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