1/*
  2 * devfreq-event: a framework to provide raw data and events of devfreq devices
  3 *
  4 * Copyright (C) 2015 Samsung Electronics
  5 * Author: Chanwoo Choi <cw00.choi@samsung.com>
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 *
 11 * This driver is based on drivers/devfreq/devfreq.c.
 12 */
 13
 14#include <linux/devfreq-event.h>
 15#include <linux/kernel.h>
 16#include <linux/err.h>
 17#include <linux/init.h>
 18#include <linux/module.h>
 19#include <linux/slab.h>
 20#include <linux/list.h>
 21#include <linux/of.h>
 22
 23static struct class *devfreq_event_class;
 24
 25/* The list of all devfreq event list */
 26static LIST_HEAD(devfreq_event_list);
 27static DEFINE_MUTEX(devfreq_event_list_lock);
 28
 29#define to_devfreq_event(DEV) container_of(DEV, struct devfreq_event_dev, dev)
 30
 31/**
 32 * devfreq_event_enable_edev() - Enable the devfreq-event dev and increase
 33 *				 the enable_count of devfreq-event dev.
 34 * @edev	: the devfreq-event device
 35 *
 36 * Note that this function increase the enable_count and enable the
 37 * devfreq-event device. The devfreq-event device should be enabled before
 38 * using it by devfreq device.
 39 */
 40int devfreq_event_enable_edev(struct devfreq_event_dev *edev)
 41{
 42	int ret = 0;
 43
 44	if (!edev || !edev->desc)
 45		return -EINVAL;
 46
 47	mutex_lock(&edev->lock);
 48	if (edev->desc->ops && edev->desc->ops->enable
 49			&& edev->enable_count == 0) {
 50		ret = edev->desc->ops->enable(edev);
 51		if (ret < 0)
 52			goto err;
 53	}
 54	edev->enable_count++;
 55err:
 56	mutex_unlock(&edev->lock);
 57
 58	return ret;
 59}
 60EXPORT_SYMBOL_GPL(devfreq_event_enable_edev);
 61
 62/**
 63 * devfreq_event_disable_edev() - Disable the devfreq-event dev and decrease
 64 *				  the enable_count of the devfreq-event dev.
 65 * @edev	: the devfreq-event device
 66 *
 67 * Note that this function decrease the enable_count and disable the
 68 * devfreq-event device. After the devfreq-event device is disabled,
 69 * devfreq device can't use the devfreq-event device for get/set/reset
 70 * operations.
 71 */
 72int devfreq_event_disable_edev(struct devfreq_event_dev *edev)
 73{
 74	int ret = 0;
 75
 76	if (!edev || !edev->desc)
 77		return -EINVAL;
 78
 79	mutex_lock(&edev->lock);
 80	if (edev->enable_count <= 0) {
 81		dev_warn(&edev->dev, "unbalanced enable_count\n");
 82		ret = -EIO;
 83		goto err;
 84	}
 85
 86	if (edev->desc->ops && edev->desc->ops->disable
 87			&& edev->enable_count == 1) {
 88		ret = edev->desc->ops->disable(edev);
 89		if (ret < 0)
 90			goto err;
 91	}
 92	edev->enable_count--;
 93err:
 94	mutex_unlock(&edev->lock);
 95
 96	return ret;
 97}
 98EXPORT_SYMBOL_GPL(devfreq_event_disable_edev);
 99
100/**
101 * devfreq_event_is_enabled() - Check whether devfreq-event dev is enabled or
102 *				not.
103 * @edev	: the devfreq-event device
104 *
105 * Note that this function check whether devfreq-event dev is enabled or not.
106 * If return true, the devfreq-event dev is enabeld. If return false, the
107 * devfreq-event dev is disabled.
108 */
109bool devfreq_event_is_enabled(struct devfreq_event_dev *edev)
110{
111	bool enabled = false;
112
113	if (!edev || !edev->desc)
114		return enabled;
115
116	mutex_lock(&edev->lock);
117
118	if (edev->enable_count > 0)
119		enabled = true;
120
121	mutex_unlock(&edev->lock);
122
123	return enabled;
124}
125EXPORT_SYMBOL_GPL(devfreq_event_is_enabled);
126
127/**
128 * devfreq_event_set_event() - Set event to devfreq-event dev to start.
