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  • only in /asuswrt-rt-n18u-9.0.0.4.380.2695/release/src-rt-6.x.4708/linux/linux-2.6.36/sound/usb/
1/*
2 *   This program is free software; you can redistribute it and/or modify
3 *   it under the terms of the GNU General Public License as published by
4 *   the Free Software Foundation; either version 2 of the License, or
5 *   (at your option) any later version.
6 *
7 *   This program is distributed in the hope that it will be useful,
8 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
9 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10 *   GNU General Public License for more details.
11 *
12 *   You should have received a copy of the GNU General Public License
13 *   along with this program; if not, write to the Free Software
14 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
15 *
16 */
17
18#include <linux/init.h>
19#include <linux/slab.h>
20#include <linux/usb.h>
21
22#include "usbaudio.h"
23#include "helper.h"
24
25/*
26 * combine bytes and get an integer value
27 */
28unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size)
29{
30	switch (size) {
31	case 1:  return *bytes;
32	case 2:  return combine_word(bytes);
33	case 3:  return combine_triple(bytes);
34	case 4:  return combine_quad(bytes);
35	default: return 0;
36	}
37}
38
39/*
40 * parse descriptor buffer and return the pointer starting the given
41 * descriptor type.
42 */
43void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype)
44{
45	u8 *p, *end, *next;
46
47	p = descstart;
48	end = p + desclen;
49	for (; p < end;) {
50		if (p[0] < 2)
51			return NULL;
52		next = p + p[0];
53		if (next > end)
54			return NULL;
55		if (p[1] == dtype && (!after || (void *)p > after)) {
56			return p;
57		}
58		p = next;
59	}
60	return NULL;
61}
62
63/*
64 * find a class-specified interface descriptor with the given subtype.
65 */
66void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype)
67{
68	unsigned char *p = after;
69
70	while ((p = snd_usb_find_desc(buffer, buflen, p,
71				      USB_DT_CS_INTERFACE)) != NULL) {
72		if (p[0] >= 3 && p[2] == dsubtype)
73			return p;
74	}
75	return NULL;
76}
77
78/*
79 * Wrapper for usb_control_msg().
80 * Allocates a temp buffer to prevent dmaing from/to the stack.
81 */
82int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
83		    __u8 requesttype, __u16 value, __u16 index, void *data,
84		    __u16 size, int timeout)
85{
86	int err;
87	void *buf = NULL;
88
89	if (size > 0) {
90		buf = kmemdup(data, size, GFP_KERNEL);
91		if (!buf)
92			return -ENOMEM;
93	}
94	err = usb_control_msg(dev, pipe, request, requesttype,
95			      value, index, buf, size, timeout);
96	if (size > 0) {
97		memcpy(data, buf, size);
98		kfree(buf);
99	}
100	return err;
101}
102
103unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip,
104					 struct usb_host_interface *alts)
105{
106	if (snd_usb_get_speed(chip->dev) == USB_SPEED_HIGH &&
107	    get_endpoint(alts, 0)->bInterval >= 1 &&
108	    get_endpoint(alts, 0)->bInterval <= 4)
109		return get_endpoint(alts, 0)->bInterval - 1;
110	else
111		return 0;
112}
113