aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/devfreq/exynos-bus.c
blob: 49f68929e024fa9fc95b8f31eda07edd5218bb53 (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
/*
 * Generic Exynos Bus frequency driver with DEVFREQ Framework
 *
 * Copyright (c) 2016 Samsung Electronics Co., Ltd.
 * Author : Chanwoo Choi <cw00.choi@samsung.com>
 *
 * This driver support Exynos Bus frequency feature by using
 * DEVFREQ framework and is based on drivers/devfreq/exynos/exynos4_bus.c.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/clk.h>
#include <linux/devfreq.h>
#include <linux/devfreq-event.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pm_opp.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>

#define DEFAULT_SATURATION_RATIO	40
#define DEFAULT_VOLTAGE_TOLERANCE	2

struct exynos_bus {
	struct device *dev;

	struct devfreq *devfreq;
	struct devfreq_event_dev **edev;
	unsigned int edev_count;
	struct mutex lock;

	unsigned long curr_freq;

	struct regulator *regulator;
	struct clk *clk;
	unsigned int voltage_tolerance;
	unsigned int ratio;
};

/*
 * Control the devfreq-event device to get the current state of bus
 */
#define exynos_bus_ops_edev(ops)				\
static int exynos_bus_##ops(struct exynos_bus *bus)		\
{								\
	int i, ret;						\
								\
	for (i = 0; i < bus->edev_count; i++) {			\
		if (!bus->edev[i])				\
			continue;				\
		ret = devfreq_event_##ops(bus->edev[i]);	\
		if (ret < 0)					\
			return ret;				\
	}							\
								\
	return 0;						\
}
exynos_bus_ops_edev(enable_edev);
exynos_bus_ops_edev(disable_edev);
exynos_bus_ops_edev(set_event);

static int exynos_bus_get_event(struct exynos_bus *bus,
				struct devfreq_event_data *edata)
{
	struct devfreq_event_data event_data;
	unsigned long load_count = 0, total_count = 0;
	int i, ret = 0;

	for (i = 0; i < bus->edev_count; i++) {
		if (!bus->edev[i])
			continue;

		ret = devfreq_event_get_event(bus->edev[i], &event_data);
		if (ret < 0)
			return ret;

		if (i == 0 || event_data.load_count > load_count) {
			load_count = event_data.load_count;
			total_count = event_data.total_count;
		}
	}

	edata->load_count = load_count;
	edata->total_count = total_count;

	return ret;
}

/*
 * Must necessary function for devfreq simple-ondemand governor
 */
static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
{
	struct exynos_bus *bus = dev_get_drvdata(dev);
	struct dev_pm_opp *new_opp;
	unsigned long old_freq, new_freq, new_volt, tol;
	int ret = 0;

	/* Get new opp-bus instance according to new bus clock */
	new_opp = devfreq_recommended_opp(dev, freq, flags);
	if (IS_ERR(new_opp)) {
		dev_err(dev, "failed to get recommended opp instance\n");
		return PTR_ERR(new_opp);
	}

	new_freq = dev_pm_opp_get_freq(new_opp);
	new_volt = dev_pm_opp_get_voltage(new_opp);
	dev_pm_opp_put(new_opp);

	old_freq = bus->curr_freq;

	if (old_freq == new_freq)
		return 0;
	tol = new_volt * bus->voltage_tolerance / 100;

	/* Change voltage and frequency according to new OPP level */
	mutex_lock(&bus->lock);

	if (old_freq < new_freq) {
		ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
		if (ret < 0) {
			dev_err(bus->dev, "failed to set voltage\n");
			goto out;
		}
	}

	ret = clk_set_rate(bus->clk, new_freq);
	if (ret < 0) {
		dev_err(dev, "failed to change clock of bus\n");
		clk_set_rate(bus->clk, old_freq);
		goto out;
	}

	if (old_freq > new_freq) {
		ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
		if (ret < 0) {
			dev_err(bus->dev, "failed to set voltage\n");
			goto out;
		}
	}
	bus->curr_freq = new_freq;

	dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
			old_freq, new_freq, clk_get_rate(bus->clk));
out:
	mutex_unlock(&bus->lock);

	return ret;
}

static int exynos_bus_get_dev_status(struct device *dev,
				     struct devfreq_dev_status *stat)
{
	struct exynos_bus *bus = dev_get_drvdata(dev);
	struct devfreq_event_data edata;
	int ret;

	stat->current_frequency = bus->curr_freq;

	ret = exynos_bus_get_event(bus, &edata);
	if (ret < 0) {
		stat->total_time = stat->busy_time = 0;
		goto err;
	}

	stat->busy_time = (edata.load_count * 100) / bus->ratio;
	stat->total_time = edata.total_count;

	dev_dbg(dev, "Usage of devfreq-event : %lu/%lu\n", stat->busy_time,
							stat->total_time);

err:
	ret = exynos_bus_set_event(bus);
	if (ret < 0) {
		dev_err(dev, "failed to set event to devfreq-event devices\n");
		return ret;
	}

	return ret;
}

static void exynos_bus_exit(struct device *dev)
{
	struct exynos_bus *bus = dev_get_drvdata(dev);
	int ret;

	ret = exynos_bus_disable_edev(bus);
	if (ret < 0)
		dev_warn(dev, "failed to disable the devfreq-event devices\n");

	if (bus->regulator)
		regulator_disable(bus->regulator);

	dev_pm_opp_of_remove_table(dev);
	clk_disable_unprepare(bus->clk);
}

/*
 * Must necessary function for devfreq passive governor
 */
static int exynos_bus_passive_target(struct device *dev, unsigned long *freq,
					u32 flags)
{
	struct exynos_bus *bus = dev_get_drvdata(dev);
	struct dev_pm_opp *new_opp;
	unsigned long old_freq, new_freq;
	int ret = 0;

	/* Get new opp-bus instance according to new bus clock */
	new_opp = devfreq_recommended_opp(dev, freq, flags);
	if (IS_ERR(new_opp)) {
		dev_err(dev, "failed to get recommended opp instance\n");
		return PTR_ERR(new_opp);
	}

	new_freq = dev_pm_opp_get_freq(new_opp);
	dev_pm_opp_put(new_opp);

	old_freq = bus->curr_freq;

	if (old_freq == new_freq)
		return 0;

	/* Change the frequency according to new OPP level */
	mutex_lock(&bus->lock);

	ret = clk_set_rate(bus->clk, new_freq);
	if (ret < 0) {
		dev_err(dev, "failed to set the clock of bus\n");
		goto out;
	}

	*freq = new_freq;
	bus->curr_freq = new_freq;

	dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
			old_freq, new_freq, clk_get_rate(bus->clk));
out:
	mutex_unlock(&bus->lock);

	return ret;
}

static void exynos_bus_passive_exit(struct device *dev)
{
	struct exynos_bus *bus = dev_get_drvdata(dev);

	dev_pm_opp_of_remove_table(dev);
	clk_disable_unprepare(bus->clk);
}

static int exynos_bus_parent_parse_of(struct device_node *np,
					struct exynos_bus *bus)
{
	struct device *dev = bus->dev;
	int i, ret, count, size;

	/* Get the regulator to provide each bus with the power */
	bus->regulator = devm_regulator_get(dev, "vdd");
	if (IS_ERR(bus->regulator)) {
		dev_err(dev, "failed to get VDD regulator\n");
		return PTR_ERR(bus->regulator);
	}

	ret = regulator_enable(bus->regulator);
	if (ret < 0) {
		dev_err(dev, "failed to enable VDD regulator\n");
		return ret;
	}

