efi: Locate all block devices in the app

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.

We cannot use printf() in the early stub or app since it is not compiled
in

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

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,
+- Add more drivers to the application side (e.g.USB, environment access).
-  environment access). This would mostly be an academic exercise as a strong
-  use case is not readily apparent, but it might be fun.
 
 - 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

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;
+	efi_handle_t handle;
-	struct efi_block_io	*blkio;
+	struct efi_block_io *blkio;
+	struct efi_device_path *device_path;
 };
 
 /* Base address of the EFI image */

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

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 +49,49 @@ int efi_info_get(enum efi_entry_t type, void **datap, int *sizep)
 	return -ENOSYS;
 }
 
+/**
+ * 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 +137,14 @@ 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 +159,150 @@ 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.
+ *
+ * @path:	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.
+		 */
+		printf("%2d: %-12s %ls\n", i, dev ? dev->name : "<partition>",
+		       name);
+	}
+	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
  *