// SPDX-License-Identifier: GPL-2.0+
/*
 * EFI device path from u-boot device-model mapping
 *
 * (C) Copyright 2017 Rob Clark
 */

#include <common.h>
#include <blk.h>
#include <dm.h>
#include <usb.h>
#include <mmc.h>
#include <nvme.h>
#include <efi_loader.h>
#include <part.h>
#include <sandboxblockdev.h>
#include <asm-generic/unaligned.h>
#include <linux/compat.h> /* U16_MAX */

#ifdef CONFIG_SANDBOX
const efi_guid_t efi_guid_host_dev = U_BOOT_HOST_DEV_GUID;
#endif

/* template END node: */
static const struct efi_device_path END = {
        .type     = DEVICE_PATH_TYPE_END,
        .sub_type = DEVICE_PATH_SUB_TYPE_END,
        .length   = sizeof(END),
};

/* template ROOT node: */
static const struct efi_device_path_vendor ROOT = {
        .dp = {
                .type     = DEVICE_PATH_TYPE_HARDWARE_DEVICE,
                .sub_type = DEVICE_PATH_SUB_TYPE_VENDOR,
                .length   = sizeof(ROOT),
        },
        .guid = U_BOOT_GUID,
};

#if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
/*
 * Determine if an MMC device is an SD card.
 *
 * @desc        block device descriptor
 * @return      true if the device is an SD card
 */
static bool is_sd(struct blk_desc *desc)
{
        struct mmc *mmc = find_mmc_device(desc->devnum);

        if (!mmc)
                return false;

        return IS_SD(mmc) != 0U;
}
#endif

static void *dp_alloc(size_t sz)
{
        void *buf;

        if (efi_allocate_pool(EFI_ALLOCATE_ANY_PAGES, sz, &buf) !=
            EFI_SUCCESS) {
                debug("EFI: ERROR: out of memory in %s\n", __func__);
                return NULL;
        }

        memset(buf, 0, sz);
        return buf;
}

/*
 * Iterate to next block in device-path, terminating (returning NULL)
 * at /End* node.
 */
struct efi_device_path *efi_dp_next(const struct efi_device_path *dp)
{
        if (dp == NULL)
                return NULL;
        if (dp->type == DEVICE_PATH_TYPE_END)
                return NULL;
        dp = ((void *)dp) + dp->length;
        if (dp->type == DEVICE_PATH_TYPE_END)
                return NULL;
        return (struct efi_device_path *)dp;
}

/*
 * Compare two device-paths, stopping when the shorter of the two hits
 * an End* node. This is useful to, for example, compare a device-path
 * representing a device with one representing a file on the device, or
 * a device with a parent device.
 */
int efi_dp_match(const struct efi_device_path *a,
                 const struct efi_device_path *b)
{
        while (1) {
                int ret;

                ret = memcmp(&a->length, &b->length, sizeof(a->length));
                if (ret)
                        return ret;

                ret = memcmp(a, b, a->length);
                if (ret)
                        return ret;

                a = efi_dp_next(a);
                b = efi_dp_next(b);

                if (!a || !b)
                        return 0;
        }
}

/*
 * We can have device paths that start with a USB WWID or a USB Class node,
 * and a few other cases which don't encode the full device path with bus
 * hierarchy:
 *
 *   - MESSAGING:USB_WWID
 *   - MESSAGING:USB_CLASS
 *   - MEDIA:FILE_PATH
 *   - MEDIA:HARD_DRIVE
 *   - MESSAGING:URI
 *
 * See UEFI spec (section 3.1.2, about short-form device-paths)
 */
static struct efi_device_path *shorten_path(struct efi_device_path *dp)
{
        while (dp) {
                /*
                 * TODO: Add MESSAGING:USB_WWID and MESSAGING:URI..
                 * in practice fallback.efi just uses MEDIA:HARD_DRIVE
                 * so not sure when we would see these other cases.
                 */
                if (EFI_DP_TYPE(dp, MESSAGING_DEVICE, MSG_USB_CLASS) ||
                    EFI_DP_TYPE(dp, MEDIA_DEVICE, HARD_DRIVE_PATH) ||
                    EFI_DP_TYPE(dp, MEDIA_DEVICE, FILE_PATH))
                        return dp;

