/*
 * f_serial.c - generic USB serial function driver
 *
 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
 * Copyright (C) 2008 by David Brownell
 * Copyright (C) 2008 by Nokia Corporation
 * Copyright (c) 2014-2015, The Linux Foundation. All rights reserved.
 *
 * This software is distributed under the terms of the GNU General
 * Public License ("GPL") as published by the Free Software Foundation,
 * either version 2 of that License or (at your option) any later version.
 */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/usb/composite.h>
#include <linux/tty.h>

#include "u_serial.h"
#include "gadget_chips.h"
#include "usb_gadget_xport.h"


/*
 * This function packages a simple "generic serial" port with no real
 * control mechanisms, just raw data transfer over two bulk endpoints.
 *
 * Because it's not standardized, this isn't as interoperable as the
 * CDC ACM driver.  However, for many purposes it's just as functional
 * if you can arrange appropriate host side drivers.
 */

#define GSERIAL_IOCTL_MAGIC		'G'
#define GSERIAL_SET_XPORT_TYPE		_IOW(GSERIAL_IOCTL_MAGIC, 0, u32)
#define GSERIAL_SMD_WRITE		_IOW(GSERIAL_IOCTL_MAGIC, 1, \
					struct ioctl_smd_write_arg_type)

#define GSERIAL_SET_XPORT_TYPE_TTY 0
#define GSERIAL_SET_XPORT_TYPE_SMD 1

#define GSERIAL_BUF_LEN  256
#define GSERIAL_NO_PORTS 3

struct ioctl_smd_write_arg_type {
	char		*buf;
	unsigned int	size;
};

struct f_gser {
	struct gserial			port;
	u8				data_id;
	u8				port_num;

	u8				online;
	enum transport_type		transport;

	atomic_t			ioctl_excl;
	atomic_t			open_excl;

	u8				pending;
	spinlock_t			lock;
	struct usb_ep			*notify;
	struct usb_request		*notify_req;

	struct usb_cdc_line_coding	port_line_coding;

	/* SetControlLineState request */
	u16				port_handshake_bits;
#define ACM_CTRL_RTS	(1 << 1)	/* unused with full duplex */
#define ACM_CTRL_DTR	(1 << 0)	/* host is ready for data r/w */

	/* SerialState notification */
	u16				serial_state;
#define ACM_CTRL_OVERRUN	(1 << 6)
#define ACM_CTRL_PARITY		(1 << 5)
#define ACM_CTRL_FRAMING	(1 << 4)
#define ACM_CTRL_RI		(1 << 3)
#define ACM_CTRL_BRK		(1 << 2)
#define ACM_CTRL_DSR		(1 << 1)
#define ACM_CTRL_DCD		(1 << 0)
};

static unsigned int no_char_bridge_ports;
static unsigned int no_tty_ports;
static unsigned int no_smd_ports;
static unsigned int no_hsic_sports;
static unsigned int nr_ports;
static unsigned int gser_next_free_port;

static struct port_info {
	enum transport_type	transport;
	unsigned		port_num;
	unsigned char		client_port_num;
	struct f_gser		*gser_ptr;
	bool			dun_w_softap_enable;
} gserial_ports[GSERIAL_NO_PORTS];

static int gser_open_dev(struct inode *ip, struct file *fp);
static int gser_release_dev(struct inode *ip, struct file *fp);
static long gser_ioctl(struct file *fp, unsigned cmd, unsigned long arg);
static void gser_ioctl_set_transport(struct f_gser *gser,
				unsigned int transport);


static const struct file_operations gser_fops = {
	.owner = THIS_MODULE,
	.open = gser_open_dev,
	.release = gser_release_dev,
	.unlocked_ioctl = gser_ioctl,
};

static struct miscdevice gser_device = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "android_serial_device",
	.fops = &gser_fops,
};

static int registered;

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

static inline struct f_gser *port_to_gser(struct gserial *p)
{
	return container_of(p, struct f_gser, port);
}
#define GS_LOG2_NOTIFY_INTERVAL		5	/* 1 << 5 == 32 msec */
#define GS_NOTIFY_MAXPACKET		10	/* notification + 2 bytes */
/*-------------------------------------------------------------------------*/

/* interface descriptor: */

static struct usb_interface_descriptor gser_interface_desc = {
	.bLength =		USB_DT_INTERFACE_SIZE,
	.bDescriptorType =	USB_DT_INTERFACE,
	/* .bInterfaceNumber = DYNAMIC */
	.bNumEndpoints =	3,
	.bInterfaceClass =	USB_CLASS_VENDOR_SPEC,
	.bInterfaceSubClass =	0,
	.bInterfaceProtocol =	0,
	/* .iInterface = DYNAMIC */
};

static struct usb_cdc_header_desc gser_header_desc  = {
	.bLength =		sizeof(gser_header_desc),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
	.bcdCDC =		cpu_to_le16(0x0110),
};

static struct usb_cdc_call_mgmt_descriptor
gser_call_mgmt_descriptor  = {
	.bLength =		sizeof(gser_call_mgmt_descriptor),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_CALL_MANAGEMENT_TYPE,
	.bmCapabilities =	0,
	/* .bDataInterface = DYNAMIC */
};

static struct usb_cdc_acm_descriptor gser_descriptor  = {
	.bLength =		sizeof(gser_descriptor),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_ACM_TYPE,
	.bmCapabilities =	USB_CDC_CAP_LINE,
};

static struct usb_cdc_union_desc gser_union_desc  = {
	.bLength =		sizeof(gser_union_desc),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
	/* .bMasterInterface0 =	DYNAMIC */
	/* .bSlaveInterface0 =	DYNAMIC */
};

