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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Net1080 based USB host-to-host cables
0004  * Copyright (C) 2000-2005 by David Brownell
0005  */
0006 
0007 // #define  DEBUG           // error path messages, extra info
0008 // #define  VERBOSE         // more; success messages
0009 
0010 #include <linux/module.h>
0011 #include <linux/netdevice.h>
0012 #include <linux/etherdevice.h>
0013 #include <linux/ethtool.h>
0014 #include <linux/workqueue.h>
0015 #include <linux/mii.h>
0016 #include <linux/usb.h>
0017 #include <linux/usb/usbnet.h>
0018 #include <linux/slab.h>
0019 
0020 #include <asm/unaligned.h>
0021 
0022 
0023 /*
0024  * Netchip 1080 driver ... http://www.netchip.com
0025  * (Sept 2004:  End-of-life announcement has been sent.)
0026  * Used in (some) LapLink cables
0027  */
0028 
0029 #define frame_errors    data[1]
0030 
0031 /*
0032  * NetChip framing of ethernet packets, supporting additional error
0033  * checks for links that may drop bulk packets from inside messages.
0034  * Odd USB length == always short read for last usb packet.
0035  *  - nc_header
0036  *  - Ethernet header (14 bytes)
0037  *  - payload
0038  *  - (optional padding byte, if needed so length becomes odd)
0039  *  - nc_trailer
0040  *
0041  * This framing is to be avoided for non-NetChip devices.
0042  */
0043 
0044 struct nc_header {      // packed:
0045     __le16  hdr_len;        // sizeof nc_header (LE, all)
0046     __le16  packet_len;     // payload size (including ethhdr)
0047     __le16  packet_id;      // detects dropped packets
0048 #define MIN_HEADER  6
0049 
0050     // all else is optional, and must start with:
0051     // __le16   vendorId;   // from usb-if
0052     // __le16   productId;
0053 } __packed;
0054 
0055 #define PAD_BYTE    ((unsigned char)0xAC)
0056 
0057 struct nc_trailer {
0058     __le16  packet_id;
0059 } __packed;
0060 
0061 // packets may use FLAG_FRAMING_NC and optional pad
0062 #define FRAMED_SIZE(mtu) (sizeof (struct nc_header) \
0063                 + sizeof (struct ethhdr) \
0064                 + (mtu) \
0065                 + 1 \
0066                 + sizeof (struct nc_trailer))
0067 
0068 #define MIN_FRAMED  FRAMED_SIZE(0)
0069 
0070 /* packets _could_ be up to 64KB... */
0071 #define NC_MAX_PACKET   32767
0072 
0073 
0074 /*
0075  * Zero means no timeout; else, how long a 64 byte bulk packet may be queued
0076  * before the hardware drops it.  If that's done, the driver will need to
0077  * frame network packets to guard against the dropped USB packets.  The win32
0078  * driver sets this for both sides of the link.
0079  */
0080 #define NC_READ_TTL_MS  ((u8)255)   // ms
0081 
0082 /*
0083  * We ignore most registers and EEPROM contents.
0084  */
0085 #define REG_USBCTL  ((u8)0x04)
0086 #define REG_TTL     ((u8)0x10)
0087 #define REG_STATUS  ((u8)0x11)
0088 
0089 /*
0090  * Vendor specific requests to read/write data
0091  */
0092 #define REQUEST_REGISTER    ((u8)0x10)
0093 #define REQUEST_EEPROM      ((u8)0x11)
0094 
0095 static int
0096 nc_vendor_read(struct usbnet *dev, u8 req, u8 regnum, u16 *retval_ptr)
0097 {
0098     int status = usbnet_read_cmd(dev, req,
0099                      USB_DIR_IN | USB_TYPE_VENDOR |
0100                      USB_RECIP_DEVICE,
0101                      0, regnum, retval_ptr,
0102                      sizeof *retval_ptr);
0103     if (status > 0)
0104         status = 0;
0105     if (!status)
0106         le16_to_cpus(retval_ptr);
0107     return status;
0108 }
0109 
0110 static inline int
0111 nc_register_read(struct usbnet *dev, u8 regnum, u16 *retval_ptr)
