Basic non-volatile storage support

src/core/nvs.c

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2006 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include <gpxe/dhcp.h>
+#include <gpxe/nvs.h>
+
+/** @file
+ *
+ * Non-volatile storage
+ *
+ */
+
+static size_t nvs_options_len ( struct nvs_device *nvs ) {
+	struct dhcp_option *option;
+	uint8_t sum;
+	unsigned int i;
+	size_t len;
+
+	for ( sum = 0, i = 0 ; i < nvs->len ; i++ ) {
+		sum += * ( ( uint8_t * ) ( nvs->options->data + i ) );
+	}
+	if ( sum != 0 ) {
+		DBG ( "NVS %p has bad checksum %02x; assuming empty\n",
+		      nvs, sum );
+		return 0;
+	}
+
+	option = nvs->options->data;
+	if ( option->tag == DHCP_PAD ) {
+		DBG ( "NVS %p has bad start; assuming empty\n", nvs );
+		return 0;
+	}
+	
+	option = find_dhcp_option ( nvs->options, DHCP_END );
+	if ( ! option ) {
+		DBG ( "NVS %p has no end tag; assuming empty\n", nvs );
+		return 0;
+	}
+
+	len = ( ( void * ) option - nvs->options->data + 1 );
+	DBG ( "NVS %p contains %zd bytes of options (maximum %zd)\n",
+	      nvs, len, nvs->len );
+
+	return len;
+}
+
+int nvs_register ( struct nvs_device *nvs ) {
+	struct dhcp_option *option;
+	int rc;
+
+	nvs->options = alloc_dhcp_options ( nvs->len );
+	if ( ! nvs->options ) {
+		DBG ( "NVS %p could not allocate %zd bytes\n", nvs, nvs->len );
+		rc = -ENOMEM;
+		goto err;
+	}
+
+	if ( ( rc = nvs->op->read ( nvs, 0, nvs->options->data,
+				    nvs->len ) ) != 0 ) {
+		DBG ( "NVS %p could not read [0,%zd)\n", nvs, nvs->len );
+		goto err;
+	}
+
+	nvs->options->len = nvs->options->max_len;
+	nvs->options->len = nvs_options_len ( nvs );
+	if ( ! nvs->options->len ) {
+		option = nvs->options->data;
+		option->tag = DHCP_END;
+		nvs->options->len = 1;
+	}
+
+	register_dhcp_options ( nvs->options );
+
+	return 0;
+	
+ err:
+	
+	free_dhcp_options ( nvs->options );
+	nvs->options = NULL;
+	return rc;
+}
+
+void nvs_unregister ( struct nvs_device *nvs ) {
+	if ( nvs->options ) {
+		unregister_dhcp_options ( nvs->options );
+		free_dhcp_options ( nvs->options );
+		nvs->options = NULL;
+	}
+}