[settings] Expose PCI configuration space via settings mechanism

Allow values to be read from PCI configuration space using the syntax

  ${pci/<busdevfn>.<offset>.<length>}

where <busdevfn> is the bus:dev.fn address of the PCI device
(expressed as a single integer, as returned by ${net0/busloc}),
<offset> is the offset within PCI configuration space, and <length> is
the length within PCI configuration space.

Values are returned in reverse byte order, since PCI configuration
space is little-endian by definition.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/bus/pci_settings.c

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdio.h>
+#include <errno.h>
+#include <ipxe/pci.h>
+#include <ipxe/settings.h>
+#include <ipxe/init.h>
+
+/** @file
+ *
+ * PCI device settings
+ *
+ */
+
+/** PCI device settings scope */
+static struct settings_scope pci_settings_scope;
+
+/**
+ * Check applicability of PCI device setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting
+ * @ret applies		Setting applies within this settings block
+ */
+static int pci_settings_applies ( struct settings *settings __unused,
+				  struct setting *setting ) {
+
+	return ( setting->scope == &pci_settings_scope );
+}
+
+/**
+ * Fetch value of PCI 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 pci_settings_fetch ( struct settings *settings __unused,
+				struct setting *setting,
+				void *data, size_t len ) {
+	struct pci_device pci;
+	unsigned int tag_busdevfn;
+	unsigned int tag_offset;
+	unsigned int tag_len;
+	unsigned int i;
+
+	/* Extract busdevfn, offset, and length from tag */
+	tag_busdevfn = ( ( setting->tag >> 16 ) & 0xffff );
+	tag_offset = ( ( setting->tag >> 8 ) & 0xff );
+	tag_len = ( ( setting->tag >> 0 ) & 0xff );
+
+	/* Locate PCI device */
+	memset ( &pci, 0, sizeof ( pci ) );
+	pci_init ( &pci, tag_busdevfn );
+	DBG ( PCI_FMT " reading %#02x+%#x\n", PCI_ARGS ( &pci ),
+	      tag_offset, tag_len );
+
+	/* Read data one byte at a time, in reverse order (since PCI
+	 * is little-endian and iPXE settings are essentially
+	 * big-endian).
+	 */
+	tag_offset += tag_len;
+	for ( i = 0 ; ( ( i < tag_len ) && ( i < len ) ); i++ ) {
+		pci_read_config_byte ( &pci, --tag_offset, data++ );
+	}
+
+	/* Set type to ":hexraw" if not already specified */
+	if ( ! setting->type )
+		setting->type = &setting_type_hexraw;
+
+	return tag_len;
+}
+
+/** PCI device settings operations */
+static struct settings_operations pci_settings_operations = {
+	.applies = pci_settings_applies,
+	.fetch = pci_settings_fetch,
+};
+
+/** PCI device settings */
+static struct settings pci_settings = {
+	.refcnt = NULL,
+	.siblings = LIST_HEAD_INIT ( pci_settings.siblings ),
+	.children = LIST_HEAD_INIT ( pci_settings.children ),
+	.op = &pci_settings_operations,
+	.default_scope = &pci_settings_scope,
+};
+
+/** Initialise PCI device settings */
+static void pci_settings_init ( void ) {
+	int rc;
+
+	if ( ( rc = register_settings ( &pci_settings, NULL, "pci" ) ) != 0 ) {
+		DBG ( "PCI could not register settings: %s\n",
+		      strerror ( rc ) );
+		return;
+	}
+}
+
+/** PCI device settings initialiser */
+struct init_fn pci_settings_init_fn __init_fn ( INIT_NORMAL ) = {
+	.initialise = pci_settings_init,
+};