	/*
	 * Get the devfreq-event devices to get the current utilization of
	 * buses. This raw data will be used in devfreq ondemand governor.
	 */
	count = devfreq_event_get_edev_count(dev);
	if (count < 0) {
		dev_err(dev, "failed to get the count of devfreq-event dev\n");
		ret = count;
		goto err_regulator;
	}
	bus->edev_count = count;

	size = sizeof(*bus->edev) * count;
	bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
	if (!bus->edev) {
		ret = -ENOMEM;
		goto err_regulator;
	}

	for (i = 0; i < count; i++) {
		bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
		if (IS_ERR(bus->edev[i])) {
			ret = -EPROBE_DEFER;
			goto err_regulator;
		}
	}

	/*
	 * Optionally, Get the saturation ratio according to Exynos SoC
	 * When measuring the utilization of each AXI bus with devfreq-event
	 * devices, the measured real cycle might be much lower than the
	 * total cycle of bus during sampling rate. In result, the devfreq
	 * simple-ondemand governor might not decide to change the current
	 * frequency due to too utilization (= real cycle/total cycle).
	 * So, this property is used to adjust the utilization when calculating
	 * the busy_time in exynos_bus_get_dev_status().
	 */
	if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
		bus->ratio = DEFAULT_SATURATION_RATIO;

	if (of_property_read_u32(np, "exynos,voltage-tolerance",
					&bus->voltage_tolerance))
		bus->voltage_tolerance = DEFAULT_VOLTAGE_TOLERANCE;

	return 0;

err_regulator:
	regulator_disable(bus->regulator);

	return ret;
}

static int exynos_bus_parse_of(struct device_node *np,
			      struct exynos_bus *bus)
{
	struct device *dev = bus->dev;
	struct dev_pm_opp *opp;
	unsigned long rate;
	int ret;

	/* Get the clock to provide each bus with source clock */
	bus->clk = devm_clk_get(dev, "bus");
	if (IS_ERR(bus->clk)) {
		dev_err(dev, "failed to get bus clock\n");
		return PTR_ERR(bus->clk);
	}

	ret = clk_prepare_enable(bus->clk);
	if (ret < 0) {
		dev_err(dev, "failed to get enable clock\n");
		return ret;
	}

	/* Get the freq and voltage from OPP table to scale the bus freq */
	ret = dev_pm_opp_of_add_table(dev);
	if (ret < 0) {
		dev_err(dev, "failed to get OPP table\n");
		goto err_clk;
	}

	rate = clk_get_rate(bus->clk);

	opp = devfreq_recommended_opp(dev, &rate, 0);
	if (IS_ERR(opp)) {
		dev_err(dev, "failed to find dev_pm_opp\n");
		ret = PTR_ERR(opp);
		goto err_opp;
	}
	bus->curr_freq = dev_pm_opp_get_freq(opp);
	dev_pm_opp_put(opp);

	return 0;

err_opp:
	dev_pm_opp_of_remove_table(dev);
err_clk:
	clk_disable_unprepare(bus->clk);

	return ret;
}

static int exynos_bus_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node, *node;
	struct devfreq_dev_profile *profile;
	struct devfreq_simple_ondemand_data *ondemand_data;
	struct devfreq_passive_data *passive_data;
	struct devfreq *parent_devfreq;
	struct exynos_bus *bus;
	int ret, max_state;
	unsigned long min_freq, max_freq;

	if (!np) {
		dev_err(dev, "failed to find devicetree node\n");
		return -EINVAL;
	}

	bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
	if (!bus)
		return -ENOMEM;
	mutex_init(&bus->lock);
	bus->dev = &pdev->dev;
	platform_set_drvdata(pdev, bus);

	/* Parse the device-tree to get the resource information */
	ret = exynos_bus_parse_of(np, bus);
	if (ret < 0)
		return ret;

	profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
	if (!profile) {
		ret = -ENOMEM;
		goto err;
	}

	node = of_parse_phandle(dev->of_node, "devfreq", 0);
	if (node) {
		of_node_put(node);
		goto passive;
	} else {
		ret = exynos_bus_parent_parse_of(np, bus);
	}

	if (ret < 0)
		goto err;

