1 /*
2 * Force feedback support for Linux input subsystem
3 *
4 * Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
5 * Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
6 */
7
8 /*
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 */
23
24 /* #define DEBUG */
25
26 #define pr_fmt(fmt) KBUILD_BASENAME ": " fmt
27
28 #include <linux/input.h>
29 #include <linux/module.h>
30 #include <linux/mutex.h>
31 #include <linux/sched.h>
32 #include <linux/slab.h>
33
34 /*
35 * Check that the effect_id is a valid effect and whether the user
36 * is the owner
37 */
check_effect_access(struct ff_device * ff,int effect_id,struct file * file)38 static int check_effect_access(struct ff_device *ff, int effect_id,
39 struct file *file)
40 {
41 if (effect_id < 0 || effect_id >= ff->max_effects ||
42 !ff->effect_owners[effect_id])
43 return -EINVAL;
44
45 if (file && ff->effect_owners[effect_id] != file)
46 return -EACCES;
47
48 return 0;
49 }
50
51 /*
52 * Checks whether 2 effects can be combined together
53 */
check_effects_compatible(struct ff_effect * e1,struct ff_effect * e2)54 static inline int check_effects_compatible(struct ff_effect *e1,
55 struct ff_effect *e2)
56 {
57 return e1->type == e2->type &&
58 (e1->type != FF_PERIODIC ||
59 e1->u.periodic.waveform == e2->u.periodic.waveform);
60 }
61
62 /*
63 * Convert an effect into compatible one
64 */
compat_effect(struct ff_device * ff,struct ff_effect * effect)65 static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
66 {
67 int magnitude;
68
69 switch (effect->type) {
70 case FF_RUMBLE:
71 if (!test_bit(FF_PERIODIC, ff->ffbit))
72 return -EINVAL;
73
74 /*
75 * calculate manginude of sine wave as average of rumble's
76 * 2/3 of strong magnitude and 1/3 of weak magnitude
77 */
78 magnitude = effect->u.rumble.strong_magnitude / 3 +
79 effect->u.rumble.weak_magnitude / 6;
80
81 effect->type = FF_PERIODIC;
82 effect->u.periodic.waveform = FF_SINE;
83 effect->u.periodic.period = 50;
84 effect->u.periodic.magnitude = max(magnitude, 0x7fff);
85 effect->u.periodic.offset = 0;
86 effect->u.periodic.phase = 0;
87 effect->u.periodic.envelope.attack_length = 0;
88 effect->u.periodic.envelope.attack_level = 0;
89 effect->u.periodic.envelope.fade_length = 0;
90 effect->u.periodic.envelope.fade_level = 0;
91
92 return 0;
93
94 default:
95 /* Let driver handle conversion */
96 return 0;
97 }
98 }
99
100 /**
101 * input_ff_upload() - upload effect into force-feedback device
102 * @dev: input device
103 * @effect: effect to be uploaded
104 * @file: owner of the effect
105 */
input_ff_upload(struct input_dev * dev,struct ff_effect * effect,struct file * file)106 int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
107 struct file *file)
108 {
109 struct ff_device *ff = dev->ff;
110 struct ff_effect *old;
111 int ret = 0;
112 int id;
113
114 if (!test_bit(EV_FF, dev->evbit))
115 return -ENOSYS;
116
117 if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
118 !test_bit(effect->type, dev->ffbit)) {
119 pr_debug("invalid or not supported effect type in upload\n");
120 return -EINVAL;
121 }
122
123 if (effect->type == FF_PERIODIC &&
124 (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
125 effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
126 !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
127 pr_debug("invalid or not supported wave form in upload\n");
128 return -EINVAL;
129 }
130
131 if (!test_bit(effect->type, ff->ffbit)) {
132 ret = compat_effect(ff, effect);
133 if (ret)
134 return ret;
135 }
136
137 mutex_lock(&ff->mutex);
138
139 if (effect->id == -1) {
140 for (id = 0; id < ff->max_effects; id++)
141 if (!ff->effect_owners[id])
142 break;
143
144 if (id >= ff->max_effects) {
145 ret = -ENOSPC;
146 goto out;
147 }
148
149 effect->id = id;
150 old = NULL;
151
152 } else {
153 id = effect->id;
154
155 ret = check_effect_access(ff, id, file);
156 if (ret)
157 goto out;
158
159 old = &ff->effects[id];
160
161 if (!check_effects_compatible(effect, old)) {
162 ret = -EINVAL;
163 goto out;
164 }
165 }
166
167 ret = ff->upload(dev, effect, old);
168 if (ret)
169 goto out;
170
171 spin_lock_irq(&dev->event_lock);
172 ff->effects[id] = *effect;
173 ff->effect_owners[id] = file;
174 spin_unlock_irq(&dev->event_lock);
175
176 out:
177 mutex_unlock(&ff->mutex);
178 return ret;
179 }
180 EXPORT_SYMBOL_GPL(input_ff_upload);
181
182 /*
183 * Erases the effect if the requester is also the effect owner. The mutex
184 * should already be locked before calling this function.
185 */
erase_effect(struct input_dev * dev,int effect_id,struct file * file)186 static int erase_effect(struct input_dev *dev, int effect_id,
187 struct file *file)
188 {
189 struct ff_device *ff = dev->ff;
190 int error;
191
192 error = check_effect_access(ff, effect_id, file);
193 if (error)
194 return error;
195
196 spin_lock_irq(&dev->event_lock);
197 ff->playback(dev, effect_id, 0);
198 ff->effect_owners[effect_id] = NULL;
199 spin_unlock_irq(&dev->event_lock);
200
201 if (ff->erase) {
202 error = ff->erase(dev, effect_id);
203 if (error) {
204 spin_lock_irq(&dev->event_lock);
205 ff->effect_owners[effect_id] = file;
206 spin_unlock_irq(&dev->event_lock);
207
208 return error;
209 }
210 }
211
212 return 0;
213 }
214
215 /**
216 * input_ff_erase - erase a force-feedback effect from device
217 * @dev: input device to erase effect from
218 * @effect_id: id of the ffect to be erased
219 * @file: purported owner of the request
220 *
221 * This function erases a force-feedback effect from specified device.
