[U-Boot,v1,05/15] efi_loader: add device-path utils

Message ID 20170810182948.27653-6-robdclark@gmail.com
State New
Delegated to: Alexander Graf
Headers show

Commit Message

Rob Clark Aug. 10, 2017, 6:29 p.m.
Helpers to construct device-paths from devices, partitions, files, and
for parsing and manipulating device-paths.

For non-legacy devices, this will use u-boot's device-model to construct
device-paths which include bus hierarchy to construct device-paths.  For
legacy devices we still fake it, but slightly more convincingly.

Signed-off-by: Rob Clark <robdclark@gmail.com>
---
 include/efi_api.h                |  10 +
 include/efi_loader.h             |  20 ++
 lib/efi_loader/Makefile          |   2 +-
 lib/efi_loader/efi_device_path.c | 489 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 520 insertions(+), 1 deletion(-)
 create mode 100644 lib/efi_loader/efi_device_path.c

Comments

Heinrich Schuchardt Aug. 11, 2017, 4:49 p.m. | #1
On 08/10/2017 08:29 PM, Rob Clark wrote:
> Helpers to construct device-paths from devices, partitions, files, and
> for parsing and manipulating device-paths.
> 
> For non-legacy devices, this will use u-boot's device-model to construct
> device-paths which include bus hierarchy to construct device-paths.  For
> legacy devices we still fake it, but slightly more convincingly.
> 
> Signed-off-by: Rob Clark <robdclark@gmail.com>
> ---
>  include/efi_api.h                |  10 +
>  include/efi_loader.h             |  20 ++
>  lib/efi_loader/Makefile          |   2 +-
>  lib/efi_loader/efi_device_path.c | 489 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 520 insertions(+), 1 deletion(-)
>  create mode 100644 lib/efi_loader/efi_device_path.c
> 
> diff --git a/include/efi_api.h b/include/efi_api.h
> index b761cf4822..4e27c82129 100644
> --- a/include/efi_api.h
> +++ b/include/efi_api.h
> @@ -314,6 +314,7 @@ struct efi_device_path_acpi_path {
>  #define DEVICE_PATH_TYPE_MESSAGING_DEVICE	0x03
>  #  define DEVICE_PATH_SUB_TYPE_MSG_USB		0x05
>  #  define DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR	0x0b
> +#  define DEVICE_PATH_SUB_TYPE_MSG_USB_CLASS	0x0f
>  #  define DEVICE_PATH_SUB_TYPE_MSG_SD		0x1a
>  #  define DEVICE_PATH_SUB_TYPE_MSG_MMC		0x1d
>  
> @@ -329,6 +330,15 @@ struct efi_device_path_mac_addr {
>  	u8 if_type;
>  } __packed;
>  
> +struct efi_device_path_usb_class {
> +	struct efi_device_path dp;
> +	u16 vendor_id;
> +	u16 product_id;
> +	u8 device_class;
> +	u8 device_subclass;
> +	u8 device_protocol;
> +} __packed;
> +
>  struct efi_device_path_sd_mmc_path {
>  	struct efi_device_path dp;
>  	u8 slot_number;
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 037cc7c543..bcca6e49ea 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -197,6 +197,26 @@ extern void *efi_bounce_buffer;
>  #define EFI_LOADER_BOUNCE_BUFFER_SIZE (64 * 1024 * 1024)
>  #endif
>  
> +
> +struct efi_device_path *efi_dp_next(struct efi_device_path *dp);
> +int efi_dp_match(struct efi_device_path *a, struct efi_device_path *b);
> +struct efi_object *efi_dp_find_obj(struct efi_device_path *dp);
> +unsigned efi_dp_size(struct efi_device_path *dp);
> +struct efi_device_path *efi_dp_dup(struct efi_device_path *dp);
> +
> +struct efi_device_path *efi_dp_from_dev(struct udevice *dev);
> +struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part);
> +struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
> +					 const char *path);
> +struct efi_device_path *efi_dp_from_eth(void);
> +void efi_dp_split_file_path(struct efi_device_path *full_path,
> +			    struct efi_device_path **device_path,
> +			    struct efi_device_path **file_path);
> +
> +#define EFI_DP_TYPE(_dp, _type, _subtype) \
> +	(((_dp)->type == DEVICE_PATH_TYPE_##_type) && \
> +	 ((_dp)->sub_type == DEVICE_PATH_SUB_TYPE_##_subtype))
> +
>  /* Convert strings from normal C strings to uEFI strings */
>  static inline void ascii2unicode(u16 *unicode, const char *ascii)
>  {
> diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
