[PATCH v6 04/27] efi: Locate all block devices in the app

Simon Glass sjg at chromium.org
Fri Dec 17 20:40:36 CET 2021


When starting the app, locate all block devices and make them available
to U-Boot. This allows listing partitions and accessing files in
filesystems.

EFI also has the concept of 'disks', meaning boot media. For now, this
is not obviously useful in U-Boot, but add code to at least locate these.
This can be expanded later as needed.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

Changes in v6:
- Add comment for dm_scan_other()
- Add comment for free_memory()
- Drop setup_disks() as U-Boot does not support it
- Fix 'have have' typo
- Update comment format for devpath_is_partition()

Changes in v2:
- Don't export efi_bind_block()
- Only bind devices for media devices, not for partitions
- Show devices that are processed
- Store device path in struct efi_media_plat
- Update documentation

 doc/develop/uefi/u-boot_on_efi.rst |   4 +-
 include/efi.h                      |   6 +-
 include/efi_api.h                  |  15 ++
 lib/efi/efi_app.c                  | 216 +++++++++++++++++++++++++++++
 4 files changed, 236 insertions(+), 5 deletions(-)

diff --git a/doc/develop/uefi/u-boot_on_efi.rst b/doc/develop/uefi/u-boot_on_efi.rst
index 5f2f850f071..8f81b799072 100644
--- a/doc/develop/uefi/u-boot_on_efi.rst
+++ b/doc/develop/uefi/u-boot_on_efi.rst
@@ -265,9 +265,7 @@ This work could be extended in a number of ways:
 
 - Figure out how to solve the interrupt problem
 
-- Add more drivers to the application side (e.g. block devices, USB,
-  environment access). This would mostly be an academic exercise as a strong
-  use case is not readily apparent, but it might be fun.
+- Add more drivers to the application side (e.g.USB, environment access).
 
 - Avoid turning off boot services in the stub. Instead allow U-Boot to make
   use of boot services in case it wants to. It is unclear what it might want
diff --git a/include/efi.h b/include/efi.h
index 0ec5913ddd1..908c5dc6ebd 100644
--- a/include/efi.h
+++ b/include/efi.h
@@ -419,10 +419,12 @@ struct efi_priv {
  *
  * @handle: handle of the controller on which this driver is installed
  * @blkio: block io protocol proxied by this driver
+ * @device_path: EFI path to the device
  */
 struct efi_media_plat {
-	efi_handle_t		handle;
-	struct efi_block_io	*blkio;
+	efi_handle_t handle;
+	struct efi_block_io *blkio;
+	struct efi_device_path *device_path;
 };
 
 /* Base address of the EFI image */
diff --git a/include/efi_api.h b/include/efi_api.h
index 80109f012bc..ec9fa89a935 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -2035,4 +2035,19 @@ struct efi_firmware_management_protocol {
 			const u16 *package_version_name);
 };
 
+#define EFI_DISK_IO_PROTOCOL_GUID	\
+	EFI_GUID(0xce345171, 0xba0b, 0x11d2, 0x8e, 0x4f, \
+		 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b)
+
+struct efi_disk {
+	u64 revision;
+	efi_status_t (EFIAPI *read_disk)(struct efi_disk *this, u32 media_id,
+					 u64 offset, efi_uintn_t buffer_size,
+					 void *buffer);
+
+	efi_status_t (EFIAPI *write_disk)(struct efi_disk *this, u32 media_id,
+					  u64 offset, efi_uintn_t buffer_size,
+					  void *buffer);
+};
+
 #endif
diff --git a/lib/efi/efi_app.c b/lib/efi/efi_app.c
index f61665686c5..6a71cef7acb 100644
--- a/lib/efi/efi_app.c
+++ b/lib/efi/efi_app.c
@@ -21,6 +21,9 @@
 #include <efi.h>
 #include <efi_api.h>
 #include <sysreset.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/root.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -46,6 +49,64 @@ int efi_info_get(enum efi_entry_t type, void **datap, int *sizep)
 	return -ENOSYS;
 }
 
