Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * USB Compaq iPAQ driver | |
3 | * | |
4 | * Copyright (C) 2001 - 2002 | |
5 | * Ganesh Varadarajan <ganesh@veritas.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | */ | |
13 | ||
14 | #ifndef __LINUX_USB_SERIAL_IPAQ_H | |
15 | #define __LINUX_USB_SERIAL_IPAQ_H | |
16 | ||
17 | /* | |
18 | * Since we can't queue our bulk write urbs (don't know why - it just | |
19 | * doesn't work), we can send down only one write urb at a time. The simplistic | |
20 | * approach taken by the generic usbserial driver will work, but it's not good | |
21 | * for performance. Therefore, we buffer upto URBDATA_QUEUE_MAX bytes of write | |
22 | * requests coming from the line discipline. This is done by chaining them | |
23 | * in lists of struct ipaq_packet, each packet holding a maximum of | |
24 | * PACKET_SIZE bytes. | |
25 | * | |
26 | * ipaq_write() can be called from bottom half context; hence we can't | |
27 | * allocate memory for packets there. So we initialize a pool of packets at | |
28 | * the first open and maintain a freelist. | |
29 | * | |
30 | * The value of PACKET_SIZE was empirically determined by | |
31 | * checking the maximum write sizes sent down by the ppp ldisc. | |
32 | * URBDATA_QUEUE_MAX is set to 64K, which is the maximum TCP window size. | |
33 | */ | |
34 | ||
35 | struct ipaq_packet { | |
36 | char *data; | |
37 | size_t len; | |
38 | size_t written; | |
39 | struct list_head list; | |
40 | }; | |
41 | ||
42 | struct ipaq_private { | |
43 | int active; | |
44 | int queue_len; | |
45 | int free_len; | |
46 | struct list_head queue; | |
47 | struct list_head freelist; | |
48 | }; | |
49 | ||
50 | #define URBDATA_SIZE 4096 | |
51 | #define URBDATA_QUEUE_MAX (64 * 1024) | |
52 | #define PACKET_SIZE 256 | |
53 | ||
54 | #endif |