1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  Force feedback support for Linux input subsystem
4 *
5 *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
6 *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
7 */
8
9/*
10 */
11
12/* #define DEBUG */
13
14#include <linux/input.h>
15#include <linux/module.h>
16#include <linux/mutex.h>
17#include <linux/sched.h>
18#include <linux/slab.h>
19
20/*
21 * Check that the effect_id is a valid effect and whether the user
22 * is the owner
23 */
24static int check_effect_access(struct ff_device *ff, int effect_id,
25				struct file *file)
26{
27	if (effect_id < 0 || effect_id >= ff->max_effects ||
28	    !ff->effect_owners[effect_id])
29		return -EINVAL;
30
31	if (file && ff->effect_owners[effect_id] != file)
32		return -EACCES;
33
34	return 0;
35}
36
37/*
38 * Checks whether 2 effects can be combined together
39 */
40static inline int check_effects_compatible(struct ff_effect *e1,
41					   struct ff_effect *e2)
42{
43	return e1->type == e2->type &&
44	       (e1->type != FF_PERIODIC ||
45		e1->u.periodic.waveform == e2->u.periodic.waveform);
46}
47
48/*
49 * Convert an effect into compatible one
50 */
51static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
52{
53	int magnitude;
54
55	switch (effect->type) {
56	case FF_RUMBLE:
57		if (!test_bit(FF_PERIODIC, ff->ffbit))
58			return -EINVAL;
59
60		/*
61		 * calculate magnitude of sine wave as average of rumble's
62		 * 2/3 of strong magnitude and 1/3 of weak magnitude
63		 */
64		magnitude = effect->u.rumble.strong_magnitude / 3 +
65			    effect->u.rumble.weak_magnitude / 6;
66
67		effect->type = FF_PERIODIC;
68		effect->u.periodic.waveform = FF_SINE;
69		effect->u.periodic.period = 50;
70		effect->u.periodic.magnitude = max(magnitude, 0x7fff);
71		effect->u.periodic.offset = 0;
72		effect->u.periodic.phase = 0;
73		effect->u.periodic.envelope.attack_length = 0;
74		effect->u.periodic.envelope.attack_level = 0;
75		effect->u.periodic.envelope.fade_length = 0;
76		effect->u.periodic.envelope.fade_level = 0;
77
78		return 0;
79
80	default:
81		/* Let driver handle conversion */
82		return 0;
83	}
84}
85
86/**
87 * input_ff_upload() - upload effect into force-feedback device
88 * @dev: input device
89 * @effect: effect to be uploaded
90 * @file: owner of the effect
91 */
92int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
93		    struct file *file)
94{
95	struct ff_device *ff = dev->ff;
96	struct ff_effect *old;
97	int ret = 0;
98	int id;
99
100	if (!test_bit(EV_FF, dev->evbit))
101		return -ENOSYS;
102
103	if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
104	    !test_bit(effect->type, dev->ffbit)) {
105		dev_dbg(&dev->dev, "invalid or not supported effect type in upload\n");
106		return -EINVAL;
107	}
108
109	if (effect->type == FF_PERIODIC &&
110	    (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
111	     effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
112	     !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
113		dev_dbg(&dev->dev, "invalid or not supported wave form in upload\n");
114		return -EINVAL;
115	}
116
117	if (!test_bit(effect->type, ff->ffbit)) {
118		ret = compat_effect(ff, effect);
119		if (ret)
120			return ret;
121	}
122
123	mutex_lock(&ff->mutex);
124
125	if (effect->id == -1) {
126		for (id = 0; id < ff->max_effects; id++)
127			if (!ff->effect_owners[id])
128				break;
129
130		if (id >= ff->max_effects) {
131			ret = -ENOSPC;
132			goto out;
133		}
134
135		effect->id = id;
136		old = NULL;
137
138	} else {
139		id = effect->id;
140
141		ret = check_effect_access(ff, id, file);
142		if (ret)
143			goto out;
144
145		old = &ff->effects[id];
146
147		if (!check_effects_compatible(effect, old)) {
148			ret = -EINVAL;
149			goto out;
150		}
151	}
152
153	ret = ff->upload(dev, effect, old);
154	if (ret)
155		goto out;
156
157	spin_lock_irq(&dev->event_lock);
158	ff->effects[id] = *effect;
159	ff->effect_owners[id] = file;
160	spin_unlock_irq(&dev->event_lock);
161
162 out:
163	mutex_unlock(&ff->mutex);
164	return ret;
165}
166EXPORT_SYMBOL_GPL(input_ff_upload);
167
168/*
169 * Erases the effect if the requester is also the effect owner. The mutex
170 * should already be locked before calling this function.
171 */
172static int erase_effect(struct input_dev *dev, int effect_id,
173			struct file *file)
174{
175	struct ff_device *ff = dev->ff;
176	int error;
177
178	error = check_effect_access(ff, effect_id, file);
179	if (error)
180		return error;
181
182	spin_lock_irq(&dev->event_lock);
183	ff->playback(dev, effect_id, 0);
184	ff->effect_owners[effect_id] = NULL;
185	spin_unlock_irq(&dev->event_lock);
186
187	if (ff->erase) {
188		error = ff->erase(dev, effect_id);
189		if (error) {
190			spin_lock_irq(&dev->event_lock);
191			ff->effect_owners[effect_id] = file;
192			spin_unlock_irq(&dev->event_lock);
193
194			return error;
195		}
196	}
197
198	return 0;
199}
200
201/**
202 * input_ff_erase - erase a force-feedback effect from device
203 * @dev: input device to erase effect from
204 * @effect_id: id of the effect to be erased
205 * @file: purported owner of the request
206 *
207 * This function erases a force-feedback effect from specified device.