+/**
+ * efi_print_str() - Print a UFT-16 string to the U-Boot console
+ *
+ * @str: String to print
+ */
+static void efi_print_str(const u16 *str)
+{
+	while (*str) {
+		int ch = *str++;
+
+		if (ch > ' ' && ch < 127)
+			putc(ch);
+	}
+}
+
+/**
+ * efi_bind_block() - bind a new block device to an EFI device
+ *
+ * Binds a new top-level EFI_MEDIA device as well as a child block device so
+ * that the block device can be accessed in U-Boot.
+ *
+ * The device can then be accessed using 'part list efi 0', 'fat ls efi 0:1',
+ * for example, just like any other interface type.
+ *
+ * @handle: handle of the controller on which this driver is installed
+ * @blkio: block io protocol proxied by this driver
+ * @device_path: EFI device path structure for this
+ * @len: Length of @device_path in bytes
+ * @devp: Returns the bound device
+ * @return 0 if OK, -ve on error
+ */
+int efi_bind_block(efi_handle_t handle, struct efi_block_io *blkio,
+		   struct efi_device_path *device_path, int len,
+		   struct udevice **devp)
+{
+	struct efi_media_plat plat;
+	struct udevice *dev;
+	char name[18];
+	int ret;
+
+	plat.handle = handle;
+	plat.blkio = blkio;
+	plat.device_path = malloc(device_path->length);
+	if (!plat.device_path)
+		return log_msg_ret("path", -ENOMEM);
+	memcpy(plat.device_path, device_path, device_path->length);
+	ret = device_bind(dm_root(), DM_DRIVER_GET(efi_media), "efi_media",
+			  &plat, ofnode_null(), &dev);
+	if (ret)
+		return log_msg_ret("bind", ret);
+
+	snprintf(name, sizeof(name), "efi_media_%x", dev_seq(dev));
+	device_set_name(dev, name);
+	*devp = dev;
+
+	return 0;
+}
+
 static efi_status_t setup_memory(struct efi_priv *priv)
 {
 	struct efi_boot_services *boot = priv->boot;
@@ -91,6 +152,14 @@ static efi_status_t setup_memory(struct efi_priv *priv)
 	return 0;
 }
 
+/**
+ * free_memory() - Free memory used by the U-Boot app
+ *
+ * This frees memory allocated in setup_memory(), in preparation for returning
+ * to UEFI. It also zeroes the global_data pointer.
+ *
+ * @priv: Private EFI data
+ */
 static void free_memory(struct efi_priv *priv)
 {
 	struct efi_boot_services *boot = priv->boot;
@@ -105,6 +174,153 @@ static void free_memory(struct efi_priv *priv)
 	global_data_ptr = NULL;
 }
 