                dp = efi_dp_next(dp);
        }

        return dp;
}

static struct efi_object *find_obj(struct efi_device_path *dp, bool short_path,
                                   struct efi_device_path **rem)
{
        struct efi_object *efiobj;
        efi_uintn_t dp_size = efi_dp_instance_size(dp);

        list_for_each_entry(efiobj, &efi_obj_list, link) {
                struct efi_handler *handler;
                struct efi_device_path *obj_dp;
                efi_status_t ret;

                ret = efi_search_protocol(efiobj,
                                          &efi_guid_device_path, &handler);
                if (ret != EFI_SUCCESS)
                        continue;
                obj_dp = handler->protocol_interface;

                do {
                        if (efi_dp_match(dp, obj_dp) == 0) {
                                if (rem) {
                                        /*
                                         * Allow partial matches, but inform
                                         * the caller.
                                         */
                                        *rem = ((void *)dp) +
                                                efi_dp_instance_size(obj_dp);
                                        return efiobj;
                                } else {
                                        /* Only return on exact matches */
                                        if (efi_dp_instance_size(obj_dp) ==
                                            dp_size)
                                                return efiobj;
                                }
                        }

                        obj_dp = shorten_path(efi_dp_next(obj_dp));
                } while (short_path && obj_dp);
        }

        return NULL;
}

/*
 * Find an efiobj from device-path, if 'rem' is not NULL, returns the
 * remaining part of the device path after the matched object.
 */
struct efi_object *efi_dp_find_obj(struct efi_device_path *dp,
                                   struct efi_device_path **rem)
{
        struct efi_object *efiobj;

        /* Search for an exact match first */
        efiobj = find_obj(dp, false, NULL);

        /* Then for a fuzzy match */
        if (!efiobj)
                efiobj = find_obj(dp, false, rem);

        /* And now for a fuzzy short match */
        if (!efiobj)
                efiobj = find_obj(dp, true, rem);

        return efiobj;
}

/*
 * Determine the last device path node that is not the end node.
 *
 * @dp          device path
 * @return      last node before the end node if it exists
 *              otherwise NULL
 */
const struct efi_device_path *efi_dp_last_node(const struct efi_device_path *dp)
{
        struct efi_device_path *ret;

        if (!dp || dp->type == DEVICE_PATH_TYPE_END)
                return NULL;
        while (dp) {
                ret = (struct efi_device_path *)dp;
                dp = efi_dp_next(dp);
        }
        return ret;
}

/* get size of the first device path instance excluding end node */
efi_uintn_t efi_dp_instance_size(const struct efi_device_path *dp)
{
        efi_uintn_t sz = 0;

        if (!dp || dp->type == DEVICE_PATH_TYPE_END)
                return 0;
        while (dp) {
                sz += dp->length;
                dp = efi_dp_next(dp);
        }

        return sz;
}

/* get size of multi-instance device path excluding end node */
efi_uintn_t efi_dp_size(const struct efi_device_path *dp)
{
        const struct efi_device_path *p = dp;

        if (!p)
                return 0;
        while (p->type != DEVICE_PATH_TYPE_END ||
               p->sub_type != DEVICE_PATH_SUB_TYPE_END)
                p = (void *)p + p->length;

        return (void *)p - (void *)dp;
}

/* copy multi-instance device path */
struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp)
{
        struct efi_device_path *ndp;
        size_t sz = efi_dp_size(dp) + sizeof(END);

        if (!dp)
                return NULL;

        ndp = dp_alloc(sz);
        if (!ndp)
                return NULL;
        memcpy(ndp, dp, sz);

        return ndp;
}

struct efi_device_path *efi_dp_append(const struct efi_device_path *dp1,
                                      const struct efi_device_path *dp2)
{
        struct efi_device_path *ret;

