drivers/serial/usbtty.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2003
 * Gerry Hamel, geh@ti.com, Texas Instruments
 *
 * (C) Copyright 2006
 * Bryan O'Donoghue, bodonoghue@codehermit.ie
 */

#include <common.h>
#include <config.h>
#include <circbuf.h>
#include <env.h>
#include <serial.h>
#include <stdio_dev.h>
#include <asm/unaligned.h>
#include "usbtty.h"
#include "usb_cdc_acm.h"
#include "usbdescriptors.h"

#ifdef DEBUG
#define TTYDBG(fmt,args...)\
	serial_printf("[%s] %s %d: "fmt, __FILE__,__FUNCTION__,__LINE__,##args)
#else
#define TTYDBG(fmt,args...) do{}while(0)
#endif

#if 1
#define TTYERR(fmt,args...)\
	serial_printf("ERROR![%s] %s %d: "fmt, __FILE__,__FUNCTION__,\
	__LINE__,##args)
#else
#define TTYERR(fmt,args...) do{}while(0)
#endif

/*
 * Defines
 */
#define NUM_CONFIGS    1
#define MAX_INTERFACES 2
#define NUM_ENDPOINTS  3
#define ACM_TX_ENDPOINT 3
#define ACM_RX_ENDPOINT 2
#define GSERIAL_TX_ENDPOINT 2
#define GSERIAL_RX_ENDPOINT 1
#define NUM_ACM_INTERFACES 2
#define NUM_GSERIAL_INTERFACES 1
#define CONFIG_USBD_DATA_INTERFACE_STR "Bulk Data Interface"
#define CONFIG_USBD_CTRL_INTERFACE_STR "Control Interface"

/*
 * Buffers to hold input and output data
 */
#define USBTTY_BUFFER_SIZE 2048
static circbuf_t usbtty_input;
static circbuf_t usbtty_output;


/*
 * Instance variables
 */
static struct stdio_dev usbttydev;
static struct usb_device_instance device_instance[1];
static struct usb_bus_instance bus_instance[1];
static struct usb_configuration_instance config_instance[NUM_CONFIGS];
static struct usb_interface_instance interface_instance[MAX_INTERFACES];
static struct usb_alternate_instance alternate_instance[MAX_INTERFACES];
/* one extra for control endpoint */
static struct usb_endpoint_instance endpoint_instance[NUM_ENDPOINTS+1];

/*
 * Global flag
 */
int usbtty_configured_flag = 0;

/*
 * Serial number
 */
static char serial_number[16];


/*
 * Descriptors, Strings, Local variables.
 */

/* defined and used by gadget/ep0.c */
extern struct usb_string_descriptor **usb_strings;

/* Indicies, References */
static unsigned short rx_endpoint = 0;
static unsigned short tx_endpoint = 0;
static unsigned short interface_count = 0;
static struct usb_string_descriptor *usbtty_string_table[STR_COUNT];

/* USB Descriptor Strings */
static u8 wstrLang[4] = {4,USB_DT_STRING,0x9,0x4};
static u8 wstrManufacturer[2 + 2*(sizeof(CONFIG_USBD_MANUFACTURER)-1)];
static u8 wstrProduct[2 + 2*(sizeof(CONFIG_USBD_PRODUCT_NAME)-1)];
static u8 wstrSerial[2 + 2*(sizeof(serial_number) - 1)];
static u8 wstrConfiguration[2 + 2*(sizeof(CONFIG_USBD_CONFIGURATION_STR)-1)];
static u8 wstrDataInterface[2 + 2*(sizeof(CONFIG_USBD_DATA_INTERFACE_STR)-1)];
static u8 wstrCtrlInterface[2 + 2*(sizeof(CONFIG_USBD_DATA_INTERFACE_STR)-1)];

