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
 25struct 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	int opp_token;
 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)				\
 45static 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}
 59exynos_bus_ops_edev(enable_edev);
 60exynos_bus_ops_edev(disable_edev);
 61exynos_bus_ops_edev(set_event);
 62
 63static 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 */
 93static 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
119static 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
141err:
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
151static 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	dev_pm_opp_put_regulators(bus->opp_token);
164}
165
166static void exynos_bus_passive_exit(struct device *dev)
167{
168	struct exynos_bus *bus = dev_get_drvdata(dev);
169
170	platform_device_unregister(bus->icc_pdev);
171
172	dev_pm_opp_of_remove_table(dev);
173}
174
175static int exynos_bus_parent_parse_of(struct device_node *np,
176					struct exynos_bus *bus)
177{
178	struct device *dev = bus->dev;
179	const char *supplies[] = { "vdd", NULL };
180	int i, ret, count, size;
181
182	ret = dev_pm_opp_set_regulators(dev, supplies);
183	if (ret < 0) {
184		dev_err(dev, "failed to set regulators %d\n", ret);
185		return ret;
186	}
187
188	bus->opp_token = ret;
189
190	/*
191	 * Get the devfreq-event devices to get the current utilization of
192	 * buses. This raw data will be used in devfreq ondemand governor.
193	 */
194	count = devfreq_event_get_edev_count(dev, "devfreq-events");
195	if (count < 0) {
196		dev_err(dev, "failed to get the count of devfreq-event dev\n");
197		ret = count;
198		goto err_regulator;
199	}
200	bus->edev_count = count;
201
202	size = sizeof(*bus->edev) * count;
203	bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
204	if (!bus->edev) {
205		ret = -ENOMEM;
206		goto err_regulator;
207	}
208
209	for (i = 0; i < count; i++) {
210		bus->edev[i] = devfreq_event_get_edev_by_phandle(dev,
211							"devfreq-events", i);
212		if (IS_ERR(bus->edev[i])) {
213			ret = -EPROBE_DEFER;
214			goto err_regulator;
215		}
216	}
217
218	/*
219	 * Optionally, Get the saturation ratio according to Exynos SoC
220	 * When measuring the utilization of each AXI bus with devfreq-event
221	 * devices, the measured real cycle might be much lower than the
222	 * total cycle of bus during sampling rate. In result, the devfreq
223	 * simple-ondemand governor might not decide to change the current
224	 * frequency due to too utilization (= real cycle/total cycle).
225	 * So, this property is used to adjust the utilization when calculating
226	 * the busy_time in exynos_bus_get_dev_status().
227	 */
228	if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
229		bus->ratio = DEFAULT_SATURATION_RATIO;
230
231	return 0;
232
233err_regulator:
234	dev_pm_opp_put_regulators(bus->opp_token);
235
236	return ret;
237}
238
239static int exynos_bus_parse_of(struct device_node *np,
240			      struct exynos_bus *bus)
241{
242	struct device *dev = bus->dev;
243	struct dev_pm_opp *opp;
244	unsigned long rate;
245	int ret;
246
247	/* Get the clock to provide each bus with source clock */
248	bus->clk = devm_clk_get_enabled(dev, "bus");
249	if (IS_ERR(bus->clk))
250		return dev_err_probe(dev, PTR_ERR(bus->clk),
251				"failed to get bus clock\n");
252
253	/* Get the freq and voltage from OPP table to scale the bus freq */
254	ret = dev_pm_opp_of_add_table(dev);
