1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 */
4
5 #include <linux/init.h>
6 #include <linux/slab.h>
7 #include <linux/usb.h>
8
9 #include "usbaudio.h"
10 #include "helper.h"
11 #include "quirks.h"
12
13 /*
14 * combine bytes and get an integer value
15 */
16 unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size)
17 {
18 switch (size) {
19 case 1: return *bytes;
20 case 2: return combine_word(bytes);
21 case 3: return combine_triple(bytes);
22 case 4: return combine_quad(bytes);
23 default: return 0;
24 }
25 }
26
27 /*
28 * parse descriptor buffer and return the pointer starting the given
29 * descriptor type.
30 */
31 void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype)
32 {
33 u8 *p, *end, *next;
34
35 p = descstart;
36 end = p + desclen;
37 for (; p < end;) {
38 if (p[0] < 2)
39 return NULL;
40 next = p + p[0];
41 if (next > end)
42 return NULL;
43 if (p[1] == dtype && (!after || (void *)p > after)) {
44 return p;
45 }
46 p = next;
47 }
48 return NULL;
49 }
50
51 /*
52 * find a class-specified interface descriptor with the given subtype.
53 */
54 void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype)
55 {
56 unsigned char *p = after;
57
58 while ((p = snd_usb_find_desc(buffer, buflen, p,
59 USB_DT_CS_INTERFACE)) != NULL) {
60 if (p[0] >= 3 && p[2] == dsubtype)
61 return p;
62 }
63 return NULL;
64 }
65
66 /*
67 * Wrapper for usb_control_msg().
68 * Allocates a temp buffer to prevent dmaing from/to the stack.
69 */
70 int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
71 __u8 requesttype, __u16 value, __u16 index, void *data,
72 __u16 size)
73 {
74 int err;
75 void *buf = NULL;
76 int timeout;
77
78 if (usb_pipe_type_check(dev, pipe))
79 return -EINVAL;
80
81 if (size > 0) {
82 buf = kmemdup(data, size, GFP_KERNEL);
83 if (!buf)
84 return -ENOMEM;
85 }
86
87 if (requesttype & USB_DIR_IN)
88 timeout = USB_CTRL_GET_TIMEOUT;
89 else
90 timeout = USB_CTRL_SET_TIMEOUT;
91
92 err = usb_control_msg(dev, pipe, request, requesttype,
93 value, index, buf, size, timeout);
94
95 if (size > 0) {
96 memcpy(data, buf, size);
97 kfree(buf);
98 }
99
100 snd_usb_ctl_msg_quirk(dev, pipe, request, requesttype,
101 value, index, data, size);
102
103 return err;
104 }
105
106 unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip,
107 struct usb_host_interface *alts)
108 {
109 switch (snd_usb_get_speed(chip->dev)) {
110 case USB_SPEED_HIGH:
111 case USB_SPEED_SUPER:
112 case USB_SPEED_SUPER_PLUS:
113 if (get_endpoint(alts, 0)->bInterval >= 1 &&
114 get_endpoint(alts, 0)->bInterval <= 4)
115 return get_endpoint(alts, 0)->bInterval - 1;
116 break;
117 default:
118 break;
119 }
120 return 0;
121 }
122
123 struct usb_host_interface *
124 snd_usb_get_host_interface(struct snd_usb_audio *chip, int ifnum, int altsetting)
125 {
126 struct usb_interface *iface;
127
128 iface = usb_ifnum_to_if(chip->dev, ifnum);
129 if (!iface)
130 return NULL;
131 return usb_altnum_to_altsetting(iface, altsetting);
132 }
133
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