// SPDX-License-Identifier: GPL-2.0+
/*
 * usb/gadget/config.c -- simplify building config descriptors
 *
 * Copyright (C) 2003 David Brownell
 */

#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/device.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/composite.h>
#include <linux/usb/otg.h>

/**
 * usb_descriptor_fillbuf - fill buffer with descriptors
 * @buf: Buffer to be filled
 * @buflen: Size of buf
 * @src: Array of descriptor pointers, terminated by null pointer.
 *
 * Copies descriptors into the buffer, returning the length or a
 * negative error code if they can't all be copied.  Useful when
 * assembling descriptors for an associated set of interfaces used
 * as part of configuring a composite device; or in other cases where
 * sets of descriptors need to be marshaled.
 */
int
usb_descriptor_fillbuf(void *buf, unsigned buflen,
                const struct usb_descriptor_header **src)
{
        u8      *dest = buf;

        if (!src)
                return -EINVAL;

        /* fill buffer from src[] until null descriptor ptr */
        for (; NULL != *src; src++) {
                unsigned                len = (*src)->bLength;

                if (len > buflen)
                        return -EINVAL;
                memcpy(dest, *src, len);
                buflen -= len;
                dest += len;
        }
        return dest - (u8 *)buf;
}
EXPORT_SYMBOL_GPL(usb_descriptor_fillbuf);

/**
 * usb_gadget_config_buf - builts a complete configuration descriptor
 * @config: Header for the descriptor, including characteristics such
 *      as power requirements and number of interfaces.
 * @desc: Null-terminated vector of pointers to the descriptors (interface,
 *      endpoint, etc) defining all functions in this device configuration.
 * @buf: Buffer for the resulting configuration descriptor.
 * @length: Length of buffer.  If this is not big enough to hold the
 *      entire configuration descriptor, an error code will be returned.
 *
 * This copies descriptors into the response buffer, building a descriptor
 * for that configuration.  It returns the buffer length or a negative
 * status code.  The config.wTotalLength field is set to match the length
 * of the result, but other descriptor fields (including power usage and
 * interface count) must be set by the caller.
 *
 * Gadget drivers could use this when constructing a config descriptor
 * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
 * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
 */
int usb_gadget_config_buf(
        const struct usb_config_descriptor      *config,
        void                                    *buf,
        unsigned                                length,
        const struct usb_descriptor_header      **desc
)
{
        struct usb_config_descriptor            *cp = buf;
        int                                     len;

        /* config descriptor first */
        if (length < USB_DT_CONFIG_SIZE || !desc)
                return -EINVAL;
        *cp = *config;

        /* then interface/endpoint/class/vendor/... */
        len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8 *)buf,
                        length - USB_DT_CONFIG_SIZE, desc);
        if (len < 0)
                return len;
        len += USB_DT_CONFIG_SIZE;
        if (len > 0xffff)
                return -EINVAL;

        /* patch up the config descriptor */
        cp->bLength = USB_DT_CONFIG_SIZE;
        cp->bDescriptorType = USB_DT_CONFIG;
        cp->wTotalLength = cpu_to_le16(len);
        cp->bmAttributes |= USB_CONFIG_ATT_ONE;
        return len;
}
EXPORT_SYMBOL_GPL(usb_gadget_config_buf);

/**
 * usb_copy_descriptors - copy a vector of USB descriptors
 * @src: null-terminated vector to copy
 * Context: initialization code, which may sleep
 *
 * This makes a copy of a vector of USB descriptors.  Its primary use
 * is to support usb_function objects which can have multiple copies,
 * each needing different descriptors.  Functions may have static
 * tables of descriptors, which are used as templates and customized
 * with identifiers (for interfaces, strings, endpoints, and more)
 * as needed by a given function instance.
 */
struct usb_descriptor_header **
usb_copy_descriptors(struct usb_descriptor_header **src)
{
        struct usb_descriptor_header **tmp;
        unsigned bytes;
        unsigned n_desc;
        void *mem;
        struct usb_descriptor_header **ret;

        /* count descriptors and their sizes; then add vector size */
        for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
                bytes += (*tmp)->bLength;
        bytes += (n_desc + 1) * sizeof(*tmp);

        mem = kmalloc(bytes, GFP_KERNEL);
        if (!mem)
                return NULL;

