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