1/*
2 * Generic Exynos Bus frequency driver with DEVFREQ Framework
3 *
4 * Copyright (c) 2016 Samsung Electronics Co., Ltd.
5 * Author : Chanwoo Choi <cw00.choi@samsung.com>
6 *
7 * This driver support Exynos Bus frequency feature by using
8 * DEVFREQ framework and is based on drivers/devfreq/exynos/exynos4_bus.c.
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/clk.h>
16#include <linux/devfreq.h>
17#include <linux/devfreq-event.h>
18#include <linux/device.h>
19#include <linux/export.h>
20#include <linux/module.h>
21#include <linux/of_device.h>
22#include <linux/pm_opp.h>
23#include <linux/platform_device.h>
24#include <linux/regulator/consumer.h>
25#include <linux/slab.h>
26
27#define DEFAULT_SATURATION_RATIO 40
28#define DEFAULT_VOLTAGE_TOLERANCE 2
29
30struct exynos_bus {
31 struct device *dev;
32
33 struct devfreq *devfreq;
34 struct devfreq_event_dev **edev;
35 unsigned int edev_count;
36 struct mutex lock;
37
38 unsigned long curr_freq;
39
40 struct regulator *regulator;
41 struct clk *clk;
42 unsigned int voltage_tolerance;
43 unsigned int ratio;
44};
45
46/*
47 * Control the devfreq-event device to get the current state of bus
48 */
49#define exynos_bus_ops_edev(ops) \
50static int exynos_bus_##ops(struct exynos_bus *bus) \
51{ \
52 int i, ret; \
53 \
54 for (i = 0; i < bus->edev_count; i++) { \
55 if (!bus->edev[i]) \
56 continue; \
57 ret = devfreq_event_##ops(bus->edev[i]); \
58 if (ret < 0) \
59 return ret; \
60 } \
61 \
62 return 0; \
63}
64exynos_bus_ops_edev(enable_edev);
65exynos_bus_ops_edev(disable_edev);
66exynos_bus_ops_edev(set_event);
67
68static int exynos_bus_get_event(struct exynos_bus *bus,
69 struct devfreq_event_data *edata)
70{
71 struct devfreq_event_data event_data;
72 unsigned long load_count = 0, total_count = 0;
73 int i, ret = 0;
74
75 for (i = 0; i < bus->edev_count; i++) {
76 if (!bus->edev[i])
77 continue;
78
79 ret = devfreq_event_get_event(bus->edev[i], &event_data);
80 if (ret < 0)
81 return ret;
82
83 if (i == 0 || event_data.load_count > load_count) {
84 load_count = event_data.load_count;
85 total_count = event_data.total_count;
86 }
87 }
88
89 edata->load_count = load_count;
90 edata->total_count = total_count;
91
92 return ret;
93}
94
95/*
96 * Must necessary function for devfreq simple-ondemand governor
97 */
98static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
99{
100 struct exynos_bus *bus = dev_get_drvdata(dev);
101 struct dev_pm_opp *new_opp;
102 unsigned long old_freq, new_freq, new_volt, tol;
103 int ret = 0;
104
105 /* Get new opp-bus instance according to new bus clock */
106 new_opp = devfreq_recommended_opp(dev, freq, flags);
107 if (IS_ERR(new_opp)) {
108 dev_err(dev, "failed to get recommended opp instance\n");
109 return PTR_ERR(new_opp);
110 }
111
112 new_freq = dev_pm_opp_get_freq(new_opp);
113 new_volt = dev_pm_opp_get_voltage(new_opp);
114 dev_pm_opp_put(new_opp);
115
116 old_freq = bus->curr_freq;
117
118 if (old_freq == new_freq)
119 return 0;
120 tol = new_volt * bus->voltage_tolerance / 100;
121
122 /* Change voltage and frequency according to new OPP level */
123 mutex_lock(&bus->lock);
124
125 if (old_freq < new_freq) {
126 ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
127 if (ret < 0) {
128 dev_err(bus->dev, "failed to set voltage\n");
129 goto out;
130 }
131 }
132
133 ret = clk_set_rate(bus->clk, new_freq);
134 if (ret < 0) {
135 dev_err(dev, "failed to change clock of bus\n");
136 clk_set_rate(bus->clk, old_freq);
137 goto out;
138 }
139
140 if (old_freq > new_freq) {
141 ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