129 * @edev	: the devfreq-event device
130 *
131 * Note that this function set the event to the devfreq-event device to start
132 * for getting the event data which could be various event type.
133 */
134int devfreq_event_set_event(struct devfreq_event_dev *edev)
135{
136	int ret;
137
138	if (!edev || !edev->desc)
139		return -EINVAL;
140
141	if (!edev->desc->ops || !edev->desc->ops->set_event)
142		return -EINVAL;
143
144	if (!devfreq_event_is_enabled(edev))
145		return -EPERM;
146
147	mutex_lock(&edev->lock);
148	ret = edev->desc->ops->set_event(edev);
149	mutex_unlock(&edev->lock);
150
151	return ret;
152}
153EXPORT_SYMBOL_GPL(devfreq_event_set_event);
154
155/**
156 * devfreq_event_get_event() - Get {load|total}_count from devfreq-event dev.
157 * @edev	: the devfreq-event device
158 * @edata	: the calculated data of devfreq-event device
159 *
160 * Note that this function get the calculated event data from devfreq-event dev
161 * after stoping the progress of whole sequence of devfreq-event dev.
162 */
163int devfreq_event_get_event(struct devfreq_event_dev *edev,
164			    struct devfreq_event_data *edata)
165{
166	int ret;
167
168	if (!edev || !edev->desc)
169		return -EINVAL;
170
171	if (!edev->desc->ops || !edev->desc->ops->get_event)
172		return -EINVAL;
173
174	if (!devfreq_event_is_enabled(edev))
175		return -EINVAL;
176
177	edata->total_count = edata->load_count = 0;
178
179	mutex_lock(&edev->lock);
180	ret = edev->desc->ops->get_event(edev, edata);
181	if (ret < 0)
182		edata->total_count = edata->load_count = 0;
183	mutex_unlock(&edev->lock);
184
185	return ret;
186}
187EXPORT_SYMBOL_GPL(devfreq_event_get_event);
188
189/**
190 * devfreq_event_reset_event() - Reset all opeations of devfreq-event dev.
191 * @edev	: the devfreq-event device
192 *
193 * Note that this function stop all operations of devfreq-event dev and reset
194 * the current event data to make the devfreq-event device into initial state.
195 */
196int devfreq_event_reset_event(struct devfreq_event_dev *edev)
197{
198	int ret = 0;
199
200	if (!edev || !edev->desc)
201		return -EINVAL;
202
203	if (!devfreq_event_is_enabled(edev))
204		return -EPERM;
205
206	mutex_lock(&edev->lock);
207	if (edev->desc->ops && edev->desc->ops->reset)
208		ret = edev->desc->ops->reset(edev);
209	mutex_unlock(&edev->lock);
210
211	return ret;
212}
213EXPORT_SYMBOL_GPL(devfreq_event_reset_event);
214
215/**
216 * devfreq_event_get_edev_by_phandle() - Get the devfreq-event dev from
217 *					 devicetree.
218 * @dev		: the pointer to the given device
219 * @index	: the index into list of devfreq-event device
220 *
221 * Note that this function return the pointer of devfreq-event device.
222 */
223struct devfreq_event_dev *devfreq_event_get_edev_by_phandle(struct device *dev,
224						      int index)
225{
226	struct device_node *node;
227	struct devfreq_event_dev *edev;
228
229	if (!dev->of_node)
230		return ERR_PTR(-EINVAL);
231
232	node = of_parse_phandle(dev->of_node, "devfreq-events", index);
233	if (!node)
234		return ERR_PTR(-ENODEV);
235
236	mutex_lock(&devfreq_event_list_lock);
237	list_for_each_entry(edev, &devfreq_event_list, node) {
238		if (!strcmp(edev->desc->name, node->name))
239			goto out;
240	}
241	edev = NULL;
242out:
243	mutex_unlock(&devfreq_event_list_lock);
244
245	if (!edev) {
246		of_node_put(node);
247		return ERR_PTR(-ENODEV);
248	}
249
250	of_node_put(node);
251
252	return edev;
253}
254EXPORT_SYMBOL_GPL(devfreq_event_get_edev_by_phandle);
255
256/**
257 * devfreq_event_get_edev_count() - Get the count of devfreq-event dev
258 * @dev		: the pointer to the given device
259 *
260 * Note that this function return the count of devfreq-event devices.
