/*
 * g_ffs.c -- user mode file system API for USB composite function controllers
 *
 * Copyright (C) 2010 Samsung Electronics
 * Author: Michal Nazarewicz <mina86@mina86.com>
 *
 * 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.
 */

#define pr_fmt(fmt) "g_ffs: " fmt

#include <linux/module.h>

/*
 * kbuild is not very cooperative with respect to linking separately
 * compiled library objects into one module.  So for now we won't use
 * separate compilation ... ensuring init/exit sections work to shrink
 * the runtime footprint, and giving us at least some parts of what
 * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
 */
#if defined CONFIG_USB_FUNCTIONFS_ETH || defined CONFIG_USB_FUNCTIONFS_RNDIS
#  if defined USB_ETH_RNDIS
#    undef USB_ETH_RNDIS
#  endif
#  ifdef CONFIG_USB_FUNCTIONFS_RNDIS
#    define USB_ETH_RNDIS y
#  endif

#  include "f_ecm.c"
#  include "f_subset.c"
#  ifdef USB_ETH_RNDIS
#    include "f_rndis.c"
#    include "rndis.c"
#  endif
#  include "u_ether.c"

static u8 gfs_hostaddr[ETH_ALEN];
#  ifdef CONFIG_USB_FUNCTIONFS_ETH
static int eth_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
#  endif
#else
#  define gether_cleanup() do { } while (0)
#  define gether_setup(gadget, hostaddr)   ((int)0)
#  define gfs_hostaddr NULL
#endif

#include "f_fs.c"

#define DRIVER_NAME     "g_ffs"
#define DRIVER_DESC     "USB Function Filesystem"
#define DRIVER_VERSION  "24 Aug 2004"

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR("Michal Nazarewicz");
MODULE_LICENSE("GPL");

#define GFS_VENDOR_ID   0x1d6b  /* Linux Foundation */
#define GFS_PRODUCT_ID  0x0105  /* FunctionFS Gadget */

#define GFS_MAX_DEVS    10

struct gfs_ffs_obj {
        const char *name;
        bool mounted;
        bool desc_ready;
        struct ffs_data *ffs_data;
};

USB_GADGET_COMPOSITE_OPTIONS();

static struct usb_device_descriptor gfs_dev_desc = {
        .bLength                = sizeof gfs_dev_desc,
        .bDescriptorType        = USB_DT_DEVICE,

        .bcdUSB                 = cpu_to_le16(0x0200),
        .bDeviceClass           = USB_CLASS_PER_INTERFACE,

        .idVendor               = cpu_to_le16(GFS_VENDOR_ID),
        .idProduct              = cpu_to_le16(GFS_PRODUCT_ID),
};

static char *func_names[GFS_MAX_DEVS];
static unsigned int func_num;

module_param_named(bDeviceClass,    gfs_dev_desc.bDeviceClass,    byte,   0644);
MODULE_PARM_DESC(bDeviceClass, "USB Device class");
module_param_named(bDeviceSubClass, gfs_dev_desc.bDeviceSubClass, byte,   0644);
MODULE_PARM_DESC(bDeviceSubClass, "USB Device subclass");
module_param_named(bDeviceProtocol, gfs_dev_desc.bDeviceProtocol, byte,   0644);
MODULE_PARM_DESC(bDeviceProtocol, "USB Device protocol");
module_param_array_named(functions, func_names, charp, &func_num, 0);
MODULE_PARM_DESC(functions, "USB Functions list");

static const struct usb_descriptor_header *gfs_otg_desc[] = {
        (const struct usb_descriptor_header *)
        &(const struct usb_otg_descriptor) {
                .bLength                = sizeof(struct usb_otg_descriptor),
                .bDescriptorType        = USB_DT_OTG,

                /*
                 * REVISIT SRP-only hardware is possible, although
                 * it would not be called "OTG" ...
                 */
                .bmAttributes           = USB_OTG_SRP | USB_OTG_HNP,
        },

        NULL
};

/* String IDs are assigned dynamically */
static struct usb_string gfs_strings[] = {
        [USB_GADGET_MANUFACTURER_IDX].s = "",
        [USB_GADGET_PRODUCT_IDX].s = DRIVER_DESC,
        [USB_GADGET_SERIAL_IDX].s = "",
#ifdef CONFIG_USB_FUNCTIONFS_RNDIS
        { .s = "FunctionFS + RNDIS" },
#endif
#ifdef CONFIG_USB_FUNCTIONFS_ETH
        { .s = "FunctionFS + ECM" },
#endif
#ifdef CONFIG_USB_FUNCTIONFS_GENERIC
        { .s = "FunctionFS" },
#endif
        {  } /* end of list */
};

static struct usb_gadget_strings *gfs_dev_strings[] = {
        &(struct usb_gadget_strings) {
                .language       = 0x0409,       /* en-us */
                .strings        = gfs_strings,
        },
        NULL,
};

struct gfs_configuration {
        struct usb_configuration c;
        int (*eth)(struct usb_configuration *c, u8 *ethaddr);
} gfs_configurations[] = {
#ifdef CONFIG_USB_FUNCTIONFS_RNDIS
        {
                .eth            = rndis_bind_config,
        },
#endif

