root/drivers/net/usb/gl620a.c

DEFINITIONS

1. genelink_rx_fixup
2. genelink_tx_fixup
3. genelink_bind

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * GeneSys GL620USB-A based links
   4  * Copyright (C) 2001 by Jiun-Jie Huang <huangjj@genesyslogic.com.tw>
   5  * Copyright (C) 2001 by Stanislav Brabec <utx@penguin.cz>
   6  */
   7 
   8 // #define      DEBUG                   // error path messages, extra info
   9 // #define      VERBOSE                 // more; success messages
  10 
  11 #include <linux/module.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/ethtool.h>
  15 #include <linux/workqueue.h>
  16 #include <linux/mii.h>
  17 #include <linux/usb.h>
  18 #include <linux/usb/usbnet.h>
  19 #include <linux/gfp.h>
  20 
  21 
  22 /*
  23  * GeneSys GL620USB-A (www.genesyslogic.com.tw)
  24  *
  25  * ... should partially interop with the Win32 driver for this hardware.
  26  * The GeneSys docs imply there's some NDIS issue motivating this framing.
  27  *
  28  * Some info from GeneSys:
  29  *  - GL620USB-A is full duplex; GL620USB is only half duplex for bulk.
  30  *    (Some cables, like the BAFO-100c, use the half duplex version.)
  31  *  - For the full duplex model, the low bit of the version code says
  32  *    which side is which ("left/right").
  33  *  - For the half duplex type, a control/interrupt handshake settles
  34  *    the transfer direction.  (That's disabled here, partially coded.)
  35  *    A control URB would block until other side writes an interrupt.
  36  *
  37  * Original code from Jiun-Jie Huang <huangjj@genesyslogic.com.tw>
  38  * and merged into "usbnet" by Stanislav Brabec <utx@penguin.cz>.
  39  */
  40 
  41 // control msg write command
  42 #define GENELINK_CONNECT_WRITE                  0xF0
  43 // interrupt pipe index
  44 #define GENELINK_INTERRUPT_PIPE                 0x03
  45 // interrupt read buffer size
  46 #define INTERRUPT_BUFSIZE                       0x08
  47 // interrupt pipe interval value
  48 #define GENELINK_INTERRUPT_INTERVAL             0x10
  49 // max transmit packet number per transmit
  50 #define GL_MAX_TRANSMIT_PACKETS                 32
  51 // max packet length
  52 #define GL_MAX_PACKET_LEN                       1514
  53 // max receive buffer size
  54 #define GL_RCV_BUF_SIZE         \
  55         (((GL_MAX_PACKET_LEN + 4) * GL_MAX_TRANSMIT_PACKETS) + 4)
  56 
  57 struct gl_packet {
  58         __le32          packet_length;
  59         char            packet_data [1];
  60 };
  61 
  62 struct gl_header {
  63         __le32                  packet_count;
  64         struct gl_packet        packets;
  65 };
  66 
  67 static int genelink_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
  68 {
  69         struct gl_header        *header;
  70         struct gl_packet        *packet;
  71         struct sk_buff          *gl_skb;
  72         u32                     size;
  73         u32                     count;
  74 
  75         /* This check is no longer done by usbnet */
  76         if (skb->len < dev->net->hard_header_len)
  77                 return 0;
  78 
  79         header = (struct gl_header *) skb->data;
  80 
  81         // get the packet count of the received skb
  82         count = le32_to_cpu(header->packet_count);
  83         if (count > GL_MAX_TRANSMIT_PACKETS) {
  84                 netdev_dbg(dev->net,
  85                            "genelink: invalid received packet count %u\n",
  86                            count);
  87                 return 0;
  88         }
  89 
  90         // set the current packet pointer to the first packet
  91         packet = &header->packets;
  92 
  93         // decrement the length for the packet count size 4 bytes
  94         skb_pull(skb, 4);
  95 
  96         while (count > 1) {
  97                 // get the packet length
  98                 size = le32_to_cpu(packet->packet_length);
  99 
 100                 // this may be a broken packet
 101                 if (size > GL_MAX_PACKET_LEN) {
 102                         netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
 103                                    size);
 104                         return 0;
 105                 }
 106 
 107                 // allocate the skb for the individual packet
 108                 gl_skb = alloc_skb(size, GFP_ATOMIC);