        if (!dp1 && !dp2) {
                /* return an end node */
                ret = efi_dp_dup(&END);
        } else if (!dp1) {
                ret = efi_dp_dup(dp2);
        } else if (!dp2) {
                ret = efi_dp_dup(dp1);
        } else {
                /* both dp1 and dp2 are non-null */
                unsigned sz1 = efi_dp_size(dp1);
                unsigned sz2 = efi_dp_size(dp2);
                void *p = dp_alloc(sz1 + sz2 + sizeof(END));
                if (!p)
                        return NULL;
                memcpy(p, dp1, sz1);
                /* the end node of the second device path has to be retained */
                memcpy(p + sz1, dp2, sz2 + sizeof(END));
                ret = p;
        }

        return ret;
}

struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
                                           const struct efi_device_path *node)
{
        struct efi_device_path *ret;

        if (!node && !dp) {
                ret = efi_dp_dup(&END);
        } else if (!node) {
                ret = efi_dp_dup(dp);
        } else if (!dp) {
                size_t sz = node->length;
                void *p = dp_alloc(sz + sizeof(END));
                if (!p)
                        return NULL;
                memcpy(p, node, sz);
                memcpy(p + sz, &END, sizeof(END));
                ret = p;
        } else {
                /* both dp and node are non-null */
                size_t sz = efi_dp_size(dp);
                void *p = dp_alloc(sz + node->length + sizeof(END));
                if (!p)
                        return NULL;
                memcpy(p, dp, sz);
                memcpy(p + sz, node, node->length);
                memcpy(p + sz + node->length, &END, sizeof(END));
                ret = p;
        }

        return ret;
}

struct efi_device_path *efi_dp_create_device_node(const u8 type,
                                                  const u8 sub_type,
                                                  const u16 length)
{
        struct efi_device_path *ret;

        if (length < sizeof(struct efi_device_path))
                return NULL;

        ret = dp_alloc(length);
        if (!ret)
                return ret;
        ret->type = type;
        ret->sub_type = sub_type;
        ret->length = length;
        return ret;
}

struct efi_device_path *efi_dp_append_instance(
                const struct efi_device_path *dp,
                const struct efi_device_path *dpi)
{
        size_t sz, szi;
        struct efi_device_path *p, *ret;

        if (!dpi)
                return NULL;
        if (!dp)
                return efi_dp_dup(dpi);
        sz = efi_dp_size(dp);
        szi = efi_dp_instance_size(dpi);
        p = dp_alloc(sz + szi + 2 * sizeof(END));
        if (!p)
                return NULL;
        ret = p;
        memcpy(p, dp, sz + sizeof(END));
        p = (void *)p + sz;
        p->sub_type = DEVICE_PATH_SUB_TYPE_INSTANCE_END;
        p = (void *)p + sizeof(END);
        memcpy(p, dpi, szi);
        p = (void *)p + szi;
        memcpy(p, &END, sizeof(END));
        return ret;
}

struct efi_device_path *efi_dp_get_next_instance(struct efi_device_path **dp,
                                                 efi_uintn_t *size)
{
        size_t sz;
        struct efi_device_path *p;

        if (size)
                *size = 0;
        if (!dp || !*dp)
                return NULL;
        sz = efi_dp_instance_size(*dp);
        p = dp_alloc(sz + sizeof(END));
        if (!p)
                return NULL;
        memcpy(p, *dp, sz + sizeof(END));
        *dp = (void *)*dp + sz;
        if ((*dp)->sub_type == DEVICE_PATH_SUB_TYPE_INSTANCE_END)
                *dp = (void *)*dp + sizeof(END);
        else
                *dp = NULL;
        if (size)
                *size = sz + sizeof(END);
        return p;
}

bool efi_dp_is_multi_instance(const struct efi_device_path *dp)
{
        const struct efi_device_path *p = dp;

        if (!p)
                return false;
        while (p->type != DEVICE_PATH_TYPE_END)
                p = (void *)p + p->length;
        return p->sub_type == DEVICE_PATH_SUB_TYPE_INSTANCE_END;
}