255	if (ret < 0) {
256		dev_err(dev, "failed to get OPP table\n");
257		return ret;
258	}
259
260	rate = clk_get_rate(bus->clk);
261
262	opp = devfreq_recommended_opp(dev, &rate, 0);
263	if (IS_ERR(opp)) {
264		dev_err(dev, "failed to find dev_pm_opp\n");
265		ret = PTR_ERR(opp);
266		goto err_opp;
267	}
268	bus->curr_freq = dev_pm_opp_get_freq(opp);
269	dev_pm_opp_put(opp);
270
271	return 0;
272
273err_opp:
274	dev_pm_opp_of_remove_table(dev);
275
276	return ret;
277}
278
279static int exynos_bus_profile_init(struct exynos_bus *bus,
280				   struct devfreq_dev_profile *profile)
281{
282	struct device *dev = bus->dev;
283	struct devfreq_simple_ondemand_data *ondemand_data;
284	int ret;
285
286	/* Initialize the struct profile and governor data for parent device */
287	profile->polling_ms = 50;
288	profile->target = exynos_bus_target;
289	profile->get_dev_status = exynos_bus_get_dev_status;
290	profile->exit = exynos_bus_exit;
291
292	ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
293	if (!ondemand_data)
294		return -ENOMEM;
295
296	ondemand_data->upthreshold = 40;
297	ondemand_data->downdifferential = 5;
298
299	/* Add devfreq device to monitor and handle the exynos bus */
300	bus->devfreq = devm_devfreq_add_device(dev, profile,
301						DEVFREQ_GOV_SIMPLE_ONDEMAND,
302						ondemand_data);
303	if (IS_ERR(bus->devfreq)) {
304		dev_err(dev, "failed to add devfreq device\n");
305		return PTR_ERR(bus->devfreq);
306	}
307
308	/* Register opp_notifier to catch the change of OPP  */
309	ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
310	if (ret < 0) {
311		dev_err(dev, "failed to register opp notifier\n");
312		return ret;
313	}
314
315	/*
316	 * Enable devfreq-event to get raw data which is used to determine
317	 * current bus load.
318	 */
319	ret = exynos_bus_enable_edev(bus);
320	if (ret < 0) {
321		dev_err(dev, "failed to enable devfreq-event devices\n");
322		return ret;
323	}
324
325	ret = exynos_bus_set_event(bus);
326	if (ret < 0) {
327		dev_err(dev, "failed to set event to devfreq-event devices\n");
328		goto err_edev;
329	}
330
331	return 0;
332
333err_edev:
334	if (exynos_bus_disable_edev(bus))
335		dev_warn(dev, "failed to disable the devfreq-event devices\n");
336
337	return ret;
338}
339
340static int exynos_bus_profile_init_passive(struct exynos_bus *bus,
341					   struct devfreq_dev_profile *profile)
342{
343	struct device *dev = bus->dev;
344	struct devfreq_passive_data *passive_data;
345	struct devfreq *parent_devfreq;
346
347	/* Initialize the struct profile and governor data for passive device */
348	profile->target = exynos_bus_target;
349	profile->exit = exynos_bus_passive_exit;
350
351	/* Get the instance of parent devfreq device */
352	parent_devfreq = devfreq_get_devfreq_by_phandle(dev, "devfreq", 0);
353	if (IS_ERR(parent_devfreq))
354		return -EPROBE_DEFER;
355
356	passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
357	if (!passive_data)
358		return -ENOMEM;
359
360	passive_data->parent = parent_devfreq;
361
362	/* Add devfreq device for exynos bus with passive governor */
363	bus->devfreq = devm_devfreq_add_device(dev, profile, DEVFREQ_GOV_PASSIVE,
364						passive_data);
365	if (IS_ERR(bus->devfreq)) {
366		dev_err(dev,
367			"failed to add devfreq dev with passive governor\n");
368		return PTR_ERR(bus->devfreq);
369	}
370
371	return 0;
372}
373
374static int exynos_bus_probe(struct platform_device *pdev)
375{
376	struct device *dev = &pdev->dev;
377	struct device_node *np = dev->of_node, *node;
