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 */
snd_usb_combine_bytes(unsigned char * bytes,int size)28 unsigned 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 */
snd_usb_find_desc(void * descstart,int desclen,void * after,u8 dtype)43 void *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 */
snd_usb_find_csint_desc(void * buffer,int buflen,void * after,u8 dsubtype)66 void *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 */
snd_usb_ctl_msg(struct usb_device * dev,unsigned int pipe,__u8 request,__u8 requesttype,__u16 value,__u16 index,void * data,__u16 size,int timeout)82 int 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
snd_usb_parse_datainterval(struct snd_usb_audio * chip,struct usb_host_interface * alts)103 unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip,
104 struct usb_host_interface *alts)
105 {
106 switch (snd_usb_get_speed(chip->dev)) {
107 case USB_SPEED_HIGH:
108 case USB_SPEED_SUPER:
109 if (get_endpoint(alts, 0)->bInterval >= 1 &&
110 get_endpoint(alts, 0)->bInterval <= 4)
111 return get_endpoint(alts, 0)->bInterval - 1;
112 break;
113 default:
114 break;
115 }
116 return 0;
117 }
118
119