Add part_find command

part_find takes a GPT GUID and searches for a partition that matches
that. It then sets the target_part environment variable to the media
type, device number and partition number that matched, allowing
$target_part to be passed directly to bootm and similar commands.

Signed-off-by: Matthew Garrett <mgarrett@aurora.tech>
Reviewed-by: Simon Glass <sjg@chromium.org>

cmd/Kconfig

@@ -1538,6 +1538,16 @@ config CMD_PART
 	  Read and display information about the partition table on
 	  various media.
 
+config CMD_PART_FIND
+	bool "part_find"
+	depends on PARTITIONS
+	select HAVE_BLOCK_DEVICE
+	select PARTITION_UUIDS
+	select PARTITION_TYPE_GUID
+	help
+	  Find a partition with a given type GUID and set the target_part
+	  environment variable if located.
+
 config CMD_PCI
 	bool "pci - Access PCI devices"
 	help

cmd/Makefile

@@ -137,6 +137,7 @@ obj-$(CONFIG_CMD_NVEDIT_EFI) += nvedit_efi.o
 obj-$(CONFIG_CMD_ONENAND) += onenand.o
 obj-$(CONFIG_CMD_OSD) += osd.o
 obj-$(CONFIG_CMD_PART) += part.o
+obj-$(CONFIG_CMD_PART_FIND) += part_find.o
 obj-$(CONFIG_CMD_PCAP) += pcap.o
 ifdef CONFIG_PCI
 obj-$(CONFIG_CMD_PCI) += pci.o

cmd/part_find.c

@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Aurora Innovation, Inc. Copyright 2022.
+ *
+ */
+
+#include <blk.h>
+#include <config.h>
+#include <command.h>
+#include <dm.h>
+#include <env.h>
+#include <part.h>
+#if defined(CONFIG_EFI) || defined(CONFIG_EFI_APP)
+#include <efi.h>
+#include <efi_api.h>
+
+static bool partition_is_on_device(const struct efi_device_path *device,
+				   const struct efi_device_path *part,
+				   __u32 *part_no)
+{
+	size_t d_len, p_len;
+	const struct efi_device_path *p, *d;
+
+	for (d = device; d->type != DEVICE_PATH_TYPE_END; d = (void *)d + d->length) {
+	}
+
+	d_len = (void *)d - (void *)device;
+
+	for (p = part; p->type != DEVICE_PATH_TYPE_END &&
+		     !(p->type == DEVICE_PATH_TYPE_MEDIA_DEVICE &&
+		       p->sub_type == DEVICE_PATH_SUB_TYPE_HARD_DRIVE_PATH);
+	     p = (void *)p + p->length) {
+	}
+
+	if (p->type != DEVICE_PATH_TYPE_MEDIA_DEVICE ||
+	    p->sub_type != DEVICE_PATH_SUB_TYPE_HARD_DRIVE_PATH) {
+		// Not a partition.
+		return false;
+	}
+
+	p_len = (void *)p - (void *)part;
+
+	if (p_len == d_len && !memcmp(device, part, p_len)) {
+		if (part_no)
+			*part_no = ((__u32 *)p)[1];
+		return true;
+	}
+	return false;
+}
+#endif
+
+static int part_find(int argc, char *const argv[])
+{
+#if defined(CONFIG_EFI) || defined(CONFIG_EFI_APP)
+	efi_guid_t efi_devpath_guid = EFI_DEVICE_PATH_PROTOCOL_GUID;
+	struct efi_device_path *loaded_image_path = NULL;
+	struct efi_boot_services *boot = efi_get_boot();
+	struct efi_priv *priv = efi_get_priv();
+	bool part_self = false;
+#endif
+	struct driver *d = ll_entry_start(struct driver, driver);
+	const int n_ents = ll_entry_count(struct driver, driver);
+	struct disk_partition info;
+	struct blk_desc *desc;
+	struct driver *entry;
+	struct udevice *udev;
+	struct uclass *uc;
+	int ret;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+
+#if defined(CONFIG_EFI) || defined (CONFIG_EFI_APP)
+	part_self = !strncmp(argv[1], "self", 6);
+	if (part_self) {
+		ret = boot->handle_protocol(priv->loaded_image->device_handle,
+					&efi_devpath_guid,
+					(void **)&loaded_image_path);
+		if (ret)
+			log_warning("failed to get device path for loaded image (ret=%d)", ret);
+	}
+#endif
+
+	ret = uclass_get(UCLASS_BLK, &uc);
+	if (ret) {
+		puts("Could not get BLK uclass.\n");
+		return CMD_RET_FAILURE;
+	}
+	for (entry = d; entry < d + n_ents; entry++) {
+		if (entry->id != UCLASS_BLK)
+			continue;
+		uclass_foreach_dev(udev, uc) {
+			int i;
+
+			if (udev->driver != entry)
+				continue;
+			desc = dev_get_uclass_plat(udev);
+#if defined(CONFIG_EFI) || defined(CONFIG_EFI_APP)
+			if (part_self) {
+				if (desc->if_type == IF_TYPE_EFI_MEDIA) {
+					struct efi_media_plat *plat =
+						dev_get_plat(udev->parent);
+					__u32 loader_part_no;
+
+					if (partition_is_on_device(plat->device_path,
+								   loaded_image_path,
+								   &loader_part_no)) {
+						char env[256];
+
+						ret = snprintf(env, sizeof(env), "%s %d:%d", blk_get_if_type_name(desc->if_type), desc->devnum, loader_part_no);
+						if (ret < 0 || ret == sizeof(env))
+							return CMD_RET_FAILURE;
+						if (env_set("target_part", env))
+							return CMD_RET_FAILURE;
+						return CMD_RET_SUCCESS;
+					}
+				}
+			} else {
+#endif
+				for (i = 1; i <= MAX_SEARCH_PARTITIONS; i++) {
+					ret = part_get_info(desc, i, &info);
+					if (ret)
+						break;
+					if (strcasecmp(argv[1], info.type_guid) == 0) {
+						char env[256];
+						ret = snprintf(env, sizeof(env), "%s %d:%d", blk_get_if_type_name(desc->if_type), desc->devnum, i);
+						if (ret < 0 || ret == sizeof(env))
+							return CMD_RET_FAILURE;
+						env_set("target_part", env);
+						debug("Setting target_part to %s\n", env);
+						return CMD_RET_SUCCESS;
+					}
+				}
+#if defined(CONFIG_EFI) || defined(CONFIG_EFI_APP)
+			}
+#endif
+		}
+	}
+
+	return CMD_RET_FAILURE;
+}
+
+static int do_part_find(struct cmd_tbl *cmdtp, int flag, int argc,
+			char *const argv[])
+{
+	return part_find(argc, argv);
+}
+
+U_BOOT_CMD(
+	part_find, 2, 0, do_part_find, "Find a partition",
+	"<guid>\n"
+	"- Examine the list of known partitions for one that has a type\n"
+	"  GUID that matches 'guid', expressed in the standard text format.\n"
+	"  If successful, the target_part environment variable will be set\n"
+	"  to the corresponding 'interface dev:part'.\n"
+);