142 if (ret < 0) {
143 dev_err(bus->dev, "failed to set voltage\n");
144 goto out;
145 }
146 }
147 bus->curr_freq = new_freq;
148
149 dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
150 old_freq, new_freq, clk_get_rate(bus->clk));
151out:
152 mutex_unlock(&bus->lock);
153
154 return ret;
155}
156
157static int exynos_bus_get_dev_status(struct device *dev,
158 struct devfreq_dev_status *stat)
159{
160 struct exynos_bus *bus = dev_get_drvdata(dev);
161 struct devfreq_event_data edata;
162 int ret;
163
164 stat->current_frequency = bus->curr_freq;
165
166 ret = exynos_bus_get_event(bus, &edata);
167 if (ret < 0) {
168 stat->total_time = stat->busy_time = 0;
169 goto err;
170 }
171
172 stat->busy_time = (edata.load_count * 100) / bus->ratio;
173 stat->total_time = edata.total_count;
174
175 dev_dbg(dev, "Usage of devfreq-event : %lu/%lu\n", stat->busy_time,
176 stat->total_time);
177
178err:
179 ret = exynos_bus_set_event(bus);
180 if (ret < 0) {
181 dev_err(dev, "failed to set event to devfreq-event devices\n");
182 return ret;
183 }
184
185 return ret;
186}
187
188static void exynos_bus_exit(struct device *dev)
189{
190 struct exynos_bus *bus = dev_get_drvdata(dev);
191 int ret;
192
193 ret = exynos_bus_disable_edev(bus);
194 if (ret < 0)
195 dev_warn(dev, "failed to disable the devfreq-event devices\n");
196
197 if (bus->regulator)
198 regulator_disable(bus->regulator);
199
200 dev_pm_opp_of_remove_table(dev);
201 clk_disable_unprepare(bus->clk);
202}
203
204/*
205 * Must necessary function for devfreq passive governor
206 */
207static int exynos_bus_passive_target(struct device *dev, unsigned long *freq,
208 u32 flags)
209{
210 struct exynos_bus *bus = dev_get_drvdata(dev);
211 struct dev_pm_opp *new_opp;
212 unsigned long old_freq, new_freq;
213 int ret = 0;
214
215 /* Get new opp-bus instance according to new bus clock */
216 new_opp = devfreq_recommended_opp(dev, freq, flags);
217 if (IS_ERR(new_opp)) {
218 dev_err(dev, "failed to get recommended opp instance\n");
219 return PTR_ERR(new_opp);
220 }
221
222 new_freq = dev_pm_opp_get_freq(new_opp);
223 dev_pm_opp_put(new_opp);
224
225 old_freq = bus->curr_freq;
226
227 if (old_freq == new_freq)
228 return 0;
229
230 /* Change the frequency according to new OPP level */
231 mutex_lock(&bus->lock);
232
233 ret = clk_set_rate(bus->clk, new_freq);
234 if (ret < 0) {
235 dev_err(dev, "failed to set the clock of bus\n");
236 goto out;
237 }
238
239 *freq = new_freq;
240 bus->curr_freq = new_freq;
241
242 dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
243 old_freq, new_freq, clk_get_rate(bus->clk));
244out:
245 mutex_unlock(&bus->lock);
246
247 return ret;
248}
249
250static void exynos_bus_passive_exit(struct device *dev)
251{
252 struct exynos_bus *bus = dev_get_drvdata(dev);
253
254 dev_pm_opp_of_remove_table(dev);
255 clk_disable_unprepare(bus->clk);
256}
257
258static int exynos_bus_parent_parse_of(struct device_node *np,
259 struct exynos_bus *bus)
260{
261 struct device *dev = bus->dev;
262 int i, ret, count, size;
263
264 /* Get the regulator to provide each bus with the power */
265 bus->regulator = devm_regulator_get(dev, "vdd");
266 if (IS_ERR(bus->regulator)) {
267 dev_err(dev, "failed to get VDD regulator\n");
268 return PTR_ERR(bus->regulator);
269 }
270
271 ret = regulator_enable(bus->regulator);
272 if (ret < 0) {
273 dev_err(dev, "failed to enable VDD regulator\n");
274 return ret;
275 }
276
277 /*
278 * Get the devfreq-event devices to get the current utilization of
279 * buses. This raw data will be used in devfreq ondemand governor.
