/* * USB Compaq iPAQ driver * * Copyright (C) 2001 - 2002 * Ganesh Varadarajan <ganesh@veritas.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * */ #ifndef __LINUX_USB_SERIAL_IPAQ_H #define __LINUX_USB_SERIAL_IPAQ_H /* * Since we can't queue our bulk write urbs (don't know why - it just * doesn't work), we can send down only one write urb at a time. The simplistic * approach taken by the generic usbserial driver will work, but it's not good * for performance. Therefore, we buffer upto URBDATA_QUEUE_MAX bytes of write * requests coming from the line discipline. This is done by chaining them * in lists of struct ipaq_packet, each packet holding a maximum of * PACKET_SIZE bytes. * * ipaq_write() can be called from bottom half context; hence we can't * allocate memory for packets there. So we initialize a pool of packets at * the first open and maintain a freelist. * * The value of PACKET_SIZE was empirically determined by * checking the maximum write sizes sent down by the ppp ldisc. * URBDATA_QUEUE_MAX is set to 64K, which is the maximum TCP window size. */ struct ipaq_packet { char *data; size_t len; size_t written; struct list_head list; }; struct ipaq_private { int active; int queue_len; int free_len; struct list_head queue; struct list_head freelist; }; #define URBDATA_SIZE 4096 #define URBDATA_QUEUE_MAX (64 * 1024) #define PACKET_SIZE 256 #endif