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/limits.h>
13 #include <linux/module.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 */
check_effect_access(struct ff_device * ff,int effect_id,struct file * file)23 static 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 */
check_effects_compatible(struct ff_effect * e1,struct ff_effect * e2)39 static 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 */
compat_effect(struct ff_device * ff,struct ff_effect * effect)50 static 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 */
input_ff_upload(struct input_dev * dev,struct ff_effect * effect,struct file * file)91 int 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 ret = 0;
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 ret = compat_effect(ff, effect);
118 if (ret)
119 return ret;
120 }
121
122 mutex_lock(&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 ret = -ENOSPC;
131 goto out;
132 }
133
134 effect->id = id;
135 old = NULL;
136
137 } else {
138 id = effect->id;
139
140 ret = check_effect_access(ff, id, file);
141 if (ret)
142 goto out;
143
144 old = &ff->effects[id];
145
146 if (!check_effects_compatible(effect, old)) {
147 ret = -EINVAL;
148 goto out;
149 }
150 }
151
152 ret = ff->upload(dev, effect, old);
153 if (ret)
154 goto out;
155
156 spin_lock_irq(&dev->event_lock);
157 ff->effects[id] = *effect;
158 ff->effect_owners[id] = file;
159 spin_unlock_irq(&dev->event_lock);
160
161 out:
162 mutex_unlock(&ff->mutex);
163 return ret;
164 }
165 EXPORT_SYMBOL_GPL(input_ff_upload);
166
167 /*
168 * Erases the effect if the requester is also the effect owner. The mutex
169 * should already be locked before calling this function.
170 */
erase_effect(struct input_dev * dev,int effect_id,struct file * file)171 static int erase_effect(struct input_dev *dev, int effect_id,
172 struct file *file)
173 {
174 struct ff_device *ff = dev->ff;
175 int error;
176
177 error = check_effect_access(ff, effect_id, file);
178 if (error)
179 return error;
180
181 spin_lock_irq(&dev->event_lock);
182 ff->playback(dev, effect_id, 0);
183 ff->effect_owners[effect_id] = NULL;
184 spin_unlock_irq(&dev->event_lock);
185
186 if (ff->erase) {
187 error = ff->erase(dev, effect_id);
188 if (error) {
189 spin_lock_irq(&dev->event_lock);
190 ff->effect_owners[effect_id] = file;
191 spin_unlock_irq(&dev->event_lock);
192
193 return error;
194 }
195 }
196
197 return 0;
198 }
199
200 /**
201 * input_ff_erase - erase a force-feedback effect from device
202 * @dev: input device to erase effect from
203 * @effect_id: id of the effect to be erased
204 * @file: purported owner of the request
205 *
206 * This function erases a force-feedback effect from specified device.
207 * The effect will only be erased if it was uploaded through the same
208 * file handle that is requesting erase.
209 */
input_ff_erase(struct input_dev * dev,int effect_id,struct file * file)210 int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
211 {
212 struct ff_device *ff = dev->ff;
213 int ret;
214
215 if (!test_bit(EV_FF, dev->evbit))
216 return -ENOSYS;
217
218 mutex_lock(&ff->mutex);
219 ret = erase_effect(dev, effect_id, file);
220 mutex_unlock(&ff->mutex);
221
222 return ret;
223 }
224 EXPORT_SYMBOL_GPL(input_ff_erase);
225
226 /*
227 * input_ff_flush - erase all effects owned by a file handle
228 * @dev: input device to erase effect from
229 * @file: purported owner of the effects
230 *
231 * This function erases all force-feedback effects associated with
232 * the given owner from specified device. Note that @file may be %NULL,
233 * in which case all effects will be erased.