280 */
281 count = devfreq_event_get_edev_count(dev);
282 if (count < 0) {
283 dev_err(dev, "failed to get the count of devfreq-event dev\n");
284 ret = count;
285 goto err_regulator;
286 }
287 bus->edev_count = count;
288
289 size = sizeof(*bus->edev) * count;
290 bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
291 if (!bus->edev) {
292 ret = -ENOMEM;
293 goto err_regulator;
294 }
295
296 for (i = 0; i < count; i++) {
297 bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
298 if (IS_ERR(bus->edev[i])) {
299 ret = -EPROBE_DEFER;
300 goto err_regulator;
301 }
302 }
303
304 /*
305 * Optionally, Get the saturation ratio according to Exynos SoC
306 * When measuring the utilization of each AXI bus with devfreq-event
307 * devices, the measured real cycle might be much lower than the
308 * total cycle of bus during sampling rate. In result, the devfreq
309 * simple-ondemand governor might not decide to change the current
310 * frequency due to too utilization (= real cycle/total cycle).
311 * So, this property is used to adjust the utilization when calculating
312 * the busy_time in exynos_bus_get_dev_status().
313 */
314 if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
315 bus->ratio = DEFAULT_SATURATION_RATIO;
316
317 if (of_property_read_u32(np, "exynos,voltage-tolerance",
318 &bus->voltage_tolerance))
319 bus->voltage_tolerance = DEFAULT_VOLTAGE_TOLERANCE;
320
321 return 0;
322
323err_regulator:
324 regulator_disable(bus->regulator);
325
326 return ret;
327}
328
329static int exynos_bus_parse_of(struct device_node *np,
330 struct exynos_bus *bus)
331{
332 struct device *dev = bus->dev;
333 struct dev_pm_opp *opp;
334 unsigned long rate;
335 int ret;
336
337 /* Get the clock to provide each bus with source clock */
338 bus->clk = devm_clk_get(dev, "bus");
339 if (IS_ERR(bus->clk)) {
340 dev_err(dev, "failed to get bus clock\n");
341 return PTR_ERR(bus->clk);
342 }
343
344 ret = clk_prepare_enable(bus->clk);
345 if (ret < 0) {
346 dev_err(dev, "failed to get enable clock\n");
347 return ret;
348 }
349
350 /* Get the freq and voltage from OPP table to scale the bus freq */
351 ret = dev_pm_opp_of_add_table(dev);
352 if (ret < 0) {
353 dev_err(dev, "failed to get OPP table\n");
354 goto err_clk;
355 }
356
357 rate = clk_get_rate(bus->clk);
358
359 opp = devfreq_recommended_opp(dev, &rate, 0);
360 if (IS_ERR(opp)) {
361 dev_err(dev, "failed to find dev_pm_opp\n");
362 ret = PTR_ERR(opp);
363 goto err_opp;
364 }
365 bus->curr_freq = dev_pm_opp_get_freq(opp);
366 dev_pm_opp_put(opp);
367
368 return 0;
369
370err_opp:
371 dev_pm_opp_of_remove_table(dev);
372err_clk:
373 clk_disable_unprepare(bus->clk);
374
375 return ret;
376}
377
378static int exynos_bus_probe(struct platform_device *pdev)
379{
380 struct device *dev = &pdev->dev;
381 struct device_node *np = dev->of_node, *node;
382 struct devfreq_dev_profile *profile;
383 struct devfreq_simple_ondemand_data *ondemand_data;
384 struct devfreq_passive_data *passive_data;
385 struct devfreq *parent_devfreq;
386 struct exynos_bus *bus;
387 int ret, max_state;
388 unsigned long min_freq, max_freq;
389
390 if (!np) {
391 dev_err(dev, "failed to find devicetree node\n");
392 return -EINVAL;
393 }
394
395 bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
396 if (!bus)
397 return -ENOMEM;
398 mutex_init(&bus->lock);
399 bus->dev = &pdev->dev;
400 platform_set_drvdata(pdev, bus);
401
402 /* Parse the device-tree to get the resource information */
403 ret = exynos_bus_parse_of(np, bus);
404 if (ret < 0)
405 return ret;
406
407 profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
408 if (!profile) {
409 ret = -ENOMEM;
410 goto err;
411 }
412
413 node = of_parse_phandle(dev->of_node, "devfreq", 0);
414 if (node) {
415 of_node_put(node);
416 goto passive;
417 } else {
418 ret = exynos_bus_parent_parse_of(np, bus);
419 }
420
421 if (ret < 0)
422 goto err;
423
424 /* Initialize the struct profile and governor data for parent device */
425 profile->polling_ms = 50;
426 profile->target = exynos_bus_target;
427 profile->get_dev_status = exynos_bus_get_dev_status;
428 profile->exit = exynos_bus_exit;
429
430 ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
431 if (!ondemand_data) {
432 ret = -ENOMEM;
433 goto err;
434 }
435 ondemand_data->upthreshold = 40;
436 ondemand_data->downdifferential = 5;
437
438 /* Add devfreq device to monitor and handle the exynos bus */
439 bus->devfreq = devm_devfreq_add_device(dev, profile,
440 DEVFREQ_GOV_SIMPLE_ONDEMAND,
441 ondemand_data);
442 if (IS_ERR(bus->devfreq)) {
443 dev_err(dev, "failed to add devfreq device\n");
444 ret = PTR_ERR(bus->devfreq);
445 goto err;
446 }
447
448 /* Register opp_notifier to catch the change of OPP */
449 ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
450 if (ret < 0) {
451 dev_err(dev, "failed to register opp notifier\n");
452 goto err;
453 }
454
455 /*
456 * Enable devfreq-event to get raw data which is used to determine
457 * current bus load.