/* Standard USB Data Structures */
static struct usb_interface_descriptor interface_descriptors[MAX_INTERFACES];
static struct usb_endpoint_descriptor *ep_descriptor_ptrs[NUM_ENDPOINTS];
static struct usb_configuration_descriptor	*configuration_descriptor = 0;
static struct usb_device_descriptor device_descriptor = {
	.bLength = sizeof(struct usb_device_descriptor),
	.bDescriptorType =	USB_DT_DEVICE,
	.bcdUSB =		cpu_to_le16(USB_BCD_VERSION),
	.bDeviceSubClass =	0x00,
	.bDeviceProtocol =	0x00,
	.bMaxPacketSize0 =	EP0_MAX_PACKET_SIZE,
	.idVendor =		cpu_to_le16(CONFIG_USBD_VENDORID),
	.bcdDevice =		cpu_to_le16(USBTTY_BCD_DEVICE),
	.iManufacturer =	STR_MANUFACTURER,
	.iProduct =		STR_PRODUCT,
	.iSerialNumber =	STR_SERIAL,
	.bNumConfigurations =	NUM_CONFIGS
};

/*
 * Static CDC ACM specific descriptors
 */

struct acm_config_desc {
	struct usb_configuration_descriptor configuration_desc;

	/* Master Interface */
	struct usb_interface_descriptor interface_desc;

	struct usb_class_header_function_descriptor usb_class_header;
	struct usb_class_call_management_descriptor usb_class_call_mgt;
	struct usb_class_abstract_control_descriptor usb_class_acm;
	struct usb_class_union_function_descriptor usb_class_union;
	struct usb_endpoint_descriptor notification_endpoint;

	/* Slave Interface */
	struct usb_interface_descriptor data_class_interface;
	struct usb_endpoint_descriptor data_endpoints[NUM_ENDPOINTS-1];
} __attribute__((packed));

static struct acm_config_desc acm_configuration_descriptors[NUM_CONFIGS] = {
	{
		.configuration_desc ={
			.bLength =
				sizeof(struct usb_configuration_descriptor),
			.bDescriptorType = USB_DT_CONFIG,
			.wTotalLength =
				cpu_to_le16(sizeof(struct acm_config_desc)),
			.bNumInterfaces = NUM_ACM_INTERFACES,
			.bConfigurationValue = 1,
			.iConfiguration = STR_CONFIG,
			.bmAttributes =
				BMATTRIBUTE_SELF_POWERED|BMATTRIBUTE_RESERVED,
			.bMaxPower = USBTTY_MAXPOWER
		},
		/* Interface 1 */
		.interface_desc = {
			.bLength  = sizeof(struct usb_interface_descriptor),
			.bDescriptorType = USB_DT_INTERFACE,
			.bInterfaceNumber = 0,
			.bAlternateSetting = 0,
			.bNumEndpoints = 0x01,
			.bInterfaceClass =
				COMMUNICATIONS_INTERFACE_CLASS_CONTROL,
			.bInterfaceSubClass = COMMUNICATIONS_ACM_SUBCLASS,
			.bInterfaceProtocol = COMMUNICATIONS_V25TER_PROTOCOL,
			.iInterface = STR_CTRL_INTERFACE,
		},
		.usb_class_header = {
			.bFunctionLength	=
				sizeof(struct usb_class_header_function_descriptor),
			.bDescriptorType	= CS_INTERFACE,
			.bDescriptorSubtype	= USB_ST_HEADER,
			.bcdCDC	= cpu_to_le16(110),
		},
		.usb_class_call_mgt = {
			.bFunctionLength	=
				sizeof(struct usb_class_call_management_descriptor),
			.bDescriptorType	= CS_INTERFACE,
			.bDescriptorSubtype	= USB_ST_CMF,
			.bmCapabilities		= 0x00,
			.bDataInterface		= 0x01,
		},
		.usb_class_acm = {
			.bFunctionLength	=
				sizeof(struct usb_class_abstract_control_descriptor),
			.bDescriptorType	= CS_INTERFACE,
			.bDescriptorSubtype	= USB_ST_ACMF,
			.bmCapabilities		= 0x00,
		},
		.usb_class_union = {
			.bFunctionLength	=
				sizeof(struct usb_class_union_function_descriptor),
			.bDescriptorType	= CS_INTERFACE,
			.bDescriptorSubtype	= USB_ST_UF,
			.bMasterInterface	= 0x00,
			.bSlaveInterface0	= 0x01,
		},
		.notification_endpoint = {
			.bLength =
				sizeof(struct usb_endpoint_descriptor),
			.bDescriptorType	= USB_DT_ENDPOINT,
			.bEndpointAddress	= UDC_INT_ENDPOINT | USB_DIR_IN,
			.bmAttributes		= USB_ENDPOINT_XFER_INT,
			.wMaxPacketSize
				= cpu_to_le16(CONFIG_USBD_SERIAL_INT_PKTSIZE),
			.bInterval		= 0xFF,
		},

