114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/usb.h>
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#include "usbaudio.h"
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#include "helper.h"
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/*
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* combine bytes and get an integer value
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*/
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unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size)
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{
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switch (size) {
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case 1: return *bytes;
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case 2: return combine_word(bytes);
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case 3: return combine_triple(bytes);
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case 4: return combine_quad(bytes);
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default: return 0;
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}
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}
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/*
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* parse descriptor buffer and return the pointer starting the given
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* descriptor type.
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*/
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void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype)
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{
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u8 *p, *end, *next;
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p = descstart;
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end = p + desclen;
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for (; p < end;) {
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if (p[0] < 2)
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return NULL;
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next = p + p[0];
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if (next > end)
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return NULL;
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if (p[1] == dtype && (!after || (void *)p > after)) {
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return p;
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}
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p = next;
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}
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return NULL;
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}
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/*
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* find a class-specified interface descriptor with the given subtype.
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*/
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void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype)
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{
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unsigned char *p = after;
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while ((p = snd_usb_find_desc(buffer, buflen, p,
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USB_DT_CS_INTERFACE)) != NULL) {
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if (p[0] >= 3 && p[2] == dsubtype)
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return p;
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}
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return NULL;
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}
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/*
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* Wrapper for usb_control_msg().
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* Allocates a temp buffer to prevent dmaing from/to the stack.
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*/
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int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
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__u8 requesttype, __u16 value, __u16 index, void *data,
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__u16 size, int timeout)
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{
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int err;
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void *buf = NULL;
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if (size > 0) {
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buf = kmemdup(data, size, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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}
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err = usb_control_msg(dev, pipe, request, requesttype,
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value, index, buf, size, timeout);
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if (size > 0) {
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memcpy(data, buf, size);
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kfree(buf);
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}
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return err;
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}
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unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip,
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struct usb_host_interface *alts)
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{
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if (snd_usb_get_speed(chip->dev) == USB_SPEED_HIGH &&
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get_endpoint(alts, 0)->bInterval >= 1 &&
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get_endpoint(alts, 0)->bInterval <= 4)
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return get_endpoint(alts, 0)->bInterval - 1;
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else
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return 0;
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}
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