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e5779998 DM |
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/usb.h> | |
20 | ||
21 | #include "usbaudio.h" | |
22 | #include "helper.h" | |
23 | ||
24 | /* | |
25 | * combine bytes and get an integer value | |
26 | */ | |
27 | unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size) | |
28 | { | |
29 | switch (size) { | |
30 | case 1: return *bytes; | |
31 | case 2: return combine_word(bytes); | |
32 | case 3: return combine_triple(bytes); | |
33 | case 4: return combine_quad(bytes); | |
34 | default: return 0; | |
35 | } | |
36 | } | |
37 | ||
38 | /* | |
39 | * parse descriptor buffer and return the pointer starting the given | |
40 | * descriptor type. | |
41 | */ | |
42 | void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype) | |
43 | { | |
44 | u8 *p, *end, *next; | |
45 | ||
46 | p = descstart; | |
47 | end = p + desclen; | |
48 | for (; p < end;) { | |
49 | if (p[0] < 2) | |
50 | return NULL; | |
51 | next = p + p[0]; | |
52 | if (next > end) | |
53 | return NULL; | |
54 | if (p[1] == dtype && (!after || (void *)p > after)) { | |
55 | return p; | |
56 | } | |
57 | p = next; | |
58 | } | |
59 | return NULL; | |
60 | } | |
61 | ||
62 | /* | |
63 | * find a class-specified interface descriptor with the given subtype. | |
64 | */ | |
65 | void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype) | |
66 | { | |
67 | unsigned char *p = after; | |
68 | ||
69 | while ((p = snd_usb_find_desc(buffer, buflen, p, | |
70 | USB_DT_CS_INTERFACE)) != NULL) { | |
71 | if (p[0] >= 3 && p[2] == dsubtype) | |
72 | return p; | |
73 | } | |
74 | return NULL; | |
75 | } | |
76 | ||
77 | /* | |
78 | * Wrapper for usb_control_msg(). | |
79 | * Allocates a temp buffer to prevent dmaing from/to the stack. | |
80 | */ | |
81 | int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request, | |
82 | __u8 requesttype, __u16 value, __u16 index, void *data, | |
83 | __u16 size, int timeout) | |
84 | { | |
85 | int err; | |
86 | void *buf = NULL; | |
87 | ||
88 | if (size > 0) { | |
89 | buf = kmemdup(data, size, GFP_KERNEL); | |
90 | if (!buf) | |
91 | return -ENOMEM; | |
92 | } | |
93 | err = usb_control_msg(dev, pipe, request, requesttype, | |
94 | value, index, buf, size, timeout); | |
95 | if (size > 0) { | |
96 | memcpy(data, buf, size); | |
97 | kfree(buf); | |
98 | } | |
99 | return err; | |
100 | } | |
101 | ||
102 | unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip, | |
103 | struct usb_host_interface *alts) | |
104 | { | |
105 | if (snd_usb_get_speed(chip->dev) == USB_SPEED_HIGH && | |
106 | get_endpoint(alts, 0)->bInterval >= 1 && | |
107 | get_endpoint(alts, 0)->bInterval <= 4) | |
108 | return get_endpoint(alts, 0)->bInterval - 1; | |
109 | else | |
110 | return 0; | |
111 | } | |
112 |