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