xref: /linux/drivers/devfreq/exynos-bus.c (revision 0be3ff0c) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Generic Exynos Bus frequency driver with DEVFREQ Framework
4  *
5  * Copyright (c) 2016 Samsung Electronics Co., Ltd.
6  * Author : Chanwoo Choi <cw00.choi@samsung.com>
7  *
8  * This driver support Exynos Bus frequency feature by using
9  * DEVFREQ framework and is based on drivers/devfreq/exynos/exynos4_bus.c.
10  */
11 
12 #include <linux/clk.h>
13 #include <linux/devfreq.h>
14 #include <linux/devfreq-event.h>
15 #include <linux/device.h>
16 #include <linux/export.h>
17 #include <linux/module.h>
18 #include <linux/of.h>
19 #include <linux/pm_opp.h>
20 #include <linux/platform_device.h>
21 #include <linux/regulator/consumer.h>
22 
23 #define DEFAULT_SATURATION_RATIO	40
24 
25 struct exynos_bus {
26 	struct device *dev;
27 	struct platform_device *icc_pdev;
28 
29 	struct devfreq *devfreq;
30 	struct devfreq_event_dev **edev;
31 	unsigned int edev_count;
32 	struct mutex lock;
33 
34 	unsigned long curr_freq;
35 
36 	struct opp_table *opp_table;
37 	struct clk *clk;
38 	unsigned int ratio;
39 };
40 
41 /*
42  * Control the devfreq-event device to get the current state of bus
43  */
44 #define exynos_bus_ops_edev(ops)				\
45 static int exynos_bus_##ops(struct exynos_bus *bus)		\
46 {								\
47 	int i, ret;						\
48 								\
49 	for (i = 0; i < bus->edev_count; i++) {			\
50 		if (!bus->edev[i])				\
51 			continue;				\
52 		ret = devfreq_event_##ops(bus->edev[i]);	\
53 		if (ret < 0)					\
54 			return ret;				\
55 	}							\
56 								\
57 	return 0;						\
58 }
59 exynos_bus_ops_edev(enable_edev);
60 exynos_bus_ops_edev(disable_edev);
61 exynos_bus_ops_edev(set_event);
62 
63 static int exynos_bus_get_event(struct exynos_bus *bus,
64 				struct devfreq_event_data *edata)
65 {
66 	struct devfreq_event_data event_data;
67 	unsigned long load_count = 0, total_count = 0;
68 	int i, ret = 0;
69 
70 	for (i = 0; i < bus->edev_count; i++) {
71 		if (!bus->edev[i])
72 			continue;
73 
74 		ret = devfreq_event_get_event(bus->edev[i], &event_data);
75 		if (ret < 0)
76 			return ret;
77 
78 		if (i == 0 || event_data.load_count > load_count) {
79 			load_count = event_data.load_count;
80 			total_count = event_data.total_count;
81 		}
82 	}
83 
84 	edata->load_count = load_count;
85 	edata->total_count = total_count;
86 
87 	return ret;
88 }
89 
90 /*
91  * devfreq function for both simple-ondemand and passive governor
92  */
93 static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
94 {
95 	struct exynos_bus *bus = dev_get_drvdata(dev);
96 	struct dev_pm_opp *new_opp;
97 	int ret = 0;
98 
99 	/* Get correct frequency for bus. */
100 	new_opp = devfreq_recommended_opp(dev, freq, flags);
101 	if (IS_ERR(new_opp)) {
102 		dev_err(dev, "failed to get recommended opp instance\n");
103 		return PTR_ERR(new_opp);
104 	}
105 
106 	dev_pm_opp_put(new_opp);
107 
108 	/* Change voltage and frequency according to new OPP level */
109 	mutex_lock(&bus->lock);
110 	ret = dev_pm_opp_set_rate(dev, *freq);
111 	if (!ret)
112 		bus->curr_freq = *freq;
113 
114 	mutex_unlock(&bus->lock);
115 
116 	return ret;
117 }
118 
119 static int exynos_bus_get_dev_status(struct device *dev,
120 				     struct devfreq_dev_status *stat)
121 {
122 	struct exynos_bus *bus = dev_get_drvdata(dev);
