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  	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)				\
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  
exynos_bus_get_event(struct exynos_bus * bus,struct devfreq_event_data * edata)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   */
exynos_bus_target(struct device * dev,unsigned long * freq,u32 flags)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  
exynos_bus_get_dev_status(struct device * dev,struct devfreq_dev_status * stat)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  
exynos_bus_exit(struct device * dev)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  	dev_pm_opp_put_regulators(bus->opp_token);
164  }
165  
exynos_bus_passive_exit(struct device * dev)166  static 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  
exynos_bus_parent_parse_of(struct device_node * np,struct exynos_bus * bus)175  static 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  
233  err_regulator:
234  	dev_pm_opp_put_regulators(bus->opp_token);
235  
236  	return ret;
237  }
238  
exynos_bus_parse_of(struct device_node * np,struct exynos_bus * bus)239  static 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  
273  err_opp:
274  	dev_pm_opp_of_remove_table(dev);
275  
276  	return ret;
277  }
278  
exynos_bus_profile_init(struct exynos_bus * bus,struct devfreq_dev_profile * profile)279  static 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  
333  err_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  
exynos_bus_profile_init_passive(struct exynos_bus * bus,struct devfreq_dev_profile * profile)340  static 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  
exynos_bus_probe(struct platform_device * pdev)374  static 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  
443  err:
444  	dev_pm_opp_of_remove_table(dev);
445  err_reg:
446  	dev_pm_opp_put_regulators(bus->opp_token);
447  
448  	return ret;
449  }
450  
exynos_bus_shutdown(struct platform_device * pdev)451  static 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  
exynos_bus_resume(struct device * dev)458  static 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  
exynos_bus_suspend(struct device * dev)472  static 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  
486  static DEFINE_SIMPLE_DEV_PM_OPS(exynos_bus_pm,
487  				exynos_bus_suspend, exynos_bus_resume);
488  
489  static const struct of_device_id exynos_bus_of_match[] = {
490  	{ .compatible = "samsung,exynos-bus", },
491  	{ /* sentinel */ },
492  };
493  MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
494  
495  static 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  };
504  module_platform_driver(exynos_bus_platdrv);
505  
506  MODULE_SOFTDEP("pre: exynos_ppmu");
507  MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
508  MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
509  MODULE_LICENSE("GPL v2");
510