        /* fill in pointers starting at "tmp",
         * to descriptors copied starting at "mem";
         * and return "ret"
         */
        tmp = mem;
        ret = mem;
        mem += (n_desc + 1) * sizeof(*tmp);
        while (*src) {
                memcpy(mem, *src, (*src)->bLength);
                *tmp = mem;
                tmp++;
                mem += (*src)->bLength;
                src++;
        }
        *tmp = NULL;

        return ret;
}
EXPORT_SYMBOL_GPL(usb_copy_descriptors);

int usb_assign_descriptors(struct usb_function *f,
                struct usb_descriptor_header **fs,
                struct usb_descriptor_header **hs,
                struct usb_descriptor_header **ss,
                struct usb_descriptor_header **ssp)
{
        struct usb_gadget *g = f->config->cdev->gadget;

        if (fs) {
                f->fs_descriptors = usb_copy_descriptors(fs);
                if (!f->fs_descriptors)
                        goto err;
        }
        if (hs && gadget_is_dualspeed(g)) {
                f->hs_descriptors = usb_copy_descriptors(hs);
                if (!f->hs_descriptors)
                        goto err;
        }
        if (ss && gadget_is_superspeed(g)) {
                f->ss_descriptors = usb_copy_descriptors(ss);
                if (!f->ss_descriptors)
                        goto err;
        }
        if (ssp && gadget_is_superspeed_plus(g)) {
                f->ssp_descriptors = usb_copy_descriptors(ssp);
                if (!f->ssp_descriptors)
                        goto err;
        }
        return 0;
err:
        usb_free_all_descriptors(f);
        return -ENOMEM;
}
EXPORT_SYMBOL_GPL(usb_assign_descriptors);

void usb_free_all_descriptors(struct usb_function *f)
{
        usb_free_descriptors(f->fs_descriptors);
        usb_free_descriptors(f->hs_descriptors);
        usb_free_descriptors(f->ss_descriptors);
        usb_free_descriptors(f->ssp_descriptors);
}
EXPORT_SYMBOL_GPL(usb_free_all_descriptors);

struct usb_descriptor_header *usb_otg_descriptor_alloc(
                                struct usb_gadget *gadget)
{
        struct usb_descriptor_header *otg_desc;
        unsigned length = 0;

        if (gadget->otg_caps && (gadget->otg_caps->otg_rev >= 0x0200))
                length = sizeof(struct usb_otg20_descriptor);
        else
                length = sizeof(struct usb_otg_descriptor);

        otg_desc = kzalloc(length, GFP_KERNEL);
        return otg_desc;
}
EXPORT_SYMBOL_GPL(usb_otg_descriptor_alloc);

int usb_otg_descriptor_init(struct usb_gadget *gadget,
                struct usb_descriptor_header *otg_desc)
{
        struct usb_otg_descriptor *otg1x_desc;
        struct usb_otg20_descriptor *otg20_desc;
        struct usb_otg_caps *otg_caps = gadget->otg_caps;
        u8 otg_attributes = 0;

        if (!otg_desc)
                return -EINVAL;

        if (otg_caps && otg_caps->otg_rev) {
                if (otg_caps->hnp_support)
                        otg_attributes |= USB_OTG_HNP;
                if (otg_caps->srp_support)
                        otg_attributes |= USB_OTG_SRP;
                if (otg_caps->adp_support && (otg_caps->otg_rev >= 0x0200))
                        otg_attributes |= USB_OTG_ADP;
        } else {
                otg_attributes = USB_OTG_SRP | USB_OTG_HNP;
        }

        if (otg_caps && (otg_caps->otg_rev >= 0x0200)) {
                otg20_desc = (struct usb_otg20_descriptor *)otg_desc;
                otg20_desc->bLength = sizeof(struct usb_otg20_descriptor);
                otg20_desc->bDescriptorType = USB_DT_OTG;
                otg20_desc->bmAttributes = otg_attributes;
                otg20_desc->bcdOTG = cpu_to_le16(otg_caps->otg_rev);
        } else {
                otg1x_desc = (struct usb_otg_descriptor *)otg_desc;
                otg1x_desc->bLength = sizeof(struct usb_otg_descriptor);
                otg1x_desc->bDescriptorType = USB_DT_OTG;
                otg1x_desc->bmAttributes = otg_attributes;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(usb_otg_descriptor_init);