/*
* Safe Encapsulated USB Serial Driver
*
* Copyright (C) 2001 Lineo
* Copyright (C) 2001 Hewlett-Packard
*
* 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.
*
* By:
* Stuart Lynne <sl@lineo.com>, Tom Rushworth <tbr@lineo.com>
*/
/*
* The encapsultaion is designed to overcome difficulties with some USB hardware.
*
* While the USB protocol has a CRC over the data while in transit, i.e. while
* being carried over the bus, there is no end to end protection. If the hardware
* has any problems getting the data into or out of the USB transmit and receive
* FIFO's then data can be lost.
*
* This protocol adds a two byte trailer to each USB packet to specify the number
* of bytes of valid data and a 10 bit CRC that will allow the receiver to verify
* that the entire USB packet was received without error.
*
* Because in this case the sender and receiver are the class and function drivers
* there is now end to end protection.
*
* There is an additional option that can be used to force all transmitted packets
* to be padded to the maximum packet size. This provides a work around for some
* devices which have problems with small USB packets.
*
* Assuming a packetsize of N:
*
* 0..N-2 data and optional padding
*
* N-2 bits 7-2 - number of bytes of valid data
* bits 1-0 top two bits of 10 bit CRC
* N-1 bottom 8 bits of 10 bit CRC
*
*
* | Data Length | 10 bit CRC |
* + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 | 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 +
*
* The 10 bit CRC is computed across the sent data, followed by the trailer with
* the length set and the CRC set to zero. The CRC is then OR'd into the trailer.
*
* When received a 10 bit CRC is computed over the entire frame including the trailer
* and should be equal to zero.
*
* Two module parameters are used to control the encapsulation, if both are
* turned of the module works as a simple serial device with NO
* encapsulation.
*
* See linux/drivers/usbd/serial_fd for a device function driver
* implementation of this.
*
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#ifndef CONFIG_USB_SERIAL_SAFE_PADDED
#define CONFIG_USB_SERIAL_SAFE_PADDED 0
#endif
static int debug;
static int safe = 1;
static int padded = CONFIG_USB_SERIAL_SAFE_PADDED;
#define DRIVER_VERSION "v0.0b"
#define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com"
#define DRIVER_DESC "USB Safe Encapsulated Serial"
MODULE_AUTHOR (DRIVER_AUTHOR);
MODULE_DESCRIPTION (DRIVER_DESC);
MODULE_LICENSE("GPL");
static __u16 vendor; // no default
static __u16 product; // no default
module_param(vendor, ushort, 0);
MODULE_PARM_DESC(vendor, "User specified USB idVendor (required)");
module_param(product, ushort, 0);
MODULE_PARM_DESC(product, "User specified USB idProduct (required)");
module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");
module_param(safe, bool, 0);
MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
module_param(padded, bool, 0);
MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
#define CDC_DEVICE_CLASS 0x02
#define CDC_INTERFACE_CLASS 0x02
#define CDC_INTERFACE_SUBCLASS 0x06
#define LINEO_INTERFACE_CLASS 0xff
#define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01
#define LINEO_SAFENET_CRC 0x01
#define LINEO_SAFENET_CRC_PADDED 0x02
#define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02
#define LINEO_SAFESERIAL_CRC 0x01
#define LINEO_SAFESERIAL_CRC_PADDED 0x02
#define MY_USB_DEVICE(vend,prod,dc,ic,isc) \
.match_flags = USB_DEVICE_ID_MATCH_DEVICE | USB_DEVICE_ID_MATCH_DEV_CLASS | \
USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS, \
.idVendor = (vend), \
.idProduct = (prod),\
.bDeviceClass = (dc),\
.bInterfaceClass = (ic), \
.bInterfaceSubClass = (isc),
static struct usb_device_id id_table[] = {
{MY_USB_DEVICE (0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Itsy
{MY_USB_DEVICE (0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Calypso
{MY_USB_DEVICE (0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Iris
{MY_USB_DEVICE (0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Collie
{MY_USB_DEVICE (0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Collie
{MY_USB_DEVICE (0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Collie
{MY_USB_DEVICE (0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Sharp tmp
// extra null entry for module
// vendor/produc parameters
{MY_USB_DEVICE (0, 0, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},
{} // terminating entry
};
MODULE_DEVICE_TABLE (usb, id_table);
static struct usb_driver safe_driver = {
.name = "safe_serial",
.probe = usb_serial_probe,
.disconnect = usb_serial_disconnect,
.id_table = id_table,
.no_dynamic_id = 1,
};
static const __u16 crc10_table[256] = {
0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff, 0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce, 0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d, 0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac, 0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b, 0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a, 0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259, 0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268, 0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377, 0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346, 0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315, 0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324, 0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3, 0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382, 0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1, 0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0, 0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
};
#define CRC10_INITFCS 0x000 // Initial FCS value
#define CRC10_GOODFCS 0x000 // Good final FCS value
#define CRC10_FCS(fcs, c) ( (((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
/**
* fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
* @sp: pointer to buffer
* @len: number of bytes
* @fcs: starting FCS
*
* Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
* new 10 bit FCS.