> index 30bf343a36..f35e5ce8a8 100644
> --- a/lib/efi_loader/Makefile
> +++ b/lib/efi_loader/Makefile
> @@ -15,7 +15,7 @@ always := $(efiprogs-y)
>  
>  obj-$(CONFIG_CMD_BOOTEFI_HELLO) += helloworld_efi.o
>  obj-y += efi_image_loader.o efi_boottime.o efi_runtime.o efi_console.o
> -obj-y += efi_memory.o efi_device_path_to_text.o
> +obj-y += efi_memory.o efi_device_path_to_text.o efi_device_path.o
>  obj-$(CONFIG_LCD) += efi_gop.o
>  obj-$(CONFIG_DM_VIDEO) += efi_gop.o
>  obj-$(CONFIG_PARTITIONS) += efi_disk.o
> diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
> new file mode 100644
> index 0000000000..e8a6bbff82
> --- /dev/null
> +++ b/lib/efi_loader/efi_device_path.c
> @@ -0,0 +1,489 @@
> +/*
> + * EFI device path from u-boot device-model mapping
> + *
> + * (C) Copyright 2017 Rob Clark
> + *
> + * SPDX-License-Identifier:	GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <blk.h>
> +#include <dm.h>
> +#include <usb.h>
> +#include <mmc.h>
> +#include <efi_loader.h>
> +#include <inttypes.h>
> +#include <part.h>
> +#include <malloc.h>
> +
> +/* 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),
> +};
> +
> +#define U_BOOT_GUID \
> +	EFI_GUID(0xe61d73b9, 0xa384, 0x4acc, \
> +		 0xae, 0xab, 0x82, 0xe8, 0x28, 0xf3, 0x62, 0x8b)
> +
> +/* template ROOT node, a fictional ACPI PNP device: */
> +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,
> +};
> +
> +
> +/*
> + * Iterate to next block in device-path, terminating (returning NULL)
> + * at /End* node.
> + */
> +struct efi_device_path *efi_dp_next(struct efi_device_path *dp)
> +{
> +	if (dp == NULL)
> +		return NULL;
> +	dp = ((void *)dp) + dp->length;
> +	if (dp->type == DEVICE_PATH_TYPE_END)
> +		return NULL;
> +	return 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(struct efi_device_path *a, 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;
> +	}
> +}
> +
> +
> +/*
> + * See UEFI spec (section 3.1.2, about short-form device-paths..
> + * tl;dr: we can have a device-path that starts with a USB WWID
> + * or 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
> + */
> +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_object *efiobj;
> +
> +	list_for_each_entry(efiobj, &efi_obj_list, link) {
> +		int i;
> +
> +		for (i = 0; i < ARRAY_SIZE(efiobj->protocols); i++) {
> +			struct efi_handler *handler = &efiobj->protocols[i];
> +			struct efi_device_path *obj_dp;
> +
> +			if (!handler->guid)
> +				break;
> +
> +			if (guidcmp(handler->guid, &efi_guid_device_path))
> +				continue;
> +
> +			obj_dp = handler->protocol_interface;
> +
> +			do {
> +				if (efi_dp_match(dp, obj_dp) == 0)
> +					return efiobj;
> +
> +				obj_dp = shorten_path(efi_dp_next(obj_dp));
> +			} while (short_path && obj_dp);
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +
> +/* Find an efiobj from device-path */
> +struct efi_object *efi_dp_find_obj(struct efi_device_path *dp)
> +{
> +	struct efi_object *efiobj;
> +
> +	efiobj = find_obj(dp, false);
> +
> +	if (!efiobj)
> +		efiobj = find_obj(dp, true);
> +
> +	return efiobj;
> +}
> +
> +/* return size not including End node: */
> +unsigned efi_dp_size(struct efi_device_path *dp)
> +{
> +	unsigned sz = 0;
> +
> +	while (dp) {
> +		sz += dp->length;
> +		dp = efi_dp_next(dp);
> +	}
> +
> +	return sz;
> +}
> +
> +struct efi_device_path *efi_dp_dup(struct efi_device_path *dp)
> +{
> +	struct efi_device_path *ndp;
> +	unsigned sz = efi_dp_size(dp) + sizeof(struct efi_device_path);
> +
> +	ndp = malloc(sz);
> +	memcpy(ndp, dp, sz);
> +
> +	return ndp;
> +}
> +
> +#ifdef CONFIG_DM
> +/* size of device-path not including END node for device and all parents
> + * up to the root device.
> + */
> +static unsigned 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_MMC:
> +		return dp_size(dev->parent) + sizeof(struct efi_device_path_sd_mmc_path);
> +	case UCLASS_MASS_STORAGE:
> +	case UCLASS_USB_HUB:
> +		return dp_size(dev->parent) + sizeof(struct efi_device_path_usb_class);

