ff-core.c revision 6a47081c37b7dd7810ce19e156c1a3bf11987e9a 
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 debug(format, arg...) pr_debug("ff-core: " format "\n", ## arg)
27
28#include <linux/input.h>
29#include <linux/module.h>
30#include <linux/mutex.h>
31#include <linux/sched.h>
32
33/*
34 * Check that the effect_id is a valid effect and whether the user
35 * is the owner
36 */
37static int check_effect_access(struct ff_device *ff, int effect_id,
38				struct file *file)
39{
40	if (effect_id < 0 || effect_id >= ff->max_effects ||
41	    !ff->effect_owners[effect_id])
42		return -EINVAL;
43
44	if (file && ff->effect_owners[effect_id] != file)
45		return -EACCES;
46
47	return 0;
48}
49
50/*
51 * Checks whether 2 effects can be combined together
52 */
53static inline int check_effects_compatible(struct ff_effect *e1,
54					   struct ff_effect *e2)
55{
56	return e1->type == e2->type &&
57	       (e1->type != FF_PERIODIC ||
58		e1->u.periodic.waveform == e2->u.periodic.waveform);
59}
60
61/*
62 * Convert an effect into compatible one
63 */
64static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
65{
66	int magnitude;
67
68	switch (effect->type) {
69	case FF_RUMBLE:
70		if (!test_bit(FF_PERIODIC, ff->ffbit))
71			return -EINVAL;
72
73		/*
74		 * calculate manginude of sine wave as average of rumble's
75		 * 2/3 of strong magnitude and 1/3 of weak magnitude
76		 */
77		magnitude = effect->u.rumble.strong_magnitude / 3 +
78			    effect->u.rumble.weak_magnitude / 6;
79
80		effect->type = FF_PERIODIC;
81		effect->u.periodic.waveform = FF_SINE;
82		effect->u.periodic.period = 50;
83		effect->u.periodic.magnitude = max(magnitude, 0x7fff);
84		effect->u.periodic.offset = 0;
85		effect->u.periodic.phase = 0;
86		effect->u.periodic.envelope.attack_length = 0;
87		effect->u.periodic.envelope.attack_level = 0;
88		effect->u.periodic.envelope.fade_length = 0;
89		effect->u.periodic.envelope.fade_level = 0;
90
91		return 0;
92
93	default:
94		/* Let driver handle conversion */
95		return 0;
96	}
97}
98
99/**
100 * input_ff_upload() - upload effect into force-feedback device
101 * @dev: input device
102 * @effect: effect to be uploaded
103 * @file: owner of the effect
104 */
105int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
106		    struct file *file)
107{
108	struct ff_device *ff = dev->ff;
109	struct ff_effect *old;
110	int ret = 0;
111	int id;
112
113	if (!test_bit(EV_FF, dev->evbit))
114		return -ENOSYS;
115
116	if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
117	    !test_bit(effect->type, dev->ffbit)) {
118		debug("invalid or not supported effect type in upload");
119		return -EINVAL;
120	}
121
122	if (effect->type == FF_PERIODIC &&
123	    (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
124	     effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
125	     !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
126		debug("invalid or not supported wave form in upload");
127		return -EINVAL;
128	}
129
130	if (!test_bit(effect->type, ff->ffbit)) {
131		ret = compat_effect(ff, effect);
132		if (ret)
133			return ret;
134	}
135
136	mutex_lock(&ff->mutex);
137
138	if (effect->id == -1) {
139		for (id = 0; id < ff->max_effects; id++)
140		     if (!ff->effect_owners[id])
141			break;
142
143		if (id >= ff->max_effects) {
144			ret = -ENOSPC;
145			goto out;
146		}
147
148		effect->id = id;
149		old = NULL;
150
151	} else {
152		id = effect->id;
153
154		ret = check_effect_access(ff, id, file);
155		if (ret)
156			goto out;
157
158		old = &ff->effects[id];
159
160		if (!check_effects_compatible(effect, old)) {
161			ret = -EINVAL;
162			goto out;
163		}
164	}
165
166	ret = ff->upload(dev, effect, old);
167	if (ret)
168		goto out;
169
170	spin_lock_irq(&dev->event_lock);
171	ff->effects[id] = *effect;
172	ff->effect_owners[id] = file;
173	spin_unlock_irq(&dev->event_lock);
174
175 out:
176	mutex_unlock(&ff->mutex);
177	return ret;
178}
179EXPORT_SYMBOL_GPL(input_ff_upload);
180
181/*
182 * Erases the effect if the requester is also the effect owner. The mutex
183 * should already be locked before calling this function.
