	param->seq.num = num;
	ret = lb_throttle();
	if (ret)
		goto exit;

	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
	if (ret < 0)
		goto exit;

	ret = count;
exit:
	kfree(msg);
	return ret;
}

static ssize_t program_store(struct device *dev, struct device_attribute *attr,
			     const char *buf, size_t count)
{
	int extra_bytes, max_size, ret;
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	/*
	 * We might need to reject the program for size reasons. The EC
	 * enforces a maximum program size, but we also don't want to try
	 * and send a program that is too big for the protocol. In order
	 * to ensure the latter, we also need to ensure we have extra bytes
	 * to represent the rest of the packet.
	 */
	extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
	max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
	if (count > max_size) {
		dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
			(unsigned int)count, max_size);

		return -EINVAL;
	}

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
		return -ENOMEM;

	ret = lb_throttle();
	if (ret)
		goto exit;

	dev_info(dev, "Copying %zu byte program to EC", count);

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_SET_PROGRAM;

	param->set_program.size = count;
	memcpy(param->set_program.data, buf, count);

	/*
	 * We need to set the message size manually or else it will use
	 * EC_LB_PROG_LEN. This might be too long, and the program
	 * is unlikely to use all of the space.
	 */
	msg->outsize = count + extra_bytes;

	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
	if (ret < 0)
		goto exit;

	ret = count;
exit:
	kfree(msg);

	return ret;
}

static ssize_t userspace_control_show(struct device *dev,
				      struct device_attribute *attr,
				      char *buf)
{
	return scnprintf(buf, PAGE_SIZE, "%d\n", userspace_control);
}

static ssize_t userspace_control_store(struct device *dev,
				       struct device_attribute *attr,
				       const char *buf,
				       size_t count)
{
	bool enable;
	int ret;

	ret = strtobool(buf, &enable);
	if (ret < 0)
		return ret;

	userspace_control = enable;

	return count;
}

/* Module initialization */

static DEVICE_ATTR_RW(interval_msec);
static DEVICE_ATTR_RO(version);
static DEVICE_ATTR_WO(brightness);
static DEVICE_ATTR_WO(led_rgb);
static DEVICE_ATTR_RW(sequence);
static DEVICE_ATTR_WO(program);
static DEVICE_ATTR_RW(userspace_control);

static struct attribute *__lb_cmds_attrs[] = {
	&dev_attr_interval_msec.attr,
	&dev_attr_version.attr,
	&dev_attr_brightness.attr,
	&dev_attr_led_rgb.attr,
	&dev_attr_sequence.attr,
	&dev_attr_program.attr,
	&dev_attr_userspace_control.attr,
	NULL,
};

static const struct attribute_group cros_ec_lightbar_attr_group = {
	.name = "lightbar",
	.attrs = __lb_cmds_attrs,
};

static int cros_ec_lightbar_probe(struct platform_device *pd)
{
	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
	struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
	struct device *dev = &pd->dev;
	int ret;

	/*
	 * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
	 * devices like 'cros_pd' doesn't have a lightbar.
	 */
	if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
		return -ENODEV;

	/*
	 * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
	 * doesn't have a lightbar.
	 */
	if (!get_lightbar_version(ec_dev, NULL, NULL))
		return -ENODEV;

	/* Take control of the lightbar from the EC. */
	lb_manual_suspend_ctrl(ec_dev, 1);

	ret = sysfs_create_group(&ec_dev->class_dev.kobj,
				 &cros_ec_lightbar_attr_group);
	if (ret < 0)
		dev_err(dev, "failed to create %s attributes. err=%d\n",
			cros_ec_lightbar_attr_group.name, ret);

	return ret;
}

static int cros_ec_lightbar_remove(struct platform_device *pd)
{
	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);

	sysfs_remove_group(&ec_dev->class_dev.kobj,
			   &cros_ec_lightbar_attr_group);

	/* Let the EC take over the lightbar again. */
	lb_manual_suspend_ctrl(ec_dev, 0);

	return 0;
}

static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
{
	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);

	if (userspace_control)
		return 0;

	return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME);
}

static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
{
	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);

	if (userspace_control)
		return 0;

	return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND);
}

static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
			 cros_ec_lightbar_suspend, cros_ec_lightbar_resume);

static struct platform_driver cros_ec_lightbar_driver = {
	.driver = {
		.name = DRV_NAME,
		.pm = &cros_ec_lightbar_pm_ops,
	},
	.probe = cros_ec_lightbar_probe,
	.remove = cros_ec_lightbar_remove,
};

module_platform_driver(cros_ec_lightbar_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");
MODULE_ALIAS("platform:" DRV_NAME);