1 files changed, 189 insertions, 0 deletions
diff --git a/src/interface/efi/efi_settings.c b/src/interface/efi/efi_settings.c
new file mode 100644
index 000000000..652396b17
--- /dev/null
+++ b/src/interface/efi/efi_settings.c
@@ -0,0 +1,189 @@
+/*
+ * Copyright (C) 2023 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+/**
+ * @file
+ *
+ * EFI variable settings
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ipxe/settings.h>
+#include <ipxe/init.h>
+#include <ipxe/efi/efi.h>
+#include <ipxe/efi/Guid/GlobalVariable.h>
+
+/** An EFI variable settings block */
+struct efivar_settings {
+	/** Settings block */
+	struct settings settings;
+	/** Vendor GUID */
+	EFI_GUID guid;
+};
+
+/** EFI settings scope */
+static const struct settings_scope efivar_scope;
+
+/**
+ * Check applicability of EFI variable setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting
+ * @ret applies		Setting applies within this settings block
+ */
+static int efivar_applies ( struct settings *settings __unused,
+			    const struct setting *setting ) {
+
+	return ( setting->scope == &efivar_scope );
+}
+
+/**
+ * Fetch value of EFI variable setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting to fetch
+ * @v data		Buffer to fill with setting data
+ * @v len		Length of buffer
+ * @ret len		Length of setting data, or negative error
+ */
+static int efivar_fetch ( struct settings *settings, struct setting *setting,
+			  void *data, size_t len ) {
+	EFI_RUNTIME_SERVICES *rs = efi_systab->RuntimeServices;
+	struct efivar_settings *efivars =
+		container_of ( settings, struct efivar_settings, settings );
+	size_t name_len = strlen ( setting->name );
+	CHAR16 wname[ name_len + 1 /* wNUL */ ];
+	UINT32 attrs;
+	UINTN size;
+	void *buf;
+	unsigned int i;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Convert name to UCS-2 */
+	for ( i = 0 ; i <= name_len ; i++ )
+		wname[i] = setting->name[i];
+
+	/* Get variable length */
+	size = 0;
+	efirc = rs->GetVariable ( wname, &efivars->guid, &attrs, &size, NULL );
+	if ( ( efirc != 0 ) && ( efirc != EFI_BUFFER_TOO_SMALL ) ) {
+		rc = -EEFI ( efirc );
+		DBGC ( efivars, "EFIVAR %s:%s not present: %s\n",
+		       efi_guid_ntoa ( &efivars->guid ), setting->name,
+		       strerror ( rc ) );
+		goto err_len;
+	}
+
+	/* Allocate temporary buffer, since GetVariable() is not
+	 * guaranteed to return partial data for an underlength
+	 * buffer.
+	 */
+	buf = malloc ( size );
+	if ( ! buf ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+
+	/* Get variable value */
+	if ( ( efirc = rs->GetVariable ( wname, &efivars->guid, &attrs, &size,
+					 buf ) ) != 0 ) {
+		rc = -EEFI ( efirc );
+		DBGC ( efivars, "EFIVAR %s:%s could not get %zd bytes: %s\n",
+		       efi_guid_ntoa ( &efivars->guid ), setting->name,
+		       ( ( size_t ) size ), strerror ( rc ) );
+		goto err_get;
+	}
+	DBGC ( efivars, "EFIVAR %s:%s:\n", efi_guid_ntoa ( &efivars->guid ),
+	       setting->name );
+	DBGC_HDA ( efivars, 0, buf, size );
+
+	/* Return setting value */
+	if ( len > size )
+		len = size;
+	memcpy ( data, buf, len );
+	if ( ! setting->type )
+		setting->type = &setting_type_hex;
+
+	/* Free temporary buffer */
+	free ( buf );
+
+	return size;
+
+ err_get:
+	free ( buf );
+ err_alloc:
+ err_len:
+	return rc;
+}
+
+/** EFI variable settings operations */
+static struct settings_operations efivar_operations = {
+	.applies = efivar_applies,
+	.fetch = efivar_fetch,
+};
+
+/** Well-known EFI variable settings blocks */
+static struct efivar_settings efivar_settings[] = {
+	{ .settings = { .name = "efi" }, .guid = EFI_GLOBAL_VARIABLE },
+};
+
+/**
+ * Initialise EFI variable settings
+ *
+ */
+static void efivar_init ( void ) {
+	struct efivar_settings *efivars;
+	const char *name;
+	unsigned int i;
+	int rc;
+
+	/* Register all settings blocks */
+	for ( i = 0 ; i < ( sizeof ( efivar_settings ) /
+			    sizeof ( efivar_settings[0] ) ) ; i++ ) {
+
+		/* Initialise settings block */
+		efivars = &efivar_settings[i];
+		settings_init ( &efivars->settings, &efivar_operations, NULL,
+				&efivar_scope );
+
+		/* Register settings block */
+		name = efivars->settings.name;
+		if ( ( rc = register_settings ( &efivars->settings, NULL,
+						name ) ) != 0 ) {
+			DBGC ( &efivar_settings, "EFIVAR could not register "
+			       "%s: %s\n", name, strerror ( rc ) );
+			/* Continue trying to register remaining blocks */
+		}
+	}
+}
+
+/** EFI variable settings initialiser */
+struct init_fn efivar_init_fn __init_fn ( INIT_NORMAL ) = {
+	.initialise = efivar_init,
+};