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

   1/*
   2 * USB network interface driver for Samsung Kalmia based LTE USB modem like the
   3 * Samsung GT-B3730 and GT-B3710.
   4 *
   5 * Copyright (C) 2011 Marius Bjoernstad Kotsbak <marius@kotsbak.com>
   6 *
   7 * Sponsored by Quicklink Video Distribution Services Ltd.
   8 *
   9 * Based on the cdc_eem module.
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License as published by
  13 * the Free Software Foundation; either version 2 of the License, or
  14 * (at your option) any later version.
  15 */
  16
  17#include <linux/module.h>
  18#include <linux/netdevice.h>
  19#include <linux/etherdevice.h>
  20#include <linux/ctype.h>
  21#include <linux/ethtool.h>
  22#include <linux/workqueue.h>
  23#include <linux/mii.h>
  24#include <linux/usb.h>
  25#include <linux/crc32.h>
  26#include <linux/usb/cdc.h>
  27#include <linux/usb/usbnet.h>
  28#include <linux/gfp.h>
  29
  30/*
  31 * The Samsung Kalmia based LTE USB modems have a CDC ACM port for modem control
  32 * handled by the "option" module and an ethernet data port handled by this
  33 * module.
  34 *
  35 * The stick must first be switched into modem mode by usb_modeswitch
  36 * or similar tool. Then the modem gets sent two initialization packets by
  37 * this module, which gives the MAC address of the device. User space can then
  38 * connect the modem using AT commands through the ACM port and then use
  39 * DHCP on the network interface exposed by this module. Network packets are
  40 * sent to and from the modem in a proprietary format discovered after watching
  41 * the behavior of the windows driver for the modem.
  42 *
  43 * More information about the use of the modem is available in usb_modeswitch
  44 * forum and the project page:
  45 *
  46 * http://www.draisberghof.de/usb_modeswitch/bb/viewtopic.php?t=465
  47 * https://github.com/mkotsbak/Samsung-GT-B3730-linux-driver
  48 */
  49
  50/* #define      DEBUG */
  51/* #define      VERBOSE */
  52
  53#define KALMIA_HEADER_LENGTH 6
  54#define KALMIA_ALIGN_SIZE 4
  55#define KALMIA_USB_TIMEOUT 10000
  56
  57/*-------------------------------------------------------------------------*/
  58
  59static int
  60kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8 init_msg_len,
  61        u8 *buffer, u8 expected_len)
  62{
  63        int act_len;
  64        int status;
  65
  66        netdev_dbg(dev->net, "Sending init packet");
  67
  68        status = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 0x02),
  69                init_msg, init_msg_len, &act_len, KALMIA_USB_TIMEOUT);
  70        if (status != 0) {
  71                netdev_err(dev->net,
  72                        "Error sending init packet. Status %i, length %i\n",
  73                        status, act_len);
  74                return status;
  75        }
  76        else if (act_len != init_msg_len) {
  77                netdev_err(dev->net,
  78                        "Did not send all of init packet. Bytes sent: %i",
  79                        act_len);
  80        }
  81        else {
  82                netdev_dbg(dev->net, "Successfully sent init packet.");
  83        }
  84
  85        status = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, 0x81),
  86                buffer, expected_len, &act_len, KALMIA_USB_TIMEOUT);
  87
  88        if (status != 0)
  89                netdev_err(dev->net,
  90                        "Error receiving init result. Status %i, length %i\n",
  91                        status, act_len);
  92        else if (act_len != expected_len)
  93                netdev_err(dev->net, "Unexpected init result length: %i\n",
  94                        act_len);
  95
  96        return status;
  97}
  98
  99static int
 100kalmia_init_and_get_ethernet_addr(struct usbnet *dev, u8 *ethernet_addr)
 101{
 102        static const char init_msg_1[] =
 103                { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
 104                0x00, 0x00 };
 105        static const char init_msg_2[] =
 106                { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4,
 107                0x00, 0x00 };
 108        static const int buflen = 28;
 109        char *usb_buf;
 110        int status;
 111
 112        usb_buf = kmalloc(buflen, GFP_DMA | GFP_KERNEL);
