Date:	Mon, 13 Jun 2011 09:57:17 -0500
From:	Dan Williams <dcbw@...hat.com>
To:	"Marius B. Kotsbak" <marius.kotsbak@...il.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, "Marius B. Kotsbak" <marius@...sbak.com>
Subject: Re: [PATCH] net/usb: Add Samsung Kalmia driver for Samsung GT-B3730

On Sat, 2011-06-11 at 01:34 +0200, Marius B. Kotsbak wrote:
> Introducing driver for the network port of Samsung Kalmia based USB LTE modems.
> It has also an ACM interface that previous patches associates with the "option"
> module. To access those interfaces, the modem must first be switched from modem
> mode using a tool like usb_modeswitch.
> 
> As the proprietary protocol has been discovered by watching the MS Windows driver
> behavior, there might be errors in the protocol handling, but stable and fast
> connection has been established for hours with Norwegian operator NetCom that
> distributes this modem with their LTE/4G subscription.

Why make the driver bind to both the switched and unswitched USB IDs?
Shouldn't the kernel bind the driver after switch when the device
reconnects with the new IDs?

Dan

> More and updated information about how to use this driver is available here:
> 
> http://www.draisberghof.de/usb_modeswitch/bb/viewtopic.php?t=465
> https://github.com/mkotsbak/Samsung-GT-B3730-linux-driver
> 
> Signed-off-by: Marius B. Kotsbak <marius@...sbak.com>
> ---
>  drivers/net/usb/Kconfig  |   10 ++
>  drivers/net/usb/Makefile |    2 +-
>  drivers/net/usb/kalmia.c |  393 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 404 insertions(+), 1 deletions(-)
>  create mode 100644 drivers/net/usb/kalmia.c
> 
> diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
> index 9d4f911..b6e4efc 100644
> --- a/drivers/net/usb/Kconfig
> +++ b/drivers/net/usb/Kconfig
> @@ -385,6 +385,16 @@ config USB_NET_CX82310_ETH
>  	  router with USB ethernet port. This driver is for routers only,
>  	  it will not work with ADSL modems (use cxacru driver instead).
>  
> +config CONFIG_USB_NET_KALMIA
> +	tristate "Samsung Kalmia based LTE USB modem"
> +	depends on USB_USBNET
> +	help
> +	  Choose this option if you have a Samsung Kalmia based USB modem
> +	  as Samsung GT-B3730.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called kalmia.
> +
>  config USB_HSO
>  	tristate "Option USB High Speed Mobile Devices"
>  	depends on USB && RFKILL
> diff --git a/drivers/net/usb/Makefile b/drivers/net/usb/Makefile
> index c7ec8a5..6091249 100644
> --- a/drivers/net/usb/Makefile
> +++ b/drivers/net/usb/Makefile
> @@ -28,4 +28,4 @@ obj-$(CONFIG_USB_SIERRA_NET)	+= sierra_net.o
>  obj-$(CONFIG_USB_NET_CX82310_ETH)	+= cx82310_eth.o
>  obj-$(CONFIG_USB_NET_CDC_NCM)	+= cdc_ncm.o
>  obj-$(CONFIG_USB_VL600)		+= lg-vl600.o
> -
> +obj-$(CONFIG_USB_NET_KALMIA)	+= kalmia.o
> diff --git a/drivers/net/usb/kalmia.c b/drivers/net/usb/kalmia.c
> new file mode 100644
> index 0000000..d1e80e0
> --- /dev/null
> +++ b/drivers/net/usb/kalmia.c
> @@ -0,0 +1,393 @@
> +/*
> + * 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.
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.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)
> +{
> +	char init_msg_1[] =
> +		{ 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
> +		0x00, 0x00 };
> +	char init_msg_2[] =
> +		{ 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4,
> +		0x00, 0x00 };
> +	char receive_buf[28];
> +	int status;
> +
> +	status = kalmia_send_init_packet(dev, init_msg_1, sizeof(init_msg_1)
> +		/ sizeof(init_msg_1[0]), receive_buf, 24);
> +	if (status != 0)
> +		return status;
> +
> +	status = kalmia_send_init_packet(dev, init_msg_2, sizeof(init_msg_2)
> +		/ sizeof(init_msg_2[0]), receive_buf, 28);
> +	if (status != 0)
> +		return status;
> +
> +	memcpy(ethernet_addr, receive_buf + 10, ETH_ALEN);
> +
> +	return status;
> +}
> +
> +static int
> +kalmia_bind(struct usbnet *dev, struct usb_interface *intf)
> +{
> +	u8 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 < 0) {
> +		usb_set_intfdata(intf, NULL);
> +		usb_driver_release_interface(driver_of(intf), intf);
> +		return status;
> +	}
> +
> +	memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN);
> +	memcpy(dev->net->perm_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;
> +	header_start[2] = (content_len & 0xff); /* low byte */
> +	header_start[3] = (content_len >> 8); /* high byte */
> +
> +	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: %02x:%02x:%02x:%02x:%02x:%02x.",
> +		content_len, padlen, header_start[0], header_start[1],
> +		header_start[2], header_start[3], header_start[4],
> +		header_start[5]);
> +
> +	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.
> +	 */
> +	const u8 HEADER_END_OF_USB_PACKET[] =
> +		{ 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 };
> +	const u8 EXPECTED_UNKNOWN_HEADER_1[] =
> +		{ 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 };
> +	const u8 EXPECTED_UNKNOWN_HEADER_2[] =
> +		{ 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 };
> +	u8 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: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> +					header_start[0], header_start[1],
> +					header_start[2], header_start[3],
> +					header_start[4], header_start[5],
> +					skb->len - KALMIA_HEADER_LENGTH);
> +			}
> +			else {
> +				netdev_err(
> +					dev->net,
> +					"Received unknown frame header: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> +					header_start[0], header_start[1],
> +					header_start[2], header_start[3],
> +					header_start[4], header_start[5],
> +					skb->len - KALMIA_HEADER_LENGTH);
> +				return 0;
> +			}
> +		}
> +		else
> +			netdev_dbg(
> +				dev->net,
> +				"Received header: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> +				header_start[0], header_start[1], header_start[2],
> +				header_start[3], header_start[4], header_start[5],
> +				skb->len - KALMIA_HEADER_LENGTH);
> +
> +		/* subtract start header and end header */
> +		usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH);
> +		ether_packet_length = header_start[2] + (header_start[3] << 8);
> +		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: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> +					header_start[0], header_start[1],
> +					header_start[2], header_start[3],
> +					header_start[4], header_start[5],
> +					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
> +};
> +
> +static int __init kalmia_init(void)
> +{
> +	return usb_register(&kalmia_driver);
> +}
> +module_init( kalmia_init);
> +
> +static void __exit kalmia_exit(void)
> +{
> +	usb_deregister(&kalmia_driver);
> +}
> +module_exit( kalmia_exit);
> +
> +MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@...sbak.com>");
> +MODULE_DESCRIPTION("Samsung Kalmia USB network driver");
> +MODULE_LICENSE("GPL");


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