/*
* 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 <marius@kotsbak.com>
*
* Sponsored by Quicklink Video Distribution Services Ltd.
*
* Based on the cdc_eem module.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ctype.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/crc32.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/gfp.h>
/*
* 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, length %i\n",
status, act_len);
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, length %i\n",
status, act_len);
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, sizeof(init_msg_1)
/ sizeof(init_msg_1[0]), usb_buf, 24);
if (status != 0)
return status;
memcpy(usb_buf, init_msg_2, 12);
status = kalmia_send_init_packet(dev, usb_buf, sizeof(init_msg_2)
/ sizeof(init_msg_2[0]), usb_buf, 28);
if (status != 0)
return status;
memcpy(ethernet_addr, usb_buf + 10, ETH_ALEN);
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) {
usb_set_intfdata(intf, NULL);
usb_driver_release_interface(driver_of(intf), intf);
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;
memset(skb_put(skb, padlen), 0, 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 swithed 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 <marius@kotsbak.com>");
MODULE_DESCRIPTION("Samsung Kalmia USB network driver");
MODULE_LICENSE("GPL");