#ifdef CONFIG_DM
/* size of device-path not including END node for device and all parents
 * up to the root device.
 */
__maybe_unused static unsigned int dp_size(struct udevice *dev)
{
        if (!dev || !dev->driver)
                return sizeof(ROOT);

        switch (dev->driver->id) {
        case UCLASS_ROOT:
        case UCLASS_SIMPLE_BUS:
                /* stop traversing parents at this point: */
                return sizeof(ROOT);
        case UCLASS_ETH:
                return dp_size(dev->parent) +
                        sizeof(struct efi_device_path_mac_addr);
#ifdef CONFIG_BLK
        case UCLASS_BLK:
                switch (dev->parent->uclass->uc_drv->id) {
#ifdef CONFIG_IDE
                case UCLASS_IDE:
                        return dp_size(dev->parent) +
                                sizeof(struct efi_device_path_atapi);
#endif
#if defined(CONFIG_SCSI) && defined(CONFIG_DM_SCSI)
                case UCLASS_SCSI:
                        return dp_size(dev->parent) +
                                sizeof(struct efi_device_path_scsi);
#endif
#if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
                case UCLASS_MMC:
                        return dp_size(dev->parent) +
                                sizeof(struct efi_device_path_sd_mmc_path);
#endif
#if defined(CONFIG_NVME)
                case UCLASS_NVME:
                        return dp_size(dev->parent) +
                                sizeof(struct efi_device_path_nvme);
#endif
#ifdef CONFIG_SANDBOX
                case UCLASS_ROOT:
                         /*
                          * Sandbox's host device will be represented
                          * as vendor device with extra one byte for
                          * device number
                          */
                        return dp_size(dev->parent)
                                + sizeof(struct efi_device_path_vendor) + 1;
#endif
                default:
                        return dp_size(dev->parent);
                }
#endif
#if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
        case UCLASS_MMC:
                return dp_size(dev->parent) +
                        sizeof(struct efi_device_path_sd_mmc_path);
#endif
        case UCLASS_MASS_STORAGE:
        case UCLASS_USB_HUB:
                return dp_size(dev->parent) +
                        sizeof(struct efi_device_path_usb_class);
        default:
                /* just skip over unknown classes: */
                return dp_size(dev->parent);
        }
}

/*
 * Recursively build a device path.
 *
 * @buf         pointer to the end of the device path
 * @dev         device
 * @return      pointer to the end of the device path
 */
__maybe_unused static void *dp_fill(void *buf, struct udevice *dev)
{
        if (!dev || !dev->driver)
                return buf;

        switch (dev->driver->id) {
        case UCLASS_ROOT:
        case UCLASS_SIMPLE_BUS: {
                /* stop traversing parents at this point: */
                struct efi_device_path_vendor *vdp = buf;
                *vdp = ROOT;
                return &vdp[1];
        }
#ifdef CONFIG_DM_ETH
        case UCLASS_ETH: {
                struct efi_device_path_mac_addr *dp =
                        dp_fill(buf, dev->parent);
                struct eth_pdata *pdata = dev->platdata;

                dp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
                dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR;
                dp->dp.length = sizeof(*dp);
                memset(&dp->mac, 0, sizeof(dp->mac));
                /* We only support IPv4 */
                memcpy(&dp->mac, &pdata->enetaddr, ARP_HLEN);
                /* Ethernet */
                dp->if_type = 1;
                return &dp[1];
        }
#endif
#ifdef CONFIG_BLK
        case UCLASS_BLK:
                switch (dev->parent->uclass->uc_drv->id) {
#ifdef CONFIG_SANDBOX
                case UCLASS_ROOT: {
                        /* stop traversing parents at this point: */
                        struct efi_device_path_vendor *dp = buf;
                        struct blk_desc *desc = dev_get_uclass_platdata(dev);

                        dp_fill(buf, dev->parent);
                        dp = buf;
                        ++dp;
                        dp->dp.type = DEVICE_PATH_TYPE_HARDWARE_DEVICE;
                        dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_VENDOR;
                        dp->dp.length = sizeof(*dp) + 1;
                        memcpy(&dp->guid, &efi_guid_host_dev,
                               sizeof(efi_guid_t));
                        dp->vendor_data[0] = desc->devnum;
                        return &dp->vendor_data[1];
                        }
#endif
#ifdef CONFIG_IDE
                case UCLASS_IDE: {
                        struct efi_device_path_atapi *dp =
                        dp_fill(buf, dev->parent);
                        struct blk_desc *desc = dev_get_uclass_platdata(dev);