458 */
459 ret = exynos_bus_enable_edev(bus);
460 if (ret < 0) {
461 dev_err(dev, "failed to enable devfreq-event devices\n");
462 goto err;
463 }
464
465 ret = exynos_bus_set_event(bus);
466 if (ret < 0) {
467 dev_err(dev, "failed to set event to devfreq-event devices\n");
468 goto err;
469 }
470
471 goto out;
472passive:
473 /* Initialize the struct profile and governor data for passive device */
474 profile->target = exynos_bus_passive_target;
475 profile->exit = exynos_bus_passive_exit;
476
477 /* Get the instance of parent devfreq device */
478 parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
479 if (IS_ERR(parent_devfreq)) {
480 ret = -EPROBE_DEFER;
481 goto err;
482 }
483
484 passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
485 if (!passive_data) {
486 ret = -ENOMEM;
487 goto err;
488 }
489 passive_data->parent = parent_devfreq;
490
491 /* Add devfreq device for exynos bus with passive governor */
492 bus->devfreq = devm_devfreq_add_device(dev, profile, DEVFREQ_GOV_PASSIVE,
493 passive_data);
494 if (IS_ERR(bus->devfreq)) {
495 dev_err(dev,
496 "failed to add devfreq dev with passive governor\n");
497 ret = PTR_ERR(bus->devfreq);
498 goto err;
499 }
500
501out:
502 max_state = bus->devfreq->profile->max_state;
503 min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
504 max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
505 pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
506 dev_name(dev), min_freq, max_freq);
507
508 return 0;
509
510err:
511 dev_pm_opp_of_remove_table(dev);
512 clk_disable_unprepare(bus->clk);
513
514 return ret;
515}
516
517#ifdef CONFIG_PM_SLEEP
518static int exynos_bus_resume(struct device *dev)
519{
520 struct exynos_bus *bus = dev_get_drvdata(dev);
521 int ret;
522
523 ret = exynos_bus_enable_edev(bus);
524 if (ret < 0) {
525 dev_err(dev, "failed to enable the devfreq-event devices\n");
526 return ret;
527 }
528
529 return 0;
530}
531
532static int exynos_bus_suspend(struct device *dev)
533{
534 struct exynos_bus *bus = dev_get_drvdata(dev);
535 int ret;
536
537 ret = exynos_bus_disable_edev(bus);
538 if (ret < 0) {
539 dev_err(dev, "failed to disable the devfreq-event devices\n");
540 return ret;
541 }
542
543 return 0;
544}
545#endif
546
547static const struct dev_pm_ops exynos_bus_pm = {
548 SET_SYSTEM_SLEEP_PM_OPS(exynos_bus_suspend, exynos_bus_resume)
549};
550
551static const struct of_device_id exynos_bus_of_match[] = {
552 { .compatible = "samsung,exynos-bus", },
553 { /* sentinel */ },
554};
555MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
556
557static struct platform_driver exynos_bus_platdrv = {
558 .probe = exynos_bus_probe,
559 .driver = {
560 .name = "exynos-bus",
561 .pm = &exynos_bus_pm,
562 .of_match_table = of_match_ptr(exynos_bus_of_match),
563 },
564};
565module_platform_driver(exynos_bus_platdrv);
566
567MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
568MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
569MODULE_LICENSE("GPL v2");
570