[deliverable/linux.git] / drivers / usb / serial / safe_serial.c

/*
 * Safe Encapsulated USB Serial Driver
 *
 *      Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
 *      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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/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 bool safe = 1;
static bool padded = CONFIG_USB_SERIAL_SAFE_PADDED;

#define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com, Johan Hovold <jhovold@gmail.com>"
#define DRIVER_DESC "USB Safe Encapsulated Serial"

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

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 */
	{}			/* terminating entry  */
};

MODULE_DEVICE_TABLE(usb, id_table);

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_process_read_urb(struct urb *urb)
{
	struct usb_serial_port *port = urb->context;
	unsigned char *data = urb->transfer_buffer;
	unsigned char length = urb->actual_length;
	int actual_length;
	__u16 fcs;

	if (!length)
		return;

	if (!safe)
		goto out;

	fcs = fcs_compute10(data, length, CRC10_INITFCS);
	if (fcs) {
		dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);
		return;
	}

	actual_length = data[length - 2] >> 2;
	if (actual_length > (length - 2)) {
		dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n",
				__func__, actual_length, length);
		return;
	}
	dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length);
	length = actual_length;
out:
	tty_insert_flip_string(&port->port, data, length);
	tty_flip_buffer_push(&port->port);
}

static int safe_prepare_write_buffer(struct usb_serial_port *port,
						void *dest, size_t size)
{
	unsigned char *buf = dest;
	int count;
	int trailer_len;
	int pkt_len;
	__u16 fcs;

	trailer_len = safe ? 2 : 0;

	count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len,
								&port->lock);
	if (!safe)
		return count;

	/* pad if necessary */
	if (padded) {
		pkt_len = size;
		memset(buf + count, '0', pkt_len - count - trailer_len);
	} else {
		pkt_len = count + trailer_len;
	}

	/* set count */
	buf[pkt_len - 2] = count << 2;
	buf[pkt_len - 1] = 0;

	/* compute fcs and insert into trailer */
	fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS);
	buf[pkt_len - 2] |= fcs >> 8;
	buf[pkt_len - 1] |= fcs & 0xff;

	return pkt_len;
}

static int safe_startup(struct usb_serial *serial)
{
	struct usb_interface_descriptor	*desc;

	if (serial->dev->descriptor.bDeviceClass != CDC_DEVICE_CLASS)
		return -ENODEV;

	desc = &serial->interface->cur_altsetting->desc;

	if (desc->bInterfaceClass != LINEO_INTERFACE_CLASS)
		return -ENODEV;
	if (desc->bInterfaceSubClass != LINEO_INTERFACE_SUBCLASS_SAFESERIAL)
		return -ENODEV;

	switch (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,
	.num_ports =		1,
	.process_read_urb =	safe_process_read_urb,
	.prepare_write_buffer =	safe_prepare_write_buffer,
	.attach =		safe_startup,
};