                        dp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
                        dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_ATAPI;
                        dp->dp.length = sizeof(*dp);
                        dp->logical_unit_number = desc->devnum;
                        dp->primary_secondary = IDE_BUS(desc->devnum);
                        dp->slave_master = desc->devnum %
                                (CONFIG_SYS_IDE_MAXDEVICE /
                                 CONFIG_SYS_IDE_MAXBUS);
                        return &dp[1];
                        }
#endif
#if defined(CONFIG_SCSI) && defined(CONFIG_DM_SCSI)
                case UCLASS_SCSI: {
                        struct efi_device_path_scsi *dp =
                                dp_fill(buf, dev->parent);
                        struct blk_desc *desc = dev_get_uclass_platdata(dev);

                        dp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
                        dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_SCSI;
                        dp->dp.length = sizeof(*dp);
                        dp->logical_unit_number = desc->lun;
                        dp->target_id = desc->target;
                        return &dp[1];
                        }
#endif
#if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
                case UCLASS_MMC: {
                        struct efi_device_path_sd_mmc_path *sddp =
                                dp_fill(buf, dev->parent);
                        struct blk_desc *desc = dev_get_uclass_platdata(dev);

                        sddp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
                        sddp->dp.sub_type = is_sd(desc) ?
                                DEVICE_PATH_SUB_TYPE_MSG_SD :
                                DEVICE_PATH_SUB_TYPE_MSG_MMC;
                        sddp->dp.length   = sizeof(*sddp);
                        sddp->slot_number = dev->seq;
                        return &sddp[1];
                        }
#endif
#if defined(CONFIG_NVME)
                case UCLASS_NVME: {
                        struct efi_device_path_nvme *dp =
                                dp_fill(buf, dev->parent);
                        u32 ns_id;

                        dp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
                        dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_NVME;
                        dp->dp.length   = sizeof(*dp);
                        nvme_get_namespace_id(dev, &ns_id, dp->eui64);
                        memcpy(&dp->ns_id, &ns_id, sizeof(ns_id));
                        return &dp[1];
                        }
#endif
                default:
                        debug("%s(%u) %s: unhandled parent class: %s (%u)\n",
                              __FILE__, __LINE__, __func__,
                              dev->name, dev->parent->uclass->uc_drv->id);
                        return dp_fill(buf, dev->parent);
                }
#endif
#if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
        case UCLASS_MMC: {
                struct efi_device_path_sd_mmc_path *sddp =
                        dp_fill(buf, dev->parent);
                struct mmc *mmc = mmc_get_mmc_dev(dev);
                struct blk_desc *desc = mmc_get_blk_desc(mmc);

                sddp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
                sddp->dp.sub_type = is_sd(desc) ?
                        DEVICE_PATH_SUB_TYPE_MSG_SD :
                        DEVICE_PATH_SUB_TYPE_MSG_MMC;
                sddp->dp.length   = sizeof(*sddp);
                sddp->slot_number = dev->seq;

                return &sddp[1];
        }
#endif
        case UCLASS_MASS_STORAGE:
        case UCLASS_USB_HUB: {
                struct efi_device_path_usb_class *udp =
                        dp_fill(buf, dev->parent);
                struct usb_device *udev = dev_get_parent_priv(dev);
                struct usb_device_descriptor *desc = &udev->descriptor;

                udp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
                udp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_USB_CLASS;
                udp->dp.length   = sizeof(*udp);
                udp->vendor_id   = desc->idVendor;
                udp->product_id  = desc->idProduct;
                udp->device_class    = desc->bDeviceClass;
                udp->device_subclass = desc->bDeviceSubClass;
                udp->device_protocol = desc->bDeviceProtocol;

                return &udp[1];
        }
        default:
                debug("%s(%u) %s: unhandled device class: %s (%u)\n",
                      __FILE__, __LINE__, __func__,
                      dev->name, dev->driver->id);
                return dp_fill(buf, dev->parent);
        }
}
#endif

static unsigned dp_part_size(struct blk_desc *desc, int part)
{
        unsigned dpsize;