123 	struct devfreq_event_data edata;
124 	int ret;
125 
126 	stat->current_frequency = bus->curr_freq;
127 
128 	ret = exynos_bus_get_event(bus, &edata);
129 	if (ret < 0) {
130 		dev_err(dev, "failed to get event from devfreq-event devices\n");
131 		stat->total_time = stat->busy_time = 0;
132 		goto err;
133 	}
134 
135 	stat->busy_time = (edata.load_count * 100) / bus->ratio;
136 	stat->total_time = edata.total_count;
137 
138 	dev_dbg(dev, "Usage of devfreq-event : %lu/%lu\n", stat->busy_time,
139 							stat->total_time);
140 
141 err:
142 	ret = exynos_bus_set_event(bus);
143 	if (ret < 0) {
144 		dev_err(dev, "failed to set event to devfreq-event devices\n");
145 		return ret;
146 	}
147 
148 	return ret;
149 }
150 
151 static void exynos_bus_exit(struct device *dev)
152 {
153 	struct exynos_bus *bus = dev_get_drvdata(dev);
154 	int ret;
155 
156 	ret = exynos_bus_disable_edev(bus);
157 	if (ret < 0)
158 		dev_warn(dev, "failed to disable the devfreq-event devices\n");
159 
160 	platform_device_unregister(bus->icc_pdev);
161 
162 	dev_pm_opp_of_remove_table(dev);
163 	clk_disable_unprepare(bus->clk);
164 	dev_pm_opp_put_regulators(bus->opp_table);
165 	bus->opp_table = NULL;
166 }
167 
168 static void exynos_bus_passive_exit(struct device *dev)
169 {
170 	struct exynos_bus *bus = dev_get_drvdata(dev);
171 
172 	platform_device_unregister(bus->icc_pdev);
173 
174 	dev_pm_opp_of_remove_table(dev);
175 	clk_disable_unprepare(bus->clk);
176 }
177 
178 static int exynos_bus_parent_parse_of(struct device_node *np,
179 					struct exynos_bus *bus)
180 {
181 	struct device *dev = bus->dev;
182 	struct opp_table *opp_table;
183 	const char *vdd = "vdd";
184 	int i, ret, count, size;
185 
186 	opp_table = dev_pm_opp_set_regulators(dev, &vdd, 1);
187 	if (IS_ERR(opp_table)) {
188 		ret = PTR_ERR(opp_table);
189 		dev_err(dev, "failed to set regulators %d\n", ret);
190 		return ret;
191 	}
192 
193 	bus->opp_table = opp_table;
194 
195 	/*
196 	 * Get the devfreq-event devices to get the current utilization of
197 	 * buses. This raw data will be used in devfreq ondemand governor.
198 	 */
199 	count = devfreq_event_get_edev_count(dev, "devfreq-events");
200 	if (count < 0) {
201 		dev_err(dev, "failed to get the count of devfreq-event dev\n");
202 		ret = count;
203 		goto err_regulator;
204 	}
205 	bus->edev_count = count;
206 
207 	size = sizeof(*bus->edev) * count;
208 	bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
209 	if (!bus->edev) {
210 		ret = -ENOMEM;
211 		goto err_regulator;
212 	}
213 
214 	for (i = 0; i < count; i++) {
215 		bus->edev[i] = devfreq_event_get_edev_by_phandle(dev,
216 							"devfreq-events", i);
217 		if (IS_ERR(bus->edev[i])) {
218 			ret = -EPROBE_DEFER;
219 			goto err_regulator;
220 		}
221 	}
222 
223 	/*
224 	 * Optionally, Get the saturation ratio according to Exynos SoC
225 	 * When measuring the utilization of each AXI bus with devfreq-event
226 	 * devices, the measured real cycle might be much lower than the
227 	 * total cycle of bus during sampling rate. In result, the devfreq
228 	 * simple-ondemand governor might not decide to change the current
229 	 * frequency due to too utilization (= real cycle/total cycle).
230 	 * So, this property is used to adjust the utilization when calculating
231 	 * the busy_time in exynos_bus_get_dev_status().