It seems you forgot to run scripts/checkpatch.pl for your patches:

Line over 80 characters. Please, use line break.

> +	default:
> +		/* just skip over unknown classes: */
> +		return dp_size(dev->parent);
> +	}
> +}
> +
> +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];
> +	}
> +#if defined(CONFIG_DM_MMC) && defined (CONFIG_MMC)

scripts/checkpatch.pl:
WARNING: space prohibited between function name and open parenthesis '('

> +	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 = (desc->if_type == IF_TYPE_MMC) ?
> +			DEVICE_PATH_SUB_TYPE_MSG_MMC :
> +			DEVICE_PATH_SUB_TYPE_MSG_SD;
> +		sddp->dp.length   = sizeof(*sddp);
> +		sddp->slot_number = 0;  // XXX ???
> +
> +		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("unhandled device class: %s (%u)\n",
> +			dev->name, dev->driver->id);

scripts/checkpatch.pl:
Alignment should match open parenthesis

> +		return dp_fill(buf, dev->parent);
> +	}
> +}
> +
> +/* Construct a device-path from a device: */
> +struct efi_device_path *efi_dp_from_dev(struct udevice *dev)
> +{
> +	void *buf, *start;
> +
> +	start = buf = calloc(1, dp_size(dev) + sizeof(END));
> +	buf = dp_fill(buf, dev);
> +	*((struct efi_device_path *)buf) = END;
> +
> +	return start;
> +}
> +#endif
> +
> +static unsigned dp_part_size(struct blk_desc *desc, int part)
> +{
> +	unsigned dpsize;
> +
> +#ifdef CONFIG_BLK
> +	dpsize = dp_size(desc->bdev->parent);
> +#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);
> +	}

Please, have a look at all warnings produced by
scripts/checkpatch.pl. Here you get:

WARNING: braces {} are not necessary for any arm of this statement
#464: FILE: lib/efi_loader/efi_device_path.c:289:
+       if (desc->part_type == PART_TYPE_ISO) {
[...]
+       } else {
[...]