208 * The effect will only be erased if it was uploaded through the same
209 * file handle that is requesting erase.
210 */
211int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
212{
213	struct ff_device *ff = dev->ff;
214	int ret;
215
216	if (!test_bit(EV_FF, dev->evbit))
217		return -ENOSYS;
218
219	mutex_lock(&ff->mutex);
220	ret = erase_effect(dev, effect_id, file);
221	mutex_unlock(&ff->mutex);
222
223	return ret;
224}
225EXPORT_SYMBOL_GPL(input_ff_erase);
226
227/*
228 * input_ff_flush - erase all effects owned by a file handle
229 * @dev: input device to erase effect from
230 * @file: purported owner of the effects
231 *
232 * This function erases all force-feedback effects associated with
233 * the given owner from specified device. Note that @file may be %NULL,
234 * in which case all effects will be erased.
235 */
236int input_ff_flush(struct input_dev *dev, struct file *file)
237{
238	struct ff_device *ff = dev->ff;
239	int i;
240
241	dev_dbg(&dev->dev, "flushing now\n");
242
243	mutex_lock(&ff->mutex);
244
245	for (i = 0; i < ff->max_effects; i++)
246		erase_effect(dev, i, file);
247
248	mutex_unlock(&ff->mutex);
249
250	return 0;
251}
252EXPORT_SYMBOL_GPL(input_ff_flush);
253
254/**
255 * input_ff_event() - generic handler for force-feedback events
256 * @dev: input device to send the effect to
257 * @type: event type (anything but EV_FF is ignored)
258 * @code: event code
259 * @value: event value
260 */
261int input_ff_event(struct input_dev *dev, unsigned int type,
262		   unsigned int code, int value)
263{
264	struct ff_device *ff = dev->ff;
265
266	if (type != EV_FF)
267		return 0;
268
269	switch (code) {
270	case FF_GAIN:
271		if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffffU)
272			break;
273
274		ff->set_gain(dev, value);
275		break;
276
277	case FF_AUTOCENTER:
278		if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffffU)
279			break;
280
281		ff->set_autocenter(dev, value);
282		break;
283
284	default:
285		if (check_effect_access(ff, code, NULL) == 0)
286			ff->playback(dev, code, value);
287		break;
288	}
289
290	return 0;
291}
292EXPORT_SYMBOL_GPL(input_ff_event);
293
294/**
295 * input_ff_create() - create force-feedback device
296 * @dev: input device supporting force-feedback
297 * @max_effects: maximum number of effects supported by the device
298 *
299 * This function allocates all necessary memory for a force feedback
300 * portion of an input device and installs all default handlers.
301 * @dev->ffbit should be already set up before calling this function.
302 * Once ff device is created you need to setup its upload, erase,
303 * playback and other handlers before registering input device
304 */
305int input_ff_create(struct input_dev *dev, unsigned int max_effects)
306{
307	struct ff_device *ff;
308	size_t ff_dev_size;
309	int i;
310
311	if (!max_effects) {
312		dev_err(&dev->dev, "cannot allocate device without any effects\n");
313		return -EINVAL;
314	}
315
316	if (max_effects > FF_MAX_EFFECTS) {
317		dev_err(&dev->dev, "cannot allocate more than FF_MAX_EFFECTS effects\n");
318		return -EINVAL;
319	}
320
321	ff_dev_size = sizeof(struct ff_device) +
322				max_effects * sizeof(struct file *);
323	if (ff_dev_size < max_effects) /* overflow */
324		return -EINVAL;
325
326	ff = kzalloc(ff_dev_size, GFP_KERNEL);
327	if (!ff)
328		return -ENOMEM;
329
330	ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
331			      GFP_KERNEL);
332	if (!ff->effects) {
333		kfree(ff);
334		return -ENOMEM;
335	}
336
337	ff->max_effects = max_effects;
338	mutex_init(&ff->mutex);
339
340	dev->ff = ff;
341	dev->flush = input_ff_flush;
342	dev->event = input_ff_event;
343	__set_bit(EV_FF, dev->evbit);
344
345	/* Copy "true" bits into ff device bitmap */
346	for_each_set_bit(i, dev->ffbit, FF_CNT)
347		__set_bit(i, ff->ffbit);
348
349	/* we can emulate RUMBLE with periodic effects */
350	if (test_bit(FF_PERIODIC, ff->ffbit))
351		__set_bit(FF_RUMBLE, dev->ffbit);
352
353	return 0;
354}
355EXPORT_SYMBOL_GPL(input_ff_create);
356
357/**
358 * input_ff_destroy() - frees force feedback portion of input device
359 * @dev: input device supporting force feedback
360 *
361 * This function is only needed in error path as input core will
362 * automatically free force feedback structures when device is
363 * destroyed.
364 */
365void input_ff_destroy(struct input_dev *dev)
366{
367	struct ff_device *ff = dev->ff;
368
369	__clear_bit(EV_FF, dev->evbit);
370	if (ff) {
371		if (ff->destroy)
372			ff->destroy(ff);
373		kfree(ff->private);
374		kfree(ff->effects);
375		kfree(ff);
376		dev->ff = NULL;
377	}
378}
379EXPORT_SYMBOL_GPL(input_ff_destroy);
380