/* full speed support: */
static struct usb_endpoint_descriptor gser_fs_notify_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
	.bInterval =		1 << GS_LOG2_NOTIFY_INTERVAL,
};

static struct usb_endpoint_descriptor gser_fs_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor gser_fs_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_OUT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
};

static struct usb_descriptor_header *gser_fs_function[] = {
	(struct usb_descriptor_header *) &gser_interface_desc,
	(struct usb_descriptor_header *) &gser_header_desc,
	(struct usb_descriptor_header *) &gser_call_mgmt_descriptor,
	(struct usb_descriptor_header *) &gser_descriptor,
	(struct usb_descriptor_header *) &gser_union_desc,
	(struct usb_descriptor_header *) &gser_fs_notify_desc,
	(struct usb_descriptor_header *) &gser_fs_in_desc,
	(struct usb_descriptor_header *) &gser_fs_out_desc,
	NULL,
};

/* high speed support: */
static struct usb_endpoint_descriptor gser_hs_notify_desc  = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
	.bInterval =		GS_LOG2_NOTIFY_INTERVAL+4,
};

static struct usb_endpoint_descriptor gser_hs_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(512),
};

static struct usb_endpoint_descriptor gser_hs_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(512),
};

static struct usb_descriptor_header *gser_hs_function[] = {
	(struct usb_descriptor_header *) &gser_interface_desc,
	(struct usb_descriptor_header *) &gser_header_desc,
	(struct usb_descriptor_header *) &gser_call_mgmt_descriptor,
	(struct usb_descriptor_header *) &gser_descriptor,
	(struct usb_descriptor_header *) &gser_union_desc,
	(struct usb_descriptor_header *) &gser_hs_notify_desc,
	(struct usb_descriptor_header *) &gser_hs_in_desc,
	(struct usb_descriptor_header *) &gser_hs_out_desc,
	NULL,
};

static struct usb_endpoint_descriptor gser_ss_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(1024),
};

static struct usb_endpoint_descriptor gser_ss_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor gser_ss_bulk_comp_desc = {
	.bLength =              sizeof gser_ss_bulk_comp_desc,
	.bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
};

static struct usb_endpoint_descriptor gser_ss_notify_desc  = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	__constant_cpu_to_le16(GS_NOTIFY_MAXPACKET),
	.bInterval =		GS_LOG2_NOTIFY_INTERVAL+4,
};

static struct usb_ss_ep_comp_descriptor gser_ss_notify_comp_desc = {
	.bLength =		sizeof gser_ss_notify_comp_desc,
	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,

	/* the following 2 values can be tweaked if necessary */
	/* .bMaxBurst =		0, */
	/* .bmAttributes =	0, */
	.wBytesPerInterval =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
};

static struct usb_descriptor_header *gser_ss_function[] = {
	(struct usb_descriptor_header *) &gser_interface_desc,
	(struct usb_descriptor_header *) &gser_header_desc,
	(struct usb_descriptor_header *) &gser_call_mgmt_descriptor,
	(struct usb_descriptor_header *) &gser_descriptor,
	(struct usb_descriptor_header *) &gser_union_desc,
	(struct usb_descriptor_header *) &gser_ss_notify_desc,
	(struct usb_descriptor_header *) &gser_ss_notify_comp_desc,
	(struct usb_descriptor_header *) &gser_ss_in_desc,
	(struct usb_descriptor_header *) &gser_ss_bulk_comp_desc,
	(struct usb_descriptor_header *) &gser_ss_out_desc,
	(struct usb_descriptor_header *) &gser_ss_bulk_comp_desc,
	NULL,
};

/* string descriptors: */

static struct usb_string gser_string_defs[] = {
	[0].s = "Generic Serial",
	{  } /* end of list */
};

static struct usb_gadget_strings gser_string_table = {
	.language =		0x0409,	/* en-us */
	.strings =		gser_string_defs,
};

static struct usb_gadget_strings *gser_strings[] = {
	&gser_string_table,
	NULL,
};

int gport_setup(struct usb_configuration *c)
{
	int ret = 0;
	int port_idx;
	int i;

	pr_debug("%s: no_tty_ports: %u no_smd_ports: %u no_hsic_sports: %u nr_ports: %u\n",
		__func__, no_tty_ports, no_smd_ports, no_hsic_sports, nr_ports);

	if (no_tty_ports) {
		for (i = 0; i < no_tty_ports; i++) {
			ret = gserial_alloc_line(
					&gserial_ports[i].client_port_num);
			if (ret)
				return ret;
		}
	}

	if (no_char_bridge_ports)
		gbridge_setup(c->cdev->gadget, no_char_bridge_ports);
	if (no_smd_ports)
		ret = gsmd_setup(c->cdev->gadget, no_smd_ports);
	if (no_hsic_sports) {
		port_idx = ghsic_data_setup(no_hsic_sports, USB_GADGET_SERIAL);
		if (port_idx < 0)
			return port_idx;

		for (i = 0; i < nr_ports; i++) {
			if (gserial_ports[i].transport ==
					USB_GADGET_XPORT_HSIC) {
				gserial_ports[i].client_port_num = port_idx;
				port_idx++;
			}
		}