 113        if (!usb_buf)
 114                return -ENOMEM;
 115
 116        memcpy(usb_buf, init_msg_1, 12);
 117        status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_1),
 118                                         usb_buf, 24);
 119        if (status != 0)
 120                return status;
 121
 122        memcpy(usb_buf, init_msg_2, 12);
 123        status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_2),
 124                                         usb_buf, 28);
 125        if (status != 0)
 126                return status;
 127
 128        memcpy(ethernet_addr, usb_buf + 10, ETH_ALEN);
 129
 130        kfree(usb_buf);
 131        return status;
 132}
 133
 134static int
 135kalmia_bind(struct usbnet *dev, struct usb_interface *intf)
 136{
 137        int status;
 138        u8 ethernet_addr[ETH_ALEN];
 139
 140        /* Don't bind to AT command interface */
 141        if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
 142                return -EINVAL;
 143
 144        dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK);
 145        dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK);
 146        dev->status = NULL;
 147
 148        dev->net->hard_header_len += KALMIA_HEADER_LENGTH;
 149        dev->hard_mtu = 1400;
 150        dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing
 151
 152        status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr);
 153        if (status)
 154                return status;
 155
 156        memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN);
 157
 158        return status;
 159}
 160
 161static struct sk_buff *
 162kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
 163{
 164        struct sk_buff *skb2 = NULL;
 165        u16 content_len;
 166        unsigned char *header_start;
 167        unsigned char ether_type_1, ether_type_2;
 168        u8 remainder, padlen = 0;
 169
 170        if (!skb_cloned(skb)) {
 171                int headroom = skb_headroom(skb);
 172                int tailroom = skb_tailroom(skb);
 173
 174                if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom
 175                        >= KALMIA_HEADER_LENGTH))
 176                        goto done;
 177
 178                if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH
 179                        + KALMIA_ALIGN_SIZE)) {
 180                        skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH,
 181                                skb->data, skb->len);
 182                        skb_set_tail_pointer(skb, skb->len);
 183                        goto done;
 184                }
 185        }
 186
 187        skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH,
 188                KALMIA_ALIGN_SIZE, flags);
 189        if (!skb2)
 190                return NULL;
 191
 192        dev_kfree_skb_any(skb);
 193        skb = skb2;
 194
 195done:
 196        header_start = skb_push(skb, KALMIA_HEADER_LENGTH);
 197        ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12];
 198        ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13];
 199
 200        netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1,
 201                ether_type_2);
 202
 203        /* According to empiric data for data packages */
 204        header_start[0] = 0x57;
 205        header_start[1] = 0x44;
 206        content_len = skb->len - KALMIA_HEADER_LENGTH;
 207
 208        put_unaligned_le16(content_len, &header_start[2]);
 209        header_start[4] = ether_type_1;
 210        header_start[5] = ether_type_2;
 211
 212        /* Align to 4 bytes by padding with zeros */
 213        remainder = skb->len % KALMIA_ALIGN_SIZE;
 214        if (remainder > 0) {
 215                padlen = KALMIA_ALIGN_SIZE - remainder;
 216                skb_put_zero(skb, padlen);
 217        }
 218
 219        netdev_dbg(dev->net,
 220                "Sending package with length %i and padding %i. Header: %6phC.",
 221                content_len, padlen, header_start);
 222
 223        return skb;
 224}
 225
 226static int
 227kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 228{
 229        /*
 230         * Our task here is to strip off framing, leaving skb with one
 231         * data frame for the usbnet framework code to process.
