efi_loader: device_path: support Sandbox's "host" devices

Sandbox's "host" devices are currently described as UCLASS_ROOT udevice
with DEV_IF_HOST block device. As the current implementation of
efi_device_path doesn't support such a type, any "host" device
on sandbox cannot be seen as a distinct object.

For example,
  => host bind 0 /foo/disk.img

  => efi devices
  Scanning disk host0...
  Found 1 disks
  Device           Device Path
  ================ ====================
  0000000015c19970 /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)
  0000000015c19d70 /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)

  => efi dh
  Handle           Protocols
  ================ ====================
  0000000015c19970 Device Path, Device Path To Text, Device Path Utilities, Unicode Collation 2, HII String, HII Database, HII Config Routing
  0000000015c19ba0 Driver Binding
  0000000015c19c10 Simple Text Output
  0000000015c19c80 Simple Text Input, Simple Text Input Ex
  0000000015c19d70 Block IO, Device Path, Simple File System

As you can see here, efi_root (0x0000000015c19970) and host0 device
(0x0000000015c19d70) have the same representation of device path.

This is not only inconvenient, but also confusing since two different
efi objects are associated with the same device path and
efi_dp_find_obj() will possibly return a wrong result.

Solution:
Each "host" device should be given an additional device path node
of "vendor device path" to make it distinguishable.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

include/efi_loader.h

@@ -24,6 +24,10 @@
 #define U_BOOT_GUID \
 	EFI_GUID(0xe61d73b9, 0xa384, 0x4acc, \
 		 0xae, 0xab, 0x82, 0xe8, 0x28, 0xf3, 0x62, 0x8b)
+/* GUID used as host device on sandbox */
+#define U_BOOT_HOST_DEV_GUID \
+	EFI_GUID(0xbbe4e671, 0x5773, 0x4ea1, \
+		 0x9a, 0xab, 0x3a, 0x7d, 0xbf, 0x40, 0xc4, 0x82)
 
 /* Root node */
 extern efi_handle_t efi_root;
@@ -121,6 +125,10 @@ uint16_t *efi_dp_str(struct efi_device_path *dp);
 
 /* GUID of the U-Boot root node */
 extern const efi_guid_t efi_u_boot_guid;
+#ifdef CONFIG_SANDBOX
+/* GUID of U-Boot host device on sandbox */
+extern const efi_guid_t efi_guid_host_dev;
+#endif
 /* GUID of the EFI_BLOCK_IO_PROTOCOL */
 extern const efi_guid_t efi_block_io_guid;
 extern const efi_guid_t efi_global_variable_guid;

lib/efi_loader/efi_device_path.c

@@ -12,8 +12,13 @@
 #include <mmc.h>
 #include <efi_loader.h>
 #include <part.h>
+#include <sandboxblockdev.h>
 #include <asm-generic/unaligned.h>
 
+#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,
@@ -445,6 +450,16 @@ static unsigned dp_size(struct udevice *dev)
 		case UCLASS_MMC:
 			return dp_size(dev->parent) +
 				sizeof(struct efi_device_path_sd_mmc_path);
+#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);
@@ -505,6 +520,24 @@ static void *dp_fill(void *buf, struct udevice *dev)
 #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 =