// SPDX-License-Identifier: GPL-2.0+
/*
 * g_ffs.c -- user mode file system API for USB composite function controllers
 *
 * Copyright (C) 2010 Samsung Electronics
 * Author: Michal Nazarewicz <mina86@mina86.com>
 */

#define pr_fmt(fmt) "g_ffs: " fmt

#include <linux/module.h>

#if defined CONFIG_USB_FUNCTIONFS_ETH || defined CONFIG_USB_FUNCTIONFS_RNDIS
#include <linux/netdevice.h>

#  if defined USB_ETH_RNDIS
#    undef USB_ETH_RNDIS
#  endif
#  ifdef CONFIG_USB_FUNCTIONFS_RNDIS
#    define USB_ETH_RNDIS y
#  endif

#  include "u_ecm.h"
#  include "u_gether.h"
#  ifdef USB_ETH_RNDIS
#    include "u_rndis.h"
#    include "rndis.h"
#  endif
#  include "u_ether.h"

USB_ETHERNET_MODULE_PARAMETERS();

#  ifdef CONFIG_USB_FUNCTIONFS_ETH
static int eth_bind_config(struct usb_configuration *c);
static struct usb_function_instance *fi_ecm;
static struct usb_function *f_ecm;
static struct usb_function_instance *fi_geth;
static struct usb_function *f_geth;
#  endif
#  ifdef CONFIG_USB_FUNCTIONFS_RNDIS
static int bind_rndis_config(struct usb_configuration *c);
static struct usb_function_instance *fi_rndis;
static struct usb_function *f_rndis;
#  endif
#endif

#include "u_fs.h"

#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

USB_GADGET_COMPOSITE_OPTIONS();

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

        /* .bcdUSB = DYNAMIC */
        .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[2];

/* 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);
        int num;
};

static struct gfs_configuration gfs_configurations[] = {
#ifdef CONFIG_USB_FUNCTIONFS_RNDIS
        {
                .eth            = bind_rndis_config,
        },
#endif

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

#ifdef CONFIG_USB_FUNCTIONFS_GENERIC
        {
        },
#endif
};

static void *functionfs_acquire_dev(struct ffs_dev *dev);
static void functionfs_release_dev(struct ffs_dev *dev);
static int functionfs_ready_callback(struct ffs_data *ffs);
static void functionfs_closed_callback(struct ffs_data *ffs);
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 struct usb_composite_driver gfs_driver = {
        .name           = DRIVER_NAME,
        .dev            = &gfs_dev_desc,
        .strings        = gfs_dev_strings,
        .max_speed      = USB_SPEED_SUPER,
        .bind           = gfs_bind,
        .unbind         = gfs_unbind,
};

static unsigned int missing_funcs;
static bool gfs_registered;
static bool gfs_single_func;
static struct usb_function_instance **fi_ffs;
static struct usb_function **f_ffs[] = {
#ifdef CONFIG_USB_FUNCTIONFS_RNDIS
        NULL,
#endif

#ifdef CONFIG_USB_FUNCTIONFS_ETH
        NULL,
#endif

#ifdef CONFIG_USB_FUNCTIONFS_GENERIC
        NULL,
#endif
};

#define N_CONF ARRAY_SIZE(f_ffs)

static int __init gfs_init(void)
{
        struct f_fs_opts *opts;
        int i;
        int ret = 0;

        if (func_num < 2) {
                gfs_single_func = true;
                func_num = 1;
        }

        /*
         * Allocate in one chunk for easier maintenance
         */
        f_ffs[0] = kzalloc_objs(*f_ffs[0], func_num * N_CONF);
        if (!f_ffs[0]) {
                ret = -ENOMEM;
                goto no_func;
        }
        for (i = 1; i < N_CONF; ++i)
                f_ffs[i] = f_ffs[0] + i * func_num;

        fi_ffs = kzalloc_objs(*fi_ffs, func_num);
        if (!fi_ffs) {
                ret = -ENOMEM;
                goto no_func;
        }

        for (i = 0; i < func_num; i++) {
                fi_ffs[i] = usb_get_function_instance("ffs");
                if (IS_ERR(fi_ffs[i])) {
                        ret = PTR_ERR(fi_ffs[i]);
                        --i;
                        goto no_dev;
                }
                opts = to_f_fs_opts(fi_ffs[i]);
                if (gfs_single_func)
                        ret = ffs_single_dev(opts->dev);
                else
                        ret = ffs_name_dev(opts->dev, func_names[i]);
                if (ret)
                        goto no_dev;
                opts->dev->ffs_ready_callback = functionfs_ready_callback;
                opts->dev->ffs_closed_callback = functionfs_closed_callback;
                opts->dev->ffs_acquire_dev_callback = functionfs_acquire_dev;
                opts->dev->ffs_release_dev_callback = functionfs_release_dev;
                opts->no_configfs = true;
        }