378	struct devfreq_dev_profile *profile;
379	struct exynos_bus *bus;
380	int ret, max_state;
381	unsigned long min_freq, max_freq;
382	bool passive = false;
383
384	if (!np) {
385		dev_err(dev, "failed to find devicetree node\n");
386		return -EINVAL;
387	}
388
389	bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
390	if (!bus)
391		return -ENOMEM;
392	mutex_init(&bus->lock);
393	bus->dev = &pdev->dev;
394	platform_set_drvdata(pdev, bus);
395
396	profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
397	if (!profile)
398		return -ENOMEM;
399
400	node = of_parse_phandle(dev->of_node, "devfreq", 0);
401	if (node) {
402		of_node_put(node);
403		passive = true;
404	} else {
405		ret = exynos_bus_parent_parse_of(np, bus);
406		if (ret < 0)
407			return ret;
408	}
409
410	/* Parse the device-tree to get the resource information */
411	ret = exynos_bus_parse_of(np, bus);
412	if (ret < 0)
413		goto err_reg;
414
415	if (passive)
416		ret = exynos_bus_profile_init_passive(bus, profile);
417	else
418		ret = exynos_bus_profile_init(bus, profile);
419
420	if (ret < 0)
421		goto err;
422
423	/* Create child platform device for the interconnect provider */
424	if (of_property_present(dev->of_node, "#interconnect-cells")) {
425		bus->icc_pdev = platform_device_register_data(
426						dev, "exynos-generic-icc",
427						PLATFORM_DEVID_AUTO, NULL, 0);
428
429		if (IS_ERR(bus->icc_pdev)) {
430			ret = PTR_ERR(bus->icc_pdev);
431			goto err;
432		}
433	}
434
435	max_state = bus->devfreq->max_state;
436	min_freq = (bus->devfreq->freq_table[0] / 1000);
437	max_freq = (bus->devfreq->freq_table[max_state - 1] / 1000);
438	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
439			dev_name(dev), min_freq, max_freq);
440
441	return 0;
442
443err:
444	dev_pm_opp_of_remove_table(dev);
445err_reg:
446	dev_pm_opp_put_regulators(bus->opp_token);
447
448	return ret;
449}
450
451static void exynos_bus_shutdown(struct platform_device *pdev)
452{
453	struct exynos_bus *bus = dev_get_drvdata(&pdev->dev);
454
455	devfreq_suspend_device(bus->devfreq);
456}
457
458static int exynos_bus_resume(struct device *dev)
459{
460	struct exynos_bus *bus = dev_get_drvdata(dev);
461	int ret;
462
463	ret = exynos_bus_enable_edev(bus);
464	if (ret < 0) {
465		dev_err(dev, "failed to enable the devfreq-event devices\n");
466		return ret;
467	}
468
469	return 0;
470}
471
472static int exynos_bus_suspend(struct device *dev)
473{
474	struct exynos_bus *bus = dev_get_drvdata(dev);
475	int ret;
476
477	ret = exynos_bus_disable_edev(bus);
478	if (ret < 0) {
479		dev_err(dev, "failed to disable the devfreq-event devices\n");
480		return ret;
481	}
482
483	return 0;
484}
485
486static DEFINE_SIMPLE_DEV_PM_OPS(exynos_bus_pm,
487				exynos_bus_suspend, exynos_bus_resume);
488
489static const struct of_device_id exynos_bus_of_match[] = {
490	{ .compatible = "samsung,exynos-bus", },
491	{ /* sentinel */ },
492};
493MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
494
495static struct platform_driver exynos_bus_platdrv = {
496	.probe		= exynos_bus_probe,
497	.shutdown	= exynos_bus_shutdown,
498	.driver = {
499		.name	= "exynos-bus",
500		.pm	= pm_sleep_ptr(&exynos_bus_pm),
501		.of_match_table = exynos_bus_of_match,
502	},
503};
504module_platform_driver(exynos_bus_platdrv);
505
506MODULE_SOFTDEP("pre: exynos_ppmu");
507MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
508MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
509MODULE_LICENSE("GPL v2");