232 	 */
233 	if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
234 		bus->ratio = DEFAULT_SATURATION_RATIO;
235 
236 	return 0;
237 
238 err_regulator:
239 	dev_pm_opp_put_regulators(bus->opp_table);
240 	bus->opp_table = NULL;
241 
242 	return ret;
243 }
244 
245 static int exynos_bus_parse_of(struct device_node *np,
246 			      struct exynos_bus *bus)
247 {
248 	struct device *dev = bus->dev;
249 	struct dev_pm_opp *opp;
250 	unsigned long rate;
251 	int ret;
252 
253 	/* Get the clock to provide each bus with source clock */
254 	bus->clk = devm_clk_get(dev, "bus");
255 	if (IS_ERR(bus->clk)) {
256 		dev_err(dev, "failed to get bus clock\n");
257 		return PTR_ERR(bus->clk);
258 	}
259 
260 	ret = clk_prepare_enable(bus->clk);
261 	if (ret < 0) {
262 		dev_err(dev, "failed to get enable clock\n");
263 		return ret;
264 	}
265 
266 	/* Get the freq and voltage from OPP table to scale the bus freq */
267 	ret = dev_pm_opp_of_add_table(dev);
268 	if (ret < 0) {
269 		dev_err(dev, "failed to get OPP table\n");
270 		goto err_clk;
271 	}
272 
273 	rate = clk_get_rate(bus->clk);
274 
275 	opp = devfreq_recommended_opp(dev, &rate, 0);
276 	if (IS_ERR(opp)) {
277 		dev_err(dev, "failed to find dev_pm_opp\n");
278 		ret = PTR_ERR(opp);
279 		goto err_opp;
280 	}
281 	bus->curr_freq = dev_pm_opp_get_freq(opp);
282 	dev_pm_opp_put(opp);
283 
284 	return 0;
285 
286 err_opp:
287 	dev_pm_opp_of_remove_table(dev);
288 err_clk:
289 	clk_disable_unprepare(bus->clk);
290 
291 	return ret;
292 }
293 
294 static int exynos_bus_profile_init(struct exynos_bus *bus,
295 				   struct devfreq_dev_profile *profile)
296 {
297 	struct device *dev = bus->dev;
298 	struct devfreq_simple_ondemand_data *ondemand_data;
299 	int ret;
300 
301 	/* Initialize the struct profile and governor data for parent device */
302 	profile->polling_ms = 50;
303 	profile->target = exynos_bus_target;
304 	profile->get_dev_status = exynos_bus_get_dev_status;
305 	profile->exit = exynos_bus_exit;
306 
307 	ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
308 	if (!ondemand_data)
309 		return -ENOMEM;
310 
311 	ondemand_data->upthreshold = 40;
312 	ondemand_data->downdifferential = 5;
313 
314 	/* Add devfreq device to monitor and handle the exynos bus */
315 	bus->devfreq = devm_devfreq_add_device(dev, profile,
316 						DEVFREQ_GOV_SIMPLE_ONDEMAND,
317 						ondemand_data);
318 	if (IS_ERR(bus->devfreq)) {
319 		dev_err(dev, "failed to add devfreq device\n");
320 		return PTR_ERR(bus->devfreq);
321 	}
322 
323 	/* Register opp_notifier to catch the change of OPP  */
324 	ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
325 	if (ret < 0) {
326 		dev_err(dev, "failed to register opp notifier\n");
327 		return ret;
328 	}
329 
330 	/*
331 	 * Enable devfreq-event to get raw data which is used to determine
332 	 * current bus load.
333 	 */
334 	ret = exynos_bus_enable_edev(bus);
335 	if (ret < 0) {
336 		dev_err(dev, "failed to enable devfreq-event devices\n");
337 		return ret;
338 	}
339 
340 	ret = exynos_bus_set_event(bus);
341 	if (ret < 0) {
342 		dev_err(dev, "failed to set event to devfreq-event devices\n");
343 		goto err_edev;
344 	}
345 
346 	return 0;
347 
348 err_edev:
349 	if (exynos_bus_disable_edev(bus))
350 		dev_warn(dev, "failed to disable the devfreq-event devices\n");
351 
352 	return ret;
353 }
354 
355 static int exynos_bus_profile_init_passive(struct exynos_bus *bus,
356 					   struct devfreq_dev_profile *profile)
357 {
358 	struct device *dev = bus->dev;
359 	struct devfreq_passive_data *passive_data;
360 	struct devfreq *parent_devfreq;
361 
362 	/* Initialize the struct profile and governor data for passive device */
363 	profile->target = exynos_bus_target;
364 	profile->exit = exynos_bus_passive_exit;
365 
366 	/* Get the instance of parent devfreq device */
367 	parent_devfreq = devfreq_get_devfreq_by_phandle(dev, "devfreq", 0);
368 	if (IS_ERR(parent_devfreq))
369 		return -EPROBE_DEFER;
370 
371 	passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
372 	if (!passive_data)
373 		return -ENOMEM;
374 
375 	passive_data->parent = parent_devfreq;
376 
377 	/* Add devfreq device for exynos bus with passive governor */