*/
static __u16 __inline__ fcs_compute10 (unsigned char *sp, int len, __u16 fcs)
{
for (; len-- > 0; fcs = CRC10_FCS (fcs, *sp++));
return fcs;
}
static void safe_read_bulk_callback (struct urb *urb)
{
struct usb_serial_port *port = urb->context;
unsigned char *data = urb->transfer_buffer;
unsigned char length = urb->actual_length;
int result;
int status = urb->status;
dbg ("%s", __func__);
if (status) {
dbg("%s - nonzero read bulk status received: %d",
__func__, status);
return;
}
dbg ("safe_read_bulk_callback length: %d", port->read_urb->actual_length);
#ifdef ECHO_RCV
{
int i;
unsigned char *cp = port->read_urb->transfer_buffer;
for (i = 0; i < port->read_urb->actual_length; i++) {
if ((i % 32) == 0) {
printk ("\nru[%02x] ", i);
}
printk ("%02x ", *cp++);
}
printk ("\n");
}
#endif
if (safe) {
__u16 fcs;
if (!(fcs = fcs_compute10 (data, length, CRC10_INITFCS))) {
int actual_length = data[length - 2] >> 2;
if (actual_length <= (length - 2)) {
info ("%s - actual: %d", __func__, actual_length);
tty_insert_flip_string(port->tty, data, actual_length);
tty_flip_buffer_push (port->tty);
} else {
err ("%s - inconsistent lengths %d:%d", __func__,
actual_length, length);
}
} else {
err ("%s - bad CRC %x", __func__, fcs);
}
} else {
tty_insert_flip_string(port->tty, data, length);
tty_flip_buffer_push (port->tty);
}
/* Continue trying to always read */
usb_fill_bulk_urb (urb, port->serial->dev,
usb_rcvbulkpipe (port->serial->dev, port->bulk_in_endpointAddress),
urb->transfer_buffer, urb->transfer_buffer_length,
safe_read_bulk_callback, port);
if ((result = usb_submit_urb (urb, GFP_ATOMIC))) {
err ("%s - failed resubmitting read urb, error %d", __func__, result);
/* FIXME: Need a mechanism to retry later if this happens */
}
}
static int safe_write (struct usb_serial_port *port, const unsigned char *buf, int count)
{
unsigned char *data;
int result;
int i;
int packet_length;
dbg ("safe_write port: %p %d urb: %p count: %d", port, port->number, port->write_urb,
count);
if (!port->write_urb) {
dbg ("%s - write urb NULL", __func__);
return 0;
}
dbg ("safe_write write_urb: %d transfer_buffer_length",
port->write_urb->transfer_buffer_length);
if (!port->write_urb->transfer_buffer_length) {
dbg ("%s - write urb transfer_buffer_length zero", __func__);
return 0;
}
if (count == 0) {
dbg ("%s - write request of 0 bytes", __func__);
return 0;
}
spin_lock_bh(&port->lock);
if (port->write_urb_busy) {
spin_unlock_bh(&port->lock);
dbg("%s - already writing", __func__);
return 0;
}
port->write_urb_busy = 1;
spin_unlock_bh(&port->lock);
packet_length = port->bulk_out_size; // get max packetsize
i = packet_length - (safe ? 2 : 0); // get bytes to send
count = (count > i) ? i : count;
// get the data into the transfer buffer
data = port->write_urb->transfer_buffer;
memset (data, '0', packet_length);
memcpy (data, buf, count);
if (safe) {
__u16 fcs;
// pad if necessary
if (!padded) {
