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\n", 69 status); 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\n", 87 status); 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 static const u8 ep_addr[] = { 136 1 | USB_DIR_IN, 137 2 | USB_DIR_OUT, 138 0}; 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 if (!usb_check_bulk_endpoints(intf, ep_addr)) 145 return -ENODEV; 146 147 dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK); 148 dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK); 149 dev->status = NULL; 150 151 dev->net->hard_header_len += KALMIA_HEADER_LENGTH; 152 dev->hard_mtu = 1400; 153 dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing 154 155 status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr); 156 if (status) 157 return status; 158 159 eth_hw_addr_set(dev->net, ethernet_addr); 160 161 return status; 162 } 163 164 static struct sk_buff * 165 kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags) 166 { 167 struct sk_buff *skb2 = NULL; 168 u16 content_len; 169 unsigned char *header_start; 170 unsigned char ether_type_1, ether_type_2; 171 u8 remainder, padlen = 0; 172 173 if (!skb_cloned(skb)) { 174 int headroom = skb_headroom(skb); 175 int tailroom = skb_tailroom(skb); 176 177 if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom 178 >= KALMIA_HEADER_LENGTH)) 179 goto done; 180 181 if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH 182 + KALMIA_ALIGN_SIZE)) { 183 skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH, 184 skb->data, skb->len); 185 skb_set_tail_pointer(skb, skb->len); 186 goto done; 187 } 188 } 189 190 skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH, 191 KALMIA_ALIGN_SIZE, flags); 192 if (!skb2) 193 return NULL; 194 195 dev_kfree_skb_any(skb); 196 skb = skb2; 197 198 done: 199 header_start = skb_push(skb, KALMIA_HEADER_LENGTH); 200 ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12]; 201 ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13]; 202 203 netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1, 204 ether_type_2); 205 206 /* According to empiric data for data packages */ 207 header_start[0] = 0x57; 208 header_start[1] = 0x44; 209 content_len = skb->len - KALMIA_HEADER_LENGTH; 210 211 put_unaligned_le16(content_len, &header_start[2]); 212 header_start[4] = ether_type_1; 213 header_start[5] = ether_type_2; 214 215 /* Align to 4 bytes by padding with zeros */ 216 remainder = skb->len % KALMIA_ALIGN_SIZE; 217 if (remainder > 0) { 218 padlen = KALMIA_ALIGN_SIZE - remainder; 219 skb_put_zero(skb, padlen); 220 } 221 222 netdev_dbg(dev->net, 223 "Sending package with length %i and padding %i. Header: %6phC.", 224 content_len, padlen, header_start); 225 226 return skb; 227 } 228 229 static int 230 kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb) 231 { 232 /* 233 * Our task here is to strip off framing, leaving skb with one 234 * data frame for the usbnet framework code to process. 235 */ 236 static const u8 HEADER_END_OF_USB_PACKET[] = 237 { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 }; 238 static const u8 EXPECTED_UNKNOWN_HEADER_1[] = 239 { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 }; 240 static const u8 EXPECTED_UNKNOWN_HEADER_2[] = 241 { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 }; 242 int i = 0; 243 244 /* incomplete header? */ 245 if (skb->len < KALMIA_HEADER_LENGTH) 246 return 0; 247 248 do { 249 struct sk_buff *skb2 = NULL; 250 u8 *header_start; 251 u16 usb_packet_length, ether_packet_length; 252 int is_last; 253 254 header_start = skb->data; 255 256 if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) { 257 if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1, 258 sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp( 259 header_start, EXPECTED_UNKNOWN_HEADER_2, 260 sizeof(EXPECTED_UNKNOWN_HEADER_2))) { 261 netdev_dbg(dev->net, 262 "Received expected unknown frame header: %6phC. Package length: %i\n", 263 header_start, 264 skb->len - KALMIA_HEADER_LENGTH); 265 } 266 else { 267 netdev_err(dev->net, 268 "Received unknown frame header: %6phC. Package length: %i\n", 269 header_start, 270 skb->len - KALMIA_HEADER_LENGTH); 271 return 0; 272 } 273 } 274 else 275 netdev_dbg(dev->net, 276 "Received header: %6phC. Package length: %i\n", 277 header_start, skb->len - KALMIA_HEADER_LENGTH); 278 279 /* subtract start header and end header */ 280 usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH); 281 ether_packet_length = get_unaligned_le16(&header_start[2]); 282 skb_pull(skb, KALMIA_HEADER_LENGTH); 283 284 /* Some small packets misses end marker */ 285 if (usb_packet_length < ether_packet_length) { 286 ether_packet_length = usb_packet_length 287 + KALMIA_HEADER_LENGTH; 288 is_last = true; 289 } 290 else { 291 netdev_dbg(dev->net, "Correct package length #%i", i 292 + 1); 293 294 is_last = (memcmp(skb->data + ether_packet_length, 295 HEADER_END_OF_USB_PACKET, 296 sizeof(HEADER_END_OF_USB_PACKET)) == 0); 297 if (!is_last) { 298 header_start = skb->data + ether_packet_length; 299 netdev_dbg(dev->net, 300 "End header: %6phC. Package length: %i\n", 301 header_start, 302 skb->len - KALMIA_HEADER_LENGTH); 303 } 304 } 305 306 if (is_last) { 307 skb2 = skb; 308 } 309 else { 310 skb2 = skb_clone(skb, GFP_ATOMIC); 311 if (unlikely(!skb2)) 312 return 0; 313 } 314 315 skb_trim(skb2, ether_packet_length); 316 317 if (is_last) { 318 return 1; 319 } 320 else { 321 usbnet_skb_return(dev, skb2); 322 skb_pull(skb, ether_packet_length); 323 } 324 325 i++; 326 } 327 while (skb->len); 328 329 return 1; 330 } 331 332 static const struct driver_info kalmia_info = { 333 .description = "Samsung Kalmia LTE USB dongle", 334 .flags = FLAG_WWAN, 335 .bind = kalmia_bind, 336 .rx_fixup = kalmia_rx_fixup, 337 .tx_fixup = kalmia_tx_fixup 338 }; 339 340 /*-------------------------------------------------------------------------*/ 341 342 static const struct usb_device_id products[] = { 343 /* The unswitched USB ID, to get the module auto loaded: */ 344 { USB_DEVICE(0x04e8, 0x689a) }, 345 /* The stick switched into modem (by e.g. usb_modeswitch): */ 346 { USB_DEVICE(0x04e8, 0x6889), 347 .driver_info = (unsigned long) &kalmia_info, }, 348 { /* EMPTY == end of list */} }; 349 MODULE_DEVICE_TABLE( usb, products); 350 351 static struct usb_driver kalmia_driver = { 352 .name = "kalmia", 353 .id_table = products, 354 .probe = usbnet_probe, 355 .disconnect = usbnet_disconnect, 356 .suspend = usbnet_suspend, 357 .resume = usbnet_resume, 358 .disable_hub_initiated_lpm = 1, 359 }; 360 361 module_usb_driver(kalmia_driver); 362 363 MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>"); 364 MODULE_DESCRIPTION("Samsung Kalmia USB network driver"); 365 MODULE_LICENSE("GPL"); 366