261 */
262int devfreq_event_get_edev_count(struct device *dev)
263{
264	int count;
265
266	if (!dev->of_node) {
267		dev_err(dev, "device does not have a device node entry\n");
268		return -EINVAL;
269	}
270
271	count = of_property_count_elems_of_size(dev->of_node, "devfreq-events",
272						sizeof(u32));
273	if (count < 0) {
274		dev_err(dev,
275			"failed to get the count of devfreq-event in %s node\n",
276			dev->of_node->full_name);
277		return count;
278	}
279
280	return count;
281}
282EXPORT_SYMBOL_GPL(devfreq_event_get_edev_count);
283
284static void devfreq_event_release_edev(struct device *dev)
285{
286	struct devfreq_event_dev *edev = to_devfreq_event(dev);
287
288	kfree(edev);
289}
290
291/**
292 * devfreq_event_add_edev() - Add new devfreq-event device.
293 * @dev		: the device owning the devfreq-event device being created
294 * @desc	: the devfreq-event device's decriptor which include essential
295 *		  data for devfreq-event device.
296 *
297 * Note that this function add new devfreq-event device to devfreq-event class
298 * list and register the device of the devfreq-event device.
299 */
300struct devfreq_event_dev *devfreq_event_add_edev(struct device *dev,
301						struct devfreq_event_desc *desc)
302{
303	struct devfreq_event_dev *edev;
304	static atomic_t event_no = ATOMIC_INIT(0);
305	int ret;
306
307	if (!dev || !desc)
308		return ERR_PTR(-EINVAL);
309
310	if (!desc->name || !desc->ops)
311		return ERR_PTR(-EINVAL);
312
313	if (!desc->ops->set_event || !desc->ops->get_event)
314		return ERR_PTR(-EINVAL);
315
316	edev = kzalloc(sizeof(struct devfreq_event_dev), GFP_KERNEL);
317	if (!edev)
318		return ERR_PTR(-ENOMEM);
319
320	mutex_init(&edev->lock);
321	edev->desc = desc;
322	edev->enable_count = 0;
323	edev->dev.parent = dev;
324	edev->dev.class = devfreq_event_class;
325	edev->dev.release = devfreq_event_release_edev;
326
327	dev_set_name(&edev->dev, "event.%d", atomic_inc_return(&event_no) - 1);
328	ret = device_register(&edev->dev);
329	if (ret < 0) {
330		put_device(&edev->dev);
331		return ERR_PTR(ret);
332	}
333	dev_set_drvdata(&edev->dev, edev);
334
335	INIT_LIST_HEAD(&edev->node);
336
337	mutex_lock(&devfreq_event_list_lock);
338	list_add(&edev->node, &devfreq_event_list);
339	mutex_unlock(&devfreq_event_list_lock);
340
341	return edev;
342}
343EXPORT_SYMBOL_GPL(devfreq_event_add_edev);
344
345/**
346 * devfreq_event_remove_edev() - Remove the devfreq-event device registered.
347 * @dev		: the devfreq-event device
348 *
349 * Note that this function remove the registered devfreq-event device.