#ifdef CONFIG_BLK
        {
                struct udevice *dev;
                int ret = blk_find_device(desc->if_type, desc->devnum, &dev);

                if (ret)
                        dev = desc->bdev->parent;
                dpsize = dp_size(dev);
        }
#else
        dpsize = sizeof(ROOT) + sizeof(struct efi_device_path_usb);
#endif

        if (part == 0) /* the actual disk, not a partition */
                return dpsize;

        if (desc->part_type == PART_TYPE_ISO)
                dpsize += sizeof(struct efi_device_path_cdrom_path);
        else
                dpsize += sizeof(struct efi_device_path_hard_drive_path);

        return dpsize;
}

/*
 * Create a device node for a block device partition.
 *
 * @buf         buffer to which the device path is written
 * @desc        block device descriptor
 * @part        partition number, 0 identifies a block device
 */
static void *dp_part_node(void *buf, struct blk_desc *desc, int part)
{
        disk_partition_t info;

        part_get_info(desc, part, &info);

        if (desc->part_type == PART_TYPE_ISO) {
                struct efi_device_path_cdrom_path *cddp = buf;

                cddp->boot_entry = part;
                cddp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
                cddp->dp.sub_type = DEVICE_PATH_SUB_TYPE_CDROM_PATH;
                cddp->dp.length = sizeof(*cddp);
                cddp->partition_start = info.start;
                cddp->partition_size = info.size;

                buf = &cddp[1];
        } else {
                struct efi_device_path_hard_drive_path *hddp = buf;

                hddp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
                hddp->dp.sub_type = DEVICE_PATH_SUB_TYPE_HARD_DRIVE_PATH;
                hddp->dp.length = sizeof(*hddp);
                hddp->partition_number = part;
                hddp->partition_start = info.start;
                hddp->partition_end = info.size;
                if (desc->part_type == PART_TYPE_EFI)
                        hddp->partmap_type = 2;
                else
                        hddp->partmap_type = 1;

                switch (desc->sig_type) {
                case SIG_TYPE_NONE:
                default:
                        hddp->signature_type = 0;
                        memset(hddp->partition_signature, 0,
                               sizeof(hddp->partition_signature));
                        break;
                case SIG_TYPE_MBR:
                        hddp->signature_type = 1;
                        memset(hddp->partition_signature, 0,
                               sizeof(hddp->partition_signature));
                        memcpy(hddp->partition_signature, &desc->mbr_sig,
                               sizeof(desc->mbr_sig));
                        break;
                case SIG_TYPE_GUID:
                        hddp->signature_type = 2;
                        memcpy(hddp->partition_signature, &desc->guid_sig,
                               sizeof(hddp->partition_signature));
                        break;
                }

                buf = &hddp[1];
        }

        return buf;
}

/*
 * Create a device path for a block device or one of its partitions.
 *
 * @buf         buffer to which the device path is written
 * @desc        block device descriptor
 * @part        partition number, 0 identifies a block device
 */
static void *dp_part_fill(void *buf, struct blk_desc *desc, int part)
{
#ifdef CONFIG_BLK
        {
                struct udevice *dev;
                int ret = blk_find_device(desc->if_type, desc->devnum, &dev);

                if (ret)
                        dev = desc->bdev->parent;
                buf = dp_fill(buf, dev);
        }
#else
        /*
         * We *could* make a more accurate path, by looking at if_type
         * and handling all the different cases like we do for non-
         * legacy (i.e. CONFIG_BLK=y) case. But most important thing
         * is just to have a unique device-path for if_type+devnum.
         * So map things to a fictitious USB device.
         */
        struct efi_device_path_usb *udp;

        memcpy(buf, &ROOT, sizeof(ROOT));
        buf += sizeof(ROOT);

        udp = buf;
        udp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
        udp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_USB;
        udp->dp.length = sizeof(*udp);
        udp->parent_port_number = desc->if_type;
        udp->usb_interface = desc->devnum;
        buf = &udp[1];
#endif

        if (part == 0) /* the actual disk, not a partition */
                return buf;

        return dp_part_node(buf, desc, part);
}

/* Construct a device-path from a partition on a block device: */
struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part)
{
        void *buf, *start;

        start = buf = dp_alloc(dp_part_size(desc, part) + sizeof(END));
        if (!buf)
                return NULL;

        buf = dp_part_fill(buf, desc, part);