		/*clinet port num is same for data setup and ctrl setup*/
		ret = ghsic_ctrl_setup(no_hsic_sports, USB_GADGET_SERIAL);
		if (ret < 0)
			return ret;
		return 0;
	}

	return ret;
}

void gport_cleanup(void)
{
	int i;

	for (i = 0; i < no_tty_ports; i++)
		gserial_free_line(gserial_ports[i].client_port_num);
}

static int gport_connect(struct f_gser *gser)
{
	unsigned	port_num;
	int		ret;

	pr_debug("%s: transport: %s f_gser: %p gserial: %p port_num: %d\n",
			__func__, xport_to_str(gser->transport),
			gser, &gser->port, gser->port_num);

	port_num = gserial_ports[gser->port_num].client_port_num;

	switch (gser->transport) {
	case USB_GADGET_XPORT_TTY:
		gserial_connect(&gser->port, port_num);
		break;
	case USB_GADGET_XPORT_SMD:
		gsmd_connect(&gser->port, port_num);
		break;
	case USB_GADGET_XPORT_CHAR_BRIDGE:
		gbridge_connect(&gser->port, port_num);
		break;
	case USB_GADGET_XPORT_HSIC:
		ret = ghsic_ctrl_connect(&gser->port, port_num);
		if (ret) {
			pr_err("%s: ghsic_ctrl_connect failed: err:%d\n",
					__func__, ret);
			return ret;
		}
		ret = ghsic_data_connect(&gser->port, port_num);
		if (ret) {
			pr_err("%s: ghsic_data_connect failed: err:%d\n",
					__func__, ret);
			ghsic_ctrl_disconnect(&gser->port, port_num);
			return ret;
		}
		break;
	default:
		pr_err("%s: Un-supported transport: %s\n", __func__,
				xport_to_str(gser->transport));
		return -ENODEV;
	}

	return 0;
}

static int gport_disconnect(struct f_gser *gser)
{
	unsigned port_num;

	port_num = gserial_ports[gser->port_num].client_port_num;

	pr_debug("%s: transport: %s f_gser: %p gserial: %p port_num: %d\n",
			__func__, xport_to_str(gser->transport),
			gser, &gser->port, gser->port_num);

	switch (gser->transport) {
	case USB_GADGET_XPORT_TTY:
		gserial_disconnect(&gser->port);
		break;
	case USB_GADGET_XPORT_SMD:
		gsmd_disconnect(&gser->port, port_num);
		break;
	case USB_GADGET_XPORT_CHAR_BRIDGE:
		gbridge_disconnect(&gser->port, port_num);
		break;
	case USB_GADGET_XPORT_HSIC:
		ghsic_ctrl_disconnect(&gser->port, port_num);
		ghsic_data_disconnect(&gser->port, port_num);
		break;
	default:
		pr_err("%s: Un-supported transport:%s\n", __func__,
				xport_to_str(gser->transport));
		return -ENODEV;
	}

	return 0;
}

static void gser_complete_set_line_coding(struct usb_ep *ep,
		struct usb_request *req)
{
	struct f_gser            *gser = ep->driver_data;
	struct usb_composite_dev *cdev = gser->port.func.config->cdev;

	if (req->status != 0) {
		dev_dbg(&cdev->gadget->dev, "gser ttyGS%d completion, err %d\n",
			gser->port_num, req->status);
		return;
	}

	/* normal completion */
	if (req->actual != sizeof(gser->port_line_coding)) {
		dev_dbg(&cdev->gadget->dev, "gser ttyGS%d short resp, len %d\n",
			gser->port_num, req->actual);
		usb_ep_set_halt(ep);
	} else {
		struct usb_cdc_line_coding	*value = req->buf;
		gser->port_line_coding = *value;
	}
}
/*-------------------------------------------------------------------------*/

static int
gser_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
	struct f_gser            *gser = func_to_gser(f);
	struct usb_composite_dev *cdev = f->config->cdev;
	struct usb_request	 *req = cdev->req;
	int			 value = -EOPNOTSUPP;
	u16			 w_index = le16_to_cpu(ctrl->wIndex);
	u16			 w_value = le16_to_cpu(ctrl->wValue);
	u16			 w_length = le16_to_cpu(ctrl->wLength);

	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {

	/* SET_LINE_CODING ... just read and save what the host sends */
	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
			| USB_CDC_REQ_SET_LINE_CODING:
		if (w_length != sizeof(struct usb_cdc_line_coding))
			goto invalid;

		value = w_length;
		cdev->gadget->ep0->driver_data = gser;
		req->complete = gser_complete_set_line_coding;
		break;

	/* GET_LINE_CODING ... return what host sent, or initial value */
	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
			| USB_CDC_REQ_GET_LINE_CODING:
		value = min_t(unsigned, w_length,
				sizeof(struct usb_cdc_line_coding));
		memcpy(req->buf, &gser->port_line_coding, value);
		break;