#ifdef CONFIG_USB_FUNCTIONFS_ETH
        {
                .eth            = eth_bind_config,
        },
#endif

#ifdef CONFIG_USB_FUNCTIONFS_GENERIC
        {
        },
#endif
};

static int gfs_bind(struct usb_composite_dev *cdev);
static int gfs_unbind(struct usb_composite_dev *cdev);
static int gfs_do_config(struct usb_configuration *c);

static __refdata struct usb_composite_driver gfs_driver = {
        .name           = DRIVER_NAME,
        .dev            = &gfs_dev_desc,
        .strings        = gfs_dev_strings,
        .max_speed      = USB_SPEED_HIGH,
        .bind           = gfs_bind,
        .unbind         = gfs_unbind,
};

static DEFINE_MUTEX(gfs_lock);
static unsigned int missing_funcs;
static bool gfs_ether_setup;
static bool gfs_registered;
static bool gfs_single_func;
static struct gfs_ffs_obj *ffs_tab;

static int __init gfs_init(void)
{
        int i;

        ENTER();

        if (!func_num) {
                gfs_single_func = true;
                func_num = 1;
        }

        ffs_tab = kcalloc(func_num, sizeof *ffs_tab, GFP_KERNEL);
        if (!ffs_tab)
                return -ENOMEM;

        if (!gfs_single_func)
                for (i = 0; i < func_num; i++)
                        ffs_tab[i].name = func_names[i];

        missing_funcs = func_num;

        return functionfs_init();
}
module_init(gfs_init);

static void __exit gfs_exit(void)
{
        ENTER();
        mutex_lock(&gfs_lock);

        if (gfs_registered)
                usb_composite_unregister(&gfs_driver);
        gfs_registered = false;

        functionfs_cleanup();

        mutex_unlock(&gfs_lock);
        kfree(ffs_tab);
}
module_exit(gfs_exit);

static struct gfs_ffs_obj *gfs_find_dev(const char *dev_name)
{
        int i;

        ENTER();

        if (gfs_single_func)
                return &ffs_tab[0];

        for (i = 0; i < func_num; i++)
                if (strcmp(ffs_tab[i].name, dev_name) == 0)
                        return &ffs_tab[i];

        return NULL;
}

static int functionfs_ready_callback(struct ffs_data *ffs)
{
        struct gfs_ffs_obj *ffs_obj;
        int ret;

        ENTER();
        mutex_lock(&gfs_lock);

        ffs_obj = ffs->private_data;
        if (!ffs_obj) {
                ret = -EINVAL;
                goto done;
        }

        if (WARN_ON(ffs_obj->desc_ready)) {
                ret = -EBUSY;
                goto done;
        }
        ffs_obj->desc_ready = true;
        ffs_obj->ffs_data = ffs;

        if (--missing_funcs) {
                ret = 0;
                goto done;
        }

        if (gfs_registered) {
                ret = -EBUSY;
                goto done;
        }
        gfs_registered = true;

        ret = usb_composite_probe(&gfs_driver);
        if (unlikely(ret < 0))
                gfs_registered = false;

done:
        mutex_unlock(&gfs_lock);
        return ret;
}

static void functionfs_closed_callback(struct ffs_data *ffs)
{
        struct gfs_ffs_obj *ffs_obj;

        ENTER();
        mutex_lock(&gfs_lock);

        ffs_obj = ffs->private_data;
        if (!ffs_obj)
                goto done;

        ffs_obj->desc_ready = false;
        missing_funcs++;

        if (gfs_registered)
                usb_composite_unregister(&gfs_driver);
        gfs_registered = false;

done:
        mutex_unlock(&gfs_lock);
}

static void *functionfs_acquire_dev_callback(const char *dev_name)
{
        struct gfs_ffs_obj *ffs_dev;

        ENTER();
        mutex_lock(&gfs_lock);

        ffs_dev = gfs_find_dev(dev_name);
        if (!ffs_dev) {
                ffs_dev = ERR_PTR(-ENODEV);
                goto done;
        }

        if (ffs_dev->mounted) {
                ffs_dev = ERR_PTR(-EBUSY);
                goto done;
        }
        ffs_dev->mounted = true;

done:
        mutex_unlock(&gfs_lock);
        return ffs_dev;
}

static void functionfs_release_dev_callback(struct ffs_data *ffs_data)
{
        struct gfs_ffs_obj *ffs_dev;

