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 55 static int 56 kalmia_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 95 static int 96 kalmia_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); 125 out: 126 kfree(usb_buf); 127 return status; 128 } 129 130 static int 131 kalmia_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 } 156 157 static struct sk_buff * 158 kalmia_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; 190 191 done: 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 } 221 222 static int 223 kalmia_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 } 324 325 static 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 /*-------------------------------------------------------------------------*/ 334 335 static 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 */} }; 342 MODULE_DEVICE_TABLE( usb, products); 343 344 static 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 }; 353 354 module_usb_driver(kalmia_driver); 355 356 MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>"); 357 MODULE_DESCRIPTION("Samsung Kalmia USB network driver"); 358 MODULE_LICENSE("GPL"); 359