		/* Interface 2 */
		.data_class_interface = {
			.bLength		=
				sizeof(struct usb_interface_descriptor),
			.bDescriptorType	= USB_DT_INTERFACE,
			.bInterfaceNumber	= 0x01,
			.bAlternateSetting	= 0x00,
			.bNumEndpoints		= 0x02,
			.bInterfaceClass	=
				COMMUNICATIONS_INTERFACE_CLASS_DATA,
			.bInterfaceSubClass	= DATA_INTERFACE_SUBCLASS_NONE,
			.bInterfaceProtocol	= DATA_INTERFACE_PROTOCOL_NONE,
			.iInterface		= STR_DATA_INTERFACE,
		},
		.data_endpoints = {
			{
				.bLength		=
					sizeof(struct usb_endpoint_descriptor),
				.bDescriptorType	= USB_DT_ENDPOINT,
				.bEndpointAddress	= UDC_OUT_ENDPOINT | USB_DIR_OUT,
				.bmAttributes		=
					USB_ENDPOINT_XFER_BULK,
				.wMaxPacketSize		=
					cpu_to_le16(CONFIG_USBD_SERIAL_BULK_PKTSIZE),
				.bInterval		= 0xFF,
			},
			{
				.bLength		=
					sizeof(struct usb_endpoint_descriptor),
				.bDescriptorType	= USB_DT_ENDPOINT,
				.bEndpointAddress	= UDC_IN_ENDPOINT | USB_DIR_IN,
				.bmAttributes		=
					USB_ENDPOINT_XFER_BULK,
				.wMaxPacketSize		=
					cpu_to_le16(CONFIG_USBD_SERIAL_BULK_PKTSIZE),
				.bInterval		= 0xFF,
			},
		},
	},
};

static struct rs232_emu rs232_desc={
		.dter		=	115200,
		.stop_bits	=	0x00,
		.parity		=	0x00,
		.data_bits	=	0x08
};


/*
 * Static Generic Serial specific data
 */


struct gserial_config_desc {

	struct usb_configuration_descriptor configuration_desc;
	struct usb_interface_descriptor	interface_desc[NUM_GSERIAL_INTERFACES];
	struct usb_endpoint_descriptor data_endpoints[NUM_ENDPOINTS];

} __attribute__((packed));

static struct gserial_config_desc
gserial_configuration_descriptors[NUM_CONFIGS] ={
	{
		.configuration_desc ={
			.bLength = sizeof(struct usb_configuration_descriptor),
			.bDescriptorType = USB_DT_CONFIG,
			.wTotalLength =
				cpu_to_le16(sizeof(struct gserial_config_desc)),
			.bNumInterfaces = NUM_GSERIAL_INTERFACES,
			.bConfigurationValue = 1,
			.iConfiguration = STR_CONFIG,
			.bmAttributes =
				BMATTRIBUTE_SELF_POWERED|BMATTRIBUTE_RESERVED,
			.bMaxPower = USBTTY_MAXPOWER
		},
		.interface_desc = {
			{
				.bLength  =
					sizeof(struct usb_interface_descriptor),
				.bDescriptorType = USB_DT_INTERFACE,
				.bInterfaceNumber = 0,
				.bAlternateSetting = 0,
				.bNumEndpoints = NUM_ENDPOINTS,
				.bInterfaceClass =
					COMMUNICATIONS_INTERFACE_CLASS_VENDOR,
				.bInterfaceSubClass =
					COMMUNICATIONS_NO_SUBCLASS,
				.bInterfaceProtocol =
					COMMUNICATIONS_NO_PROTOCOL,
				.iInterface = STR_DATA_INTERFACE
			},
		},
		.data_endpoints  = {
			{
				.bLength =
					sizeof(struct usb_endpoint_descriptor),
				.bDescriptorType =	USB_DT_ENDPOINT,
				.bEndpointAddress =	UDC_OUT_ENDPOINT | USB_DIR_OUT,
				.bmAttributes =		USB_ENDPOINT_XFER_BULK,
				.wMaxPacketSize =
					cpu_to_le16(CONFIG_USBD_SERIAL_OUT_PKTSIZE),
				.bInterval=		0xFF,
			},
			{
				.bLength =
					sizeof(struct usb_endpoint_descriptor),
				.bDescriptorType =	USB_DT_ENDPOINT,
				.bEndpointAddress =	UDC_IN_ENDPOINT | USB_DIR_IN,
				.bmAttributes =		USB_ENDPOINT_XFER_BULK,
				.wMaxPacketSize =
					cpu_to_le16(CONFIG_USBD_SERIAL_IN_PKTSIZE),
				.bInterval =		0xFF,
			},
			{
				.bLength =
					sizeof(struct usb_endpoint_descriptor),
				.bDescriptorType =	USB_DT_ENDPOINT,
				.bEndpointAddress =	UDC_INT_ENDPOINT | USB_DIR_IN,
				.bmAttributes =		USB_ENDPOINT_XFER_INT,
				.wMaxPacketSize =
					cpu_to_le16(CONFIG_USBD_SERIAL_INT_PKTSIZE),
				.bInterval =		0xFF,
			},
		},
	},
};

