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301 lines
9.7 KiB
301 lines
9.7 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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/* |
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* Safe Encapsulated USB Serial Driver |
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* |
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* Copyright (C) 2010 Johan Hovold <[email protected]> |
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* Copyright (C) 2001 Lineo |
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* Copyright (C) 2001 Hewlett-Packard |
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* |
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* By: |
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* Stuart Lynne <[email protected]>, Tom Rushworth <[email protected]> |
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*/ |
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/* |
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* The encapsultaion is designed to overcome difficulties with some USB |
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* hardware. |
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* |
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* While the USB protocol has a CRC over the data while in transit, i.e. while |
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* being carried over the bus, there is no end to end protection. If the |
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* hardware has any problems getting the data into or out of the USB transmit |
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* and receive FIFO's then data can be lost. |
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* |
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* This protocol adds a two byte trailer to each USB packet to specify the |
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* number of bytes of valid data and a 10 bit CRC that will allow the receiver |
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* to verify that the entire USB packet was received without error. |
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* |
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* Because in this case the sender and receiver are the class and function |
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* drivers there is now end to end protection. |
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* |
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* There is an additional option that can be used to force all transmitted |
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* packets to be padded to the maximum packet size. This provides a work |
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* around for some devices which have problems with small USB packets. |
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* |
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* Assuming a packetsize of N: |
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* |
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* 0..N-2 data and optional padding |
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* |
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* N-2 bits 7-2 - number of bytes of valid data |
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* bits 1-0 top two bits of 10 bit CRC |
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* N-1 bottom 8 bits of 10 bit CRC |
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* |
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* |
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* | Data Length | 10 bit CRC | |
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* + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 | 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 + |
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* |
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* The 10 bit CRC is computed across the sent data, followed by the trailer |
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* with the length set and the CRC set to zero. The CRC is then OR'd into |
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* the trailer. |
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* |
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* When received a 10 bit CRC is computed over the entire frame including |
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* the trailer and should be equal to zero. |
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* |
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* Two module parameters are used to control the encapsulation, if both are |
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* turned of the module works as a simple serial device with NO |
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* encapsulation. |
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* |
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* See linux/drivers/usbd/serial_fd for a device function driver |
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* implementation of this. |
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* |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/kernel.h> |
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#include <linux/errno.h> |
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#include <linux/gfp.h> |
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#include <linux/tty.h> |
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#include <linux/tty_driver.h> |
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#include <linux/tty_flip.h> |
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#include <linux/module.h> |
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#include <linux/spinlock.h> |
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#include <linux/uaccess.h> |
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#include <linux/usb.h> |
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#include <linux/usb/serial.h> |
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static bool safe = true; |
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static bool padded = IS_ENABLED(CONFIG_USB_SERIAL_SAFE_PADDED); |
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#define DRIVER_AUTHOR "[email protected], [email protected], Johan Hovold <[email protected]>" |
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#define DRIVER_DESC "USB Safe Encapsulated Serial" |
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MODULE_AUTHOR(DRIVER_AUTHOR); |
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MODULE_DESCRIPTION(DRIVER_DESC); |
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MODULE_LICENSE("GPL"); |
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module_param(safe, bool, 0); |
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MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off"); |
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module_param(padded, bool, 0); |
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MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off"); |
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#define CDC_DEVICE_CLASS 0x02 |
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#define CDC_INTERFACE_CLASS 0x02 |
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#define CDC_INTERFACE_SUBCLASS 0x06 |
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#define LINEO_INTERFACE_CLASS 0xff |
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#define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01 |
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#define LINEO_SAFENET_CRC 0x01 |
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#define LINEO_SAFENET_CRC_PADDED 0x02 |
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#define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02 |
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#define LINEO_SAFESERIAL_CRC 0x01 |
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#define LINEO_SAFESERIAL_CRC_PADDED 0x02 |
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#define MY_USB_DEVICE(vend, prod, dc, ic, isc) \ |
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.match_flags = USB_DEVICE_ID_MATCH_DEVICE | \ |
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USB_DEVICE_ID_MATCH_DEV_CLASS | \ |
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USB_DEVICE_ID_MATCH_INT_CLASS | \ |
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USB_DEVICE_ID_MATCH_INT_SUBCLASS, \ |
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.idVendor = (vend), \ |
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.idProduct = (prod),\ |
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.bDeviceClass = (dc),\ |
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.bInterfaceClass = (ic), \ |
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.bInterfaceSubClass = (isc), |
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static const struct usb_device_id id_table[] = { |
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{MY_USB_DEVICE(0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Itsy */ |
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{MY_USB_DEVICE(0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Calypso */ |
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{MY_USB_DEVICE(0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Iris */ |
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{MY_USB_DEVICE(0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */ |
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{MY_USB_DEVICE(0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */ |
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{MY_USB_DEVICE(0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */ |
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{MY_USB_DEVICE(0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Sharp tmp */ |
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{} /* terminating entry */ |
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}; |
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MODULE_DEVICE_TABLE(usb, id_table); |
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static const __u16 crc10_table[256] = { |
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0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff, |
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0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe, |
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0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce, |
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0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf, |
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0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d, |
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0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c, |
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0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac, |
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0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad, |
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0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b, |
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0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a, |
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0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a, |