0112 {
0113     return nc_vendor_read(dev, REQUEST_REGISTER, regnum, retval_ptr);
0114 }
0115 
0116 static void
0117 nc_vendor_write(struct usbnet *dev, u8 req, u8 regnum, u16 value)
0118 {
0119     usbnet_write_cmd(dev, req,
0120              USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0121              value, regnum, NULL, 0);
0122 }
0123 
0124 static inline void
0125 nc_register_write(struct usbnet *dev, u8 regnum, u16 value)
0126 {
0127     nc_vendor_write(dev, REQUEST_REGISTER, regnum, value);
0128 }
0129 
0130 
0131 #if 0
0132 static void nc_dump_registers(struct usbnet *dev)
0133 {
0134     u8  reg;
0135     u16 *vp = kmalloc(sizeof (u16));
0136 
0137     if (!vp)
0138         return;
0139 
0140     netdev_dbg(dev->net, "registers:\n");
0141     for (reg = 0; reg < 0x20; reg++) {
0142         int retval;
0143 
0144         // reading some registers is trouble
0145         if (reg >= 0x08 && reg <= 0xf)
0146             continue;
0147         if (reg >= 0x12 && reg <= 0x1e)
0148             continue;
0149 
0150         retval = nc_register_read(dev, reg, vp);
0151         if (retval < 0)
0152             netdev_dbg(dev->net, "reg [0x%x] ==> error %d\n",
0153                    reg, retval);
0154         else
0155             netdev_dbg(dev->net, "reg [0x%x] = 0x%x\n", reg, *vp);
0156     }
0157     kfree(vp);
0158 }
0159 #endif
0160 
0161 
0162 /*-------------------------------------------------------------------------*/
0163 
0164 /*
0165  * Control register
0166  */
0167 
0168 #define USBCTL_WRITABLE_MASK    0x1f0f
0169 // bits 15-13 reserved, r/o
0170 #define USBCTL_ENABLE_LANG  (1 << 12)
0171 #define USBCTL_ENABLE_MFGR  (1 << 11)
0172 #define USBCTL_ENABLE_PROD  (1 << 10)
0173 #define USBCTL_ENABLE_SERIAL    (1 << 9)
0174 #define USBCTL_ENABLE_DEFAULTS  (1 << 8)
0175 // bits 7-4 reserved, r/o
0176 #define USBCTL_FLUSH_OTHER  (1 << 3)
0177 #define USBCTL_FLUSH_THIS   (1 << 2)
0178 #define USBCTL_DISCONN_OTHER    (1 << 1)
0179 #define USBCTL_DISCONN_THIS (1 << 0)
0180 
0181 static inline void nc_dump_usbctl(struct usbnet *dev, u16 usbctl)
0182 {
0183     netif_dbg(dev, link, dev->net,
0184           "net1080 %s-%s usbctl 0x%x:%s%s%s%s%s; this%s%s; other%s%s; r/o 0x%x\n",
0185           dev->udev->bus->bus_name, dev->udev->devpath,
0186           usbctl,
0187           (usbctl & USBCTL_ENABLE_LANG) ? " lang" : "",
0188           (usbctl & USBCTL_ENABLE_MFGR) ? " mfgr" : "",
0189           (usbctl & USBCTL_ENABLE_PROD) ? " prod" : "",
0190           (usbctl & USBCTL_ENABLE_SERIAL) ? " serial" : "",
0191           (usbctl & USBCTL_ENABLE_DEFAULTS) ? " defaults" : "",
0192 
0193           (usbctl & USBCTL_FLUSH_THIS) ? " FLUSH" : "",
0194           (usbctl & USBCTL_DISCONN_THIS) ? " DIS" : "",
0195 
0196           (usbctl & USBCTL_FLUSH_OTHER) ? " FLUSH" : "",
0197           (usbctl & USBCTL_DISCONN_OTHER) ? " DIS" : "",
0198 
0199           usbctl & ~USBCTL_WRITABLE_MASK);
0200 }
0201 
0202 /*-------------------------------------------------------------------------*/
0203 
0204 /*
0205  * Status register
0206  */
0207 
0208 #define STATUS_PORT_A       (1 << 15)
0209 
0210 #define STATUS_CONN_OTHER   (1 << 14)
0211 #define STATUS_SUSPEND_OTHER    (1 << 13)
0212 #define STATUS_MAILBOX_OTHER    (1 << 12)
0213 #define STATUS_PACKETS_OTHER(n) (((n) >> 8) & 0x03)
0214 
0215 #define STATUS_CONN_THIS    (1 << 6)
0216 #define STATUS_SUSPEND_THIS (1 << 5)
0217 #define STATUS_MAILBOX_THIS (1 << 4)
0218 #define STATUS_PACKETS_THIS(n)  (((n) >> 0) & 0x03)
0219 
0220 #define STATUS_UNSPEC_MASK  0x0c8c