/*
 * Static Function Prototypes
 */

static void usbtty_init_strings (void);
static void usbtty_init_instances (void);
static void usbtty_init_endpoints (void);
static void usbtty_init_terminal_type(short type);
static void usbtty_event_handler (struct usb_device_instance *device,
				usb_device_event_t event, int data);
static int usbtty_cdc_setup(struct usb_device_request *request,
				struct urb *urb);
static int usbtty_configured (void);
static int write_buffer (circbuf_t * buf);
static int fill_buffer (circbuf_t * buf);

void usbtty_poll (void);

/* utility function for converting char* to wide string used by USB */
static void str2wide (char *str, u16 * wide)
{
	int i;
	for (i = 0; i < strlen (str) && str[i]; i++){
		#if defined(__LITTLE_ENDIAN)
			wide[i] = (u16) str[i];
		#elif defined(__BIG_ENDIAN)
			wide[i] = ((u16)(str[i])<<8);
		#else
			#error "__LITTLE_ENDIAN or __BIG_ENDIAN undefined"
		#endif
	}
}

/*
 * Test whether a character is in the RX buffer
 */

int usbtty_tstc(struct stdio_dev *dev)
{
	struct usb_endpoint_instance *endpoint =
		&endpoint_instance[rx_endpoint];

	/* If no input data exists, allow more RX to be accepted */
	if(usbtty_input.size <= 0){
		udc_unset_nak(endpoint->endpoint_address&0x03);
	}

	usbtty_poll ();
	return (usbtty_input.size > 0);
}

/*
 * Read a single byte from the usb client port. Returns 1 on success, 0
 * otherwise. When the function is succesfull, the character read is
 * written into its argument c.
 */

int usbtty_getc(struct stdio_dev *dev)
{
	char c;
	struct usb_endpoint_instance *endpoint =
		&endpoint_instance[rx_endpoint];

	while (usbtty_input.size <= 0) {
		udc_unset_nak(endpoint->endpoint_address&0x03);
		usbtty_poll ();
	}

	buf_pop (&usbtty_input, &c, 1);
	udc_set_nak(endpoint->endpoint_address&0x03);

	return c;
}

/*
 * Output a single byte to the usb client port.
 */
void usbtty_putc(struct stdio_dev *dev, const char c)
{
	if (!usbtty_configured ())
		return;

	/* If \n, also do \r */
	if (c == '\n')
		buf_push (&usbtty_output, "\r", 1);

	buf_push(&usbtty_output, &c, 1);

	/* Poll at end to handle new data... */
	if ((usbtty_output.size + 2) >= usbtty_output.totalsize) {
		usbtty_poll ();
	}
}

/* usbtty_puts() helper function for finding the next '\n' in a string */
static int next_nl_pos (const char *s)
{
	int i;

	for (i = 0; s[i] != '\0'; i++) {
		if (s[i] == '\n')
			return i;
	}
	return i;
}

/*
 * Output a string to the usb client port - implementing flow control
 */

static void __usbtty_puts (const char *str, int len)
{
	int maxlen = usbtty_output.totalsize;
	int space, n;