378 	bus->devfreq = devm_devfreq_add_device(dev, profile, DEVFREQ_GOV_PASSIVE,
379 						passive_data);
380 	if (IS_ERR(bus->devfreq)) {
381 		dev_err(dev,
382 			"failed to add devfreq dev with passive governor\n");
383 		return PTR_ERR(bus->devfreq);
384 	}
385 
386 	return 0;
387 }
388 
389 static int exynos_bus_probe(struct platform_device *pdev)
390 {
391 	struct device *dev = &pdev->dev;
392 	struct device_node *np = dev->of_node, *node;
393 	struct devfreq_dev_profile *profile;
394 	struct exynos_bus *bus;
395 	int ret, max_state;
396 	unsigned long min_freq, max_freq;
397 	bool passive = false;
398 
399 	if (!np) {
400 		dev_err(dev, "failed to find devicetree node\n");
401 		return -EINVAL;
402 	}
403 
404 	bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
405 	if (!bus)
406 		return -ENOMEM;
407 	mutex_init(&bus->lock);
408 	bus->dev = &pdev->dev;
409 	platform_set_drvdata(pdev, bus);
410 
411 	profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
412 	if (!profile)
413 		return -ENOMEM;
414 
415 	node = of_parse_phandle(dev->of_node, "devfreq", 0);
416 	if (node) {
417 		of_node_put(node);
418 		passive = true;
419 	} else {
420 		ret = exynos_bus_parent_parse_of(np, bus);
421 		if (ret < 0)
422 			return ret;
423 	}
424 
425 	/* Parse the device-tree to get the resource information */
426 	ret = exynos_bus_parse_of(np, bus);
427 	if (ret < 0)
428 		goto err_reg;
429 
430 	if (passive)
431 		ret = exynos_bus_profile_init_passive(bus, profile);
432 	else
433 		ret = exynos_bus_profile_init(bus, profile);
434 
435 	if (ret < 0)
436 		goto err;
437 
438 	/* Create child platform device for the interconnect provider */
439 	if (of_get_property(dev->of_node, "#interconnect-cells", NULL)) {
440 		bus->icc_pdev = platform_device_register_data(
441 						dev, "exynos-generic-icc",
442 						PLATFORM_DEVID_AUTO, NULL, 0);
443 
444 		if (IS_ERR(bus->icc_pdev)) {
445 			ret = PTR_ERR(bus->icc_pdev);
446 			goto err;
447 		}
448 	}
449 
450 	max_state = bus->devfreq->profile->max_state;
451 	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
452 	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
453 	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
454 			dev_name(dev), min_freq, max_freq);
455 
456 	return 0;
457 
458 err:
459 	dev_pm_opp_of_remove_table(dev);
460 	clk_disable_unprepare(bus->clk);
461 err_reg:
462 	dev_pm_opp_put_regulators(bus->opp_table);
463 	bus->opp_table = NULL;
464 
465 	return ret;
466 }
467 
468 static void exynos_bus_shutdown(struct platform_device *pdev)
469 {
470 	struct exynos_bus *bus = dev_get_drvdata(&pdev->dev);
471 
472 	devfreq_suspend_device(bus->devfreq);
473 }
474 
475 #ifdef CONFIG_PM_SLEEP
476 static int exynos_bus_resume(struct device *dev)
477 {
478 	struct exynos_bus *bus = dev_get_drvdata(dev);
479 	int ret;
480 
481 	ret = exynos_bus_enable_edev(bus);
482 	if (ret < 0) {
483 		dev_err(dev, "failed to enable the devfreq-event devices\n");
484 		return ret;
485 	}
486 
487 	return 0;
488 }
489 
490 static int exynos_bus_suspend(struct device *dev)
491 {
492 	struct exynos_bus *bus = dev_get_drvdata(dev);
493 	int ret;
494 
495 	ret = exynos_bus_disable_edev(bus);
496 	if (ret < 0) {
497 		dev_err(dev, "failed to disable the devfreq-event devices\n");
498 		return ret;
499 	}
500 
501 	return 0;
502 }
503 #endif
504 
505 static const struct dev_pm_ops exynos_bus_pm = {
506 	SET_SYSTEM_SLEEP_PM_OPS(exynos_bus_suspend, exynos_bus_resume)
507 };
508 
509 static const struct of_device_id exynos_bus_of_match[] = {
510 	{ .compatible = "samsung,exynos-bus", },
511 	{ /* sentinel */ },
512 };
513 MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
514 
515 static struct platform_driver exynos_bus_platdrv = {
516 	.probe		= exynos_bus_probe,
517 	.shutdown	= exynos_bus_shutdown,
518 	.driver = {
519 		.name	= "exynos-bus",
520 		.pm	= &exynos_bus_pm,
521 		.of_match_table = of_match_ptr(exynos_bus_of_match),
522 	},
523 };
524 module_platform_driver(exynos_bus_platdrv);
525 
526 MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
527 MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
528 MODULE_LICENSE("GPL v2");
529