static struct usb_serial_driver * const serial_drivers[] = {
	&safe_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Safe Encapsulated USB Serial Driver
	3	*
241c80ea	4	* Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
1da177e4 LT	5	* Copyright (C) 2001 Lineo
	6	* Copyright (C) 2001 Hewlett-Packard
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2 of the License, or
	11	* (at your option) any later version.
	12	*
	13	* By:
	14	* Stuart Lynne <sl@lineo.com>, Tom Rushworth <tbr@lineo.com>
	15	*/
	16
43c8f435 AC	17	/*
	18	* The encapsultaion is designed to overcome difficulties with some USB
	19	* hardware.
1da177e4 LT	20	*
1da177e4 LT	21	* While the USB protocol has a CRC over the data while in transit, i.e. while
43c8f435 AC	22	* being carried over the bus, there is no end to end protection. If the
	23	* hardware has any problems getting the data into or out of the USB transmit
	24	* and receive FIFO's then data can be lost.
1da177e4	25	*
43c8f435 AC	26	* This protocol adds a two byte trailer to each USB packet to specify the
	27	* number of bytes of valid data and a 10 bit CRC that will allow the receiver
	28	* to verify that the entire USB packet was received without error.
1da177e4	29	*
43c8f435 AC	30	* Because in this case the sender and receiver are the class and function
43c8f435 AC	31	* drivers there is now end to end protection.
1da177e4	32	*
43c8f435 AC	33	* There is an additional option that can be used to force all transmitted
	34	* packets to be padded to the maximum packet size. This provides a work
	35	* around for some devices which have problems with small USB packets.
1da177e4 LT	36	*
	37	* Assuming a packetsize of N:
	38	*
	39	* 0..N-2 data and optional padding
	40	*
	41	* N-2 bits 7-2 - number of bytes of valid data
	42	* bits 1-0 top two bits of 10 bit CRC
	43	* N-1 bottom 8 bits of 10 bit CRC
	44	*
	45	*
	46	* \| Data Length \| 10 bit CRC \|
	47	* + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 \| 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 +
	48	*
43c8f435 AC	49	* The 10 bit CRC is computed across the sent data, followed by the trailer
	50	* with the length set and the CRC set to zero. The CRC is then OR'd into
	51	* the trailer.
1da177e4	52	*
43c8f435 AC	53	* When received a 10 bit CRC is computed over the entire frame including
43c8f435 AC	54	* the trailer and should be equal to zero.
1da177e4 LT	55	*
	56	* Two module parameters are used to control the encapsulation, if both are
	57	* turned of the module works as a simple serial device with NO
	58	* encapsulation.
	59	*
	60	* See linux/drivers/usbd/serial_fd for a device function driver
	61	* implementation of this.
	62	*
	63	*/
	64
93ba0f03	65	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
1da177e4	66
1da177e4 LT	67	#include <linux/kernel.h>
1da177e4 LT	68	#include <linux/errno.h>
5a0e3ad6	69	#include <linux/gfp.h>
1da177e4	70	#include <linux/init.h>
1da177e4 LT	71	#include <linux/tty.h>
	72	#include <linux/tty_driver.h>
	73	#include <linux/tty_flip.h>
	74	#include <linux/module.h>
	75	#include <linux/spinlock.h>
43c8f435	76	#include <linux/uaccess.h>
1da177e4	77	#include <linux/usb.h>
a969888c	78	#include <linux/usb/serial.h>
1da177e4 LT	79
1da177e4 LT	80
3aec6e26 RD	81	#ifndef CONFIG_USB_SERIAL_SAFE_PADDED
3aec6e26 RD	82	#define CONFIG_USB_SERIAL_SAFE_PADDED 0
1da177e4 LT	83	#endif
1da177e4 LT	84
90ab5ee9 RR	85	static bool safe = 1;
90ab5ee9 RR	86	static bool padded = CONFIG_USB_SERIAL_SAFE_PADDED;
1da177e4	87
241c80ea	88	#define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com, Johan Hovold <jhovold@gmail.com>"
1da177e4 LT	89	#define DRIVER_DESC "USB Safe Encapsulated Serial"
1da177e4 LT	90
43c8f435 AC	91	MODULE_AUTHOR(DRIVER_AUTHOR);
43c8f435 AC	92	MODULE_DESCRIPTION(DRIVER_DESC);
1da177e4 LT	93	MODULE_LICENSE("GPL");
1da177e4 LT	94
1da177e4 LT	95	module_param(safe, bool, 0);
	96	MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
	97
	98	module_param(padded, bool, 0);
	99	MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
	100
	101	#define CDC_DEVICE_CLASS 0x02
	102
	103	#define CDC_INTERFACE_CLASS 0x02
	104	#define CDC_INTERFACE_SUBCLASS 0x06
	105
	106	#define LINEO_INTERFACE_CLASS 0xff
	107
	108	#define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01
	109	#define LINEO_SAFENET_CRC 0x01
	110	#define LINEO_SAFENET_CRC_PADDED 0x02
	111
	112	#define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02
	113	#define LINEO_SAFESERIAL_CRC 0x01
	114	#define LINEO_SAFESERIAL_CRC_PADDED 0x02
	115
	116
43c8f435 AC	117	#define MY_USB_DEVICE(vend, prod, dc, ic, isc) \
	118	.match_flags = USB_DEVICE_ID_MATCH_DEVICE \| \
	119	USB_DEVICE_ID_MATCH_DEV_CLASS \| \
	120	USB_DEVICE_ID_MATCH_INT_CLASS \| \
	121	USB_DEVICE_ID_MATCH_INT_SUBCLASS, \
	122	.idVendor = (vend), \
	123	.idProduct = (prod),\
	124	.bDeviceClass = (dc),\
	125	.bInterfaceClass = (ic), \
	126	.bInterfaceSubClass = (isc),
1da177e4 LT	127
1da177e4 LT	128	static struct usb_device_id id_table[] = {
43c8f435 AC	129	{MY_USB_DEVICE(0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Itsy */
	130	{MY_USB_DEVICE(0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Calypso */
	131	{MY_USB_DEVICE(0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Iris */
	132	{MY_USB_DEVICE(0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
	133	{MY_USB_DEVICE(0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
	134	{MY_USB_DEVICE(0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
	135	{MY_USB_DEVICE(0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Sharp tmp */
43c8f435	136	{} /* terminating entry */
1da177e4 LT	137	};
1da177e4 LT	138
43c8f435	139	MODULE_DEVICE_TABLE(usb, id_table);
1da177e4	140
4c4c9432	141	static const __u16 crc10_table[256] = {
43c8f435 AC	142	0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff,
	143	0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
	144	0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce,