	/* break str into chunks < buffer size, if needed */
	while (len > 0) {
		usbtty_poll ();

		space = maxlen - usbtty_output.size;
		/* Empty buffer here, if needed, to ensure space... */
		if (space) {
			write_buffer (&usbtty_output);

			n = min(space, min(len, maxlen));
			buf_push (&usbtty_output, str, n);

			str += n;
			len -= n;
		}
	}
}

void usbtty_puts(struct stdio_dev *dev, const char *str)
{
	int n;
	int len;

	if (!usbtty_configured ())
		return;

	len = strlen (str);
	/* add '\r' for each '\n' */
	while (len > 0) {
		n = next_nl_pos (str);

		if (str[n] == '\n') {
			__usbtty_puts(str, n);
			__usbtty_puts("\r\n", 2);
			str += (n + 1);
			len -= (n + 1);
		} else {
			/* No \n found.	 All done. */
			__usbtty_puts (str, n);
			break;
		}
	}

	/* Poll at end to handle new data... */
	usbtty_poll ();
}

/*
 * Initialize the usb client port.
 *
 */
int drv_usbtty_init (void)
{
	int rc;
	char * sn;
	char * tt;
	int snlen;

	/* Get serial number */
	sn = env_get("serial#");
	if (!sn)
		sn = "000000000000";
	snlen = strlen(sn);
	if (snlen > sizeof(serial_number) - 1) {
		printf ("Warning: serial number %s is too long (%d > %lu)\n",
			sn, snlen, (ulong)(sizeof(serial_number) - 1));
		snlen = sizeof(serial_number) - 1;
	}
	memcpy (serial_number, sn, snlen);
	serial_number[snlen] = '\0';

	/* Decide on which type of UDC device to be.
	 */
	tt = env_get("usbtty");
	if (!tt)
		tt = "generic";
	usbtty_init_terminal_type(strcmp(tt,"cdc_acm"));

	/* prepare buffers... */
	buf_init (&usbtty_input, USBTTY_BUFFER_SIZE);
	buf_init (&usbtty_output, USBTTY_BUFFER_SIZE);

	/* Now, set up USB controller and infrastructure */
	udc_init ();		/* Basic USB initialization */

	usbtty_init_strings ();
	usbtty_init_instances ();

	usbtty_init_endpoints ();

	udc_startup_events (device_instance);/* Enable dev, init udc pointers */
	udc_connect ();		/* Enable pullup for host detection */

	/* Device initialization */
	memset (&usbttydev, 0, sizeof (usbttydev));

	strcpy (usbttydev.name, "usbtty");
	usbttydev.ext = 0;	/* No extensions */
	usbttydev.flags = DEV_FLAGS_INPUT | DEV_FLAGS_OUTPUT;
	usbttydev.tstc = usbtty_tstc;	/* 'tstc' function */
	usbttydev.getc = usbtty_getc;	/* 'getc' function */
	usbttydev.putc = usbtty_putc;	/* 'putc' function */
	usbttydev.puts = usbtty_puts;	/* 'puts' function */

	rc = stdio_register (&usbttydev);

	return (rc == 0) ? 1 : rc;
}

static void usbtty_init_strings (void)
{
	struct usb_string_descriptor *string;

	usbtty_string_table[STR_LANG] =
		(struct usb_string_descriptor*)wstrLang;

	string = (struct usb_string_descriptor *) wstrManufacturer;
	string->bLength = sizeof(wstrManufacturer);
	string->bDescriptorType = USB_DT_STRING;
	str2wide (CONFIG_USBD_MANUFACTURER, string->wData);
	usbtty_string_table[STR_MANUFACTURER]=string;


	string = (struct usb_string_descriptor *) wstrProduct;
	string->bLength = sizeof(wstrProduct);
	string->bDescriptorType = USB_DT_STRING;
	str2wide (CONFIG_USBD_PRODUCT_NAME, string->wData);
	usbtty_string_table[STR_PRODUCT]=string;


	string = (struct usb_string_descriptor *) wstrSerial;
	string->bLength = sizeof(serial_number);
	string->bDescriptorType = USB_DT_STRING;
	str2wide (serial_number, string->wData);
	usbtty_string_table[STR_SERIAL]=string;