        missing_funcs = func_num;

        return 0;
no_dev:
        while (i >= 0)
                usb_put_function_instance(fi_ffs[i--]);
        kfree(fi_ffs);
no_func:
        kfree(f_ffs[0]);
        return ret;
}
module_init(gfs_init);

static void __exit gfs_exit(void)
{
        int i;

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

        kfree(f_ffs[0]);

        for (i = 0; i < func_num; i++)
                usb_put_function_instance(fi_ffs[i]);

        kfree(fi_ffs);
}
module_exit(gfs_exit);

static void *functionfs_acquire_dev(struct ffs_dev *dev)
{
        if (!try_module_get(THIS_MODULE))
                return ERR_PTR(-ENOENT);

        return NULL;
}

static void functionfs_release_dev(struct ffs_dev *dev)
{
        module_put(THIS_MODULE);
}

/*
 * The caller of this function takes ffs_lock
 */
static int functionfs_ready_callback(struct ffs_data *ffs)
{
        int ret = 0;

        if (--missing_funcs)
                return 0;

        if (gfs_registered)
                return -EBUSY;

        gfs_registered = true;

        ret = usb_composite_probe(&gfs_driver);
        if (unlikely(ret < 0)) {
                ++missing_funcs;
                gfs_registered = false;
        }

        return ret;
}

/*
 * The caller of this function takes ffs_lock
 */
static void functionfs_closed_callback(struct ffs_data *ffs)
{
        missing_funcs++;

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

/*
 * It is assumed that gfs_bind is called from a context where ffs_lock is held
 */
static int gfs_bind(struct usb_composite_dev *cdev)
{
#if defined CONFIG_USB_FUNCTIONFS_ETH || defined CONFIG_USB_FUNCTIONFS_RNDIS
        struct net_device *net;
#endif
        int ret, i;

        if (missing_funcs)
                return -ENODEV;
#if defined CONFIG_USB_FUNCTIONFS_ETH
        if (can_support_ecm(cdev->gadget)) {
                struct f_ecm_opts *ecm_opts;

                fi_ecm = usb_get_function_instance("ecm");
                if (IS_ERR(fi_ecm))
                        return PTR_ERR(fi_ecm);
                ecm_opts = container_of(fi_ecm, struct f_ecm_opts, func_inst);
                net = ecm_opts->net;
        } else {
                struct f_gether_opts *geth_opts;

                fi_geth = usb_get_function_instance("geth");
                if (IS_ERR(fi_geth))
                        return PTR_ERR(fi_geth);
                geth_opts = container_of(fi_geth, struct f_gether_opts,
                                         func_inst);
                net = geth_opts->net;
        }
#endif

#ifdef CONFIG_USB_FUNCTIONFS_RNDIS
        {
                fi_rndis = usb_get_function_instance("rndis");
                if (IS_ERR(fi_rndis)) {
                        ret = PTR_ERR(fi_rndis);
                        goto error;
                }
#ifndef CONFIG_USB_FUNCTIONFS_ETH
                net = container_of(fi_rndis, struct f_rndis_opts,
                                   func_inst)->net;
#endif
        }
#endif

#if defined CONFIG_USB_FUNCTIONFS_ETH || defined CONFIG_USB_FUNCTIONFS_RNDIS
        gether_set_qmult(net, qmult);
        if (!gether_set_host_addr(net, host_addr))
                pr_info("using host ethernet address: %s", host_addr);
        if (!gether_set_dev_addr(net, dev_addr))
                pr_info("using self ethernet address: %s", dev_addr);
#endif