222 * The effect will only be erased if it was uploaded through the same
223 * file handle that is requesting erase.
224 */
input_ff_erase(struct input_dev * dev,int effect_id,struct file * file)225 int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
226 {
227 struct ff_device *ff = dev->ff;
228 int ret;
229
230 if (!test_bit(EV_FF, dev->evbit))
231 return -ENOSYS;
232
233 mutex_lock(&ff->mutex);
234 ret = erase_effect(dev, effect_id, file);
235 mutex_unlock(&ff->mutex);
236
237 return ret;
238 }
239 EXPORT_SYMBOL_GPL(input_ff_erase);
240
241 /*
242 * flush_effects - erase all effects owned by a file handle
243 */
flush_effects(struct input_dev * dev,struct file * file)244 static int flush_effects(struct input_dev *dev, struct file *file)
245 {
246 struct ff_device *ff = dev->ff;
247 int i;
248
249 pr_debug("flushing now\n");
250
251 mutex_lock(&ff->mutex);
252
253 for (i = 0; i < ff->max_effects; i++)
254 erase_effect(dev, i, file);
255
256 mutex_unlock(&ff->mutex);
257
258 return 0;
259 }
260
261 /**
262 * input_ff_event() - generic handler for force-feedback events
263 * @dev: input device to send the effect to
264 * @type: event type (anything but EV_FF is ignored)
265 * @code: event code
266 * @value: event value
267 */
input_ff_event(struct input_dev * dev,unsigned int type,unsigned int code,int value)268 int input_ff_event(struct input_dev *dev, unsigned int type,
269 unsigned int code, int value)
270 {
271 struct ff_device *ff = dev->ff;
272
273 if (type != EV_FF)
274 return 0;
275
276 switch (code) {
277 case FF_GAIN:
278 if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffff)
279 break;
280
281 ff->set_gain(dev, value);
282 break;
283
284 case FF_AUTOCENTER:
285 if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffff)
286 break;
287
288 ff->set_autocenter(dev, value);
289 break;
290
291 default:
292 if (check_effect_access(ff, code, NULL) == 0)
293 ff->playback(dev, code, value);
294 break;
295 }
296
297 return 0;
298 }
299 EXPORT_SYMBOL_GPL(input_ff_event);
300
301 /**
302 * input_ff_create() - create force-feedback device
303 * @dev: input device supporting force-feedback
304 * @max_effects: maximum number of effects supported by the device
305 *
306 * This function allocates all necessary memory for a force feedback
307 * portion of an input device and installs all default handlers.
308 * @dev->ffbit should be already set up before calling this function.
309 * Once ff device is created you need to setup its upload, erase,
310 * playback and other handlers before registering input device
311 */
input_ff_create(struct input_dev * dev,unsigned int max_effects)312 int input_ff_create(struct input_dev *dev, unsigned int max_effects)
313 {
314 struct ff_device *ff;
315 size_t ff_dev_size;
316 int i;
317
318 if (!max_effects) {
319 pr_err("cannot allocate device without any effects\n");
320 return -EINVAL;
321 }
322
323 ff_dev_size = sizeof(struct ff_device) +
324 max_effects * sizeof(struct file *);
325 if (ff_dev_size < max_effects) /* overflow */
326 return -EINVAL;
327
328 ff = kzalloc(ff_dev_size, GFP_KERNEL);
329 if (!ff)
330 return -ENOMEM;
331
332 ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
333 GFP_KERNEL);
334 if (!ff->effects) {
335 kfree(ff);
336 return -ENOMEM;
337 }
338
339 ff->max_effects = max_effects;
340 mutex_init(&ff->mutex);
341
342 dev->ff = ff;
343 dev->flush = flush_effects;
344 dev->event = input_ff_event;
345 __set_bit(EV_FF, dev->evbit);
346
347 /* Copy "true" bits into ff device bitmap */
348 for (i = 0; i <= FF_MAX; i++)
349 if (test_bit(i, dev->ffbit))
350 __set_bit(i, ff->ffbit);
351
352 /* we can emulate RUMBLE with periodic effects */
353 if (test_bit(FF_PERIODIC, ff->ffbit))
354 __set_bit(FF_RUMBLE, dev->ffbit);
355
356 return 0;
357 }
358 EXPORT_SYMBOL_GPL(input_ff_create);
359
360 /**
361 * input_ff_destroy() - frees force feedback portion of input device
362 * @dev: input device supporting force feedback
363 *
364 * This function is only needed in error path as input core will
365 * automatically free force feedback structures when device is
366 * destroyed.
367 */
input_ff_destroy(struct input_dev * dev)368 void input_ff_destroy(struct input_dev *dev)
369 {
370 struct ff_device *ff = dev->ff;
371
372 __clear_bit(EV_FF, dev->evbit);
373 if (ff) {
374 if (ff->destroy)
375 ff->destroy(ff);
376 kfree(ff->private);
377 kfree(ff->effects);
378 kfree(ff);
379 dev->ff = NULL;
380 }
381 }
382 EXPORT_SYMBOL_GPL(input_ff_destroy);
383