 232         */
 233        static const u8 HEADER_END_OF_USB_PACKET[] =
 234                { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 };
 235        static const u8 EXPECTED_UNKNOWN_HEADER_1[] =
 236                { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 };
 237        static const u8 EXPECTED_UNKNOWN_HEADER_2[] =
 238                { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 };
 239        int i = 0;
 240
 241        /* incomplete header? */
 242        if (skb->len < KALMIA_HEADER_LENGTH)
 243                return 0;
 244
 245        do {
 246                struct sk_buff *skb2 = NULL;
 247                u8 *header_start;
 248                u16 usb_packet_length, ether_packet_length;
 249                int is_last;
 250
 251                header_start = skb->data;
 252
 253                if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) {
 254                        if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1,
 255                                sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp(
 256                                header_start, EXPECTED_UNKNOWN_HEADER_2,
 257                                sizeof(EXPECTED_UNKNOWN_HEADER_2))) {
 258                                netdev_dbg(dev->net,
 259                                        "Received expected unknown frame header: %6phC. Package length: %i\n",
 260                                        header_start,
 261                                        skb->len - KALMIA_HEADER_LENGTH);
 262                        }
 263                        else {
 264                                netdev_err(dev->net,
 265                                        "Received unknown frame header: %6phC. Package length: %i\n",
 266                                        header_start,
 267                                        skb->len - KALMIA_HEADER_LENGTH);
 268                                return 0;
 269                        }
 270                }
 271                else
 272                        netdev_dbg(dev->net,
 273                                "Received header: %6phC. Package length: %i\n",
 274                                header_start, skb->len - KALMIA_HEADER_LENGTH);
 275
 276                /* subtract start header and end header */
 277                usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH);
 278                ether_packet_length = get_unaligned_le16(&header_start[2]);
 279                skb_pull(skb, KALMIA_HEADER_LENGTH);
 280
 281                /* Some small packets misses end marker */
 282                if (usb_packet_length < ether_packet_length) {
 283                        ether_packet_length = usb_packet_length
 284                                + KALMIA_HEADER_LENGTH;
 285                        is_last = true;
 286                }
 287                else {
 288                        netdev_dbg(dev->net, "Correct package length #%i", i
 289                                + 1);
 290
 291                        is_last = (memcmp(skb->data + ether_packet_length,
 292                                HEADER_END_OF_USB_PACKET,
 293                                sizeof(HEADER_END_OF_USB_PACKET)) == 0);
 294                        if (!is_last) {
 295                                header_start = skb->data + ether_packet_length;
 296                                netdev_dbg(dev->net,
 297                                        "End header: %6phC. Package length: %i\n",
 298                                        header_start,
 299                                        skb->len - KALMIA_HEADER_LENGTH);
 300                        }
 301                }
 302
 303                if (is_last) {
 304                        skb2 = skb;
 305                }
 306                else {
 307                        skb2 = skb_clone(skb, GFP_ATOMIC);
 308                        if (unlikely(!skb2))
 309                                return 0;
 310                }
 311
 312                skb_trim(skb2, ether_packet_length);
 313
 314                if (is_last) {
 315                        return 1;
 316                }
 317                else {
 318                        usbnet_skb_return(dev, skb2);
 319                        skb_pull(skb, ether_packet_length);
 320                }
 321
 322                i++;
 323        }
 324        while (skb->len);
 325
 326        return 1;
 327}
 328
 329static const struct driver_info kalmia_info = {
 330        .description = "Samsung Kalmia LTE USB dongle",
 331        .flags = FLAG_WWAN,
 332        .bind = kalmia_bind,
 333        .rx_fixup = kalmia_rx_fixup,
 334        .tx_fixup = kalmia_tx_fixup
 335};
 336
 337/*-------------------------------------------------------------------------*/
 338
 339static const struct usb_device_id products[] = {
 340        /* The unswitched USB ID, to get the module auto loaded: */
 341        { USB_DEVICE(0x04e8, 0x689a) },
 342        /* The stick switched into modem (by e.g. usb_modeswitch): */
 343        { USB_DEVICE(0x04e8, 0x6889),
 344                .driver_info = (unsigned long) &kalmia_info, },
 345        { /* EMPTY == end of list */} };
 346MODULE_DEVICE_TABLE( usb, products);
 347
 348static struct usb_driver kalmia_driver = {
 349        .name = "kalmia",
 350        .id_table = products,
 351        .probe = usbnet_probe,
 352        .disconnect = usbnet_disconnect,
 353        .suspend = usbnet_suspend,
 354        .resume = usbnet_resume,
 355        .disable_hub_initiated_lpm = 1,
 356};
 357
 358module_usb_driver(kalmia_driver);
 359
 360MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>");
 361MODULE_DESCRIPTION("Samsung Kalmia USB network driver");
 362MODULE_LICENSE("GPL");
 363