Best regards

Heinrich


> +
> +	return dpsize;
> +}
> +
> +static void *dp_part_fill(void *buf, struct blk_desc *desc, int part)
> +{
> +	disk_partition_t info;
> +
> +#ifdef CONFIG_BLK
> +	buf = dp_fill(buf, desc->bdev->parent);
> +#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 (ie 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 fictional 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;
> +
> +	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 - 1;
> +		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_end = 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 - 1;
> +		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;
> +		hddp->signature_type = desc->sig_type;
> +		if (hddp->signature_type != 0)
> +			memcpy(hddp->partition_signature, &desc->guid_sig,
> +			       sizeof(hddp->partition_signature));
> +
> +		buf = &hddp[1];
> +	}
> +
> +	return buf;
> +}
> +
> +
> +/* Construct a device-path from a partition on a blk device: */
> +struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part)
> +{
> +	void *buf, *start;
> +
> +	start = buf = calloc(1, dp_part_size(desc, part) + sizeof(END));
> +
> +	buf = dp_part_fill(buf, desc, part);
> +
> +	*((struct efi_device_path *)buf) = END;
> +
> +	return start;
> +}
> +
> +/* convert path to an UEFI style path (ie. DOS style backslashes and utf16) */
> +static void path_to_uefi(u16 *uefi, const char *path)
> +{
> +	while (*path) {
> +		char c = *(path++);
> +		if (c == '/')
> +			c = '\\';
> +		*(uefi++) = c;
> +	}
> +	*uefi = '\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;
> +	unsigned dpsize = 0, fpsize;
> +
> +	if (desc)
> +		dpsize = dp_part_size(desc, part);
> +
> +	// TODO efi_device_path_file_path should be variable length:
> +	fpsize = sizeof(struct efi_device_path) + 2 * (strlen(path) + 1);
> +	dpsize += fpsize;
> +
> +	start = buf = calloc(1, dpsize + sizeof(END));
> +
> +	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 = 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)
> +{
> +	struct efi_device_path_mac_addr *ndp;
> +	void *buf, *start;
> +	unsigned dpsize = 0;
> +
> +	assert(eth_get_dev());
> +
> +#ifdef CONFIG_DM_ETH
> +	dpsize += dp_size(eth_get_dev());
> +#else
> +	dpsize += sizeof(ROOT);
> +#endif
> +	dpsize += sizeof(*ndp);
> +
> +	start = buf = calloc(1, dpsize + sizeof(END));
> +
> +#ifdef CONFIG_DM_ETH
> +	buf = dp_fill(buf, eth_get_dev());
> +#else
> +	memcpy(buf, &ROOT, sizeof(ROOT));
> +	buf += sizeof(ROOT);
> +#endif
> +
> +	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);
> +	memcpy(ndp->mac.addr, eth_get_ethaddr(), ARP_HLEN);
> +	buf = &ndp[1];
> +
> +	*((struct efi_device_path *)buf) = END;
> +
> +	return start;
> +}
> +#endif
> +
> +/*
> + * Helper to split a full device path (containing both device and file
> + * parts) into it's constituent parts.
> + */
> +void 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;
> +
> +	dp = efi_dp_dup(full_path);
> +	p = dp;
> +	while (!EFI_DP_TYPE(p, MEDIA_DEVICE, FILE_PATH))
> +		p = efi_dp_next(p);
> +	fp = efi_dp_dup(p);
> +
> +	p->type = DEVICE_PATH_TYPE_END;
> +	p->sub_type = DEVICE_PATH_SUB_TYPE_END;
> +	p->length = sizeof(*p);
> +
> +	*device_path = dp;
> +	*file_path = fp;
> +}
>

Patch

diff --git a/include/efi_api.h b/include/efi_api.h
index b761cf4822..4e27c82129 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -314,6 +314,7 @@  struct efi_device_path_acpi_path {
 #define DEVICE_PATH_TYPE_MESSAGING_DEVICE	0x03
 #  define DEVICE_PATH_SUB_TYPE_MSG_USB		0x05
 #  define DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR	0x0b
+#  define DEVICE_PATH_SUB_TYPE_MSG_USB_CLASS	0x0f
 #  define DEVICE_PATH_SUB_TYPE_MSG_SD		0x1a
 #  define DEVICE_PATH_SUB_TYPE_MSG_MMC		0x1d
 
@@ -329,6 +330,15 @@  struct efi_device_path_mac_addr {
 	u8 if_type;
 } __packed;
 
+struct efi_device_path_usb_class {
+	struct efi_device_path dp;
+	u16 vendor_id;
+	u16 product_id;
+	u8 device_class;
+	u8 device_subclass;
+	u8 device_protocol;
+} __packed;
+
 struct efi_device_path_sd_mmc_path {
 	struct efi_device_path dp;
 	u8 slot_number;
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 037cc7c543..bcca6e49ea 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -197,6 +197,26 @@  extern void *efi_bounce_buffer;
 #define EFI_LOADER_BOUNCE_BUFFER_SIZE (64 * 1024 * 1024)
 #endif
 
+
+struct efi_device_path *efi_dp_next(struct efi_device_path *dp);
+int efi_dp_match(struct efi_device_path *a, struct efi_device_path *b);
+struct efi_object *efi_dp_find_obj(struct efi_device_path *dp);
+unsigned efi_dp_size(struct efi_device_path *dp);
+struct efi_device_path *efi_dp_dup(struct efi_device_path *dp);
+
+struct efi_device_path *efi_dp_from_dev(struct udevice *dev);
+struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part);
+struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
+					 const char *path);
+struct efi_device_path *efi_dp_from_eth(void);
+void efi_dp_split_file_path(struct efi_device_path *full_path,
+			    struct efi_device_path **device_path,
+			    struct efi_device_path **file_path);
+
+#define EFI_DP_TYPE(_dp, _type, _subtype) \
+	(((_dp)->type == DEVICE_PATH_TYPE_##_type) && \
+	 ((_dp)->sub_type == DEVICE_PATH_SUB_TYPE_##_subtype))
+
 /* Convert strings from normal C strings to uEFI strings */
 static inline void ascii2unicode(u16 *unicode, const char *ascii)
 {
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 30bf343a36..f35e5ce8a8 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -15,7 +15,7 @@  always := $(efiprogs-y)
 