	string = (struct usb_string_descriptor *) wstrConfiguration;
	string->bLength = sizeof(wstrConfiguration);
	string->bDescriptorType = USB_DT_STRING;
	str2wide (CONFIG_USBD_CONFIGURATION_STR, string->wData);
	usbtty_string_table[STR_CONFIG]=string;


	string = (struct usb_string_descriptor *) wstrDataInterface;
	string->bLength = sizeof(wstrDataInterface);
	string->bDescriptorType = USB_DT_STRING;
	str2wide (CONFIG_USBD_DATA_INTERFACE_STR, string->wData);
	usbtty_string_table[STR_DATA_INTERFACE]=string;

	string = (struct usb_string_descriptor *) wstrCtrlInterface;
	string->bLength = sizeof(wstrCtrlInterface);
	string->bDescriptorType = USB_DT_STRING;
	str2wide (CONFIG_USBD_CTRL_INTERFACE_STR, string->wData);
	usbtty_string_table[STR_CTRL_INTERFACE]=string;

	/* Now, initialize the string table for ep0 handling */
	usb_strings = usbtty_string_table;
}

#define init_wMaxPacketSize(x)	le16_to_cpu(get_unaligned(\
			&ep_descriptor_ptrs[(x) - 1]->wMaxPacketSize));

static void usbtty_init_instances (void)
{
	int i;

	/* initialize device instance */
	memset (device_instance, 0, sizeof (struct usb_device_instance));
	device_instance->device_state = STATE_INIT;
	device_instance->device_descriptor = &device_descriptor;
	device_instance->event = usbtty_event_handler;
	device_instance->cdc_recv_setup = usbtty_cdc_setup;
	device_instance->bus = bus_instance;
	device_instance->configurations = NUM_CONFIGS;
	device_instance->configuration_instance_array = config_instance;

	/* initialize bus instance */
	memset (bus_instance, 0, sizeof (struct usb_bus_instance));
	bus_instance->device = device_instance;
	bus_instance->endpoint_array = endpoint_instance;
	bus_instance->max_endpoints = 1;
	bus_instance->maxpacketsize = 64;
	bus_instance->serial_number_str = serial_number;

	/* configuration instance */
	memset (config_instance, 0,
		sizeof (struct usb_configuration_instance));
	config_instance->interfaces = interface_count;
	config_instance->configuration_descriptor = configuration_descriptor;
	config_instance->interface_instance_array = interface_instance;

	/* interface instance */
	memset (interface_instance, 0,
		sizeof (struct usb_interface_instance));
	interface_instance->alternates = 1;
	interface_instance->alternates_instance_array = alternate_instance;

	/* alternates instance */
	memset (alternate_instance, 0,
		sizeof (struct usb_alternate_instance));
	alternate_instance->interface_descriptor = interface_descriptors;
	alternate_instance->endpoints = NUM_ENDPOINTS;
	alternate_instance->endpoints_descriptor_array = ep_descriptor_ptrs;

	/* endpoint instances */
	memset (&endpoint_instance[0], 0,
		sizeof (struct usb_endpoint_instance));
	endpoint_instance[0].endpoint_address = 0;
	endpoint_instance[0].rcv_packetSize = EP0_MAX_PACKET_SIZE;
	endpoint_instance[0].rcv_attributes = USB_ENDPOINT_XFER_CONTROL;
	endpoint_instance[0].tx_packetSize = EP0_MAX_PACKET_SIZE;
	endpoint_instance[0].tx_attributes = USB_ENDPOINT_XFER_CONTROL;
	udc_setup_ep (device_instance, 0, &endpoint_instance[0]);

	for (i = 1; i <= NUM_ENDPOINTS; i++) {
		memset (&endpoint_instance[i], 0,
			sizeof (struct usb_endpoint_instance));

		endpoint_instance[i].endpoint_address =
			ep_descriptor_ptrs[i - 1]->bEndpointAddress;

		endpoint_instance[i].rcv_attributes =
			ep_descriptor_ptrs[i - 1]->bmAttributes;

		endpoint_instance[i].rcv_packetSize = init_wMaxPacketSize(i);

		endpoint_instance[i].tx_attributes =
			ep_descriptor_ptrs[i - 1]->bmAttributes;

		endpoint_instance[i].tx_packetSize = init_wMaxPacketSize(i);

		endpoint_instance[i].tx_attributes =
			ep_descriptor_ptrs[i - 1]->bmAttributes;