184 */
185static int erase_effect(struct input_dev *dev, int effect_id,
186			struct file *file)
187{
188	struct ff_device *ff = dev->ff;
189	int error;
190
191	error = check_effect_access(ff, effect_id, file);
192	if (error)
193		return error;
194
195	spin_lock_irq(&dev->event_lock);
196	ff->playback(dev, effect_id, 0);
197	ff->effect_owners[effect_id] = NULL;
198	spin_unlock_irq(&dev->event_lock);
199
200	if (ff->erase) {
201		error = ff->erase(dev, effect_id);
202		if (error) {
203			spin_lock_irq(&dev->event_lock);
204			ff->effect_owners[effect_id] = file;
205			spin_unlock_irq(&dev->event_lock);
206
207			return error;
208		}
209	}
210
211	return 0;
212}
213
214/**
215 * input_ff_erase - erase a force-feedback effect from device
216 * @dev: input device to erase effect from
217 * @effect_id: id of the ffect to be erased
218 * @file: purported owner of the request
219 *
220 * This function erases a force-feedback effect from specified device.
221 * The effect will only be erased if it was uploaded through the same
222 * file handle that is requesting erase.
223 */
224int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
225{
226	struct ff_device *ff = dev->ff;
227	int ret;
228
229	if (!test_bit(EV_FF, dev->evbit))
230		return -ENOSYS;
231
232	mutex_lock(&ff->mutex);
233	ret = erase_effect(dev, effect_id, file);
234	mutex_unlock(&ff->mutex);
235
236	return ret;
237}
238EXPORT_SYMBOL_GPL(input_ff_erase);
239
240/*
241 * flush_effects - erase all effects owned by a file handle
242 */
243static int flush_effects(struct input_dev *dev, struct file *file)
244{
245	struct ff_device *ff = dev->ff;
246	int i;
247
248	debug("flushing now");
249
250	mutex_lock(&ff->mutex);
251
252	for (i = 0; i < ff->max_effects; i++)
253		erase_effect(dev, i, file);
254
255	mutex_unlock(&ff->mutex);
256
257	return 0;
258}
259
260/**
261 * input_ff_event() - generic handler for force-feedback events
262 * @dev: input device to send the effect to
263 * @type: event type (anything but EV_FF is ignored)
264 * @code: event code
265 * @value: event value
266 */
267int input_ff_event(struct input_dev *dev, unsigned int type,
268		   unsigned int code, int value)
269{
270	struct ff_device *ff = dev->ff;
271
272	if (type != EV_FF)
273		return 0;
274
275	switch (code) {
276	case FF_GAIN:
277		if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffff)
278			break;
279
280		ff->set_gain(dev, value);
281		break;
282
283	case FF_AUTOCENTER:
284		if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffff)
285			break;
286
287		ff->set_autocenter(dev, value);
288		break;
289
290	default:
291		if (check_effect_access(ff, code, NULL) == 0)
292			ff->playback(dev, code, value);
293		break;
294	}
295
296	return 0;
297}
298EXPORT_SYMBOL_GPL(input_ff_event);
299
300/**
301 * input_ff_create() - create force-feedback device
302 * @dev: input device supporting force-feedback
303 * @max_effects: maximum number of effects supported by the device
304 *
305 * This function allocates all necessary memory for a force feedback
306 * portion of an input device and installs all default handlers.
307 * @dev->ffbit should be already set up before calling this function.
308 * Once ff device is created you need to setup its upload, erase,
309 * playback and other handlers before registering input device
310 */
311int input_ff_create(struct input_dev *dev, int max_effects)
312{
313	struct ff_device *ff;
314	int i;
315
316	if (!max_effects) {
317		printk(KERN_ERR
318		       "ff-core: cannot allocate device without any effects\n");
319		return -EINVAL;
320	}
321
322	ff = kzalloc(sizeof(struct ff_device) +
323		     max_effects * sizeof(struct file *), 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 = flush_effects;
339	dev->event = input_ff_event;
340	__set_bit(EV_FF, dev->evbit);
341
342	/* Copy "true" bits into ff device bitmap */
343	for (i = 0; i <= FF_MAX; i++)
344		if (test_bit(i, dev->ffbit))
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}
353EXPORT_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 */
363void 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}
377EXPORT_SYMBOL_GPL(input_ff_destroy);
378