LXR linux/drivers/net/usb/kalmia.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * USB network interface driver for Samsung Kalmia based LTE USB modem like the
   4 * Samsung GT-B3730 and GT-B3710.
   5 *
   6 * Copyright (C) 2011 Marius Bjoernstad Kotsbak <marius@kotsbak.com>
   7 *
   8 * Sponsored by Quicklink Video Distribution Services Ltd.
   9 *
  10 * Based on the cdc_eem module.
  11 */
  12
  13#include <linux/module.h>
  14#include <linux/netdevice.h>
  15#include <linux/etherdevice.h>
  16#include <linux/ctype.h>
  17#include <linux/ethtool.h>
  18#include <linux/workqueue.h>
  19#include <linux/mii.h>
  20#include <linux/usb.h>
  21#include <linux/crc32.h>
  22#include <linux/usb/cdc.h>
  23#include <linux/usb/usbnet.h>
  24#include <linux/gfp.h>
  25
  26/*
  27 * The Samsung Kalmia based LTE USB modems have a CDC ACM port for modem control
  28 * handled by the "option" module and an ethernet data port handled by this
  29 * module.
  30 *
  31 * The stick must first be switched into modem mode by usb_modeswitch
  32 * or similar tool. Then the modem gets sent two initialization packets by
  33 * this module, which gives the MAC address of the device. User space can then
  34 * connect the modem using AT commands through the ACM port and then use
  35 * DHCP on the network interface exposed by this module. Network packets are
  36 * sent to and from the modem in a proprietary format discovered after watching
  37 * the behavior of the windows driver for the modem.
  38 *
  39 * More information about the use of the modem is available in usb_modeswitch
  40 * forum and the project page:
  41 *
  42 * http://www.draisberghof.de/usb_modeswitch/bb/viewtopic.php?t=465
  43 * https://github.com/mkotsbak/Samsung-GT-B3730-linux-driver
  44 */
  45
  46/* #define      DEBUG */
  47/* #define      VERBOSE */
  48
  49#define KALMIA_HEADER_LENGTH 6
  50#define KALMIA_ALIGN_SIZE 4
  51#define KALMIA_USB_TIMEOUT 10000
  52
  53/*-------------------------------------------------------------------------*/
  54
  55static int
  56kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8 init_msg_len,
  57        u8 *buffer, u8 expected_len)
  58{
  59        int act_len;
  60        int status;
  61
  62        netdev_dbg(dev->net, "Sending init packet");
  63
  64        status = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 0x02),
  65                init_msg, init_msg_len, &act_len, KALMIA_USB_TIMEOUT);
  66        if (status != 0) {
  67                netdev_err(dev->net,
  68                        "Error sending init packet. Status %i, length %i\n",
  69                        status, act_len);
  70                return status;
  71        }
  72        else if (act_len != init_msg_len) {
  73                netdev_err(dev->net,
  74                        "Did not send all of init packet. Bytes sent: %i",
  75                        act_len);
  76        }
  77        else {
  78                netdev_dbg(dev->net, "Successfully sent init packet.");
  79        }
  80
  81        status = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, 0x81),
  82                buffer, expected_len, &act_len, KALMIA_USB_TIMEOUT);
  83
  84        if (status != 0)
  85                netdev_err(dev->net,
  86                        "Error receiving init result. Status %i, length %i\n",
  87                        status, act_len);
  88        else if (act_len != expected_len)
  89                netdev_err(dev->net, "Unexpected init result length: %i\n",
  90                        act_len);
  91
  92        return status;
  93}
  94
  95static int
  96kalmia_init_and_get_ethernet_addr(struct usbnet *dev, u8 *ethernet_addr)
  97{
  98        static const char init_msg_1[] =
  99                { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
 100                0x00, 0x00 };
 101        static const char init_msg_2[] =
 102                { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4,
 103                0x00, 0x00 };
 104        static const int buflen = 28;
 105        char *usb_buf;
 106        int status;
 107
 108        usb_buf = kmalloc(buflen, GFP_DMA | GFP_KERNEL);
 109        if (!usb_buf)
 110                return -ENOMEM;