 obj-$(CONFIG_CMD_BOOTEFI_HELLO) += helloworld_efi.o
 obj-y += efi_image_loader.o efi_boottime.o efi_runtime.o efi_console.o
-obj-y += efi_memory.o efi_device_path_to_text.o
+obj-y += efi_memory.o efi_device_path_to_text.o efi_device_path.o
 obj-$(CONFIG_LCD) += efi_gop.o
 obj-$(CONFIG_DM_VIDEO) += efi_gop.o
 obj-$(CONFIG_PARTITIONS) += efi_disk.o
diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
new file mode 100644
index 0000000000..e8a6bbff82
--- /dev/null
+++ b/lib/efi_loader/efi_device_path.c
@@ -0,0 +1,489 @@ 
+/*
+ * EFI device path from u-boot device-model mapping
+ *
+ * (C) Copyright 2017 Rob Clark
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <blk.h>
+#include <dm.h>
+#include <usb.h>
+#include <mmc.h>
+#include <efi_loader.h>
+#include <inttypes.h>
+#include <part.h>
+#include <malloc.h>
+
+/* 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),
+};
+
+#define U_BOOT_GUID \
+	EFI_GUID(0xe61d73b9, 0xa384, 0x4acc, \
+		 0xae, 0xab, 0x82, 0xe8, 0x28, 0xf3, 0x62, 0x8b)
+
+/* template ROOT node, a fictional ACPI PNP device: */
+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,
+};
+
+
+/*
+ * Iterate to next block in device-path, terminating (returning NULL)
+ * at /End* node.
+ */
+struct efi_device_path *efi_dp_next(struct efi_device_path *dp)
+{
+	if (dp == NULL)
+		return NULL;
+	dp = ((void *)dp) + dp->length;
+	if (dp->type == DEVICE_PATH_TYPE_END)
+		return NULL;
+	return 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(struct efi_device_path *a, 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;
+	}
+}
+
+
+/*
+ * See UEFI spec (section 3.1.2, about short-form device-paths..
+ * tl;dr: we can have a device-path that starts with a USB WWID
+ * or 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
+ */
+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_object *efiobj;
+
+	list_for_each_entry(efiobj, &efi_obj_list, link) {
+		int i;
+
+		for (i = 0; i < ARRAY_SIZE(efiobj->protocols); i++) {
+			struct efi_handler *handler = &efiobj->protocols[i];
+			struct efi_device_path *obj_dp;
+
+			if (!handler->guid)
+				break;
+
+			if (guidcmp(handler->guid, &efi_guid_device_path))
+				continue;
+
+			obj_dp = handler->protocol_interface;
+
+			do {
+				if (efi_dp_match(dp, obj_dp) == 0)
+					return efiobj;
+
+				obj_dp = shorten_path(efi_dp_next(obj_dp));
+			} while (short_path && obj_dp);
+		}
+	}
+
+	return NULL;
+}
+
+
+/* Find an efiobj from device-path */
+struct efi_object *efi_dp_find_obj(struct efi_device_path *dp)
+{
+	struct efi_object *efiobj;
+
+	efiobj = find_obj(dp, false);
+
+	if (!efiobj)
+		efiobj = find_obj(dp, true);
+
+	return efiobj;
+}
+
+/* return size not including End node: */
+unsigned efi_dp_size(struct efi_device_path *dp)
+{
+	unsigned sz = 0;
+
+	while (dp) {
+		sz += dp->length;
+		dp = efi_dp_next(dp);
+	}
+
+	return sz;
+}
+
+struct efi_device_path *efi_dp_dup(struct efi_device_path *dp)
+{
+	struct efi_device_path *ndp;
+	unsigned sz = efi_dp_size(dp) + sizeof(struct efi_device_path);
+
+	ndp = malloc(sz);
+	memcpy(ndp, dp, sz);
+
+	return ndp;
+}
+
+#ifdef CONFIG_DM
+/* size of device-path not including END node for device and all parents
+ * up to the root device.
+ */
+static unsigned 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_MMC:
+		return dp_size(dev->parent) + sizeof(struct efi_device_path_sd_mmc_path);
+	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);
+	}
+}
+
+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];
+	}
+#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 = (desc->if_type == IF_TYPE_MMC) ?
+			DEVICE_PATH_SUB_TYPE_MSG_MMC :
+			DEVICE_PATH_SUB_TYPE_MSG_SD;
+		sddp->dp.length   = sizeof(*sddp);
