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/*****************************************************************************
*
* Filename: ks959-sir.c
* Version: 0.1.2
* Description: Irda KingSun KS-959 USB Dongle
* Status: Experimental
* Author: Alex Villacís Lasso <a_villacis@palosanto.com>
* with help from Domen Puncer <domen@coderock.org>
*
* Based on stir4200, mcs7780, kingsun-sir drivers.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*****************************************************************************/
/*
* Following is my most current (2007-07-17) understanding of how the Kingsun
* KS-959 dongle is supposed to work. This information was deduced by
* reverse-engineering and examining the USB traffic captured with USBSnoopy
* from the WinXP driver. Feel free to update here as more of the dongle is
* known.
*
* My most sincere thanks must go to Domen Puncer <domen@coderock.org> for
* invaluable help in cracking the obfuscation and padding required for this
* dongle.
*
* General: This dongle exposes one interface with one interrupt IN endpoint.
* However, the interrupt endpoint is NOT used at all for this dongle. Instead,
* this dongle uses control transfers for everything, including sending and
* receiving the IrDA frame data. Apparently the interrupt endpoint is just a
* dummy to ensure the dongle has a valid interface to present to the PC.And I
* thought the DonShine dongle was weird... In addition, this dongle uses
* obfuscation (?!?!), applied at the USB level, to hide the traffic, both sent
* and received, from the dongle. I call it obfuscation because the XOR keying
* and padding required to produce an USB traffic acceptable for the dongle can
* not be explained by any other technical requirement.
*
* Transmission: To transmit an IrDA frame, the driver must prepare a control
* URB with the following as a setup packet:
* bRequestType USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE
* bRequest 0x09
* wValue <length of valid data before padding, little endian>
* wIndex 0x0000
* wLength <length of padded data>
* The payload packet must be manually wrapped and escaped (as in stir4200.c),
* then padded and obfuscated before being sent. Both padding and obfuscation
* are implemented in the procedure obfuscate_tx_buffer(). Suffice to say, the
* designer/programmer of the dongle used his name as a source for the
* obfuscation. WTF?!
* Apparently the dongle cannot handle payloads larger than 256 bytes. The
* driver has to perform fragmentation in order to send anything larger than
* this limit.
*
* Reception: To receive data, the driver must poll the dongle regularly (like
* kingsun-sir.c) with control URBs and the following as a setup packet:
* bRequestType USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE
* bRequest 0x01
* wValue 0x0200
* wIndex 0x0000
* wLength 0x0800 (size of available buffer)
* If there is data to be read, it will be returned as the response payload.
* This data is (apparently) not padded, but it is obfuscated. To de-obfuscate
* it, the driver must XOR every byte, in sequence, with a value that starts at
* 1 and is incremented with each byte processed, and then with 0x55. The value
* incremented with each byte processed overflows as an unsigned char. The
* resulting bytes form a wrapped SIR frame that is unwrapped and unescaped
* as in stir4200.c The incremented value is NOT reset with each frame, but is
* kept across the entire session with the dongle. Also, the dongle inserts an
* extra garbage byte with value 0x95 (after decoding) every 0xff bytes, which
* must be skipped.
*
* Speed change: To change the speed of the dongle, the driver prepares a
* control URB with the following as a setup packet:
* bRequestType USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE
* bRequest 0x09
* wValue 0x0200
* wIndex 0x0001
* wLength 0x0008 (length of the payload)
* The payload is a 8-byte record, apparently identical to the one used in
* drivers/usb/serial/cypress_m8.c to change speed:
* __u32 baudSpeed;
* unsigned int dataBits : 2; // 0 - 5 bits 3 - 8 bits
* unsigned int : 1;
* unsigned int stopBits : 1;
* unsigned int parityEnable : 1;
* unsigned int parityType : 1;
* unsigned int : 1;
* unsigned int reset : 1;
* unsigned char reserved[3]; // set to 0
*
