// SPDX-License-Identifier: GPL-2.0-or-later /* * USB network interface driver for Samsung Kalmia based LTE USB modem like the * Samsung GT-B3730 and GT-B3710. * * Copyright (C) 2011 Marius Bjoernstad Kotsbak * * Sponsored by Quicklink Video Distribution Services Ltd. * * Based on the cdc_eem module. */ #include #include #include #include #include #include #include #include #include #include #include #include /* * The Samsung Kalmia based LTE USB modems have a CDC ACM port for modem control * handled by the "option" module and an ethernet data port handled by this * module. * * The stick must first be switched into modem mode by usb_modeswitch * or similar tool. Then the modem gets sent two initialization packets by * this module, which gives the MAC address of the device. User space can then * connect the modem using AT commands through the ACM port and then use * DHCP on the network interface exposed by this module. Network packets are * sent to and from the modem in a proprietary format discovered after watching * the behavior of the windows driver for the modem. * * More information about the use of the modem is available in usb_modeswitch * forum and the project page: * * http://www.draisberghof.de/usb_modeswitch/bb/viewtopic.php?t=465 * https://github.com/mkotsbak/Samsung-GT-B3730-linux-driver */ /* #define DEBUG */ /* #define VERBOSE */ #define KALMIA_HEADER_LENGTH 6 #define KALMIA_ALIGN_SIZE 4 #define KALMIA_USB_TIMEOUT 10000 /*-------------------------------------------------------------------------*/ static int kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8 init_msg_len, u8 *buffer, u8 expected_len) { int act_len; int status; netdev_dbg(dev->net, "Sending init packet"); status = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 0x02), init_msg, init_msg_len, &act_len, KALMIA_USB_TIMEOUT); if (status != 0) { netdev_err(dev->net, "Error sending init packet. Status %i\n", status); return status; } else if (act_len != init_msg_len) { netdev_err(dev->net, "Did not send all of init packet. Bytes sent: %i", act_len); } else { netdev_dbg(dev->net, "Successfully sent init packet."); } status = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, 0x81), buffer, expected_len, &act_len, KALMIA_USB_TIMEOUT); if (status != 0) netdev_err(dev->net, "Error receiving init result. Status %i\n", status); else if (act_len != expected_len) netdev_err(dev->net, "Unexpected init result length: %i\n", act_len); return status; } static int kalmia_init_and_get_ethernet_addr(struct usbnet *dev, u8 *ethernet_addr) { static const char init_msg_1[] = { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0x00 }; static const char init_msg_2[] = { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4, 0x00, 0x00 }; static const int buflen = 28; char *usb_buf; int status; usb_buf = kmalloc(buflen, GFP_DMA | GFP_KERNEL); if (!usb_buf) return -ENOMEM; memcpy(usb_buf, init_msg_1, 12); status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_1), usb_buf, 24); if (status != 0) goto out; memcpy(usb_buf, init_msg_2, 12); status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_2), usb_buf, 28); if (status != 0) goto out; memcpy(ethernet_addr, usb_buf + 10, ETH_ALEN); out: kfree(usb_buf); return status; } static int kalmia_bind(struct usbnet *dev, struct usb_interface *intf) { int status; u8 ethernet_addr[ETH_ALEN]; /* Don't bind to AT command interface */ if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC) return -EINVAL; dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK); dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK); dev->status = NULL; dev->net->hard_header_len += KALMIA_HEADER_LENGTH; dev->hard_mtu = 1400; dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr); if (status) return status; memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN); return status; } static struct sk_buff * kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags) { struct sk_buff *skb2 = NULL; u16 content_len; unsigned char *header_start; unsigned char ether_type_1, ether_type_2; u8 remainder, padlen = 0; if (!skb_cloned(skb)) { int headroom = skb_headroom(skb); int tailroom = skb_tailroom(skb); if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom >= KALMIA_HEADER_LENGTH)) goto done; if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH + KALMIA_ALIGN_SIZE)) { skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH, skb->data, skb->len); skb_set_tail_pointer(skb, skb->len); goto done; } } skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH, KALMIA_ALIGN_SIZE, flags); if (!skb2) return NULL; dev_kfree_skb_any(skb); skb = skb2; done: header_start = skb_push(skb, KALMIA_HEADER_LENGTH); ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12]; ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13]; netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1, ether_type_2); /* According to empiric data for data packages */ header_start[0] = 0x57; header_start[1] = 0x44; content_len = skb->len - KALMIA_HEADER_LENGTH; put_unaligned_le16(content_len, &header_start[2]); header_start[4] = ether_type_1; header_start[5] = ether_type_2; /* Align to 4 bytes by padding with zeros */ remainder = skb->len % KALMIA_ALIGN_SIZE; if (remainder > 0) { padlen = KALMIA_ALIGN_SIZE - remainder; skb_put_zero(skb, padlen); } netdev_dbg(dev->net, "Sending package with length %i and padding %i. Header: %6phC.", content_len, padlen, header_start); return skb; } static int kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb) { /* * Our task here is to strip off framing, leaving skb with one * data frame for the usbnet framework code to process. */ static const u8 HEADER_END_OF_USB_PACKET[] = { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 }; static const u8 EXPECTED_UNKNOWN_HEADER_1[] = { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 }; static const u8 EXPECTED_UNKNOWN_HEADER_2[] = { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 }; int i = 0; /* incomplete header? */ if (skb->len < KALMIA_HEADER_LENGTH) return 0; do { struct sk_buff *skb2 = NULL; u8 *header_start; u16 usb_packet_length, ether_packet_length; int is_last; header_start = skb->data; if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) { if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1, sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp( header_start, EXPECTED_UNKNOWN_HEADER_2, sizeof(EXPECTED_UNKNOWN_HEADER_2))) { netdev_dbg(dev->net, "Received expected unknown frame header: %6phC. Package length: %i\n", header_start, skb->len - KALMIA_HEADER_LENGTH); } else { netdev_err(dev->net, "Received unknown frame header: %6phC. Package length: %i\n", header_start, skb->len - KALMIA_HEADER_LENGTH); return 0; } } else netdev_dbg(dev->net, "Received header: %6phC. Package length: %i\n", header_start, skb->len - KALMIA_HEADER_LENGTH); /* subtract start header and end header */ usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH); ether_packet_length = get_unaligned_le16(&header_start[2]); skb_pull(skb, KALMIA_HEADER_LENGTH); /* Some small packets misses end marker */ if (usb_packet_length < ether_packet_length) { ether_packet_length = usb_packet_length + KALMIA_HEADER_LENGTH; is_last = true; } else { netdev_dbg(dev->net, "Correct package length #%i", i + 1); is_last = (memcmp(skb->data + ether_packet_length, HEADER_END_OF_USB_PACKET, sizeof(HEADER_END_OF_USB_PACKET)) == 0); if (!is_last) { header_start = skb->data + ether_packet_length; netdev_dbg(dev->net, "End header: %6phC. Package length: %i\n", header_start, skb->len - KALMIA_HEADER_LENGTH); } } if (is_last) { skb2 = skb; } else { skb2 = skb_clone(skb, GFP_ATOMIC); if (unlikely(!skb2)) return 0; } skb_trim(skb2, ether_packet_length); if (is_last) { return 1; } else { usbnet_skb_return(dev, skb2); skb_pull(skb, ether_packet_length); } i++; } while (skb->len); return 1; } static const struct driver_info kalmia_info = { .description = "Samsung Kalmia LTE USB dongle", .flags = FLAG_WWAN, .bind = kalmia_bind, .rx_fixup = kalmia_rx_fixup, .tx_fixup = kalmia_tx_fixup }; /*-------------------------------------------------------------------------*/ static const struct usb_device_id products[] = { /* The unswitched USB ID, to get the module auto loaded: */ { USB_DEVICE(0x04e8, 0x689a) }, /* The stick switched into modem (by e.g. usb_modeswitch): */ { USB_DEVICE(0x04e8, 0x6889), .driver_info = (unsigned long) &kalmia_info, }, { /* EMPTY == end of list */} }; MODULE_DEVICE_TABLE( usb, products); static struct usb_driver kalmia_driver = { .name = "kalmia", .id_table = products, .probe = usbnet_probe, .disconnect = usbnet_disconnect, .suspend = usbnet_suspend, .resume = usbnet_resume, .disable_hub_initiated_lpm = 1, }; module_usb_driver(kalmia_driver); MODULE_AUTHOR("Marius Bjoernstad Kotsbak "); MODULE_DESCRIPTION("Samsung Kalmia USB network driver"); MODULE_LICENSE("GPL");