Root/drivers/input/ff-core.c

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 */
38static 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 */
54static 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 */
65static 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 */
106int 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}
180EXPORT_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 */
186static 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 */
225int 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}
239EXPORT_SYMBOL_GPL(input_ff_erase);
240
241/*
242 * flush_effects - erase all effects owned by a file handle
243 */
244static 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 */
268int 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}
299EXPORT_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 */
312int 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}
358EXPORT_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 */
368void 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}
382EXPORT_SYMBOL_GPL(input_ff_destroy);
383

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