350 */
351int devfreq_event_remove_edev(struct devfreq_event_dev *edev)
352{
353	if (!edev)
354		return -EINVAL;
355
356	WARN_ON(edev->enable_count);
357
358	mutex_lock(&devfreq_event_list_lock);
359	list_del(&edev->node);
360	mutex_unlock(&devfreq_event_list_lock);
361
362	device_unregister(&edev->dev);
363
364	return 0;
365}
366EXPORT_SYMBOL_GPL(devfreq_event_remove_edev);
367
368static int devm_devfreq_event_match(struct device *dev, void *res, void *data)
369{
370	struct devfreq_event_dev **r = res;
371
372	if (WARN_ON(!r || !*r))
373		return 0;
374
375	return *r == data;
376}
377
378static void devm_devfreq_event_release(struct device *dev, void *res)
379{
380	devfreq_event_remove_edev(*(struct devfreq_event_dev **)res);
381}
382
383/**
384 * devm_devfreq_event_add_edev() - Resource-managed devfreq_event_add_edev()
385 * @dev		: the device owning the devfreq-event device being created
386 * @desc	: the devfreq-event device's decriptor which include essential
387 *		  data for devfreq-event device.
388 *
389 * Note that this function manages automatically the memory of devfreq-event
390 * device using device resource management and simplify the free operation
391 * for memory of devfreq-event device.
392 */
393struct devfreq_event_dev *devm_devfreq_event_add_edev(struct device *dev,
394						struct devfreq_event_desc *desc)
395{
396	struct devfreq_event_dev **ptr, *edev;
397
398	ptr = devres_alloc(devm_devfreq_event_release, sizeof(*ptr),
399				GFP_KERNEL);
400	if (!ptr)
401		return ERR_PTR(-ENOMEM);
402
403	edev = devfreq_event_add_edev(dev, desc);
404	if (IS_ERR(edev)) {
405		devres_free(ptr);
406		return ERR_PTR(-ENOMEM);
407	}
408
409	*ptr = edev;
410	devres_add(dev, ptr);
411
412	return edev;
413}
414EXPORT_SYMBOL_GPL(devm_devfreq_event_add_edev);
415
416/**
417 * devm_devfreq_event_remove_edev()- Resource-managed devfreq_event_remove_edev()
418 * @dev		: the device owning the devfreq-event device being created
419 * @edev	: the devfreq-event device
420 *
421 * Note that this function manages automatically the memory of devfreq-event
422 * device using device resource management.
423 */
424void devm_devfreq_event_remove_edev(struct device *dev,
425				struct devfreq_event_dev *edev)
426{
427	WARN_ON(devres_release(dev, devm_devfreq_event_release,
428			       devm_devfreq_event_match, edev));
429}
430EXPORT_SYMBOL_GPL(devm_devfreq_event_remove_edev);
431
432/*
433 * Device attributes for devfreq-event class.
434 */
435static ssize_t name_show(struct device *dev, struct device_attribute *attr,
436			 char *buf)
437{
438	struct devfreq_event_dev *edev = to_devfreq_event(dev);
439
440	if (!edev || !edev->desc)
441		return -EINVAL;
442
443	return sprintf(buf, "%s\n", edev->desc->name);
444}
445static DEVICE_ATTR_RO(name);
446
447static ssize_t enable_count_show(struct device *dev,
448				  struct device_attribute *attr, char *buf)
449{
450	struct devfreq_event_dev *edev = to_devfreq_event(dev);
451
452	if (!edev || !edev->desc)
453		return -EINVAL;
454
455	return sprintf(buf, "%d\n", edev->enable_count);
456}
457static DEVICE_ATTR_RO(enable_count);
458
459static struct attribute *devfreq_event_attrs[] = {
460	&dev_attr_name.attr,
461	&dev_attr_enable_count.attr,
462	NULL,
463};
464ATTRIBUTE_GROUPS(devfreq_event);
465
466static int __init devfreq_event_init(void)
467{
468	devfreq_event_class = class_create(THIS_MODULE, "devfreq-event");
469	if (IS_ERR(devfreq_event_class)) {
470		pr_err("%s: couldn't create class\n", __FILE__);
471		return PTR_ERR(devfreq_event_class);
472	}
473
474	devfreq_event_class->dev_groups = devfreq_event_groups;
475
476	return 0;
477}
478subsys_initcall(devfreq_event_init);
479
480static void __exit devfreq_event_exit(void)
481{
482	class_destroy(devfreq_event_class);
483}
484module_exit(devfreq_event_exit);
485
486MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
487MODULE_DESCRIPTION("DEVFREQ-Event class support");
488MODULE_LICENSE("GPL");