[pci] Add minimal PCI bridge driver

Add a minimal driver for PCI bridges that can be used to locate the
bridge to which a PCI device is attached.

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

1 files changed, 132 insertions, 0 deletions

diff --git a/src/drivers/bus/pcibridge.c b/src/drivers/bus/pcibridge.c
new file mode 100644
index 000000000..d2763faf9
--- /dev/null
+++ b/src/drivers/bus/pcibridge.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2022 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 <stddef.h>
+#include <stdint.h>
+#include <errno.h>
+#include <byteswap.h>
+#include <ipxe/pci.h>
+#include <ipxe/pcibridge.h>
+
+/** @file
+ *
+ * PCI-to-PCI bridge
+ *
+ */
+
+/** List of all PCI bridges */
+static LIST_HEAD ( pcibridges );
+
+/**
+ * Find bridge attached to a PCI device
+ *
+ * @v pci		PCI device
+ * @ret bridge		PCI bridge, or NULL
+ */
+struct pci_bridge * pcibridge_find ( struct pci_device *pci ) {
+	unsigned int bus = PCI_BUS ( pci->busdevfn );
+	struct pci_bridge *bridge;
+
+	/* Find matching bridge */
+	list_for_each_entry ( bridge, &pcibridges, list ) {
+		if ( bus == bridge->secondary )
+			return bridge;
+	}
+
+	return NULL;
+}
+
+/**
+ * Probe PCI device
+ *
+ * @v pci		PCI device
+ * @ret rc		Return status code
+ */
+static int pcibridge_probe ( struct pci_device *pci ) {
+	struct pci_bridge *bridge;
+	uint16_t base;
+	uint16_t limit;
+	int rc;
+
+	/* Allocate and initialise structure */
+	bridge = zalloc ( sizeof ( *bridge ) );
+	if ( ! bridge ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	bridge->pci = pci;
+
+	/* Read configuration */
+	pci_read_config_dword ( pci, PCI_PRIMARY, &bridge->buses );
+	cpu_to_le32s ( &buses );
+	pci_read_config_word ( pci, PCI_MEM_BASE, &base );
+	bridge->membase = ( ( base & ~PCI_MEM_MASK ) << 16 );
+	pci_read_config_word ( pci, PCI_MEM_LIMIT, &limit );
+	bridge->memlimit = ( ( ( ( limit | PCI_MEM_MASK ) + 1 ) << 16 ) - 1 );
+	DBGC ( bridge, "BRIDGE " PCI_FMT " bus %02x to [%02x,%02x) mem "
+	       "[%08x,%08x)\n", PCI_ARGS ( pci ), bridge->primary,
+	       bridge->secondary, bridge->subordinate, bridge->membase,
+	       bridge->memlimit );
+
+	/* Add to list of PCI bridges */
+	list_add ( &bridge->list, &pcibridges );
+
+	pci_set_drvdata ( pci, bridge );
+	return 0;
+
+	free ( bridge );
+ err_alloc:
+	return rc;
+}
+
+/**
+ * Remove PCI device
+ *
+ * @v pci		PCI device
+ */
+static void pcibridge_remove ( struct pci_device *pci ) {
+	struct pci_bridge *bridge = pci_get_drvdata ( pci );
+
+	/* Remove from list of bridges */
+	list_del ( &bridge->list );
+
+	/* Free device */
+	free ( bridge );
+}
+
+/** Bridge PCI device IDs */
+static struct pci_device_id pcibridge_ids[] = {
+	PCI_ROM ( 0xffff, 0xffff, "bridge", "Bridge", 0 ),
+};
+
+/** Bridge PCI driver */
+struct pci_driver pcibridge_driver __pci_driver = {
+	.ids = pcibridge_ids,
+	.id_count = ( sizeof ( pcibridge_ids ) / sizeof ( pcibridge_ids[0] ) ),
+	.class = PCI_CLASS_ID ( PCI_CLASS_BRIDGE, PCI_CLASS_BRIDGE_PCI,
+				PCI_ANY_ID ),
+	.probe = pcibridge_probe,
+	.remove = pcibridge_remove,
+};