/*
 * 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
 *
 * 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/device.h>

#include "u_serial.h"
#include "gadget_chips.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.
 */

struct gser_descs {
        struct usb_endpoint_descriptor  *in;
        struct usb_endpoint_descriptor  *out;
};

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

        struct gser_descs               fs;
        struct gser_descs               hs;
};

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

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

/* interface descriptor: */

static struct usb_interface_descriptor gser_interface_desc __initdata = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,
        /* .bInterfaceNumber = DYNAMIC */
        .bNumEndpoints =        2,
        .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
        .bInterfaceSubClass =   0,
        .bInterfaceProtocol =   0,
        /* .iInterface = DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor gser_fs_in_desc __initdata = {
        .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 __initdata = {
        .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[] __initdata = {
        (struct usb_descriptor_header *) &gser_interface_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_in_desc __initdata = {
        .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 __initdata = {
        .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[] __initdata = {
        (struct usb_descriptor_header *) &gser_interface_desc,
        (struct usb_descriptor_header *) &gser_hs_in_desc,
        (struct usb_descriptor_header *) &gser_hs_out_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,
};

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

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;

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

        if (gser->port.in->driver_data) {
                DBG(cdev, "reset generic ttyGS%d\n", gser->port_num);
                gserial_disconnect(&gser->port);
        } else {
                DBG(cdev, "activate generic ttyGS%d\n", gser->port_num);
                gser->port.in_desc = ep_choose(cdev->gadget,
                                gser->hs.in, gser->fs.in);
                gser->port.out_desc = ep_choose(cdev->gadget,
                                gser->hs.out, gser->fs.out);
        }
        gserial_connect(&gser->port, gser->port_num);
        return 0;
}

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

        DBG(cdev, "generic ttyGS%d deactivated\n", gser->port_num);
        gserial_disconnect(&gser->port);
}

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

/* serial function driver setup/binding */

static int __init
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;

        /* 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 */

        /* copy descriptors, and track endpoint copies */
        f->descriptors = usb_copy_descriptors(gser_fs_function);

        gser->fs.in = usb_find_endpoint(gser_fs_function,
                        f->descriptors, &gser_fs_in_desc);
        gser->fs.out = usb_find_endpoint(gser_fs_function,
                        f->descriptors, &gser_fs_out_desc);


        /* support all relevant hardware speeds... we expect that when
         * hardware is dual speed, all bulk-capable endpoints work at
         * both speeds
         */
        if (gadget_is_dualspeed(c->cdev->gadget)) {
                gser_hs_in_desc.bEndpointAddress =
                                gser_fs_in_desc.bEndpointAddress;
                gser_hs_out_desc.bEndpointAddress =
                                gser_fs_out_desc.bEndpointAddress;

                /* copy descriptors, and track endpoint copies */
                f->hs_descriptors = usb_copy_descriptors(gser_hs_function);

                gser->hs.in = usb_find_endpoint(gser_hs_function,
                                f->hs_descriptors, &gser_hs_in_desc);
                gser->hs.out = usb_find_endpoint(gser_hs_function,
                                f->hs_descriptors, &gser_hs_out_desc);
        }

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

fail:
        /* 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 void
gser_unbind(struct usb_configuration *c, struct usb_function *f)
{
        if (gadget_is_dualspeed(c->cdev->gadget))
                usb_free_descriptors(f->hs_descriptors);
        usb_free_descriptors(f->descriptors);
        kfree(func_to_gser(f));
}

/**
 * gser_bind_config - add a generic serial function to a configuration
 * @c: the configuration to support the serial instance
 * @port_num: /dev/ttyGS* port this interface will use
 * Context: single threaded during gadget setup
 *
 * Returns zero on success, else negative errno.
 *
 * Caller must have called @gserial_setup() with enough ports to
 * handle all the ones it binds.  Caller is also responsible
 * for calling @gserial_cleanup() before module unload.
 */
int __init gser_bind_config(struct usb_configuration *c, u8 port_num)
{
        struct f_gser   *gser;
        int             status;

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

        gser->port_num = 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;

        status = usb_add_function(c, &gser->port.func);
        if (status)
                kfree(gser);
        return status;
}