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