0221 #define STATUS_NOISE_MASK   ((u16)~(0x0303|STATUS_UNSPEC_MASK))
0222 
0223 
0224 static inline void nc_dump_status(struct usbnet *dev, u16 status)
0225 {
0226     netif_dbg(dev, link, dev->net,
0227           "net1080 %s-%s status 0x%x: this (%c) PKT=%d%s%s%s; other PKT=%d%s%s%s; unspec 0x%x\n",
0228           dev->udev->bus->bus_name, dev->udev->devpath,
0229           status,
0230 
0231           // XXX the packet counts don't seem right
0232           // (1 at reset, not 0); maybe UNSPEC too
0233 
0234           (status & STATUS_PORT_A) ? 'A' : 'B',
0235           STATUS_PACKETS_THIS(status),
0236           (status & STATUS_CONN_THIS) ? " CON" : "",
0237           (status & STATUS_SUSPEND_THIS) ? " SUS" : "",
0238           (status & STATUS_MAILBOX_THIS) ? " MBOX" : "",
0239 
0240           STATUS_PACKETS_OTHER(status),
0241           (status & STATUS_CONN_OTHER) ? " CON" : "",
0242           (status & STATUS_SUSPEND_OTHER) ? " SUS" : "",
0243           (status & STATUS_MAILBOX_OTHER) ? " MBOX" : "",
0244 
0245           status & STATUS_UNSPEC_MASK);
0246 }
0247 
0248 /*-------------------------------------------------------------------------*/
0249 
0250 /*
0251  * TTL register
0252  */
0253 
0254 #define TTL_OTHER(ttl)  (0x00ff & (ttl >> 8))
0255 #define MK_TTL(this,other)  ((u16)(((other)<<8)|(0x00ff&(this))))
0256 
0257 /*-------------------------------------------------------------------------*/
0258 
0259 static int net1080_reset(struct usbnet *dev)
0260 {
0261     u16     usbctl, status, ttl;
0262     u16     vp;
0263     int     retval;
0264 
0265     // nc_dump_registers(dev);
0266 
0267     if ((retval = nc_register_read(dev, REG_STATUS, &vp)) < 0) {
0268         netdev_dbg(dev->net, "can't read %s-%s status: %d\n",
0269                dev->udev->bus->bus_name, dev->udev->devpath, retval);
0270         goto done;
0271     }
0272     status = vp;
0273     nc_dump_status(dev, status);
0274 
0275     if ((retval = nc_register_read(dev, REG_USBCTL, &vp)) < 0) {
0276         netdev_dbg(dev->net, "can't read USBCTL, %d\n", retval);
0277         goto done;
0278     }
0279     usbctl = vp;
0280     nc_dump_usbctl(dev, usbctl);
0281 
0282     nc_register_write(dev, REG_USBCTL,
0283             USBCTL_FLUSH_THIS | USBCTL_FLUSH_OTHER);
0284 
0285     if ((retval = nc_register_read(dev, REG_TTL, &vp)) < 0) {
0286         netdev_dbg(dev->net, "can't read TTL, %d\n", retval);
0287         goto done;
0288     }
0289     ttl = vp;
0290 
0291     nc_register_write(dev, REG_TTL,
0292             MK_TTL(NC_READ_TTL_MS, TTL_OTHER(ttl)) );
0293     netdev_dbg(dev->net, "assigned TTL, %d ms\n", NC_READ_TTL_MS);
0294 
0295     netif_info(dev, link, dev->net, "port %c, peer %sconnected\n",
0296            (status & STATUS_PORT_A) ? 'A' : 'B',
0297            (status & STATUS_CONN_OTHER) ? "" : "dis");
0298     retval = 0;
0299 
0300 done:
0301     return retval;
0302 }
0303 
0304 static int net1080_check_connect(struct usbnet *dev)
0305 {
0306     int         retval;
0307     u16         status;
0308     u16         vp;
0309 
0310     retval = nc_register_read(dev, REG_STATUS, &vp);
0311     status = vp;
0312     if (retval != 0) {
0313         netdev_dbg(dev->net, "net1080_check_conn read - %d\n", retval);
0314         return retval;
0315     }
0316     if ((status & STATUS_CONN_OTHER) != STATUS_CONN_OTHER)
0317         return -ENOLINK;
0318     return 0;
0319 }
0320 
0321 static void nc_ensure_sync(struct usbnet *dev)
0322 {
0323     if (++dev->frame_errors <= 5)
0324         return;
0325 
0326     if (usbnet_write_cmd_async(dev, REQUEST_REGISTER,
0327                     USB_DIR_OUT | USB_TYPE_VENDOR |
