efi_loader: implement EFI_DEVICE_PATH_TO_TEXT_PROTOCOL

ConvertPathToText is implemented for
* type 4    - media device path
* subtype 4 - file path

This is the kind of device path we hand out for block devices.

All other cases may be implemented later.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
[agraf: fix whitespace]
Signed-off-by: Alexander Graf <agraf@suse.de>

cmd/bootefi.c

@@ -84,6 +84,10 @@ static struct efi_object loaded_image_info_obj = {
 			.guid = &efi_guid_console_control,
 			.protocol_interface = (void *) &efi_console_control
 		},
+		{
+			.guid = &efi_guid_device_path_to_text_protocol,
+			.protocol_interface = (void *) &efi_device_path_to_text
+		},
 	},
 };
 

include/efi_api.h

@@ -395,6 +395,30 @@ struct efi_console_control_protocol
 			uint16_t *password);
 };
 
+#define EFI_DEVICE_PATH_TO_TEXT_PROTOCOL_GUID \
+	EFI_GUID(0x8b843e20, 0x8132, 0x4852, \
+		 0x90, 0xcc, 0x55, 0x1a, 0x4e, 0x4a, 0x7f, 0x1c)
+
+struct efi_device_path_protocol
+{
+	uint8_t type;
+	uint8_t sub_type;
+	uint16_t length;
+	uint8_t data[];
+};
+
+struct efi_device_path_to_text_protocol
+{
+	uint16_t *(EFIAPI *convert_device_node_to_text)(
+			struct efi_device_path_protocol *device_node,
+			bool display_only,
+			bool allow_shortcuts);
+	uint16_t *(EFIAPI *convert_device_path_to_text)(
+			struct efi_device_path_protocol *device_path,
+			bool display_only,
+			bool allow_shortcuts);
+};
+
 #define EFI_GOP_GUID \
 	EFI_GUID(0x9042a9de, 0x23dc, 0x4a38, \
 		 0x96, 0xfb, 0x7a, 0xde, 0xd0, 0x80, 0x51, 0x6a)

include/efi_loader.h

@@ -28,10 +28,12 @@ extern struct efi_system_table systab;
 extern const struct efi_simple_text_output_protocol efi_con_out;
 extern const struct efi_simple_input_interface efi_con_in;
 extern const struct efi_console_control_protocol efi_console_control;
+extern const struct efi_device_path_to_text_protocol efi_device_path_to_text;
 
 extern const efi_guid_t efi_guid_console_control;
 extern const efi_guid_t efi_guid_device_path;
 extern const efi_guid_t efi_guid_loaded_image;
+extern const efi_guid_t efi_guid_device_path_to_text_protocol;
 
 extern unsigned int __efi_runtime_start, __efi_runtime_stop;
 extern unsigned int __efi_runtime_rel_start, __efi_runtime_rel_stop;

lib/efi_loader/Makefile

@@ -15,7 +15,7 @@ always := $(efiprogs-y)
 
 obj-$(CONFIG_CMD_BOOTEFI_HELLO) += helloworld_efi.o
 obj-y += efi_image_loader.o efi_boottime.o efi_runtime.o efi_console.o
-obj-y += efi_memory.o
+obj-y += efi_memory.o efi_device_path_to_text.o
 obj-$(CONFIG_LCD) += efi_gop.o
 obj-$(CONFIG_PARTITIONS) += efi_disk.o
 obj-$(CONFIG_NET) += efi_net.o

lib/efi_loader/efi_device_path_to_text.c

@@ -0,0 +1,67 @@
+/*
+ *  EFI device path interface
+ *
+ *  Copyright (c) 2017 Heinrich Schuchardt
+ *
+ *  SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <efi_loader.h>
+
+#define MEDIA_DEVICE_PATH 4
+#define FILE_PATH_MEDIA_DEVICE_PATH 4
+
+const efi_guid_t efi_guid_device_path_to_text_protocol =
+		EFI_DEVICE_PATH_TO_TEXT_PROTOCOL_GUID;
+
+uint16_t *efi_convert_device_node_to_text(
+		struct efi_device_path_protocol *device_node,
+		bool display_only,
+		bool allow_shortcuts)
+{
+	EFI_ENTRY("%p, %d, %d", device_node, display_only, allow_shortcuts);
+
+	EFI_EXIT(EFI_UNSUPPORTED);
+	return NULL;
+}
+
+uint16_t *efi_convert_device_path_to_text(
+		struct efi_device_path_protocol *device_path,
+		bool display_only,
+		bool allow_shortcuts)
+{
+	EFI_ENTRY("%p, %d, %d", device_path, display_only, allow_shortcuts);
+
+	unsigned long buffer_size;
+	efi_status_t r;
+	uint16_t *buffer = NULL;
+
+	switch (device_path->type) {
+	case MEDIA_DEVICE_PATH:
+		switch (device_path->sub_type) {
+		case FILE_PATH_MEDIA_DEVICE_PATH:
+			buffer_size = device_path->length - 4;
+			r = efi_allocate_pool(EFI_ALLOCATE_ANY_PAGES,
+					      buffer_size, (void **) &buffer);
+			if (r == EFI_SUCCESS)
+				memcpy(buffer, device_path->data, buffer_size);
+			break;
+		}
+	}
+
+	if (buffer) {
+		EFI_EXIT(EFI_SUCCESS);
+	} else {
+		debug("type %d, subtype %d\n",
+		      device_path->type, device_path->sub_type);
+		EFI_EXIT(EFI_UNSUPPORTED);
+	}
+
+	return buffer;
+}
+
+const struct efi_device_path_to_text_protocol efi_device_path_to_text = {
+	.convert_device_node_to_text = efi_convert_device_node_to_text,
+	.convert_device_path_to_text = efi_convert_device_path_to_text,
+};