drivers/usb/serial/omninet.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * USB ZyXEL omni.net LCD PLUS driver
   4  *
   5  * Copyright (C) 2013,2017 Johan Hovold <johan@kernel.org>
   6  *
   7  * See Documentation/usb/usb-serial.rst for more information on using this
   8  * driver
   9  *
  10  * Please report both successes and troubles to the author at omninet@kroah.com
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/slab.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_driver.h>
  18 #include <linux/tty_flip.h>
  19 #include <linux/module.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/usb.h>
  22 #include <linux/usb/serial.h>
  23
  24 #define DRIVER_AUTHOR "Alessandro Zummo"
  25 #define DRIVER_DESC "USB ZyXEL omni.net LCD PLUS Driver"
  26
  27 #define ZYXEL_VENDOR_ID         0x0586
  28 #define ZYXEL_OMNINET_ID        0x1000
  29 /* This one seems to be a re-branded ZyXEL device */
  30 #define BT_IGNITIONPRO_ID       0x2000
  31
  32 /* function prototypes */
  33 static void omninet_process_read_urb(struct urb *urb);
  34 static int omninet_prepare_write_buffer(struct usb_serial_port *port,
  35                                 void *buf, size_t count);
  36 static int omninet_calc_num_ports(struct usb_serial *serial,
  37                                 struct usb_serial_endpoints *epds);
  38 static int omninet_port_probe(struct usb_serial_port *port);
  39 static int omninet_port_remove(struct usb_serial_port *port);
  40
  41 static const struct usb_device_id id_table[] = {
  42         { USB_DEVICE(ZYXEL_VENDOR_ID, ZYXEL_OMNINET_ID) },
  43         { USB_DEVICE(ZYXEL_VENDOR_ID, BT_IGNITIONPRO_ID) },
  44         { }                                             /* Terminating entry */
  45 };
  46 MODULE_DEVICE_TABLE(usb, id_table);
  47
  48 static struct usb_serial_driver zyxel_omninet_device = {
  49         .driver = {
  50                 .owner =        THIS_MODULE,
  51                 .name =         "omninet",
  52         },
  53         .description =          "ZyXEL - omni.net lcd plus usb",
  54         .id_table =             id_table,
  55         .num_bulk_out =         2,
  56         .calc_num_ports =       omninet_calc_num_ports,
  57         .port_probe =           omninet_port_probe,
  58         .port_remove =          omninet_port_remove,
  59         .process_read_urb =     omninet_process_read_urb,
  60         .prepare_write_buffer = omninet_prepare_write_buffer,
  61 };
  62
  63 static struct usb_serial_driver * const serial_drivers[] = {
  64         &zyxel_omninet_device, NULL
  65 };
  66
  67
  68 /*
  69  * The protocol.
  70  *
  71  * The omni.net always exchange 64 bytes of data with the host. The first
  72  * four bytes are the control header.
  73  *
  74  * oh_seq is a sequence number. Don't know if/how it's used.
  75  * oh_len is the length of the data bytes in the packet.
  76  * oh_xxx Bit-mapped, related to handshaking and status info.
  77  *      I normally set it to 0x03 in transmitted frames.
  78  *      7: Active when the TA is in a CONNECTed state.
  79  *      6: unknown
  80  *      5: handshaking, unknown
  81  *      4: handshaking, unknown
  82  *      3: unknown, usually 0
  83  *      2: unknown, usually 0
  84  *      1: handshaking, unknown, usually set to 1 in transmitted frames
  85  *      0: handshaking, unknown, usually set to 1 in transmitted frames
  86  * oh_pad Probably a pad byte.
  87  *
  88  * After the header you will find data bytes if oh_len was greater than zero.
  89  */
  90 struct omninet_header {
  91         __u8    oh_seq;
  92         __u8    oh_len;
  93         __u8    oh_xxx;
  94         __u8    oh_pad;
  95 };
  96
  97 struct omninet_data {
  98         __u8    od_outseq;      /* Sequence number for bulk_out URBs */
  99 };
 100
 101 static int omninet_calc_num_ports(struct usb_serial *serial,
 102                                         struct usb_serial_endpoints *epds)
 103 {
 104         /* We need only the second bulk-out for our single-port device. */
 105         epds->bulk_out[0] = epds->bulk_out[1];
 106         epds->num_bulk_out = 1;
 107
 108         return 1;
 109 }
 110
 111 static int omninet_port_probe(struct usb_serial_port *port)
 112 {
 113         struct omninet_data *od;
 114
 115         od = kzalloc(sizeof(*od), GFP_KERNEL);
 116         if (!od)
 117                 return -ENOMEM;
 118
 119         usb_set_serial_port_data(port, od);
 120
 121         return 0;
 122 }
 123
 124 static int omninet_port_remove(struct usb_serial_port *port)
 125 {
 126         struct omninet_data *od;
 127
 128         od = usb_get_serial_port_data(port);
 129         kfree(od);
 130
 131         return 0;
 132 }
 133
 134 #define OMNINET_HEADERLEN       4
 135 #define OMNINET_BULKOUTSIZE     64
 136 #define OMNINET_PAYLOADSIZE     (OMNINET_BULKOUTSIZE - OMNINET_HEADERLEN)
 137
 138 static void omninet_process_read_urb(struct urb *urb)
 139 {
 140         struct usb_serial_port *port = urb->context;
 141         const struct omninet_header *hdr = urb->transfer_buffer;
 142         const unsigned char *data;
 143         size_t data_len;
 144
 145         if (urb->actual_length <= OMNINET_HEADERLEN || !hdr->oh_len)
 146                 return;
 147
 148         data = (char *)urb->transfer_buffer + OMNINET_HEADERLEN;
 149         data_len = min_t(size_t, urb->actual_length - OMNINET_HEADERLEN,
 150                                                                 hdr->oh_len);
 151         tty_insert_flip_string(&port->port, data, data_len);
 152         tty_flip_buffer_push(&port->port);
 153 }
 154
 155 static int omninet_prepare_write_buffer(struct usb_serial_port *port,
 156                                         void *buf, size_t count)
 157 {
 158         struct omninet_data *od = usb_get_serial_port_data(port);
 159         struct omninet_header *header = buf;
 160
 161         count = min_t(size_t, count, OMNINET_PAYLOADSIZE);
 162
 163         count = kfifo_out_locked(&port->write_fifo, buf + OMNINET_HEADERLEN,
 164                         count, &port->lock);
 165
 166         header->oh_seq = od->od_outseq++;
 167         header->oh_len = count;
 168         header->oh_xxx = 0x03;
 169         header->oh_pad = 0x00;
 170
 171         /* always 64 bytes */
 172         return OMNINET_BULKOUTSIZE;
 173 }
 174
 175 module_usb_serial_driver(serial_drivers, id_table);
 176
 177 MODULE_AUTHOR(DRIVER_AUTHOR);
 178 MODULE_DESCRIPTION(DRIVER_DESC);
 179 MODULE_LICENSE("GPL v2");