 111
 112        memcpy(usb_buf, init_msg_1, 12);
 113        status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_1),
 114                                         usb_buf, 24);
 115        if (status != 0)
 116                goto out;
 117
 118        memcpy(usb_buf, init_msg_2, 12);
 119        status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_2),
 120                                         usb_buf, 28);
 121        if (status != 0)
 122                goto out;
 123
 124        memcpy(ethernet_addr, usb_buf + 10, ETH_ALEN);
 125out:
 126        kfree(usb_buf);
 127        return status;
 128}
 129
 130static int
 131kalmia_bind(struct usbnet *dev, struct usb_interface *intf)
 132{
 133        int status;
 134        u8 ethernet_addr[ETH_ALEN];
 135
 136        /* Don't bind to AT command interface */
 137        if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
 138                return -EINVAL;
 139
 140        dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK);
 141        dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK);
 142        dev->status = NULL;
 143
 144        dev->net->hard_header_len += KALMIA_HEADER_LENGTH;
 145        dev->hard_mtu = 1400;
 146        dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing
 147
 148        status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr);
 149        if (status)
 150                return status;
 151
 152        memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN);
 153
 154        return status;
 155}
 156
 157static struct sk_buff *
 158kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
 159{
 160        struct sk_buff *skb2 = NULL;
 161        u16 content_len;
 162        unsigned char *header_start;
 163        unsigned char ether_type_1, ether_type_2;
 164        u8 remainder, padlen = 0;
 165
 166        if (!skb_cloned(skb)) {
 167                int headroom = skb_headroom(skb);
 168                int tailroom = skb_tailroom(skb);
 169
 170                if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom
 171                        >= KALMIA_HEADER_LENGTH))
 172                        goto done;
 173
 174                if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH
 175                        + KALMIA_ALIGN_SIZE)) {
 176                        skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH,
 177                                skb->data, skb->len);
 178                        skb_set_tail_pointer(skb, skb->len);
 179                        goto done;
 180                }
 181        }
 182
 183        skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH,
 184                KALMIA_ALIGN_SIZE, flags);
 185        if (!skb2)
 186                return NULL;
 187
 188        dev_kfree_skb_any(skb);
 189        skb = skb2;
 190
 191done:
 192        header_start = skb_push(skb, KALMIA_HEADER_LENGTH);
 193        ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12];
 194        ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13];
 195
 196        netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1,
 197                ether_type_2);
 198
 199        /* According to empiric data for data packages */
 200        header_start[0] = 0x57;
 201        header_start[1] = 0x44;
 202        content_len = skb->len - KALMIA_HEADER_LENGTH;
 203
 204        put_unaligned_le16(content_len, &header_start[2]);
 205        header_start[4] = ether_type_1;
 206        header_start[5] = ether_type_2;
 207
 208        /* Align to 4 bytes by padding with zeros */
 209        remainder = skb->len % KALMIA_ALIGN_SIZE;
 210        if (remainder > 0) {
 211                padlen = KALMIA_ALIGN_SIZE - remainder;
 212                skb_put_zero(skb, padlen);
 213        }
 214
 215        netdev_dbg(dev->net,
 216                "Sending package with length %i and padding %i. Header: %6phC.",
 217                content_len, padlen, header_start);
 218
 219        return skb;
 220}
 221
 222static int
 223kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 224{
 225        /*
 226         * Our task here is to strip off framing, leaving skb with one
 227         * data frame for the usbnet framework code to process.
