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 59 static int 60 kalmia_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 99 static int 100 kalmia_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, sizeof(init_msg_1) 118 / sizeof(init_msg_1[0]), 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, sizeof(init_msg_2) 124 / sizeof(init_msg_2[0]), 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 } 133 134 static int 135 kalmia_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); 153 154 if (status) { 155 usb_set_intfdata(intf, NULL); 156 usb_driver_release_interface(driver_of(intf), intf); 157 return status; 158 } 159 160 memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN); 161 162 return status; 163 } 164 165 static struct sk_buff * 166 kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags) 167 { 168 struct sk_buff *skb2 = NULL; 169 u16 content_len; 170 unsigned char *header_start; 171 unsigned char ether_type_1, ether_type_2; 172 u8 remainder, padlen = 0; 173 174 if (!skb_cloned(skb)) { 175 int headroom = skb_headroom(skb); 176 int tailroom = skb_tailroom(skb); 177 178 if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom 179 >= KALMIA_HEADER_LENGTH)) 180 goto done; 181 182 if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH 183 + KALMIA_ALIGN_SIZE)) { 184 skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH, 185 skb->data, skb->len); 186 skb_set_tail_pointer(skb, skb->len); 187 goto done; 188 } 189 } 190 191 skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH, 192 KALMIA_ALIGN_SIZE, flags); 193 if (!skb2) 194 return NULL; 195 196 dev_kfree_skb_any(skb); 197 skb = skb2; 198 199 done: 200 header_start = skb_push(skb, KALMIA_HEADER_LENGTH); 201 ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12]; 202 ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13]; 203 204 netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1, 205 ether_type_2); 206 207 /* According to empiric data for data packages */ 208 header_start[0] = 0x57; 209 header_start[1] = 0x44; 210 content_len = skb->len - KALMIA_HEADER_LENGTH; 211 212 put_unaligned_le16(content_len, &header_start[2]); 213 header_start[4] = ether_type_1; 214 header_start[5] = ether_type_2; 215 216 /* Align to 4 bytes by padding with zeros */ 217 remainder = skb->len % KALMIA_ALIGN_SIZE; 218 if (remainder > 0) { 219 padlen = KALMIA_ALIGN_SIZE - remainder; 220 skb_put_zero(skb, padlen); 221 } 222 223 netdev_dbg(dev->net, 224 "Sending package with length %i and padding %i. Header: %6phC.", 225 content_len, padlen, header_start); 226 227 return skb; 228 } 229 230 static int 231 kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb) 232 { 233 /* 234 * Our task here is to strip off framing, leaving skb with one 235 * data frame for the usbnet framework code to process. 236 */ 237 static const u8 HEADER_END_OF_USB_PACKET[] = 238 { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 }; 239 static const u8 EXPECTED_UNKNOWN_HEADER_1[] = 240 { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 }; 241 static const u8 EXPECTED_UNKNOWN_HEADER_2[] = 242 { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 }; 243 int i = 0; 244 245 /* incomplete header? */ 246 if (skb->len < KALMIA_HEADER_LENGTH) 247 return 0; 248 249 do { 250 struct sk_buff *skb2 = NULL; 251 u8 *header_start; 252 u16 usb_packet_length, ether_packet_length; 253 int is_last; 254 255 header_start = skb->data; 256 257 if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) { 258 if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1, 259 sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp( 260 header_start, EXPECTED_UNKNOWN_HEADER_2, 261 sizeof(EXPECTED_UNKNOWN_HEADER_2))) { 262 netdev_dbg(dev->net, 263 "Received expected unknown frame header: %6phC. Package length: %i\n", 264 header_start, 265 skb->len - KALMIA_HEADER_LENGTH); 266 } 267 else { 268 netdev_err(dev->net, 269 "Received unknown frame header: %6phC. Package length: %i\n", 270 header_start, 271 skb->len - KALMIA_HEADER_LENGTH); 272 return 0; 273 } 274 } 275 else 276 netdev_dbg(dev->net, 277 "Received header: %6phC. Package length: %i\n", 278 header_start, skb->len - KALMIA_HEADER_LENGTH); 279 280 /* subtract start header and end header */ 281 usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH); 282 ether_packet_length = get_unaligned_le16(&header_start[2]); 283 skb_pull(skb, KALMIA_HEADER_LENGTH); 284 285 /* Some small packets misses end marker */ 286 if (usb_packet_length < ether_packet_length) { 287 ether_packet_length = usb_packet_length 288 + KALMIA_HEADER_LENGTH; 289 is_last = true; 290 } 291 else { 292 netdev_dbg(dev->net, "Correct package length #%i", i 293 + 1); 294 295 is_last = (memcmp(skb->data + ether_packet_length, 296 HEADER_END_OF_USB_PACKET, 297 sizeof(HEADER_END_OF_USB_PACKET)) == 0); 298 if (!is_last) { 299 header_start = skb->data + ether_packet_length; 300 netdev_dbg(dev->net, 301 "End header: %6phC. Package length: %i\n", 302 header_start, 303 skb->len - KALMIA_HEADER_LENGTH); 304 } 305 } 306 307 if (is_last) { 308 skb2 = skb; 309 } 310 else { 311 skb2 = skb_clone(skb, GFP_ATOMIC); 312 if (unlikely(!skb2)) 313 return 0; 314 } 315 316 skb_trim(skb2, ether_packet_length); 317 318 if (is_last) { 319 return 1; 320 } 321 else { 322 usbnet_skb_return(dev, skb2); 323 skb_pull(skb, ether_packet_length); 324 } 325 326 i++; 327 } 328 while (skb->len); 329 330 return 1; 331 } 332 333 static const struct driver_info kalmia_info = { 334 .description = "Samsung Kalmia LTE USB dongle", 335 .flags = FLAG_WWAN, 336 .bind = kalmia_bind, 337 .rx_fixup = kalmia_rx_fixup, 338 .tx_fixup = kalmia_tx_fixup 339 }; 340 341 /*-------------------------------------------------------------------------*/ 342 343 static const struct usb_device_id products[] = { 344 /* The unswitched USB ID, to get the module auto loaded: */ 345 { USB_DEVICE(0x04e8, 0x689a) }, 346 /* The stick switched into modem (by e.g. usb_modeswitch): */ 347 { USB_DEVICE(0x04e8, 0x6889), 348 .driver_info = (unsigned long) &kalmia_info, }, 349 { /* EMPTY == end of list */} }; 350 MODULE_DEVICE_TABLE( usb, products); 351 352 static struct usb_driver kalmia_driver = { 353 .name = "kalmia", 354 .id_table = products, 355 .probe = usbnet_probe, 356 .disconnect = usbnet_disconnect, 357 .suspend = usbnet_suspend, 358 .resume = usbnet_resume, 359 .disable_hub_initiated_lpm = 1, 360 }; 361 362 module_usb_driver(kalmia_driver); 363 364 MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>"); 365 MODULE_DESCRIPTION("Samsung Kalmia USB network driver"); 366 MODULE_LICENSE("GPL"); 367