// SPDX-License-Identifier: GPL-2.0
/*
 * func_utils.h
 *
 * Utility definitions for USB functions
 *
 * Copyright (c) 2013 Samsung Electronics Co., Ltd.
 *              http://www.samsung.com
 *
 * Author: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com>
 */

#ifndef _FUNC_UTILS_H_
#define _FUNC_UTILS_H_

#include <linux/usb/gadget.h>
#include <linux/overflow.h>

/* Variable Length Array Macros **********************************************/
#define vla_group(groupname) size_t groupname##__next = 0
#define vla_group_size(groupname) groupname##__next

#define vla_item(groupname, type, name, n) \
        size_t groupname##_##name##__offset = ({                               \
                size_t offset = 0;                                             \
                if (groupname##__next != SIZE_MAX) {                           \
                        size_t align_mask = __alignof__(type) - 1;             \
                        size_t size = array_size(n, sizeof(type));             \
                        offset = (groupname##__next + align_mask) &            \
                                  ~align_mask;                                 \
                        if (check_add_overflow(offset, size,                   \
                                               &groupname##__next)) {          \
                                groupname##__next = SIZE_MAX;                  \
                                offset = 0;                                    \
                        }                                                      \
                }                                                              \
                offset;                                                        \
        })

#define vla_item_with_sz(groupname, type, name, n) \
        size_t groupname##_##name##__sz = array_size(n, sizeof(type));          \
        size_t groupname##_##name##__offset = ({                                \
                size_t offset = 0;                                              \
                if (groupname##__next != SIZE_MAX) {                            \
                        size_t align_mask = __alignof__(type) - 1;              \
                        offset = (groupname##__next + align_mask) &             \
                                  ~align_mask;                                  \
                        if (check_add_overflow(offset, groupname##_##name##__sz,\
                                                        &groupname##__next)) {  \
                                groupname##__next = SIZE_MAX;                   \
                                offset = 0;                                     \
                        }                                                       \
                }                                                               \
                offset;                                                         \
        })

#define vla_ptr(ptr, groupname, name) \
        ((void *) ((char *)ptr + groupname##_##name##__offset))

struct usb_ep;
struct usb_request;

/**
 * alloc_ep_req - returns a usb_request allocated by the gadget driver and
 * allocates the request's buffer.
 *
 * @ep: the endpoint to allocate a usb_request
 * @len: usb_requests's buffer suggested size
 *
 * In case @ep direction is OUT, the @len will be aligned to ep's
 * wMaxPacketSize. In order to avoid memory leaks or drops, *always* use
 * usb_requests's length (req->length) to refer to the allocated buffer size.
 * Requests allocated via alloc_ep_req() *must* be freed by free_ep_req().
 */
struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len);

/* Frees a usb_request previously allocated by alloc_ep_req() */
static inline void free_ep_req(struct usb_ep *ep, struct usb_request *req)
{
        WARN_ON(req->buf == NULL);
        kfree(req->buf);
        req->buf = NULL;
        usb_ep_free_request(ep, req);
}

#endif /* _FUNC_UTILS_H_ */