	/* SET_CONTROL_LINE_STATE ... save what the host sent */
	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
			| USB_CDC_REQ_SET_CONTROL_LINE_STATE:

		value = 0;
		gser->port_handshake_bits = w_value;
		pr_debug("%s: USB_CDC_REQ_SET_CONTROL_LINE_STATE: DTR:%d RST:%d\n",
			__func__, w_value & ACM_CTRL_DTR ? 1 : 0,
			w_value & ACM_CTRL_RTS ? 1 : 0);
		if (gser->port.notify_modem) {
			unsigned port_num =
				gserial_ports[gser->port_num].client_port_num;

			gser->port.notify_modem(&gser->port,
					port_num, w_value);
		}
		break;

	default:
invalid:
		dev_dbg(&cdev->gadget->dev,
			"invalid control req%02x.%02x v%04x i%04x l%d\n",
			ctrl->bRequestType, ctrl->bRequest,
			w_value, w_index, w_length);
	}

	/* respond with data transfer or status phase? */
	if (value >= 0) {
		dev_dbg(&cdev->gadget->dev,
			"gser ttyGS%d req%02x.%02x v%04x i%04x l%d\n",
			gser->port_num, ctrl->bRequestType, ctrl->bRequest,
			w_value, w_index, w_length);
		req->zero = 0;
		req->length = value;
		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
		if (value < 0)
			ERROR(cdev, "gser response on ttyGS%d, err %d\n",
					gser->port_num, value);
	}

	/* device either stalls (value < 0) or reports success */
	return value;
}

static int gser_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
	struct f_gser		*gser = func_to_gser(f);
	struct usb_composite_dev *cdev = f->config->cdev;
	int rc = 0;

	/* we know alt == 0, so this is an activation or a reset */

	if (gser->notify->driver_data) {
		dev_dbg(&cdev->gadget->dev,
			"reset generic ctl ttyGS%d\n", gser->port_num);
		usb_ep_disable(gser->notify);
	}

	if (!gser->notify->desc) {
		if (config_ep_by_speed(cdev->gadget, f, gser->notify)) {
			gser->notify->desc = NULL;
			return -EINVAL;
		}
	}
	rc = usb_ep_enable(gser->notify);

	if (rc) {
		ERROR(cdev, "can't enable %s, result %d\n",
					gser->notify->name, rc);
		return rc;
	}
	gser->notify->driver_data = gser;

	if (gser->port.in->driver_data) {
		dev_dbg(&cdev->gadget->dev,
			"reset generic data ttyGS%d\n", gser->port_num);
		gport_disconnect(gser);
	}
	if (!gser->port.in->desc || !gser->port.out->desc) {
		dev_dbg(&cdev->gadget->dev,
			"activate generic ttyGS%d\n", gser->port_num);
		if (config_ep_by_speed(cdev->gadget, f, gser->port.in) ||
		    config_ep_by_speed(cdev->gadget, f, gser->port.out)) {
			gser->port.in->desc = NULL;
			gser->port.out->desc = NULL;
			return -EINVAL;
		}
	}

	gport_connect(gser);

	gser->online = 1;
	return rc;
}

static void gser_disable(struct usb_function *f)
{
	struct f_gser	*gser = func_to_gser(f);
	struct usb_composite_dev *cdev = f->config->cdev;

	dev_dbg(&cdev->gadget->dev,
		"generic ttyGS%d deactivated\n", gser->port_num);

	gport_disconnect(gser);

	usb_ep_fifo_flush(gser->notify);
	usb_ep_disable(gser->notify);
	gser->notify->driver_data = NULL;
	gser->online = 0;
}

static void gser_suspend(struct usb_function *f)
{
	struct f_gser	*gser = func_to_gser(f);
	unsigned port_num;

	port_num = gserial_ports[gser->port_num].client_port_num;

	pr_debug("%s: transport: %s f_gser: %p gserial: %p port_num: %d\n",
			__func__, xport_to_str(gser->transport),
			gser, &gser->port, gser->port_num);

	switch (gser->transport) {
	case USB_GADGET_XPORT_SMD:
		gsmd_suspend(&gser->port, port_num);
		break;
	default:
		pr_err("%s: Un-supported transport: %s\n", __func__,
			xport_to_str(gser->transport));
	}
}

static void gser_resume(struct usb_function *f)
{
	struct f_gser	*gser = func_to_gser(f);
	unsigned port_num;

	port_num = gserial_ports[gser->port_num].client_port_num;

	pr_debug("%s: transport: %s f_gser: %p gserial: %p port_num: %d\n",
			__func__, xport_to_str(gser->transport),
			gser, &gser->port, gser->port_num);

	switch (gser->transport) {
	case USB_GADGET_XPORT_SMD:
		gsmd_resume(&gser->port, port_num);
		break;
	default:
		pr_err("%s: Un-supported transport: %s\n", __func__,
			xport_to_str(gser->transport));
	}
}

static int gser_notify(struct f_gser *gser, u8 type, u16 value,
		void *data, unsigned length)
{
	struct usb_ep			*ep = gser->notify;
	struct usb_request		*req;
	struct usb_cdc_notification	*notify;
	const unsigned			len = sizeof(*notify) + length;
	void				*buf;
	int				status;
	struct usb_composite_dev *cdev = gser->port.func.config->cdev;

