path: root/drivers/usb/gadget/f_ncm.c

/*
 * f_ncm.c -- USB CDC Network (NCM) link function driver
 *
 * Copyright (C) 2010 Nokia Corporation
 * Contact: Yauheni Kaliuta <yauheni.kaliuta@nokia.com>
 *
 * The driver borrows from f_ecm.c which is:
 *
 * Copyright (C) 2003-2005,2008 David Brownell
 * Copyright (C) 2008 Nokia Corporation
 *
 * 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/kernel.h>
#include <linux/device.h>
#include <linux/etherdevice.h>
#include <linux/crc32.h>

#include <linux/usb/cdc.h>

#include "u_ether.h"

/*
 * This function is a "CDC Network Control Model" (CDC NCM) Ethernet link.
 * NCM is intended to be used with high-speed network attachments.
 *
 * Note that NCM requires the use of "alternate settings" for its data
 * interface.  This means that the set_alt() method has real work to do,
 * and also means that a get_alt() method is required.
 */

/* to trigger crc/non-crc ndp signature */

#define NCM_NDP_HDR_CRC_MASK	0x01000000
#define NCM_NDP_HDR_CRC		0x01000000
#define NCM_NDP_HDR_NOCRC	0x00000000

enum ncm_notify_state {
	NCM_NOTIFY_NONE,		/* don't notify */
	NCM_NOTIFY_CONNECT,		/* issue CONNECT next */
	NCM_NOTIFY_SPEED,		/* issue SPEED_CHANGE next */
};

struct f_ncm {
	struct gether			port;
	u8				ctrl_id, data_id;

	char				ethaddr[14];

	struct usb_ep			*notify;
	struct usb_request		*notify_req;
	u8				notify_state;
	bool				is_open;

	struct ndp_parser_opts		*parser_opts;
	bool				is_crc;

	/*
	 * for notification, it is accessed from both
	 * callback and ethernet open/close
	 */
	spinlock_t			lock;
};

static inline struct f_ncm *func_to_ncm(struct usb_function *f)
{
	return container_of(f, struct f_ncm, port.func);
}

/* peak (theoretical) bulk transfer rate in bits-per-second */
static inline unsigned ncm_bitrate(struct usb_gadget *g)
{
	if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
		return 13 * 512 * 8 * 1000 * 8;
	else
		return 19 *  64 * 1 * 1000 * 8;
}

/*-------------------------------------------------------------------------*/

/*
 * We cannot group frames so use just the minimal size which ok to put
 * one max-size ethernet frame.
 * If the host can group frames, allow it to do that, 16K is selected,
 * because it's used by default by the current linux host driver
 */
#define NTB_DEFAULT_IN_SIZE	USB_CDC_NCM_NTB_MIN_IN_SIZE
#define NTB_OUT_SIZE		16384

/*
 * skbs of size less than that will not be aligned
 * to NCM's dwNtbInMaxSize to save bus bandwidth
 */

#define	MAX_TX_NONFIXED		(512 * 3)

#define FORMATS_SUPPORTED	(USB_CDC_NCM_NTB16_SUPPORTED |	\
				 USB_CDC_NCM_NTB32_SUPPORTED)

static struct usb_cdc_ncm_ntb_parameters ntb_parameters = {
	.wLength = sizeof ntb_parameters,
	.bmNtbFormatsSupported = cpu_to_le16(FORMATS_SUPPORTED),
	.dwNtbInMaxSize = cpu_to_le32(NTB_DEFAULT_IN_SIZE),
	.wNdpInDivisor = cpu_to_le16(4),
	.wNdpInPayloadRemainder = cpu_to_le16(0),
	.wNdpInAlignment = cpu_to_le16(4),

	.dwNtbOutMaxSize = cpu_to_le32(NTB_OUT_SIZE),
	.wNdpOutDivisor = cpu_to_le16(4),
	.wNdpOutPayloadRemainder = cpu_to_le16(0),
	.wNdpOutAlignment = cpu_to_le16(4),
};

/*
 * Use wMaxPacketSize big enough to fit CDC_NOTIFY_SPEED_CHANGE in one
 * packet, to simplify cancellation; and a big transfer interval, to
 * waste less bandwidth.
 */

#define LOG2_STATUS_INTERVAL_MSEC	5	/* 1 << 5 == 32 msec */
#define NCM_STATUS_BYTECOUNT		16	/* 8 byte header + data */

static struct usb_interface_assoc_descriptor ncm_iad_desc __initdata = {
	.bLength =		sizeof ncm_iad_desc,
	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,

	/* .bFirstInterface =	DYNAMIC, */
	.bInterfaceCount =	2,	/* control + data */
	.bFunctionClass =	USB_CLASS_COMM,
	.bFunctionSubClass =	USB_CDC_SUBCLASS_NCM,
	.bFunctionProtocol =	USB_CDC_PROTO_NONE,
	/* .iFunction =		DYNAMIC */
};

/* interface descriptor: */

static struct usb_interface_descriptor ncm_control_intf __initdata = {
	.bLength =		sizeof ncm_control_intf,
	.bDescriptorType =	USB_DT_INTERFACE,

	/* .bInterfaceNumber = DYNAMIC */
	.bNumEndpoints =	1,
	.bInterfaceClass =	USB_CLASS_COMM,
	.bInterfaceSubClass =	USB_CDC_SUBCLASS_NCM,
	.bInterfaceProtocol =	USB_CDC_PROTO_NONE,
	/* .iInterface = DYNAMIC */
};

static struct usb_cdc_header_desc ncm_header_desc __initdata = {
	.bLength =		sizeof ncm_header_desc,
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,

	.bcdCDC =		cpu_to_le16(0x0110),
};

static struct usb_cdc_union_desc ncm_union_desc __initdata = {
	.bLength =		sizeof(ncm_union_desc),
	.bDescriptorType =	USB_DT_CS_INTERFACE