        ENTER();
        mutex_lock(&gfs_lock);

        ffs_dev = ffs_data->private_data;
        if (ffs_dev)
                ffs_dev->mounted = false;

        mutex_unlock(&gfs_lock);
}

/*
 * It is assumed that gfs_bind is called from a context where gfs_lock is held
 */
static int gfs_bind(struct usb_composite_dev *cdev)
{
        int ret, i;

        ENTER();

        if (missing_funcs)
                return -ENODEV;

        ret = gether_setup(cdev->gadget, gfs_hostaddr);
        if (unlikely(ret < 0))
                goto error_quick;
        gfs_ether_setup = true;

        ret = usb_string_ids_tab(cdev, gfs_strings);
        if (unlikely(ret < 0))
                goto error;
        gfs_dev_desc.iProduct = gfs_strings[USB_GADGET_PRODUCT_IDX].id;

        for (i = func_num; i--; ) {
                ret = functionfs_bind(ffs_tab[i].ffs_data, cdev);
                if (unlikely(ret < 0)) {
                        while (++i < func_num)
                                functionfs_unbind(ffs_tab[i].ffs_data);
                        goto error;
                }
        }

        for (i = 0; i < ARRAY_SIZE(gfs_configurations); ++i) {
                struct gfs_configuration *c = gfs_configurations + i;
                int sid = USB_GADGET_FIRST_AVAIL_IDX + i;

                c->c.label                      = gfs_strings[sid].s;
                c->c.iConfiguration             = gfs_strings[sid].id;
                c->c.bConfigurationValue        = 1 + i;
                c->c.bmAttributes               = USB_CONFIG_ATT_SELFPOWER;

                ret = usb_add_config(cdev, &c->c, gfs_do_config);
                if (unlikely(ret < 0))
                        goto error_unbind;
        }
        usb_composite_overwrite_options(cdev, &coverwrite);
        return 0;

error_unbind:
        for (i = 0; i < func_num; i++)
                functionfs_unbind(ffs_tab[i].ffs_data);
error:
        gether_cleanup();
error_quick:
        gfs_ether_setup = false;
        return ret;
}

/*
 * It is assumed that gfs_unbind is called from a context where gfs_lock is held
 */
static int gfs_unbind(struct usb_composite_dev *cdev)
{
        int i;

        ENTER();

        /*
         * We may have been called in an error recovery from
         * composite_bind() after gfs_unbind() failure so we need to
         * check if gfs_ffs_data is not NULL since gfs_bind() handles
         * all error recovery itself.  I'd rather we werent called
         * from composite on orror recovery, but what you're gonna
         * do...?
         */
        if (gfs_ether_setup)
                gether_cleanup();
        gfs_ether_setup = false;

        for (i = func_num; i--; )
                if (ffs_tab[i].ffs_data)
                        functionfs_unbind(ffs_tab[i].ffs_data);

        return 0;
}

/*
 * It is assumed that gfs_do_config is called from a context where
 * gfs_lock is held
 */
static int gfs_do_config(struct usb_configuration *c)
{
        struct gfs_configuration *gc =
                container_of(c, struct gfs_configuration, c);
        int i;
        int ret;

        if (missing_funcs)
                return -ENODEV;

        if (gadget_is_otg(c->cdev->gadget)) {
                c->descriptors = gfs_otg_desc;
                c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
        }

        if (gc->eth) {
                ret = gc->eth(c, gfs_hostaddr);
                if (unlikely(ret < 0))
                        return ret;
        }

        for (i = 0; i < func_num; i++) {
                ret = functionfs_bind_config(c->cdev, c, ffs_tab[i].ffs_data);
                if (unlikely(ret < 0))
                        return ret;
        }

        /*
         * After previous do_configs there may be some invalid
         * pointers in c->interface array.  This happens every time
         * a user space function with fewer interfaces than a user
         * space function that was run before the new one is run.  The
         * compasit's set_config() assumes that if there is no more
         * then MAX_CONFIG_INTERFACES interfaces in a configuration
         * then there is a NULL pointer after the last interface in
         * c->interface array.  We need to make sure this is true.
         */
        if (c->next_interface_id < ARRAY_SIZE(c->interface))
                c->interface[c->next_interface_id] = NULL;

        return 0;
}

#ifdef CONFIG_USB_FUNCTIONFS_ETH

static int eth_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN])
{
        return can_support_ecm(c->cdev->gadget)
                ? ecm_bind_config(c, ethaddr)
                : geth_bind_config(c, ethaddr);
}

#endif