0328                     USB_RECIP_DEVICE,
0329                     USBCTL_FLUSH_THIS |
0330                     USBCTL_FLUSH_OTHER,
0331                     REG_USBCTL, NULL, 0))
0332         return;
0333 
0334     netif_dbg(dev, rx_err, dev->net,
0335           "flush net1080; too many framing errors\n");
0336     dev->frame_errors = 0;
0337 }
0338 
0339 static int net1080_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
0340 {
0341     struct nc_header    *header;
0342     struct nc_trailer   *trailer;
0343     u16         hdr_len, packet_len;
0344 
0345     /* This check is no longer done by usbnet */
0346     if (skb->len < dev->net->hard_header_len)
0347         return 0;
0348 
0349     if (!(skb->len & 0x01)) {
0350         netdev_dbg(dev->net, "rx framesize %d range %d..%d mtu %d\n",
0351                skb->len, dev->net->hard_header_len, dev->hard_mtu,
0352                dev->net->mtu);
0353         dev->net->stats.rx_frame_errors++;
0354         nc_ensure_sync(dev);
0355         return 0;
0356     }
0357 
0358     header = (struct nc_header *) skb->data;
0359     hdr_len = le16_to_cpup(&header->hdr_len);
0360     packet_len = le16_to_cpup(&header->packet_len);
0361     if (FRAMED_SIZE(packet_len) > NC_MAX_PACKET) {
0362         dev->net->stats.rx_frame_errors++;
0363         netdev_dbg(dev->net, "packet too big, %d\n", packet_len);
0364         nc_ensure_sync(dev);
0365         return 0;
0366     } else if (hdr_len < MIN_HEADER) {
0367         dev->net->stats.rx_frame_errors++;
0368         netdev_dbg(dev->net, "header too short, %d\n", hdr_len);
0369         nc_ensure_sync(dev);
0370         return 0;
0371     } else if (hdr_len > MIN_HEADER) {
0372         // out of band data for us?
0373         netdev_dbg(dev->net, "header OOB, %d bytes\n", hdr_len - MIN_HEADER);
0374         nc_ensure_sync(dev);
0375         // switch (vendor/product ids) { ... }
0376     }
0377     skb_pull(skb, hdr_len);
0378 
0379     trailer = (struct nc_trailer *)
0380         (skb->data + skb->len - sizeof *trailer);
0381     skb_trim(skb, skb->len - sizeof *trailer);
0382 
0383     if ((packet_len & 0x01) == 0) {
0384         if (skb->data [packet_len] != PAD_BYTE) {
0385             dev->net->stats.rx_frame_errors++;
0386             netdev_dbg(dev->net, "bad pad\n");
0387             return 0;
0388         }
0389         skb_trim(skb, skb->len - 1);
0390     }
0391     if (skb->len != packet_len) {
0392         dev->net->stats.rx_frame_errors++;
0393         netdev_dbg(dev->net, "bad packet len %d (expected %d)\n",
0394                skb->len, packet_len);
0395         nc_ensure_sync(dev);
0396         return 0;
0397     }
0398     if (header->packet_id != get_unaligned(&trailer->packet_id)) {
0399         dev->net->stats.rx_fifo_errors++;
0400         netdev_dbg(dev->net, "(2+ dropped) rx packet_id mismatch 0x%x 0x%x\n",
0401                le16_to_cpu(header->packet_id),
0402                le16_to_cpu(trailer->packet_id));
0403         return 0;
0404     }
0405 #if 0
0406     netdev_dbg(dev->net, "frame <rx h %d p %d id %d\n", header->hdr_len,
0407            header->packet_len, header->packet_id);
0408 #endif
0409     dev->frame_errors = 0;
0410     return 1;
0411 }
0412 
0413 static struct sk_buff *
0414 net1080_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
0415 {
0416     struct sk_buff      *skb2;
0417     struct nc_header    *header = NULL;
0418     struct nc_trailer   *trailer = NULL;
0419     int         padlen = sizeof (struct nc_trailer);
0420     int         len = skb->len;
0421 