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0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b, |
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0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259, |
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0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158, |
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0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268, |
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0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169, |
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0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377, |
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0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076, |
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0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346, |
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0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047, |
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0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315, |
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0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014, |
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0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324, |
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0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025, |
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0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3, |
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0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2, |
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0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382, |
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0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083, |
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0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1, |
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0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0, |
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0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0, |
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0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1, |
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}; |
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#define CRC10_INITFCS 0x000 /* Initial FCS value */ |
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#define CRC10_GOODFCS 0x000 /* Good final FCS value */ |
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#define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c)) |
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/** |
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* fcs_compute10 - memcpy and calculate 10 bit CRC across buffer |
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* @sp: pointer to buffer |
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* @len: number of bytes |
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* @fcs: starting FCS |
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* |
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* Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return |
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* new 10 bit FCS. |
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*/ |
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static inline __u16 fcs_compute10(unsigned char *sp, int len, __u16 fcs) |
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{ |
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for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++)); |
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return fcs; |
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} |
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static void safe_process_read_urb(struct urb *urb) |
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{ |
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struct usb_serial_port *port = urb->context; |
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unsigned char *data = urb->transfer_buffer; |
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unsigned char length = urb->actual_length; |
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int actual_length; |
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__u16 fcs; |
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if (!length) |
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return; |
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if (!safe) |
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goto out; |
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if (length < 2) { |
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dev_err(&port->dev, "malformed packet\n"); |
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return; |
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} |
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fcs = fcs_compute10(data, length, CRC10_INITFCS); |
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if (fcs) { |
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dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs); |
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return; |
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} |
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actual_length = data[length - 2] >> 2; |
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if (actual_length > (length - 2)) { |
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dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n", |
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__func__, actual_length, length); |
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return; |
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} |
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dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length); |
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length = actual_length; |
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out: |
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tty_insert_flip_string(&port->port, data, length); |
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tty_flip_buffer_push(&port->port); |
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} |
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static int safe_prepare_write_buffer(struct usb_serial_port *port, |
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void *dest, size_t size) |
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{ |
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unsigned char *buf = dest; |
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int count; |
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int trailer_len; |
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int pkt_len; |
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__u16 fcs; |
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trailer_len = safe ? 2 : 0; |
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count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len, |
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&port->lock); |
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if (!safe) |
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return count; |
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/* pad if necessary */ |
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if (padded) { |
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pkt_len = size; |
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memset(buf + count, '0', pkt_len - count - trailer_len); |
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} else { |
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pkt_len = count + trailer_len; |
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} |
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/* set count */ |
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buf[pkt_len - 2] = count << 2; |
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buf[pkt_len - 1] = 0; |
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/* compute fcs and insert into trailer */ |
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fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS); |
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buf[pkt_len - 2] |= fcs >> 8; |
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buf[pkt_len - 1] |= fcs & 0xff; |
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return pkt_len; |
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} |
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static int safe_startup(struct usb_serial *serial) |
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{ |
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struct usb_interface_descriptor *desc; |
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if (serial->dev->descriptor.bDeviceClass != CDC_DEVICE_CLASS) |
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return -ENODEV; |
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desc = &serial->interface->cur_altsetting->desc; |
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if (desc->bInterfaceClass != LINEO_INTERFACE_CLASS) |
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return -ENODEV; |
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if (desc->bInterfaceSubClass != LINEO_INTERFACE_SUBCLASS_SAFESERIAL) |
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return -ENODEV; |
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switch (desc->bInterfaceProtocol) { |
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case LINEO_SAFESERIAL_CRC: |
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break; |
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case LINEO_SAFESERIAL_CRC_PADDED: |
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padded = true; |
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break; |
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default: |
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return -EINVAL; |
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} |
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return 0; |
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} |
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static struct usb_serial_driver safe_device = { |
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.driver = { |
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.owner = THIS_MODULE, |
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.name = "safe_serial", |
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}, |
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.id_table = id_table, |
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.num_ports = 1, |
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.process_read_urb = safe_process_read_urb, |
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.prepare_write_buffer = safe_prepare_write_buffer, |
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.attach = safe_startup, |
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}; |
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static struct usb_serial_driver * const serial_drivers[] = { |
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&safe_device, NULL |
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}; |
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module_usb_serial_driver(serial_drivers, id_table);
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