	req = gser->notify_req;
	gser->notify_req = NULL;
	gser->pending = false;

	req->length = len;
	notify = req->buf;
	buf = notify + 1;

	notify->bmRequestType = USB_DIR_IN | USB_TYPE_CLASS
			| USB_RECIP_INTERFACE;
	notify->bNotificationType = type;
	notify->wValue = cpu_to_le16(value);
	notify->wIndex = cpu_to_le16(gser->data_id);
	notify->wLength = cpu_to_le16(length);
	memcpy(buf, data, length);

	status = usb_ep_queue(ep, req, GFP_ATOMIC);
	if (status < 0) {
		ERROR(cdev, "gser ttyGS%d can't notify serial state, %d\n",
				gser->port_num, status);
		gser->notify_req = req;
	}

	return status;
}

static int gser_notify_serial_state(struct f_gser *gser)
{
	int			 status;
	unsigned long flags;
	struct usb_composite_dev *cdev = gser->port.func.config->cdev;

	spin_lock_irqsave(&gser->lock, flags);
	if (gser->notify_req) {
		dev_dbg(&cdev->gadget->dev, "gser ttyGS%d serial state %04x\n",
				gser->port_num, gser->serial_state);
		status = gser_notify(gser, USB_CDC_NOTIFY_SERIAL_STATE,
				0, &gser->serial_state,
					sizeof(gser->serial_state));
	} else {
		gser->pending = true;
		status = 0;
	}
	spin_unlock_irqrestore(&gser->lock, flags);
	return status;
}

static void gser_notify_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct f_gser *gser = req->context;
	u8	      doit = false;
	unsigned long flags;

	/* on this call path we do NOT hold the port spinlock,
	 * which is why ACM needs its own spinlock
	 */
	spin_lock_irqsave(&gser->lock, flags);
	if (req->status != -ESHUTDOWN)
		doit = gser->pending;
	gser->notify_req = req;
	spin_unlock_irqrestore(&gser->lock, flags);

	if (doit && gser->online)
		gser_notify_serial_state(gser);
}
static void gser_connect(struct gserial *port)
{
	struct f_gser *gser = port_to_gser(port);

	gser->serial_state |= ACM_CTRL_DSR | ACM_CTRL_DCD;
	gser_notify_serial_state(gser);
}

unsigned int gser_get_dtr(struct gserial *port)
{
	struct f_gser *gser = port_to_gser(port);

	if (gser->port_handshake_bits & ACM_CTRL_DTR)
		return 1;
	else
		return 0;
}

unsigned int gser_get_rts(struct gserial *port)
{
	struct f_gser *gser = port_to_gser(port);

	if (gser->port_handshake_bits & ACM_CTRL_RTS)
		return 1;
	else
		return 0;
}

unsigned int gser_send_carrier_detect(struct gserial *port, unsigned int yes)
{
	struct f_gser *gser = port_to_gser(port);
	u16			state;

	state = gser->serial_state;
	state &= ~ACM_CTRL_DCD;
	if (yes)
		state |= ACM_CTRL_DCD;

	gser->serial_state = state;
	return gser_notify_serial_state(gser);

}

unsigned int gser_send_ring_indicator(struct gserial *port, unsigned int yes)
{
	struct f_gser *gser = port_to_gser(port);
	u16			state;

	state = gser->serial_state;
	state &= ~ACM_CTRL_RI;
	if (yes)
		state |= ACM_CTRL_RI;

	gser->serial_state = state;
	return gser_notify_serial_state(gser);

}
static void gser_disconnect(struct gserial *port)
{
	struct f_gser *gser = port_to_gser(port);

	gser->serial_state &= ~(ACM_CTRL_DSR | ACM_CTRL_DCD);
	gser_notify_serial_state(gser);
}

static int gser_send_break(struct gserial *port, int duration)
{
	struct f_gser *gser = port_to_gser(port);
	u16			state;

	state = gser->serial_state;
	state &= ~ACM_CTRL_BRK;
	if (duration)
		state |= ACM_CTRL_BRK;

	gser->serial_state = state;
	return gser_notify_serial_state(gser);
}

static int gser_send_modem_ctrl_bits(struct gserial *port, int ctrl_bits)
{
	struct f_gser *gser = port_to_gser(port);

	gser->serial_state = ctrl_bits;

	return gser_notify_serial_state(gser);
}
/*-------------------------------------------------------------------------*/

/* serial function driver setup/binding */

static int gser_bind(struct usb_configuration *c, struct usb_function *f)
{
	struct usb_composite_dev *cdev = c->cdev;
	struct f_gser		*gser = func_to_gser(f);
	int			status;
	struct usb_ep		*ep;

	/* REVISIT might want instance-specific strings to help
	 * distinguish instances ...
	 */

	/* maybe allocate device-global string ID */
	if (gser_string_defs[0].id == 0) {
		status = usb_string_id(c->cdev);
		if (status < 0)
			return status;
		gser_string_defs[0].id = status;
	}

	/* allocate instance-specific interface IDs */
	status = usb_interface_id(c, f);
	if (status < 0)
		goto fail;
	gser->data_id = status;
	gser_interface_desc.bInterfaceNumber = status;

	status = -ENODEV;

