[pci] Add generic configuration space backup/restore facility

Some devices can only be reset via a mechanism that also resets the
card's PCI core, thus necessitating a backup and restore of all or
part of the PCI configuration space across a reset.

src/drivers/bus/pcibackup.c

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2009 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.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <gpxe/pci.h>
+#include <gpxe/pcibackup.h>
+
+/** @file
+ *
+ * PCI configuration space backup and restoration
+ *
+ */
+
+/**
+ * Check PCI configuration space offset against exclusion list
+ *
+ * @v pci		PCI device
+ * @v offset		Offset within PCI configuration space
+ * @v exclude		PCI configuration space backup exclusion list, or NULL
+ */
+static int
+pci_backup_excluded ( struct pci_device *pci, unsigned int offset,
+		      const uint8_t *exclude ) {
+
+	if ( ! exclude )
+		return 0;
+	for ( ; *exclude != PCI_CONFIG_BACKUP_EXCLUDE_END ; exclude++ ) {
+		if ( offset == *exclude ) {
+			DBGC ( pci, "PCI %p skipping configuration offset "
+			       "%02x\n", pci, offset );
+			return 1;
+		}
+	}
+	return 0;
+}
+
+/**
+ * Back up PCI configuration space
+ *
+ * @v pci		PCI device
+ * @v backup		PCI configuration space backup
+ * @v exclude		PCI configuration space backup exclusion list, or NULL
+ */
+void pci_backup ( struct pci_device *pci, struct pci_config_backup *backup,
+		  const uint8_t *exclude ) {
+	unsigned int offset;
+	uint32_t *dword;
+
+	for ( offset = 0, dword = backup->dwords ; offset < 0x100 ;
+	      offset += sizeof ( *dword ) , dword++ ) {
+		if ( ! pci_backup_excluded ( pci, offset, exclude ) )
+			pci_read_config_dword ( pci, offset, dword );
+	}
+}
+
+/**
+ * Restore PCI configuration space
+ *
+ * @v pci		PCI device
+ * @v backup		PCI configuration space backup
+ * @v exclude		PCI configuration space backup exclusion list, or NULL
+ */
+void pci_restore ( struct pci_device *pci, struct pci_config_backup *backup,
+		   const uint8_t *exclude ) {
+	unsigned int offset;
+	uint32_t *dword;
+
+	for ( offset = 0, dword = backup->dwords ; offset < 0x100 ;
+	      offset += sizeof ( *dword ) , dword++ ) {
+		if ( ! pci_backup_excluded ( pci, offset, exclude ) )
+			pci_write_config_dword ( pci, offset, *dword );
+	}
+}

src/include/gpxe/pcibackup.h

@@ -0,0 +1,33 @@
+#ifndef _GPXE_PCIBACKUP_H
+#define _GPXE_PCIBACKUP_H
+
+/** @file
+ *
+ * PCI configuration space backup and restoration
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+
+/** A PCI configuration space backup */
+struct pci_config_backup {
+	uint32_t dwords[64];
+};
+
+/** PCI configuration space backup exclusion list end marker */
+#define PCI_CONFIG_BACKUP_EXCLUDE_END 0xff
+
+/** Define a PCI configuration space backup exclusion list */
+#define PCI_CONFIG_BACKUP_EXCLUDE(...) \
+	{ __VA_ARGS__, PCI_CONFIG_BACKUP_EXCLUDE_END }
+
+extern void pci_backup ( struct pci_device *pci,
+			 struct pci_config_backup *backup,
+			 const uint8_t *exclude );
+extern void pci_restore ( struct pci_device *pci,
+			  struct pci_config_backup *backup,
+			  const uint8_t *exclude );
+
+#endif /* _GPXE_PCIBACKUP_H */