1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * AIRcable USB Bluetooth Dongle Driver. 4 * 5 * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com> 6 * Copyright (C) 2006 Manuel Francisco Naranjo (naranjo.manuel@gmail.com) 7 * 8 * This program is free software; you can redistribute it and/or modify it under 9 * the terms of the GNU General Public License version 2 as published by the 10 * Free Software Foundation. 11 * 12 * The device works as an standard CDC device, it has 2 interfaces, the first 13 * one is for firmware access and the second is the serial one. 14 * The protocol is very simply, there are two possibilities reading or writing. 15 * When writing the first urb must have a Header that starts with 0x20 0x29 the 16 * next two bytes must say how much data will be sent. 17 * When reading the process is almost equal except that the header starts with 18 * 0x00 0x20. 19 * 20 * The device simply need some stuff to understand data coming from the usb 21 * buffer: The First and Second byte is used for a Header, the Third and Fourth 22 * tells the device the amount of information the package holds. 23 * Packages are 60 bytes long Header Stuff. 24 * When writing to the device the first two bytes of the header are 0x20 0x29 25 * When reading the bytes are 0x00 0x20, or 0x00 0x10, there is an strange 26 * situation, when too much data arrives to the device because it sends the data 27 * but with out the header. I will use a simply hack to override this situation, 28 * if there is data coming that does not contain any header, then that is data 29 * that must go directly to the tty, as there is no documentation about if there 30 * is any other control code, I will simply check for the first 31 * one. 32 * 33 * I have taken some info from a Greg Kroah-Hartman article: 34 * http://www.linuxjournal.com/article/6573 35 * And from Linux Device Driver Kit CD, which is a great work, the authors taken 36 * the work to recompile lots of information an knowledge in drivers development 37 * and made it all available inside a cd. 38 * URL: http://kernel.org/pub/linux/kernel/people/gregkh/ddk/ 39 * 40 */ 41 42 #include <asm/unaligned.h> 43 #include <linux/tty.h> 44 #include <linux/slab.h> 45 #include <linux/module.h> 46 #include <linux/tty_flip.h> 47 #include <linux/usb.h> 48 #include <linux/usb/serial.h> 49 50 /* Vendor and Product ID */ 51 #define AIRCABLE_VID 0x16CA 52 #define AIRCABLE_USB_PID 0x1502 53 54 /* Protocol Stuff */ 55 #define HCI_HEADER_LENGTH 0x4 56 #define TX_HEADER_0 0x20 57 #define TX_HEADER_1 0x29 58 #define RX_HEADER_0 0x00 59 #define RX_HEADER_1 0x20 60 #define HCI_COMPLETE_FRAME 64 61 62 /* rx_flags */ 63 #define THROTTLED 0x01 64 #define ACTUALLY_THROTTLED 0x02 65 66 #define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>" 67 #define DRIVER_DESC "AIRcable USB Driver" 68 69 /* ID table that will be registered with USB core */ 70 static const struct usb_device_id id_table[] = { 71 { USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) }, 72 { }, 73 }; 74 MODULE_DEVICE_TABLE(usb, id_table); 75 76 static int aircable_prepare_write_buffer(struct usb_serial_port *port, 77 void *dest, size_t size) 78 { 79 int count; 80 unsigned char *buf = dest; 81 82 count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH, 83 size - HCI_HEADER_LENGTH, &port->lock); 84 buf[0] = TX_HEADER_0; 85 buf[1] = TX_HEADER_1; 86 put_unaligned_le16(count, &buf[2]); 87 88 return count + HCI_HEADER_LENGTH; 89 } 90 91 static int aircable_calc_num_ports(struct usb_serial *serial, 92 struct usb_serial_endpoints *epds) 93 { 94 /* Ignore the first interface, which has no bulk endpoints. */ 95 if (epds->num_bulk_out == 0) { 96 dev_dbg(&serial->interface->dev, 97 "ignoring interface with no bulk-out endpoints\n"); 98 return -ENODEV; 99 } 100 101 return 1; 102 } 103 104 static int aircable_process_packet(struct usb_serial_port *port, 105 int has_headers, char *packet, int len) 106 { 107 if (has_headers) { 108 len -= HCI_HEADER_LENGTH; 109 packet += HCI_HEADER_LENGTH; 110 } 111 if (len <= 0) { 112 dev_dbg(&port->dev, "%s - malformed packet\n", __func__); 113 return 0; 114 } 115 116 tty_insert_flip_string(&port->port, packet, len); 117 118 return len; 119 } 120 121 static void aircable_process_read_urb(struct urb *urb) 122 { 123 struct usb_serial_port *port = urb->context; 124 char *data = (char *)urb->transfer_buffer; 125 int has_headers; 126 int count; 127 int len; 128 int i; 129 130 has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0); 131 132 count = 0; 133 for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) { 134 len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME); 135 count += aircable_process_packet(port, has_headers, 136 &data[i], len); 137 } 138 139 if (count) 140 tty_flip_buffer_push(&port->port); 141 } 142 143 static struct usb_serial_driver aircable_device = { 144 .driver = { 145 .owner = THIS_MODULE, 146 .name = "aircable", 147 }, 148 .id_table = id_table, 149 .bulk_out_size = HCI_COMPLETE_FRAME, 150 .calc_num_ports = aircable_calc_num_ports, 151 .process_read_urb = aircable_process_read_urb, 152 .prepare_write_buffer = aircable_prepare_write_buffer, 153 .throttle = usb_serial_generic_throttle, 154 .unthrottle = usb_serial_generic_unthrottle, 155 }; 156 157 static struct usb_serial_driver * const serial_drivers[] = { 158 &aircable_device, NULL 159 }; 160 161 module_usb_serial_driver(serial_drivers, id_table); 162 163 MODULE_AUTHOR(DRIVER_AUTHOR); 164 MODULE_DESCRIPTION(DRIVER_DESC); 165 MODULE_LICENSE("GPL"); 166