	/* allocate instance-specific endpoints */
	ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_in_desc);
	if (!ep)
		goto fail;
	gser->port.in = ep;
	ep->driver_data = cdev;	/* claim */

	ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_out_desc);
	if (!ep)
		goto fail;
	gser->port.out = ep;
	ep->driver_data = cdev;	/* claim */

	ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_notify_desc);
	if (!ep)
		goto fail;
	gser->notify = ep;
	ep->driver_data = cdev;	/* claim */
	/* allocate notification */
	gser->notify_req = gs_alloc_req(ep,
			sizeof(struct usb_cdc_notification) + 2,
			(cdev->gadget->extra_buf_alloc), GFP_KERNEL);
	if (!gser->notify_req)
		goto fail;

	gser->notify_req->complete = gser_notify_complete;
	gser->notify_req->context = gser;

	/* support all relevant hardware speeds... we expect that when
	 * hardware is dual speed, all bulk-capable endpoints work at
	 * both speeds
	 */
	gser_hs_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
	gser_hs_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;

	gser_ss_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
	gser_ss_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;

	if (gadget_is_dualspeed(c->cdev->gadget)) {
		gser_hs_notify_desc.bEndpointAddress =
				gser_fs_notify_desc.bEndpointAddress;
	}
	if (gadget_is_superspeed(c->cdev->gadget)) {
		gser_ss_notify_desc.bEndpointAddress =
				gser_fs_notify_desc.bEndpointAddress;
	}

	status = usb_assign_descriptors(f, gser_fs_function, gser_hs_function,
			gser_ss_function);
	if (status)
		goto fail;

	gserial_ports[gser->port_num].gser_ptr = gser;

	dev_dbg(&cdev->gadget->dev, "generic ttyGS%d: %s speed IN/%s OUT/%s\n",
		gser->port_num,
		gadget_is_superspeed(c->cdev->gadget) ? "super" :
		gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
		gser->port.in->name, gser->port.out->name);
	return 0;

fail:
	if (gser->notify_req)
		gs_free_req(gser->notify, gser->notify_req);

	/* we might as well release our claims on endpoints */
	if (gser->notify)
		gser->notify->driver_data = NULL;
	/* we might as well release our claims on endpoints */
	if (gser->port.out)
		gser->port.out->driver_data = NULL;
	if (gser->port.in)
		gser->port.in->driver_data = NULL;

	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);

	return status;
}

static inline struct f_serial_opts *to_f_serial_opts(struct config_item *item)
{
	return container_of(to_config_group(item), struct f_serial_opts,
			    func_inst.group);
}

CONFIGFS_ATTR_STRUCT(f_serial_opts);
static ssize_t f_serial_attr_show(struct config_item *item,
				  struct configfs_attribute *attr,
				  char *page)
{
	struct f_serial_opts *opts = to_f_serial_opts(item);
	struct f_serial_opts_attribute *f_serial_opts_attr =
		container_of(attr, struct f_serial_opts_attribute, attr);
	ssize_t ret = 0;

	if (f_serial_opts_attr->show)
		ret = f_serial_opts_attr->show(opts, page);

	return ret;
}

static void serial_attr_release(struct config_item *item)
{
	struct f_serial_opts *opts = to_f_serial_opts(item);

	usb_put_function_instance(&opts->func_inst);
}

static struct configfs_item_operations serial_item_ops = {
	.release	= serial_attr_release,
	.show_attribute = f_serial_attr_show,
};

static ssize_t f_serial_port_num_show(struct f_serial_opts *opts, char *page)
{
	return sprintf(page, "%u\n", opts->port_num);
}

static struct f_serial_opts_attribute f_serial_port_num =
	__CONFIGFS_ATTR_RO(port_num, f_serial_port_num_show);

static struct configfs_attribute *acm_attrs[] = {
	&f_serial_port_num.attr,
	NULL,
};

static struct config_item_type serial_func_type = {
	.ct_item_ops	= &serial_item_ops,
	.ct_attrs	= acm_attrs,
	.ct_owner	= THIS_MODULE,
};

static void gser_free_inst(struct usb_function_instance *f)
{
	struct f_serial_opts *opts;

	opts = container_of(f, struct f_serial_opts, func_inst);
	if (!nr_ports)
		gserial_free_line(opts->port_num);

	kfree(opts);
}

static struct usb_function_instance *gser_alloc_inst(void)
{
	struct f_serial_opts *opts;
	int ret;

	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
	if (!opts)
		return ERR_PTR(-ENOMEM);

	opts->func_inst.free_func_inst = gser_free_inst;