0422     if (!((len + padlen + sizeof (struct nc_header)) & 0x01))
0423         padlen++;
0424     if (!skb_cloned(skb)) {
0425         int headroom = skb_headroom(skb);
0426         int tailroom = skb_tailroom(skb);
0427 
0428         if (padlen <= tailroom &&
0429             sizeof(struct nc_header) <= headroom)
0430             /* There's enough head and tail room */
0431             goto encapsulate;
0432 
0433         if ((sizeof (struct nc_header) + padlen) <
0434                 (headroom + tailroom)) {
0435             /* There's enough total room, so just readjust */
0436             skb->data = memmove(skb->head
0437                         + sizeof (struct nc_header),
0438                         skb->data, skb->len);
0439             skb_set_tail_pointer(skb, len);
0440             goto encapsulate;
0441         }
0442     }
0443 
0444     /* Create a new skb to use with the correct size */
0445     skb2 = skb_copy_expand(skb,
0446                 sizeof (struct nc_header),
0447                 padlen,
0448                 flags);
0449     dev_kfree_skb_any(skb);
0450     if (!skb2)
0451         return skb2;
0452     skb = skb2;
0453 
0454 encapsulate:
0455     /* header first */
0456     header = skb_push(skb, sizeof *header);
0457     header->hdr_len = cpu_to_le16(sizeof (*header));
0458     header->packet_len = cpu_to_le16(len);
0459     header->packet_id = cpu_to_le16((u16)dev->xid++);
0460 
0461     /* maybe pad; then trailer */
0462     if (!((skb->len + sizeof *trailer) & 0x01))
0463         skb_put_u8(skb, PAD_BYTE);
0464     trailer = skb_put(skb, sizeof *trailer);
0465     put_unaligned(header->packet_id, &trailer->packet_id);
0466 #if 0
0467     netdev_dbg(dev->net, "frame >tx h %d p %d id %d\n",
0468            header->hdr_len, header->packet_len,
0469            header->packet_id);
0470 #endif
0471     return skb;
0472 }
0473 
0474 static int net1080_bind(struct usbnet *dev, struct usb_interface *intf)
0475 {
0476     unsigned    extra = sizeof (struct nc_header)
0477                 + 1
0478                 + sizeof (struct nc_trailer);
0479 
0480     dev->net->hard_header_len += extra;
0481     dev->rx_urb_size = dev->net->hard_header_len + dev->net->mtu;
0482     dev->hard_mtu = NC_MAX_PACKET;
0483     return usbnet_get_endpoints (dev, intf);
0484 }
0485 
0486 static const struct driver_info net1080_info = {
0487     .description =  "NetChip TurboCONNECT",
0488     .flags =    FLAG_POINTTOPOINT | FLAG_FRAMING_NC,
0489     .bind =     net1080_bind,
0490     .reset =    net1080_reset,
0491     .check_connect = net1080_check_connect,
0492     .rx_fixup = net1080_rx_fixup,
0493     .tx_fixup = net1080_tx_fixup,
0494 };
0495 
0496 static const struct usb_device_id   products [] = {
0497 {
0498     USB_DEVICE(0x0525, 0x1080), // NetChip ref design
0499     .driver_info =  (unsigned long) &net1080_info,
0500 }, {
0501     USB_DEVICE(0x06D0, 0x0622), // Laplink Gold
0502     .driver_info =  (unsigned long) &net1080_info,
0503 },
0504     { },        // END
0505 };
0506 MODULE_DEVICE_TABLE(usb, products);
0507 
0508 static struct usb_driver net1080_driver = {
0509     .name =     "net1080",
0510     .id_table = products,
0511     .probe =    usbnet_probe,
0512     .disconnect =   usbnet_disconnect,
0513     .suspend =  usbnet_suspend,
0514     .resume =   usbnet_resume,
0515     .disable_hub_initiated_lpm = 1,
0516 };
0517 
0518 module_usb_driver(net1080_driver);
0519 
0520 MODULE_AUTHOR("David Brownell");
0521 MODULE_DESCRIPTION("NetChip 1080 based USB Host-to-Host Links");
0522 MODULE_LICENSE("GPL");
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