 228         */
 229        static const u8 HEADER_END_OF_USB_PACKET[] =
 230                { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 };
 231        static const u8 EXPECTED_UNKNOWN_HEADER_1[] =
 232                { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 };
 233        static const u8 EXPECTED_UNKNOWN_HEADER_2[] =
 234                { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 };
 235        int i = 0;
 236
 237        /* incomplete header? */
 238        if (skb->len < KALMIA_HEADER_LENGTH)
 239                return 0;
 240
 241        do {
 242                struct sk_buff *skb2 = NULL;
 243                u8 *header_start;
 244                u16 usb_packet_length, ether_packet_length;
 245                int is_last;
 246
 247                header_start = skb->data;
 248
 249                if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) {
 250                        if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1,
 251                                sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp(
 252                                header_start, EXPECTED_UNKNOWN_HEADER_2,
 253                                sizeof(EXPECTED_UNKNOWN_HEADER_2))) {
 254                                netdev_dbg(dev->net,
 255                                        "Received expected unknown frame header: %6phC. Package length: %i\n",
 256                                        header_start,
 257                                        skb->len - KALMIA_HEADER_LENGTH);
 258                        }
 259                        else {
 260                                netdev_err(dev->net,
 261                                        "Received unknown frame header: %6phC. Package length: %i\n",
 262                                        header_start,
 263                                        skb->len - KALMIA_HEADER_LENGTH);
 264                                return 0;
 265                        }
 266                }
 267                else
 268                        netdev_dbg(dev->net,
 269                                "Received header: %6phC. Package length: %i\n",
 270                                header_start, skb->len - KALMIA_HEADER_LENGTH);
 271
 272                /* subtract start header and end header */
 273                usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH);
 274                ether_packet_length = get_unaligned_le16(&header_start[2]);
 275                skb_pull(skb, KALMIA_HEADER_LENGTH);
 276
 277                /* Some small packets misses end marker */
 278                if (usb_packet_length < ether_packet_length) {
 279                        ether_packet_length = usb_packet_length
 280                                + KALMIA_HEADER_LENGTH;
 281                        is_last = true;
 282                }
 283                else {
 284                        netdev_dbg(dev->net, "Correct package length #%i", i
 285                                + 1);
 286
 287                        is_last = (memcmp(skb->data + ether_packet_length,
 288                                HEADER_END_OF_USB_PACKET,
 289                                sizeof(HEADER_END_OF_USB_PACKET)) == 0);
 290                        if (!is_last) {
 291                                header_start = skb->data + ether_packet_length;
 292                                netdev_dbg(dev->net,
 293                                        "End header: %6phC. Package length: %i\n",
 294                                        header_start,
 295                                        skb->len - KALMIA_HEADER_LENGTH);
 296                        }
 297                }
 298
 299                if (is_last) {
 300                        skb2 = skb;
 301                }
 302                else {
 303                        skb2 = skb_clone(skb, GFP_ATOMIC);
 304                        if (unlikely(!skb2))
 305                                return 0;
 306                }
 307
 308                skb_trim(skb2, ether_packet_length);
 309
 310                if (is_last) {
 311                        return 1;
 312                }
 313                else {
 314                        usbnet_skb_return(dev, skb2);
 315                        skb_pull(skb, ether_packet_length);
 316                }
 317
 318                i++;
 319        }
 320        while (skb->len);
 321
 322        return 1;
 323}
 324
 325static const struct driver_info kalmia_info = {
 326        .description = "Samsung Kalmia LTE USB dongle",
 327        .flags = FLAG_WWAN,
 328        .bind = kalmia_bind,
 329        .rx_fixup = kalmia_rx_fixup,
 330        .tx_fixup = kalmia_tx_fixup
 331};
 332
 333/*-------------------------------------------------------------------------*/
 334
 335static const struct usb_device_id products[] = {
 336        /* The unswitched USB ID, to get the module auto loaded: */
 337        { USB_DEVICE(0x04e8, 0x689a) },
 338        /* The stick switched into modem (by e.g. usb_modeswitch): */
 339        { USB_DEVICE(0x04e8, 0x6889),
 340                .driver_info = (unsigned long) &kalmia_info, },
 341        { /* EMPTY == end of list */} };
 342MODULE_DEVICE_TABLE( usb, products);
 343
 344static struct usb_driver kalmia_driver = {
 345        .name = "kalmia",
 346        .id_table = products,
 347        .probe = usbnet_probe,
 348        .disconnect = usbnet_disconnect,
 349        .suspend = usbnet_suspend,
 350        .resume = usbnet_resume,
 351        .disable_hub_initiated_lpm = 1,
 352};
 353
 354module_usb_driver(kalmia_driver);
 355
 356MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>");
 357MODULE_DESCRIPTION("Samsung Kalmia USB network driver");
 358MODULE_LICENSE("GPL");
 359