	/* Check if tty registration is handled here or not */
	if (!nr_ports) {
		ret = gserial_alloc_line(&opts->port_num);
		if (ret) {
			kfree(opts);
			return ERR_PTR(ret);
		}
	}
	config_group_init_type_name(&opts->func_inst.group, "",
				    &serial_func_type);

	return &opts->func_inst;
}

static void gser_free(struct usb_function *f)
{
	struct f_gser *serial;

	serial = func_to_gser(f);
	pr_debug("%s: port %d", __func__, serial->port_num);

	gserial_ports[serial->port_num].gser_ptr = NULL;
	kfree(serial);
	gser_next_free_port--;
}

static void gser_unbind(struct usb_configuration *c, struct usb_function *f)
{
	struct f_gser *gser = func_to_gser(f);

	usb_free_all_descriptors(f);
	gs_free_req(gser->notify, gser->notify_req);

	gserial_ports[gser->port_num].gser_ptr = NULL;
}

static int gser_init(void)
{
	int ret;

	pr_debug("%s: initialize serial function instance", __func__);

	if (registered)
		return 0;

	ret = misc_register(&gser_device);
	if (ret)
		pr_err("Serial driver failed to register");
	else
		registered = 1;

	return ret;
}

static struct usb_function *gser_alloc(struct usb_function_instance *fi)
{
	struct f_gser	*gser;
	struct f_serial_opts *opts;

	/* allocate and initialize one new instance */
	gser = kzalloc(sizeof(*gser), GFP_KERNEL);
	if (!gser)
		return ERR_PTR(-ENOMEM);

	opts = container_of(fi, struct f_serial_opts, func_inst);

	spin_lock_init(&gser->lock);
	if (nr_ports)
		opts->port_num = gser_next_free_port++;

	gser->port_num = opts->port_num;

	gser->port.func.name = "gser";
	gser->port.func.strings = gser_strings;
	gser->port.func.bind = gser_bind;
	gser->port.func.unbind = gser_unbind;
	gser->port.func.set_alt = gser_set_alt;
	gser->port.func.disable = gser_disable;
	gser->port.func.free_func = gser_free;
	gser->transport		= gserial_ports[opts->port_num].transport;
	/* We support only three ports for now */
	if (opts->port_num == 0)
		gser->port.func.name = "modem";
	else if (opts->port_num == 1)
		gser->port.func.name = "nmea";
	else
		gser->port.func.name = "modem2";
	gser->port.func.setup = gser_setup;
	gser->port.func.suspend = gser_suspend;
	gser->port.func.resume = gser_resume;
	gser->port.connect = gser_connect;
	gser->port.get_dtr = gser_get_dtr;
	gser->port.get_rts = gser_get_rts;
	gser->port.send_carrier_detect = gser_send_carrier_detect;
	gser->port.send_ring_indicator = gser_send_ring_indicator;
	gser->port.send_modem_ctrl_bits = gser_send_modem_ctrl_bits;
	gser->port.disconnect = gser_disconnect;
	gser->port.send_break = gser_send_break;
	gserial_ports[gser->port_num].gser_ptr = gser;
	gser_init();

	return &gser->port.func;
}

DECLARE_USB_FUNCTION_INIT(gser, gser_alloc_inst, gser_alloc);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Al Borchers");
MODULE_AUTHOR("David Brownell");

/**
 * gserial_init_port - bind a gserial_port to its transport
 */
int gserial_init_port(int port_num, const char *name,
		const char *port_name)
{
	enum transport_type transport;
	int ret = 0;

	if (port_num >= GSERIAL_NO_PORTS)
		return -ENODEV;

	transport = str_to_xport(name);
	pr_debug("%s, port:%d, transport:%s\n", __func__,
			port_num, xport_to_str(transport));

	gserial_ports[port_num].transport = transport;
	gserial_ports[port_num].port_num = port_num;

	switch (transport) {
	case USB_GADGET_XPORT_TTY:
		no_tty_ports++;
		break;
	case USB_GADGET_XPORT_SMD:
		gserial_ports[port_num].client_port_num = no_smd_ports;
		no_smd_ports++;
		break;
	case USB_GADGET_XPORT_CHAR_BRIDGE:
		no_char_bridge_ports++;
		break;
	case USB_GADGET_XPORT_HSIC:
		ghsic_ctrl_set_port_name(port_name, name);
		ghsic_data_set_port_name(port_name, name);

		/*client port number will be updated in gport_setup*/
		no_hsic_sports++;
		break;
	default:
		pr_err("%s: Un-supported transport transport: %u\n",
				__func__, gserial_ports[port_num].transport);
		return -ENODEV;
	}

	nr_ports++;

	return ret;
}


bool gserial_is_connected(void)
{
	if (gserial_ports[0].gser_ptr != NULL)
		return gserial_ports[0].gser_ptr->online;
	return 0;
}

bool gserial_is_dun_w_softap_enabled(void)
{
	if (gserial_ports[0].gser_ptr != NULL)
		return gserial_ports[0].dun_w_softap_enable;
	return 0;
}

void gserial_dun_w_softap_enable(bool enable)
{
	pr_debug("android_usb: Setting dun_w_softap_enable to %u.",
		enable);

	gserial_ports[0].dun_w_softap_enable = enable;
}

bool gserial_is_dun_w_softap_active(void)
{
	if (gserial_ports[0].gser_ptr != NULL)
		return gserial_ports[0].dun_w_softap_enable &&
			gserial_ports[0].gser_ptr->online;
	return 0;
}

static inline int gser_device_lock(atomic_t *excl)
{
	if (atomic_inc_return(excl) == 1) {
		return 0;
	} else {
		atomic_dec(excl);
		return -EBUSY;
	}
}

static inline void gser_device_unlock(atomic_t *excl)
{
	atomic_dec(excl);
}

static int gser_open_dev(struct inode *ip, struct file *fp)
{
	struct f_gser *gser = gserial_ports[0].gser_ptr;