+		sddp->slot_number = 0;  // XXX ???
+
+		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("unhandled device class: %s (%u)\n",
+			dev->name, dev->driver->id);
+		return dp_fill(buf, dev->parent);
+	}
+}
+
+/* Construct a device-path from a device: */
+struct efi_device_path *efi_dp_from_dev(struct udevice *dev)
+{
+	void *buf, *start;
+
+	start = buf = calloc(1, dp_size(dev) + sizeof(END));
+	buf = dp_fill(buf, dev);
+	*((struct efi_device_path *)buf) = END;
+
+	return start;
+}
+#endif
+
+static unsigned dp_part_size(struct blk_desc *desc, int part)
+{
+	unsigned dpsize;
+
+#ifdef CONFIG_BLK
+	dpsize = dp_size(desc->bdev->parent);
+#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;
+}
+
+static void *dp_part_fill(void *buf, struct blk_desc *desc, int part)
+{
+	disk_partition_t info;
+
+#ifdef CONFIG_BLK
+	buf = dp_fill(buf, desc->bdev->parent);
+#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 (ie 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 fictional 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;
+
+	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 - 1;
+		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_end = 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 - 1;
+		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;
+		hddp->signature_type = desc->sig_type;
+		if (hddp->signature_type != 0)
+			memcpy(hddp->partition_signature, &desc->guid_sig,
+			       sizeof(hddp->partition_signature));
+
+		buf = &hddp[1];
+	}
+
+	return buf;
+}
+
+
+/* Construct a device-path from a partition on a blk device: */
+struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part)
+{
+	void *buf, *start;
+
+	start = buf = calloc(1, dp_part_size(desc, part) + sizeof(END));
+
+	buf = dp_part_fill(buf, desc, part);
+
+	*((struct efi_device_path *)buf) = END;
+
+	return start;
+}
+
+/* convert path to an UEFI style path (ie. DOS style backslashes and utf16) */
+static void path_to_uefi(u16 *uefi, const char *path)
+{
+	while (*path) {
+		char c = *(path++);
+		if (c == '/')
+			c = '\\';
+		*(uefi++) = c;
+	}
+	*uefi = '\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;
+	unsigned dpsize = 0, fpsize;
+
+	if (desc)
+		dpsize = dp_part_size(desc, part);
+
+	// TODO efi_device_path_file_path should be variable length:
+	fpsize = sizeof(struct efi_device_path) + 2 * (strlen(path) + 1);
+	dpsize += fpsize;
+
+	start = buf = calloc(1, dpsize + sizeof(END));
+
+	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 = 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)
+{
+	struct efi_device_path_mac_addr *ndp;
+	void *buf, *start;
+	unsigned dpsize = 0;
+
+	assert(eth_get_dev());
+
+#ifdef CONFIG_DM_ETH
+	dpsize += dp_size(eth_get_dev());
+#else
+	dpsize += sizeof(ROOT);
+#endif
+	dpsize += sizeof(*ndp);
+
+	start = buf = calloc(1, dpsize + sizeof(END));
+
+#ifdef CONFIG_DM_ETH
+	buf = dp_fill(buf, eth_get_dev());
+#else
+	memcpy(buf, &ROOT, sizeof(ROOT));
+	buf += sizeof(ROOT);
+#endif
+
+	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);
+	memcpy(ndp->mac.addr, eth_get_ethaddr(), ARP_HLEN);
+	buf = &ndp[1];
+
+	*((struct efi_device_path *)buf) = END;
+
+	return start;
+}
+#endif
+
+/*
+ * Helper to split a full device path (containing both device and file
+ * parts) into it's constituent parts.
+ */
+void 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;
+
+	dp = efi_dp_dup(full_path);
+	p = dp;
+	while (!EFI_DP_TYPE(p, MEDIA_DEVICE, FILE_PATH))
+		p = efi_dp_next(p);
+	fp = efi_dp_dup(p);
+
+	p->type = DEVICE_PATH_TYPE_END;
+	p->sub_type = DEVICE_PATH_SUB_TYPE_END;
+	p->length = sizeof(*p);
+
+	*device_path = dp;
+	*file_path = fp;
+}