+/**
+ * devpath_is_partition() - Figure out if a device path is a partition
+ *
+ * Checks if a device path refers to a partition on some media device. This
+ * works by checking for a valid partition number in a hard-driver media device
+ * as the final component of the device path.
+ *
+ * Return: true if a partition, false if not (e.g. it might be media which
+ *	contains partitions)
+ */
+static bool devpath_is_partition(const struct efi_device_path *path)
+{
+	const struct efi_device_path *p;
+	bool was_part;
+
+	for (p = path; p->type != DEVICE_PATH_TYPE_END;
+	     p = (void *)p + p->length) {
+		was_part = false;
+		if (p->type == DEVICE_PATH_TYPE_MEDIA_DEVICE &&
+		    p->sub_type == DEVICE_PATH_SUB_TYPE_HARD_DRIVE_PATH) {
+			struct efi_device_path_hard_drive_path *hd =
+				(void *)path;
+
+			if (hd->partition_number)
+				was_part = true;
+		}
+	}
+
+	return was_part;
+}
+
+/**
+ * setup_block() - Find all block devices and setup EFI devices for them
+ *
+ * Partitions are ignored, since U-Boot has partition handling. Errors with
+ * particular devices produce a warning but execution continues to try to
+ * find others.
+ *
+ * Return: 0 if found, -ENOSYS if there is no boot-services table, -ENOTSUPP
+ *	if a required protocol is not supported
+ */
+static int setup_block(void)
+{
+	efi_guid_t efi_blkio_guid = EFI_BLOCK_IO_PROTOCOL_GUID;
+	efi_guid_t efi_devpath_guid = EFI_DEVICE_PATH_PROTOCOL_GUID;
+	efi_guid_t efi_pathutil_guid = EFI_DEVICE_PATH_UTILITIES_PROTOCOL_GUID;
+	efi_guid_t efi_pathtext_guid = EFI_DEVICE_PATH_TO_TEXT_PROTOCOL_GUID;
+	struct efi_boot_services *boot = efi_get_boot();
+	struct efi_device_path_utilities_protocol *util;
+	struct efi_device_path_to_text_protocol *text;
+	struct efi_device_path *path;
+	struct efi_block_io *blkio;
+	efi_uintn_t num_handles;
+	efi_handle_t *handle;
+	int ret, i;
+
+	if (!boot)
+		return log_msg_ret("sys", -ENOSYS);
+
+	/* Find all devices which support the block I/O protocol */
+	ret = boot->locate_handle_buffer(BY_PROTOCOL, &efi_blkio_guid, NULL,
+				  &num_handles, &handle);
+	if (ret)
+		return log_msg_ret("loc", -ENOTSUPP);
+	log_debug("Found %d handles:\n", (int)num_handles);
+
+	/* We need to look up the path size and convert it to text */
+	ret = boot->locate_protocol(&efi_pathutil_guid, NULL, (void **)&util);
+	if (ret)
+		return log_msg_ret("util", -ENOTSUPP);
+	ret = boot->locate_protocol(&efi_pathtext_guid, NULL, (void **)&text);
+	if (ret)
+		return log_msg_ret("text", -ENOTSUPP);
+
+	for (i = 0; i < num_handles; i++) {
+		struct udevice *dev;
+		const u16 *name;
+		bool is_part;
+		int len;
+
+		ret = boot->handle_protocol(handle[i], &efi_devpath_guid,
+					    (void **)&path);
+		if (ret) {
+			log_warning("- devpath %d failed (ret=%d)\n", i, ret);
+			continue;
+		}
+
+		ret = boot->handle_protocol(handle[i], &efi_blkio_guid,
+					    (void **)&blkio);
+		if (ret) {
+			log_warning("- blkio %d failed (ret=%d)\n", i, ret);
+			continue;
+		}
+
+		name = text->convert_device_path_to_text(path, true, false);
+		is_part = devpath_is_partition(path);
+
+		if (!is_part) {
+			len = util->get_device_path_size(path);
+			ret = efi_bind_block(handle[i], blkio, path, len, &dev);
+			if (ret) {
+				log_warning("- blkio bind %d failed (ret=%d)\n",
+					    i, ret);
+				continue;
+			}
+		} else {
+			dev = NULL;
+		}
+
+		/*
+		 * Show the device name if we created one. Otherwise indicate
+		 * that it is a partition.
+		 *
+		 * We don't seem to have a way to print unicode on the U-Boot
+		 * console at present, so use our own function.
+		 */
+		printf("%2d: %-12s ", i, dev ? dev->name : "<partition>");
+		efi_print_str(name);
+		printf("\n");
+	}
+	boot->free_pool(handle);
+
+	return 0;
+}
+
+/**
+ * dm_scan_other() - Scan for UEFI devices that should be available to U-Boot
+ *
+ * This sets up block devices within U-Boot for those found in UEFI. With this,
+ * U-Boot can access those devices
+ *
+ * @pre_reloc_only: true to only bind pre-relocation devices (ignored)
+ * Returns: 0 on success, -ve on error
+ */
+int dm_scan_other(bool pre_reloc_only)
+{
+	if (gd->flags & GD_FLG_RELOC) {
+		int ret;
+
+		ret = setup_block();
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 /**
  * efi_main() - Start an EFI image
  *
-- 
2.34.1.173.g76aa8bc2d0-goog



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