		urb_link_init (&endpoint_instance[i].rcv);
		urb_link_init (&endpoint_instance[i].rdy);
		urb_link_init (&endpoint_instance[i].tx);
		urb_link_init (&endpoint_instance[i].done);

		if (endpoint_instance[i].endpoint_address & USB_DIR_IN)
			endpoint_instance[i].tx_urb =
				usbd_alloc_urb (device_instance,
						&endpoint_instance[i]);
		else
			endpoint_instance[i].rcv_urb =
				usbd_alloc_urb (device_instance,
						&endpoint_instance[i]);
	}
}

static void usbtty_init_endpoints (void)
{
	int i;

	bus_instance->max_endpoints = NUM_ENDPOINTS + 1;
	for (i = 1; i <= NUM_ENDPOINTS; i++) {
		udc_setup_ep (device_instance, i, &endpoint_instance[i]);
	}
}

/* usbtty_init_terminal_type
 *
 * Do some late binding for our device type.
 */
static void usbtty_init_terminal_type(short type)
{
	switch(type){
		/* CDC ACM */
		case 0:
			/* Assign endpoint descriptors */
			ep_descriptor_ptrs[0] =
				&acm_configuration_descriptors[0].notification_endpoint;
			ep_descriptor_ptrs[1] =
				&acm_configuration_descriptors[0].data_endpoints[0];
			ep_descriptor_ptrs[2] =
				&acm_configuration_descriptors[0].data_endpoints[1];

			/* Enumerate Device Descriptor */
			device_descriptor.bDeviceClass =
				COMMUNICATIONS_DEVICE_CLASS;
			device_descriptor.idProduct =
				cpu_to_le16(CONFIG_USBD_PRODUCTID_CDCACM);

			/* Assign endpoint indices */
			tx_endpoint = ACM_TX_ENDPOINT;
			rx_endpoint = ACM_RX_ENDPOINT;

			/* Configuration Descriptor */
			configuration_descriptor =
				(struct usb_configuration_descriptor*)
				&acm_configuration_descriptors;

			/* Interface count */
			interface_count = NUM_ACM_INTERFACES;
		break;

		/* BULK IN/OUT & Default */
		case 1:
		default:
			/* Assign endpoint descriptors */
			ep_descriptor_ptrs[0] =
				&gserial_configuration_descriptors[0].data_endpoints[0];
			ep_descriptor_ptrs[1] =
				&gserial_configuration_descriptors[0].data_endpoints[1];
			ep_descriptor_ptrs[2] =
				&gserial_configuration_descriptors[0].data_endpoints[2];

			/* Enumerate Device Descriptor */
			device_descriptor.bDeviceClass = 0xFF;
			device_descriptor.idProduct =
				cpu_to_le16(CONFIG_USBD_PRODUCTID_GSERIAL);
			/* Assign endpoint indices */
			tx_endpoint = GSERIAL_TX_ENDPOINT;
			rx_endpoint = GSERIAL_RX_ENDPOINT;

			/* Configuration Descriptor */
			configuration_descriptor =
				(struct usb_configuration_descriptor*)
				&gserial_configuration_descriptors;

			/* Interface count */
			interface_count = NUM_GSERIAL_INTERFACES;
		break;
	}
}

/******************************************************************************/

static struct urb *next_urb (struct usb_device_instance *device,
			     struct usb_endpoint_instance *endpoint)
{
	struct urb *current_urb = NULL;
	int space;

	/* If there's a queue, then we should add to the last urb */
	if (!endpoint->tx_queue) {
		current_urb = endpoint->tx_urb;
	} else {
		/* Last urb from tx chain */
		current_urb =
			p2surround (struct urb, link, endpoint->tx.prev);
	}

	/* Make sure this one has enough room */
	space = current_urb->buffer_length - current_urb->actual_length;
	if (space > 0) {
		return current_urb;
	} else {		/* No space here */
		/* First look at done list */
		current_urb = first_urb_detached (&endpoint->done);
		if (!current_urb) {
			current_urb = usbd_alloc_urb (device, endpoint);
		}

		urb_append (&endpoint->tx, current_urb);
		endpoint->tx_queue++;
	}
	return current_urb;
}

static int write_buffer (circbuf_t * buf)
{
	if (!usbtty_configured ()) {
		return 0;
	}

	struct usb_endpoint_instance *endpoint =
			&endpoint_instance[tx_endpoint];
	struct urb *current_urb = NULL;