	/* Initialize the struct profile and governor data for parent device */
	profile->polling_ms = 50;
	profile->target = exynos_bus_target;
	profile->get_dev_status = exynos_bus_get_dev_status;
	profile->exit = exynos_bus_exit;

	ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
	if (!ondemand_data) {
		ret = -ENOMEM;
		goto err;
	}
	ondemand_data->upthreshold = 40;
	ondemand_data->downdifferential = 5;

	/* Add devfreq device to monitor and handle the exynos bus */
	bus->devfreq = devm_devfreq_add_device(dev, profile, "simple_ondemand",
						ondemand_data);
	if (IS_ERR(bus->devfreq)) {
		dev_err(dev, "failed to add devfreq device\n");
		ret = PTR_ERR(bus->devfreq);
		goto err;
	}

	/* Register opp_notifier to catch the change of OPP  */
	ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
	if (ret < 0) {
		dev_err(dev, "failed to register opp notifier\n");
		goto err;
	}

	/*
	 * Enable devfreq-event to get raw data which is used to determine
	 * current bus load.
	 */
	ret = exynos_bus_enable_edev(bus);
	if (ret < 0) {
		dev_err(dev, "failed to enable devfreq-event devices\n");
		goto err;
	}

	ret = exynos_bus_set_event(bus);
	if (ret < 0) {
		dev_err(dev, "failed to set event to devfreq-event devices\n");
		goto err;
	}

	goto out;
passive:
	/* Initialize the struct profile and governor data for passive device */
	profile->target = exynos_bus_passive_target;
	profile->exit = exynos_bus_passive_exit;

	/* Get the instance of parent devfreq device */
	parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
	if (IS_ERR(parent_devfreq)) {
		ret = -EPROBE_DEFER;
		goto err;
	}

	passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
	if (!passive_data) {
		ret = -ENOMEM;
		goto err;
	}
	passive_data->parent = parent_devfreq;

	/* Add devfreq device for exynos bus with passive governor */
	bus->devfreq = devm_devfreq_add_device(dev, profile, "passive",
						passive_data);
	if (IS_ERR(bus->devfreq)) {
		dev_err(dev,
			"failed to add devfreq dev with passive governor\n");
		ret = PTR_ERR(bus->devfreq);
		goto err;
	}

out:
	max_state = bus->devfreq->profile->max_state;
	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
			dev_name(dev), min_freq, max_freq);

	return 0;

err:
	dev_pm_opp_of_remove_table(dev);
	clk_disable_unprepare(bus->clk);

	return ret;
}

#ifdef CONFIG_PM_SLEEP
static int exynos_bus_resume(struct device *dev)
{
	struct exynos_bus *bus = dev_get_drvdata(dev);
	int ret;

	ret = exynos_bus_enable_edev(bus);
	if (ret < 0) {
		dev_err(dev, "failed to enable the devfreq-event devices\n");
		return ret;
	}

	return 0;
}

static int exynos_bus_suspend(struct device *dev)
{
	struct exynos_bus *bus = dev_get_drvdata(dev);
	int ret;

	ret = exynos_bus_disable_edev(bus);
	if (ret < 0) {
		dev_err(dev, "failed to disable the devfreq-event devices\n");
		return ret;
	}

	return 0;
}
#endif

static const struct dev_pm_ops exynos_bus_pm = {
	SET_SYSTEM_SLEEP_PM_OPS(exynos_bus_suspend, exynos_bus_resume)
};

static const struct of_device_id exynos_bus_of_match[] = {
	{ .compatible = "samsung,exynos-bus", },
	{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, exynos_bus_of_match);

static struct platform_driver exynos_bus_platdrv = {
	.probe		= exynos_bus_probe,
	.driver = {
		.name	= "exynos-bus",
		.pm	= &exynos_bus_pm,
		.of_match_table = of_match_ptr(exynos_bus_of_match),
	},
};
module_platform_driver(exynos_bus_platdrv);

MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
MODULE_LICENSE("GPL v2");

Privacy Policy