        *((struct efi_device_path *)buf) = END;

        return start;
}

/*
 * Create a device node for a block device partition.
 *
 * @buf         buffer to which the device path is written
 * @desc        block device descriptor
 * @part        partition number, 0 identifies a block device
 */
struct efi_device_path *efi_dp_part_node(struct blk_desc *desc, int part)
{
        efi_uintn_t dpsize;
        void *buf;

        if (desc->part_type == PART_TYPE_ISO)
                dpsize = sizeof(struct efi_device_path_cdrom_path);
        else
                dpsize = sizeof(struct efi_device_path_hard_drive_path);
        buf = dp_alloc(dpsize);

        dp_part_node(buf, desc, part);

        return buf;
}

/**
 * path_to_uefi() - convert UTF-8 path to an UEFI style path
 *
 * Convert UTF-8 path to a UEFI style path (i.e. with backslashes as path
 * separators and UTF-16).
 *
 * @src:        source buffer
 * @uefi:       target buffer, possibly unaligned
 */
static void path_to_uefi(void *uefi, const char *src)
{
        u16 *pos = uefi;

        /*
         * efi_set_bootdev() calls this routine indirectly before the UEFI
         * subsystem is initialized. So we cannot assume unaligned access to be
         * enabled.
         */
        allow_unaligned();

        while (*src) {
                s32 code = utf8_get(&src);

                if (code < 0)
                        code = '?';
                else if (code == '/')
                        code = '\\';
                utf16_put(code, &pos);
        }
        *pos = 0;
}

/*
 * If desc is NULL, this creates a path with only the file component,
 * otherwise it creates a full path with both device and file components
 */
struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
                const char *path)
{
        struct efi_device_path_file_path *fp;
        void *buf, *start;
        size_t dpsize = 0, fpsize;

        if (desc)
                dpsize = dp_part_size(desc, part);

        fpsize = sizeof(struct efi_device_path) +
                 2 * (utf8_utf16_strlen(path) + 1);
        if (fpsize > U16_MAX)
                return NULL;

        dpsize += fpsize;

        start = buf = dp_alloc(dpsize + sizeof(END));
        if (!buf)
                return NULL;

        if (desc)
                buf = dp_part_fill(buf, desc, part);

        /* add file-path: */
        fp = buf;
        fp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
        fp->dp.sub_type = DEVICE_PATH_SUB_TYPE_FILE_PATH;
        fp->dp.length = (u16)fpsize;
        path_to_uefi(fp->str, path);
        buf += fpsize;

        *((struct efi_device_path *)buf) = END;

        return start;
}

#ifdef CONFIG_NET
struct efi_device_path *efi_dp_from_eth(void)
{
#ifndef CONFIG_DM_ETH
        struct efi_device_path_mac_addr *ndp;
#endif
        void *buf, *start;
        unsigned dpsize = 0;

        assert(eth_get_dev());

#ifdef CONFIG_DM_ETH
        dpsize += dp_size(eth_get_dev());
#else
        dpsize += sizeof(ROOT);
        dpsize += sizeof(*ndp);
#endif

        start = buf = dp_alloc(dpsize + sizeof(END));
        if (!buf)
                return NULL;

#ifdef CONFIG_DM_ETH
        buf = dp_fill(buf, eth_get_dev());
#else
        memcpy(buf, &ROOT, sizeof(ROOT));
        buf += sizeof(ROOT);

        ndp = buf;
        ndp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
        ndp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR;
        ndp->dp.length = sizeof(*ndp);
        ndp->if_type = 1; /* Ethernet */
        memcpy(ndp->mac.addr, eth_get_ethaddr(), ARP_HLEN);
        buf = &ndp[1];
#endif