	/* TX data still exists - send it now
	 */
	if(endpoint->sent < endpoint->tx_urb->actual_length){
		if(udc_endpoint_write (endpoint)){
			/* Write pre-empted by RX */
			return -1;
		}
	}

	if (buf->size) {
		char *dest;

		int space_avail;
		int popnum, popped;
		int total = 0;

		/* Break buffer into urb sized pieces,
		 * and link each to the endpoint
		 */
		while (buf->size > 0) {

			current_urb = next_urb (device_instance, endpoint);

			dest = (char*)current_urb->buffer +
				current_urb->actual_length;

			space_avail =
				current_urb->buffer_length -
				current_urb->actual_length;
			popnum = min(space_avail, (int)buf->size);
			if (popnum == 0)
				break;

			popped = buf_pop (buf, dest, popnum);
			if (popped == 0)
				break;
			current_urb->actual_length += popped;
			total += popped;

			/* If endpoint->last == 0, then transfers have
			 * not started on this endpoint
			 */
			if (endpoint->last == 0) {
				if(udc_endpoint_write (endpoint)){
					/* Write pre-empted by RX */
					return -1;
				}
			}

		}/* end while */
		return total;
	}

	return 0;
}

static int fill_buffer (circbuf_t * buf)
{
	struct usb_endpoint_instance *endpoint =
		&endpoint_instance[rx_endpoint];

	if (endpoint->rcv_urb && endpoint->rcv_urb->actual_length) {
		unsigned int nb = 0;
		char *src = (char *) endpoint->rcv_urb->buffer;
		unsigned int rx_avail = buf->totalsize - buf->size;

		if(rx_avail >= endpoint->rcv_urb->actual_length){

			nb = endpoint->rcv_urb->actual_length;
			buf_push (buf, src, nb);
			endpoint->rcv_urb->actual_length = 0;

		}
		return nb;
	}
	return 0;
}

static int usbtty_configured (void)
{
	return usbtty_configured_flag;
}

/******************************************************************************/

static void usbtty_event_handler (struct usb_device_instance *device,
				  usb_device_event_t event, int data)
{
	switch (event) {
	case DEVICE_RESET:
	case DEVICE_BUS_INACTIVE:
		usbtty_configured_flag = 0;
		break;
	case DEVICE_CONFIGURED:
		usbtty_configured_flag = 1;
		break;

	case DEVICE_ADDRESS_ASSIGNED:
		usbtty_init_endpoints ();

	default:
		break;
	}
}

/******************************************************************************/

int usbtty_cdc_setup(struct usb_device_request *request, struct urb *urb)
{
	switch (request->bRequest){

		case ACM_SET_CONTROL_LINE_STATE:	/* Implies DTE ready */
			break;
		case ACM_SEND_ENCAPSULATED_COMMAND :	/* Required */
			break;
		case ACM_SET_LINE_ENCODING :		/* DTE stop/parity bits
							 * per character */
			break;
		case ACM_GET_ENCAPSULATED_RESPONSE :	/* request response */
			break;
		case ACM_GET_LINE_ENCODING :		/* request DTE rate,
							 * stop/parity bits */
			memcpy (urb->buffer , &rs232_desc, sizeof(rs232_desc));
			urb->actual_length = sizeof(rs232_desc);

			break;
		default:
			return 1;
	}
	return 0;
}

/******************************************************************************/

/*
 * Since interrupt handling has not yet been implemented, we use this function
 * to handle polling.  This is called by the tstc,getc,putc,puts routines to
 * update the USB state.
 */
void usbtty_poll (void)
{
	/* New interrupts? */
	udc_irq();

	/* Write any output data to host buffer
	 * (do this before checking interrupts to avoid missing one)
	 */
	if (usbtty_configured ()) {
		write_buffer (&usbtty_output);
	}

	/* New interrupts? */
	udc_irq();

	/* Check for new data from host..
	 * (do this after checking interrupts to get latest data)
	 */
	if (usbtty_configured ()) {
		fill_buffer (&usbtty_input);
	}

	/* New interrupts? */
	udc_irq();

}