 109                 if (gl_skb) {
 110 
 111                         // copy the packet data to the new skb
 112                         skb_put_data(gl_skb, packet->packet_data, size);
 113                         usbnet_skb_return(dev, gl_skb);
 114                 }
 115 
 116                 // advance to the next packet
 117                 packet = (struct gl_packet *)&packet->packet_data[size];
 118                 count--;
 119 
 120                 // shift the data pointer to the next gl_packet
 121                 skb_pull(skb, size + 4);
 122         }
 123 
 124         // skip the packet length field 4 bytes
 125         skb_pull(skb, 4);
 126 
 127         if (skb->len > GL_MAX_PACKET_LEN) {
 128                 netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
 129                            skb->len);
 130                 return 0;
 131         }
 132         return 1;
 133 }
 134 
 135 static struct sk_buff *
 136 genelink_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
 137 {
 138         int     padlen;
 139         int     length = skb->len;
 140         int     headroom = skb_headroom(skb);
 141         int     tailroom = skb_tailroom(skb);
 142         __le32  *packet_count;
 143         __le32  *packet_len;
 144 
 145         // FIXME:  magic numbers, bleech
 146         padlen = ((skb->len + (4 + 4*1)) % 64) ? 0 : 1;
 147 
 148         if ((!skb_cloned(skb))
 149                         && ((headroom + tailroom) >= (padlen + (4 + 4*1)))) {
 150                 if ((headroom < (4 + 4*1)) || (tailroom < padlen)) {
 151                         skb->data = memmove(skb->head + (4 + 4*1),
 152                                              skb->data, skb->len);
 153                         skb_set_tail_pointer(skb, skb->len);
 154                 }
 155         } else {
 156                 struct sk_buff  *skb2;
 157                 skb2 = skb_copy_expand(skb, (4 + 4*1) , padlen, flags);
 158                 dev_kfree_skb_any(skb);
 159                 skb = skb2;
 160                 if (!skb)
 161                         return NULL;
 162         }
 163 
 164         // attach the packet count to the header
 165         packet_count = skb_push(skb, (4 + 4 * 1));
 166         packet_len = packet_count + 1;
 167 
 168         *packet_count = cpu_to_le32(1);
 169         *packet_len = cpu_to_le32(length);
 170 
 171         // add padding byte
 172         if ((skb->len % dev->maxpacket) == 0)
 173                 skb_put(skb, 1);
 174 
 175         return skb;
 176 }
 177 
 178 static int genelink_bind(struct usbnet *dev, struct usb_interface *intf)
 179 {
 180         dev->hard_mtu = GL_RCV_BUF_SIZE;
 181         dev->net->hard_header_len += 4;
 182         dev->in = usb_rcvbulkpipe(dev->udev, dev->driver_info->in);
 183         dev->out = usb_sndbulkpipe(dev->udev, dev->driver_info->out);
 184         return 0;
 185 }
 186 
 187 static const struct driver_info genelink_info = {
 188         .description =  "Genesys GeneLink",
 189         .flags =        FLAG_POINTTOPOINT | FLAG_FRAMING_GL | FLAG_NO_SETINT,
 190         .bind =         genelink_bind,
 191         .rx_fixup =     genelink_rx_fixup,
 192         .tx_fixup =     genelink_tx_fixup,
 193 
 194         .in = 1, .out = 2,
 195 
 196 #ifdef  GENELINK_ACK
 197         .check_connect =genelink_check_connect,
 198 #endif
 199 };
 200 
 201 static const struct usb_device_id       products [] = {
 202 
 203 {
 204         USB_DEVICE(0x05e3, 0x0502),     // GL620USB-A
 205         .driver_info =  (unsigned long) &genelink_info,
 206 },
 207         /* NOT: USB_DEVICE(0x05e3, 0x0501),     // GL620USB
 208          * that's half duplex, not currently supported
 209          */
 210         { },            // END
 211 };
 212 MODULE_DEVICE_TABLE(usb, products);
 213 
 214 static struct usb_driver gl620a_driver = {
 215         .name =         "gl620a",
 216         .id_table =     products,
 217         .probe =        usbnet_probe,
 218         .disconnect =   usbnet_disconnect,
 219         .suspend =      usbnet_suspend,
 220         .resume =       usbnet_resume,
 221         .disable_hub_initiated_lpm = 1,
 222 };
 223 
 224 module_usb_driver(gl620a_driver);
 225 
 226 MODULE_AUTHOR("Jiun-Jie Huang");
 227 MODULE_DESCRIPTION("GL620-USB-A Host-to-Host Link cables");
 228 MODULE_LICENSE("GPL");
 229