#if defined CONFIG_USB_FUNCTIONFS_RNDIS && defined CONFIG_USB_FUNCTIONFS_ETH
        gether_set_gadget(net, cdev->gadget);
        ret = gether_register_netdev(net);
        if (ret)
                goto error_rndis;

        if (can_support_ecm(cdev->gadget)) {
                struct f_ecm_opts *ecm_opts;

                ecm_opts = container_of(fi_ecm, struct f_ecm_opts, func_inst);
                ecm_opts->bound = true;
        } else {
                struct f_gether_opts *geth_opts;

                geth_opts = container_of(fi_geth, struct f_gether_opts,
                                         func_inst);
                geth_opts->bound = true;
        }

        rndis_borrow_net(fi_rndis, net);
#endif

        /* TODO: gstrings_attach? */
        ret = usb_string_ids_tab(cdev, gfs_strings);
        if (unlikely(ret < 0))
                goto error_rndis;
        gfs_dev_desc.iProduct = gfs_strings[USB_GADGET_PRODUCT_IDX].id;

        if (gadget_is_otg(cdev->gadget) && !gfs_otg_desc[0]) {
                struct usb_descriptor_header *usb_desc;

                usb_desc = usb_otg_descriptor_alloc(cdev->gadget);
                if (!usb_desc) {
                        ret = -ENOMEM;
                        goto error_rndis;
                }
                usb_otg_descriptor_init(cdev->gadget, usb_desc);
                gfs_otg_desc[0] = usb_desc;
                gfs_otg_desc[1] = NULL;
        }

        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;

                c->num = i;

                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;

/* TODO */
error_unbind:
        kfree(gfs_otg_desc[0]);
        gfs_otg_desc[0] = NULL;
error_rndis:
#ifdef CONFIG_USB_FUNCTIONFS_RNDIS
        usb_put_function_instance(fi_rndis);
error:
#endif
#if defined CONFIG_USB_FUNCTIONFS_ETH
        if (can_support_ecm(cdev->gadget))
                usb_put_function_instance(fi_ecm);
        else
                usb_put_function_instance(fi_geth);
#endif
        return ret;
}

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

#ifdef CONFIG_USB_FUNCTIONFS_RNDIS
        usb_put_function(f_rndis);
        usb_put_function_instance(fi_rndis);
#endif

#if defined CONFIG_USB_FUNCTIONFS_ETH
        if (can_support_ecm(cdev->gadget)) {
                usb_put_function(f_ecm);
                usb_put_function_instance(fi_ecm);
        } else {
                usb_put_function(f_geth);
                usb_put_function_instance(fi_geth);
        }
#endif
        for (i = 0; i < N_CONF * func_num; ++i)
                usb_put_function(*(f_ffs[0] + i));

        kfree(gfs_otg_desc[0]);
        gfs_otg_desc[0] = NULL;

        return 0;
}

/*
 * It is assumed that gfs_do_config is called from a context where
 * ffs_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);
                if (unlikely(ret < 0))
                        return ret;
        }

        for (i = 0; i < func_num; i++) {
                f_ffs[gc->num][i] = usb_get_function(fi_ffs[i]);
                if (IS_ERR(f_ffs[gc->num][i])) {
                        ret = PTR_ERR(f_ffs[gc->num][i]);
                        goto error;
                }
                ret = usb_add_function(c, f_ffs[gc->num][i]);
                if (ret < 0) {
                        usb_put_function(f_ffs[gc->num][i]);
                        goto error;
                }
        }

        /*
         * 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;
error:
        while (--i >= 0) {
                if (!IS_ERR(f_ffs[gc->num][i]))
                        usb_remove_function(c, f_ffs[gc->num][i]);
                usb_put_function(f_ffs[gc->num][i]);
        }
        return ret;
}

#ifdef CONFIG_USB_FUNCTIONFS_ETH

static int eth_bind_config(struct usb_configuration *c)
{
        int status = 0;

        if (can_support_ecm(c->cdev->gadget)) {
                f_ecm = usb_get_function(fi_ecm);
                if (IS_ERR(f_ecm))
                        return PTR_ERR(f_ecm);

                status = usb_add_function(c, f_ecm);
                if (status < 0)
                        usb_put_function(f_ecm);

        } else {
                f_geth = usb_get_function(fi_geth);
                if (IS_ERR(f_geth))
                        return PTR_ERR(f_geth);

                status = usb_add_function(c, f_geth);
                if (status < 0)
                        usb_put_function(f_geth);
        }
        return status;
}

#endif

#ifdef CONFIG_USB_FUNCTIONFS_RNDIS

static int bind_rndis_config(struct usb_configuration *c)
{
        int status = 0;

        f_rndis = usb_get_function(fi_rndis);
        if (IS_ERR(f_rndis))
                return PTR_ERR(f_rndis);

        status = usb_add_function(c, f_rndis);
        if (status < 0)
                usb_put_function(f_rndis);

        return status;
}

#endif