234 */
input_ff_flush(struct input_dev * dev,struct file * file)235 int input_ff_flush(struct input_dev *dev, struct file *file)
236 {
237 struct ff_device *ff = dev->ff;
238 int i;
239
240 dev_dbg(&dev->dev, "flushing now\n");
241
242 mutex_lock(&ff->mutex);
243
244 for (i = 0; i < ff->max_effects; i++)
245 erase_effect(dev, i, file);
246
247 mutex_unlock(&ff->mutex);
248
249 return 0;
250 }
251 EXPORT_SYMBOL_GPL(input_ff_flush);
252
253 /**
254 * input_ff_event() - generic handler for force-feedback events
255 * @dev: input device to send the effect to
256 * @type: event type (anything but EV_FF is ignored)
257 * @code: event code
258 * @value: event value
259 */
input_ff_event(struct input_dev * dev,unsigned int type,unsigned int code,int value)260 int input_ff_event(struct input_dev *dev, unsigned int type,
261 unsigned int code, int value)
262 {
263 struct ff_device *ff = dev->ff;
264
265 if (type != EV_FF)
266 return 0;
267
268 switch (code) {
269 case FF_GAIN:
270 if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffffU)
271 break;
272
273 ff->set_gain(dev, value);
274 break;
275
276 case FF_AUTOCENTER:
277 if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffffU)
278 break;
279
280 ff->set_autocenter(dev, value);
281 break;
282
283 default:
284 if (check_effect_access(ff, code, NULL) == 0)
285 ff->playback(dev, code, value);
286 break;
287 }
288
289 return 0;
290 }
291 EXPORT_SYMBOL_GPL(input_ff_event);
292
293 /**
294 * input_ff_create() - create force-feedback device
295 * @dev: input device supporting force-feedback
296 * @max_effects: maximum number of effects supported by the device
297 *
298 * This function allocates all necessary memory for a force feedback
299 * portion of an input device and installs all default handlers.
300 * @dev->ffbit should be already set up before calling this function.
301 * Once ff device is created you need to setup its upload, erase,
302 * playback and other handlers before registering input device
303 */
input_ff_create(struct input_dev * dev,unsigned int max_effects)304 int input_ff_create(struct input_dev *dev, unsigned int max_effects)
305 {
306 struct ff_device *ff;
307 size_t ff_dev_size;
308 int i;
309
310 if (!max_effects) {
311 dev_err(&dev->dev, "cannot allocate device without any effects\n");
312 return -EINVAL;
313 }
314
315 if (max_effects > FF_MAX_EFFECTS) {
316 dev_err(&dev->dev, "cannot allocate more than FF_MAX_EFFECTS effects\n");
317 return -EINVAL;
318 }
319
320 ff_dev_size = struct_size(ff, effect_owners, max_effects);
321 if (ff_dev_size == SIZE_MAX) /* overflow */
322 return -EINVAL;
323
324 ff = kzalloc(ff_dev_size, GFP_KERNEL);
325 if (!ff)
326 return -ENOMEM;
327
328 ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
329 GFP_KERNEL);
330 if (!ff->effects) {
331 kfree(ff);
332 return -ENOMEM;
333 }
334
335 ff->max_effects = max_effects;
336 mutex_init(&ff->mutex);
337
338 dev->ff = ff;
339 dev->flush = input_ff_flush;
340 dev->event = input_ff_event;
341 __set_bit(EV_FF, dev->evbit);
342
343 /* Copy "true" bits into ff device bitmap */
344 for_each_set_bit(i, dev->ffbit, FF_CNT)
345 __set_bit(i, ff->ffbit);
346
347 /* we can emulate RUMBLE with periodic effects */
348 if (test_bit(FF_PERIODIC, ff->ffbit))
349 __set_bit(FF_RUMBLE, dev->ffbit);
350
351 return 0;
352 }
353 EXPORT_SYMBOL_GPL(input_ff_create);
354
355 /**
356 * input_ff_destroy() - frees force feedback portion of input device
357 * @dev: input device supporting force feedback
358 *
359 * This function is only needed in error path as input core will
360 * automatically free force feedback structures when device is
361 * destroyed.
362 */
input_ff_destroy(struct input_dev * dev)363 void input_ff_destroy(struct input_dev *dev)
364 {
365 struct ff_device *ff = dev->ff;
366
367 __clear_bit(EV_FF, dev->evbit);
368 if (ff) {
369 if (ff->destroy)
370 ff->destroy(ff);
371 kfree(ff->private);
372 kfree(ff->effects);
373 kfree(ff);
374 dev->ff = NULL;
375 }
376 }
377 EXPORT_SYMBOL_GPL(input_ff_destroy);
378