        *((struct efi_device_path *)buf) = END;

        return start;
}
#endif

/* Construct a device-path for memory-mapped image */
struct efi_device_path *efi_dp_from_mem(uint32_t memory_type,
                                        uint64_t start_address,
                                        uint64_t end_address)
{
        struct efi_device_path_memory *mdp;
        void *buf, *start;

        start = buf = dp_alloc(sizeof(*mdp) + sizeof(END));
        if (!buf)
                return NULL;

        mdp = buf;
        mdp->dp.type = DEVICE_PATH_TYPE_HARDWARE_DEVICE;
        mdp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MEMORY;
        mdp->dp.length = sizeof(*mdp);
        mdp->memory_type = memory_type;
        mdp->start_address = start_address;
        mdp->end_address = end_address;
        buf = &mdp[1];

        *((struct efi_device_path *)buf) = END;

        return start;
}

/**
 * efi_dp_split_file_path() - split of relative file path from device path
 *
 * Given a device path indicating a file on a device, separate the device
 * path in two: the device path of the actual device and the file path
 * relative to this device.
 *
 * @full_path:          device path including device and file path
 * @device_path:        path of the device
 * @file_path:          relative path of the file or NULL if there is none
 * Return:              status code
 */
efi_status_t efi_dp_split_file_path(struct efi_device_path *full_path,
                                    struct efi_device_path **device_path,
                                    struct efi_device_path **file_path)
{
        struct efi_device_path *p, *dp, *fp = NULL;

        *device_path = NULL;
        *file_path = NULL;
        dp = efi_dp_dup(full_path);
        if (!dp)

                return EFI_OUT_OF_RESOURCES;
        p = dp;
        while (!EFI_DP_TYPE(p, MEDIA_DEVICE, FILE_PATH)) {
                p = efi_dp_next(p);
                if (!p)
                        goto out;
        }
        fp = efi_dp_dup(p);
        if (!fp)
                return EFI_OUT_OF_RESOURCES;
        p->type = DEVICE_PATH_TYPE_END;
        p->sub_type = DEVICE_PATH_SUB_TYPE_END;
        p->length = sizeof(*p);

out:
        *device_path = dp;
        *file_path = fp;
        return EFI_SUCCESS;
}

/**
 * efi_dp_from_name() - convert U-Boot device and file path to device path
 *
 * @dev:        U-Boot device, e.g. 'mmc'
 * @devnr:      U-Boot device number, e.g. 1 for 'mmc:1'
 * @path:       file path relative to U-Boot device, may be NULL
 * @device:     pointer to receive device path of the device
 * @file:       pointer to receive device path for the file
 * Return:      status code
 */
efi_status_t efi_dp_from_name(const char *dev, const char *devnr,
                              const char *path,
                              struct efi_device_path **device,
                              struct efi_device_path **file)
{
        int is_net;
        struct blk_desc *desc = NULL;
        disk_partition_t fs_partition;
        int part = 0;
        char filename[32] = { 0 }; /* dp->str is u16[32] long */
        char *s;

        if (path && !file)
                return EFI_INVALID_PARAMETER;

        is_net = !strcmp(dev, "Net");
        if (!is_net) {
                part = blk_get_device_part_str(dev, devnr, &desc, &fs_partition,
                                               1);
                if (part < 0 || !desc)
                        return EFI_INVALID_PARAMETER;

                if (device)
                        *device = efi_dp_from_part(desc, part);
        } else {
#ifdef CONFIG_NET
                if (device)
                        *device = efi_dp_from_eth();
#endif
        }

        if (!path)
                return EFI_SUCCESS;

        snprintf(filename, sizeof(filename), "%s", path);
        /* DOS style file path: */
        s = filename;
        while ((s = strchr(s, '/')))
                *s++ = '\\';
        *file = efi_dp_from_file(is_net ? NULL : desc, part, filename);

        if (!*file)
                return EFI_INVALID_PARAMETER;

        return EFI_SUCCESS;
}