packet_length = count + 2;
}
// set count
data[packet_length - 2] = count << 2;
data[packet_length - 1] = 0;
// compute fcs and insert into trailer
fcs = fcs_compute10 (data, packet_length, CRC10_INITFCS);
data[packet_length - 2] |= fcs >> 8;
data[packet_length - 1] |= fcs & 0xff;
// set length to send
port->write_urb->transfer_buffer_length = packet_length;
} else {
port->write_urb->transfer_buffer_length = count;
}
usb_serial_debug_data(debug, &port->dev, __func__, count, port->write_urb->transfer_buffer);
#ifdef ECHO_TX
{
int i;
unsigned char *cp = port->write_urb->transfer_buffer;
for (i = 0; i < port->write_urb->transfer_buffer_length; i++) {
if ((i % 32) == 0) {
printk ("\nsu[%02x] ", i);
}
printk ("%02x ", *cp++);
}
printk ("\n");
}
#endif
port->write_urb->dev = port->serial->dev;
if ((result = usb_submit_urb (port->write_urb, GFP_KERNEL))) {
port->write_urb_busy = 0;
err ("%s - failed submitting write urb, error %d", __func__, result);
return 0;
}
dbg ("%s urb: %p submitted", __func__, port->write_urb);
return (count);
}
static int safe_write_room (struct usb_serial_port *port)
{
int room = 0; /* Default: no room */
unsigned long flags;
dbg ("%s", __func__);
spin_lock_irqsave(&port->lock, flags);
if (port->write_urb_busy)
room = port->bulk_out_size - (safe ? 2 : 0);
spin_unlock_irqrestore(&port->lock, flags);
if (room) {
dbg ("safe_write_room returns %d", room);
}
return room;
}
static int safe_startup (struct usb_serial *serial)
{
switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) {
case LINEO_SAFESERIAL_CRC:
break;
case LINEO_SAFESERIAL_CRC_PADDED:
padded = 1;
break;
default:
return -EINVAL;
}
return 0;
}
static struct usb_serial_driver safe_device = {
.driver = {
.owner = THIS_MODULE,
.name = "safe_serial",
},
.id_table = id_table,
.usb_driver = &safe_driver,
.num_ports = 1,
.write = safe_write,
.write_room = safe_write_room,
.read_bulk_callback = safe_read_bulk_callback,
.attach = safe_startup,
};
static int __init safe_init (void)
{
int i, retval;
info (DRIVER_VERSION " " DRIVER_AUTHOR);
info (DRIVER_DESC);
info ("vendor: %x product: %x safe: %d padded: %d\n", vendor, product, safe, padded);
// if we have vendor / product parameters patch them into id list
if (vendor || product) {
info ("vendor: %x product: %x\n", vendor, product);
for (i = 0; i < ARRAY_SIZE(id_table); i++) {
if (!id_table[i].idVendor && !id_table[i].idProduct) {
id_table[i].idVendor = vendor;
id_table[i].idProduct = product;
break;
}
}
}
retval = usb_serial_register(&safe_device);
if (retval)
goto failed_usb_serial_register;
retval = usb_register(&safe_driver);
if (retval)
goto failed_usb_register;
return 0;
failed_usb_register:
usb_serial_deregister(&safe_device);
failed_usb_serial_register:
return retval;
}
static void __exit safe_exit (void)
{
usb_deregister (&safe_driver);
usb_serial_deregister (&safe_device);
}
module_init (safe_init);
module_exit (safe_exit);