	145	0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
	146	0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d,
	147	0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
	148	0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac,
	149	0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
	150	0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b,
	151	0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
	152	0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a,
	153	0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
	154	0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259,
	155	0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
	156	0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268,
	157	0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
	158	0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377,
	159	0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
	160	0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346,
	161	0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
	162	0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315,
	163	0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
	164	0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324,
	165	0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
	166	0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3,
	167	0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
	168	0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382,
	169	0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
	170	0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1,
	171	0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
	172	0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0,
	173	0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
1da177e4 LT	174	};
1da177e4 LT	175
43c8f435 AC	176	#define CRC10_INITFCS 0x000 /* Initial FCS value */
	177	#define CRC10_GOODFCS 0x000 /* Good final FCS value */
	178	#define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
1da177e4	179
43c8f435	180	/**
1da177e4 LT	181	* fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
	182	* @sp: pointer to buffer
	183	* @len: number of bytes
	184	* @fcs: starting FCS
	185	*
	186	* Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
	187	* new 10 bit FCS.
	188	*/
43c8f435	189	static __u16 __inline__ fcs_compute10(unsigned char *sp, int len, __u16 fcs)
1da177e4	190	{
43c8f435	191	for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++));
1da177e4 LT	192	return fcs;
	193	}
	194
12e2e52c	195	static void safe_process_read_urb(struct urb *urb)
1da177e4	196	{
12e2e52c	197	struct usb_serial_port *port = urb->context;
1da177e4 LT	198	unsigned char *data = urb->transfer_buffer;
1da177e4 LT	199	unsigned char length = urb->actual_length;
6d1bf48e	200	int actual_length;
6d1bf48e	201	__u16 fcs;
1da177e4	202
12e2e52c	203	if (!length)
1da177e4	204	return;
1da177e4	205
6d1bf48e JH	206	if (!safe)
	207	goto out;
	208
	209	fcs = fcs_compute10(data, length, CRC10_INITFCS);
	210	if (fcs) {
	211	dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);
2e124b4a	212	return;
1da177e4 LT	213	}
1da177e4 LT	214
6d1bf48e JH	215	actual_length = data[length - 2] >> 2;
	216	if (actual_length > (length - 2)) {
	217	dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n",
	218	__func__, actual_length, length);
2e124b4a	219	return;
6d1bf48e JH	220	}
	221	dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length);
	222	length = actual_length;
	223	out:
05c7cd39	224	tty_insert_flip_string(&port->port, data, length);
2e124b4a	225	tty_flip_buffer_push(&port->port);
1da177e4 LT	226	}
1da177e4 LT	227
241c80ea JH	228	static int safe_prepare_write_buffer(struct usb_serial_port *port,
241c80ea JH	229	void *dest, size_t size)
1da177e4	230	{
241c80ea JH	231	unsigned char *buf = dest;
	232	int count;
	233	int trailer_len;
	234	int pkt_len;
	235	__u16 fcs;
	236
	237	trailer_len = safe ? 2 : 0;
	238
	239	count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len,
	240	&port->lock);
	241	if (!safe)
	242	return count;
	243
	244	/* pad if necessary */
	245	if (padded) {
	246	pkt_len = size;
	247	memset(buf + count, '0', pkt_len - count - trailer_len);
1da177e4	248	} else {
241c80ea	249	pkt_len = count + trailer_len;
1da177e4	250	}
1da177e4	251
241c80ea JH	252	/* set count */
	253	buf[pkt_len - 2] = count << 2;
	254	buf[pkt_len - 1] = 0;
1da177e4	255
241c80ea JH	256	/* compute fcs and insert into trailer */
	257	fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS);
	258	buf[pkt_len - 2] \|= fcs >> 8;
	259	buf[pkt_len - 1] \|= fcs & 0xff;
1da177e4	260
241c80ea	261	return pkt_len;
1da177e4 LT	262	}
1da177e4 LT	263
43c8f435	264	static int safe_startup(struct usb_serial *serial)
1da177e4	265	{
8b61d927 JH	266	struct usb_interface_descriptor *desc;
	267
	268	if (serial->dev->descriptor.bDeviceClass != CDC_DEVICE_CLASS)
	269	return -ENODEV;
	270
	271	desc = &serial->interface->cur_altsetting->desc;
	272
	273	if (desc->bInterfaceClass != LINEO_INTERFACE_CLASS)
	274	return -ENODEV;
	275	if (desc->bInterfaceSubClass != LINEO_INTERFACE_SUBCLASS_SAFESERIAL)
	276	return -ENODEV;
	277
	278	switch (desc->bInterfaceProtocol) {
1da177e4 LT	279	case LINEO_SAFESERIAL_CRC:
	280	break;
	281	case LINEO_SAFESERIAL_CRC_PADDED:
	282	padded = 1;
	283	break;
	284	default:
	285	return -EINVAL;
	286	}
	287	return 0;
	288	}
	289
ea65370d	290	static struct usb_serial_driver safe_device = {
18fcac35 GKH	291	.driver = {
18fcac35 GKH	292	.owner = THIS_MODULE,
269bda1c	293	.name = "safe_serial",
18fcac35	294	},
1da177e4	295	.id_table = id_table,
1da177e4	296	.num_ports = 1,
12e2e52c	297	.process_read_urb = safe_process_read_urb,
241c80ea	298	.prepare_write_buffer = safe_prepare_write_buffer,
1da177e4 LT	299	.attach = safe_startup,
	300	};
	301
d860322f AS	302	static struct usb_serial_driver * const serial_drivers[] = {
	303	&safe_device, NULL
	304	};
	305
8b61d927	306	module_usb_serial_driver(serial_drivers, id_table);