	pr_debug("%s: Open serial device", __func__);

	if (!gser) {
		pr_err("%s: Serial device not created yet", __func__);
		return -ENODEV;
	}

	if (gser_device_lock(&gser->open_excl)) {
		pr_err("%s: Already opened", __func__);
		return -EBUSY;
	}

	fp->private_data = gser;
	pr_debug("%s: Serial device opened", __func__);

	return 0;
}

static int gser_release_dev(struct inode *ip, struct file *fp)
{
	struct f_gser *gser = fp->private_data;

	pr_debug("%s: Close serial device", __func__);

	if (!gser) {
		pr_err("Serial device not created yet\n");
		return -ENODEV;
	}

	gser_device_unlock(&gser->open_excl);

	return 0;
}

static void gser_ioctl_set_transport(struct f_gser *gser,
	unsigned int transport)
{
	int ret;
	enum transport_type new_transport;
	const struct usb_endpoint_descriptor *ep_in_desc_backup;
	const struct usb_endpoint_descriptor *ep_out_desc_backup;

	if (transport == GSERIAL_SET_XPORT_TYPE_TTY) {
		new_transport = USB_GADGET_XPORT_TTY;
		pr_debug("%s: Switching modem transport to TTY.", __func__);
		gser->port.flags |= ASYNC_LOW_LATENCY;
	} else if (transport == GSERIAL_SET_XPORT_TYPE_SMD) {
		new_transport = USB_GADGET_XPORT_SMD;
		pr_debug("%s: Switching modem transport to SMD.", __func__);
	} else {
		pr_err("%s: Wrong transport type %d", __func__, transport);
		return;
	}

	if (gser->transport == new_transport) {
		pr_debug("%s: Modem transport aready set to this type.",
			__func__);
		return;
	}

	ep_in_desc_backup  = gser->port.in->desc;
	ep_out_desc_backup = gser->port.out->desc;
	gport_disconnect(gser);
	if (new_transport == USB_GADGET_XPORT_TTY) {
		ret = gserial_alloc_line(
			&gserial_ports[gser->port_num].client_port_num);
		if (ret)
			pr_debug("%s: Unable to alloc TTY line", __func__);
	}

	gser->port.in->desc  = ep_in_desc_backup;
	gser->port.out->desc = ep_out_desc_backup;
	gser->transport = new_transport;
	gport_connect(gser);
	pr_debug("%s: Modem transport switch is complete.", __func__);

}

static long gser_ioctl(struct file *fp, unsigned cmd, unsigned long arg)
{
	int ret = 0;
	int count;
	int xport_type;
	int smd_port_num;
	char smd_write_buf[GSERIAL_BUF_LEN];
	struct ioctl_smd_write_arg_type smd_write_arg;
	struct f_gser *gser;
	void __user *argp = (void __user *)arg;

	if (!fp || !fp->private_data) {
		pr_err("%s: Invalid file handle", __func__);
		return -EBADFD;
	}

	gser = fp->private_data;
	pr_debug("Received command %d", cmd);

	if (gser_device_lock(&gser->ioctl_excl))
		return -EBUSY;

	switch (cmd) {
	case GSERIAL_SET_XPORT_TYPE:
		if (copy_from_user(&xport_type, argp, sizeof(xport_type))) {
			pr_err("%s: failed to copy IOCTL set transport type",
				__func__);
			ret = -EFAULT;
			break;
		}

		gser_ioctl_set_transport(gser, xport_type);
		break;

	case GSERIAL_SMD_WRITE:
		if (gser->transport != USB_GADGET_XPORT_SMD) {
			pr_err("%s: ERR: Got SMD WR cmd when not in SMD mode",
				__func__);

			break;
		}

		pr_debug("%s: Copy GSERIAL_SMD_WRITE IOCTL command argument",
			__func__);
		if (copy_from_user(&smd_write_arg, argp,
			sizeof(smd_write_arg))) {
			ret = -EFAULT;

			pr_err("%s: failed to copy IOCTL GSERIAL_SMD_WRITE arg",
				__func__);

			break;
		}
		smd_port_num =
			gserial_ports[gser->port_num].client_port_num;

		if (smd_write_arg.size > GSERIAL_BUF_LEN) {
			pr_err("%s: Invalid size:%u, max: %u", __func__,
				smd_write_arg.size, GSERIAL_BUF_LEN);
			ret = -EINVAL;
			break;
		}

		pr_debug("%s: Copying %d bytes from user buffer to local\n",
			__func__, smd_write_arg.size);

		if (copy_from_user(smd_write_buf, smd_write_arg.buf,
			smd_write_arg.size)) {

			pr_err("%s: failed to copy buf for GSERIAL_SMD_WRITE",
				__func__);

			ret = -EFAULT;
			break;
		}

		pr_debug("%s: Writing %d bytes to SMD channel\n",
			__func__, smd_write_arg.size);

		count = gsmd_write(smd_port_num, smd_write_buf,
			smd_write_arg.size);

		if (count != smd_write_arg.size)
			ret = -EFAULT;

		break;
	default:
		pr_err("Unsupported IOCTL");
		ret = -EINVAL;
	}

	gser_device_unlock(&gser->ioctl_excl);
	return ret;
}