1 files changed, 176 insertions, 0 deletions
diff --git a/src/drivers/bus/usb_settings.c b/src/drivers/bus/usb_settings.c
new file mode 100644
index 000000000..db6f94d8a
--- /dev/null
+++ b/src/drivers/bus/usb_settings.c
@@ -0,0 +1,176 @@
+/*
+ * Copyright (C) 2024 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 (at your option) 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 );
+
+#include <stdio.h>
+#include <errno.h>
+#include <ipxe/usb.h>
+#include <ipxe/settings.h>
+#include <ipxe/init.h>
+
+/** @file
+ *
+ * USB device settings
+ *
+ */
+
+/** USB device settings scope */
+static const struct settings_scope usb_settings_scope;
+
+/**
+ * Check applicability of USB device setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting
+ * @ret applies		Setting applies within this settings block
+ */
+static int usb_settings_applies ( struct settings *settings __unused,
+				  const struct setting *setting ) {
+
+	return ( setting->scope == &usb_settings_scope );
+}
+
+/**
+ * Fetch value of USB device 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 usb_settings_fetch ( struct settings *settings __unused,
+				struct setting *setting,
+				void *data, size_t len ) {
+	uint8_t *dst = data;
+	const uint8_t *src;
+	const uint8_t *desc;
+	struct usb_bus *bus;
+	struct usb_device *usb;
+	int tag_direction;
+	unsigned int tag_busdev;
+	unsigned int tag_offset;
+	unsigned int tag_len;
+	unsigned int index;
+	int rc;
+
+	/* Extract parameters from tag */
+	tag_direction = ( ( setting->tag & ( 1 << 31 ) ) ? +1 : -1 );
+	tag_busdev = ( ( setting->tag >> 16 ) & 0x7fff );
+	tag_offset = ( ( setting->tag >> 8 ) & 0xff );
+	tag_len = ( ( setting->tag >> 0 ) & 0xff );
+
+	/* Locate USB device */
+	bus = find_usb_bus ( USB_BUS ( tag_busdev ) );
+	if ( ! bus )
+		return -ENODEV;
+	usb = find_usb ( bus, USB_DEV ( tag_busdev ) );
+	if ( ! usb )
+		return -ENODEV;
+	desc = ( ( const uint8_t * ) &usb->device );
+
+	/* Following the usage of SMBIOS settings tags, a <length> of
+	 * zero indicates that the byte at <offset> contains a string
+	 * index.  An <offset> of zero indicates that the <length>
+	 * contains a literal string index.
+	 *
+	 * Since the byte at offset zero can never contain a string
+	 * index, and a literal string index can never be zero, the
+	 * combination of both <length> and <offset> being zero
+	 * indicates that the entire structure is to be read.
+	 *
+	 * By default we reverse the byte direction since USB values
+	 * are little-endian and iPXE settings are big-endian.  We
+	 * invert this default when reading the entire structure.
+	 */
+	if ( ( tag_len == 0 ) && ( tag_offset == 0 ) ) {
+		tag_len = sizeof ( usb->device );
+		tag_direction = -tag_direction;
+	} else if ( ( tag_len == 0 ) || ( tag_offset == 0 ) ) {
+		index = tag_len;
+		if ( ( ! index ) && ( tag_offset < sizeof ( usb->device ) ) )
+			index = desc[tag_offset];
+		if ( ( rc = usb_get_string_descriptor ( usb, index, 0, data,
+							len ) ) < 0 ) {
+			return rc;
+		}
+		if ( ! setting->type )
+			setting->type = &setting_type_string;
+		return rc;
+	}
+
+	/* Limit length */
+	if ( tag_offset > sizeof ( usb->device ) ) {
+		tag_len = 0;
+	} else if ( ( tag_offset + tag_len ) > sizeof ( usb->device ) ) {
+		tag_len = ( sizeof ( usb->device ) - tag_offset );
+	}
+
+	/* Copy data, reversing endianness if applicable */
+	dst = data;
+	src = ( desc + tag_offset );
+	if ( tag_direction < 0 )
+		src += ( tag_len - 1 );
+	if ( len > tag_len )
+		len = tag_len;
+	for ( ; len-- ; src += tag_direction, dst++ )
+		*dst = *src;
+
+	/* Set type to ":hexraw" if not already specified */
+	if ( ! setting->type )
+		setting->type = &setting_type_hexraw;
+
+	return tag_len;
+}
+
+/** USB device settings operations */
+static struct settings_operations usb_settings_operations = {
+	.applies = usb_settings_applies,
+	.fetch = usb_settings_fetch,
+};
+
+/** USB device settings */
+static struct settings usb_settings = {
+	.refcnt = NULL,
+	.siblings = LIST_HEAD_INIT ( usb_settings.siblings ),
+	.children = LIST_HEAD_INIT ( usb_settings.children ),
+	.op = &usb_settings_operations,
+	.default_scope = &usb_settings_scope,
+};
+
+/** Initialise USB device settings */
+static void usb_settings_init ( void ) {
+	int rc;
+
+	if ( ( rc = register_settings ( &usb_settings, NULL, "usb" ) ) != 0 ) {
+		DBG ( "USB could not register settings: %s\n",
+		      strerror ( rc ) );
+		return;
+	}
+}
+
+/** USB device settings initialiser */
+struct init_fn usb_settings_init_fn __init_fn ( INIT_NORMAL ) = {
+	.initialise = usb_settings_init,
+};