* For now only SIR speeds have been observed with this dongle. Therefore,
* nothing is known on what changes (if any) must be done to frame wrapping /
* unwrapping for higher than SIR speeds. This driver assumes no change is
* necessary and announces support for all the way to 57600 bps. Although the
* package announces support for up to 4MBps, tests with a Sony Ericcson K300
* phone show corruption when receiving large frames at 115200 bps, the highest
* speed announced by the phone. However, transmission at 115200 bps is OK. Go
* figure. Since I don't know whether the phone or the dongle is at fault, max
* announced speed is 57600 bps until someone produces a device that can run
* at higher speeds with this dongle.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/kref.h>
#include <linux/usb.h>
#include <linux/device.h>
#include <linux/crc32.h>
#include <asm/unaligned.h>
#include <asm/byteorder.h>
#include <asm/uaccess.h>
#include <net/irda/irda.h>
#include <net/irda/wrapper.h>
#include <net/irda/crc.h>
#define KS959_VENDOR_ID 0x07d0
#define KS959_PRODUCT_ID 0x4959
/* These are the currently known USB ids */
static struct usb_device_id dongles[] = {
/* KingSun Co,Ltd IrDA/USB Bridge */
{USB_DEVICE(KS959_VENDOR_ID, KS959_PRODUCT_ID)},
{}
};
MODULE_DEVICE_TABLE(usb, dongles);
#define KINGSUN_MTT 0x07
#define KINGSUN_REQ_RECV 0x01
#define KINGSUN_REQ_SEND 0x09
#define KINGSUN_RCV_FIFO_SIZE 2048 /* Max length we can receive */
#define KINGSUN_SND_FIFO_SIZE 2048 /* Max packet we can send */
#define KINGSUN_SND_PACKET_SIZE 256 /* Max packet dongle can handle */
struct ks959_speedparams {
__le32 baudrate; /* baud rate, little endian */
__u8 flags;
__u8 reserved[3];
} __attribute__ ((packed));
#define KS_DATA_5_BITS 0x00
#define KS_DATA_6_BITS 0x01
#define KS_DATA_7_BITS 0x02
#define KS_DATA_8_BITS 0x03
#define KS_STOP_BITS_1 0x00
#define KS_STOP_BITS_2 0x08
#define KS_PAR_DISABLE 0x00
#define KS_PAR_EVEN 0x10
#define KS_PAR_ODD 0x30
#define KS_RESET 0x80
struct ks959_cb {
struct usb_device *usbdev; /* init: probe_irda */
struct net_device *netdev; /* network layer */
struct irlap_cb *irlap; /* The link layer we are binded to */
struct qos_info qos;
struct usb_ctrlrequest *tx_setuprequest;
struct urb *tx_urb;
__u8 *tx_buf_clear;
unsigned int tx_buf_clear_used;
unsigned int tx_buf_clear_sent;
__u8 *tx_buf_xored;
struct usb_ctrlrequest *rx_setuprequest;
struct urb *rx_urb;
__u8 *rx_buf;
__u8 rx_variable_xormask;
iobuff_t rx_unwrap_buff;
struct timeval rx_time;
struct usb_ctrlrequest *speed_setuprequest;
struct urb *speed_urb;
struct ks959_speedparams speedparams;
unsigned int new_speed;
spinlock_t lock;
int receiving;
};
/* Procedure to perform the obfuscation/padding expected by the dongle
*
* buf_cleartext (IN) Cleartext version of the IrDA frame to transmit
* len_cleartext (IN) Length of the cleartext version of IrDA frame
* buf_xoredtext (OUT) Obfuscated version of frame built by proc
* len_maxbuf (OUT) Maximum space available at buf_xoredtext
*
* (return) length of obfuscated frame with padding
*
* If not enough space (as indicated by len_maxbuf vs. required padding),
* zero is returned
*
* The value of lookup_string is actually a required portion of the algorithm.
* Seems the designer of the dongle wanted to state who exactly is responsible
* for implementing obfuscation. Send your best (or other) wishes to him ]:-)
*/
static unsigned int obfuscate_tx_buffer(const __u8 * buf_cleartext,
unsigned int len_cleartext,
__u8 * buf_xoredtext,
unsigned int len_maxbuf)
{
unsigned int len_xoredtext;
/* Calculate required length with padding, check for necessary space */
len_xoredtext = ((len_cleartext + 7) & ~0x7) + 0x10;
if (len_xoredtext <= len_maxbuf) {
static const __u8 lookup_string[] = "wangshuofei19710";
__u8 xor_mask;
/* Unlike the WinXP driver, we *do* clear out the padding */
memset(buf_xoredtext, 0, len_xoredtext);
xor_mask = lookup_string[(len_cleartext & 0x0f) ^ 0x06] ^ 0x55;
while (len_cleartext-- > 0) {
*buf_xoredtext++ = *buf_cleartext++ ^ xor_mask;
}
} else {
len_xoredtext = 0;
}
return len_xoredtext;
}
/* Callback transmission routine */
static void ks959_speed_irq(struct urb *urb)
{
/* unlink, shutdown, unplug, other nasties */
if (urb->status != 0) {
err("ks959_speed_irq: urb asynchronously failed - %d",
urb->status);
}
}
/
|