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 * The device works as an standard CDC device, it has 2 interfaces, the first 9 * one is for firmware access and the second is the serial one. 10 * The protocol is very simply, there are two possibilities reading or writing. 11 * When writing the first urb must have a Header that starts with 0x20 0x29 the 12 * next two bytes must say how much data will be sent. 13 * When reading the process is almost equal except that the header starts with 14 * 0x00 0x20. 15 * 16 * The device simply need some stuff to understand data coming from the usb 17 * buffer: The First and Second byte is used for a Header, the Third and Fourth 18 * tells the device the amount of information the package holds. 19 * Packages are 60 bytes long Header Stuff. 20 * When writing to the device the first two bytes of the header are 0x20 0x29 21 * When reading the bytes are 0x00 0x20, or 0x00 0x10, there is an strange 22 * situation, when too much data arrives to the device because it sends the data 23 * but with out the header. I will use a simply hack to override this situation, 24 * if there is data coming that does not contain any header, then that is data 25 * that must go directly to the tty, as there is no documentation about if there 26 * is any other control code, I will simply check for the first 27 * one. 28 * 29 * I have taken some info from a Greg Kroah-Hartman article: 30 * http://www.linuxjournal.com/article/6573 31 * And from Linux Device Driver Kit CD, which is a great work, the authors taken 32 * the work to recompile lots of information an knowledge in drivers development 33 * and made it all available inside a cd. 34 * URL: http://kernel.org/pub/linux/kernel/people/gregkh/ddk/ 35 * 36 */ 37 38 #include <asm/unaligned.h> 39 #include <linux/tty.h> 40 #include <linux/slab.h> 41 #include <linux/module.h> 42 #include <linux/tty_flip.h> 43 #include <linux/usb.h> 44 #include <linux/usb/serial.h> 45 46 /* Vendor and Product ID */ 47 #define AIRCABLE_VID 0x16CA 48 #define AIRCABLE_USB_PID 0x1502 49 50 /* Protocol Stuff */ 51 #define HCI_HEADER_LENGTH 0x4 52 #define TX_HEADER_0 0x20 53 #define TX_HEADER_1 0x29 54 #define RX_HEADER_0 0x00 55 #define RX_HEADER_1 0x20 56 #define HCI_COMPLETE_FRAME 64 57 58 /* rx_flags */ 59 #define THROTTLED 0x01 60 #define ACTUALLY_THROTTLED 0x02 61 62 #define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>" 63 #define DRIVER_DESC "AIRcable USB Driver" 64 65 /* ID table that will be registered with USB core */ 66 static const struct usb_device_id id_table[] = { 67 { USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) }, 68 { }, 69 }; 70 MODULE_DEVICE_TABLE(usb, id_table); 71 72 static int aircable_prepare_write_buffer(struct usb_serial_port *port, 73 void *dest, size_t size) 74 { 75 int count; 76 unsigned char *buf = dest; 77 78 count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH, 79 size - HCI_HEADER_LENGTH, &port->lock); 80 buf[0] = TX_HEADER_0; 81 buf[1] = TX_HEADER_1; 82 put_unaligned_le16(count, &buf[2]); 83 84 return count + HCI_HEADER_LENGTH; 85 } 86 87 static int aircable_calc_num_ports(struct usb_serial *serial, 88 struct usb_serial_endpoints *epds) 89 { 90 /* Ignore the first interface, which has no bulk endpoints. */ 91 if (epds->num_bulk_out == 0) { 92 dev_dbg(&serial->interface->dev, 93 "ignoring interface with no bulk-out endpoints\n"); 94 return -ENODEV; 95 } 96 97 return 1; 98 } 99 100 static int aircable_process_packet(struct usb_serial_port *port, 101 int has_headers, char *packet, int len) 102 { 103 if (has_headers) { 104 len -= HCI_HEADER_LENGTH; 105 packet += HCI_HEADER_LENGTH; 106 } 107 if (len <= 0) { 108 dev_dbg(&port->dev, "%s - malformed packet\n", __func__); 109 return 0; 110 } 111 112 tty_insert_flip_string(&port->port, packet, len); 113 114 return len; 115 } 116 117 static void aircable_process_read_urb(struct urb *urb) 118 { 119 struct usb_serial_port *port = urb->context; 120 char *data = urb->transfer_buffer; 121 int has_headers; 122 int count; 123 int len; 124 int i; 125 126 has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0); 127 128 count = 0; 129 for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) { 130 len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME); 131 count += aircable_process_packet(port, has_headers, 132 &data[i], len); 133 } 134 135 if (count) 136 tty_flip_buffer_push(&port->port); 137 } 138 139 static struct usb_serial_driver aircable_device = { 140 .driver = { 141 .owner = THIS_MODULE, 142 .name = "aircable", 143 }, 144 .id_table = id_table, 145 .bulk_out_size = HCI_COMPLETE_FRAME, 146 .calc_num_ports = aircable_calc_num_ports, 147 .process_read_urb = aircable_process_read_urb, 148 .prepare_write_buffer = aircable_prepare_write_buffer, 149 .throttle = usb_serial_generic_throttle, 150 .unthrottle = usb_serial_generic_unthrottle, 151 }; 152 153 static struct usb_serial_driver * const serial_drivers[] = { 154 &aircable_device, NULL 155 }; 156 157 module_usb_serial_driver(serial_drivers, id_table); 158 159 MODULE_AUTHOR(DRIVER_AUTHOR); 160 MODULE_DESCRIPTION(DRIVER_DESC); 161 MODULE_LICENSE("GPL v2"); 162