[pci] Add support for PCI Enhanced Allocation

Some embedded devices have immovable BARs, which are described via a
PCI Enhanced Allocation capability.

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

1 files changed, 149 insertions, 0 deletions

diff --git a/src/drivers/bus/pciea.c b/src/drivers/bus/pciea.c
new file mode 100644
index 00000000..aaa69cf4
--- /dev/null
+++ b/src/drivers/bus/pciea.c
@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2016 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 <stdint.h>
+#include <errno.h>
+#include <ipxe/pci.h>
+#include <ipxe/pciea.h>
+
+/** @file
+ *
+ * PCI Enhanced Allocation
+ *
+ */
+
+/**
+ * Locate PCI Enhanced Allocation BAR equivalent entry
+ *
+ * @v pci		PCI device
+ * @v bei		BAR equivalent indicator
+ * @ret offset		PCI Enhanced Allocation entry offset, or negative error
+ */
+static int pciea_offset ( struct pci_device *pci, unsigned int bei ) {
+	uint8_t entries;
+	uint32_t desc;
+	unsigned int i;
+	int offset;
+
+	/* Locate Enhanced Allocation capability */
+	offset = pci_find_capability ( pci, PCI_CAP_ID_EA );
+	if ( offset < 0 )
+		return offset;
+
+	/* Get number of entries */
+	pci_read_config_byte ( pci, ( offset + PCIEA_ENTRIES ), &entries );
+	entries &= PCIEA_ENTRIES_MASK;
+
+	/* Locate first entry */
+	offset += PCIEA_FIRST;
+
+	/* Search for a matching entry */
+	for ( i = 0 ; i < entries ; i++ ) {
+
+		/* Read entry descriptor */
+		pci_read_config_dword ( pci, offset, &desc );
+
+		/* Check for a matching entry */
+		if ( ( desc & PCIEA_DESC_ENABLED ) &&
+		     ( bei == PCIEA_DESC_BEI ( desc ) ) )
+			return offset;
+
+		/* Move to next entry */
+		offset += ( ( PCIEA_DESC_SIZE ( desc ) + 1 ) << 2 );
+	}
+
+	return -ENOENT;
+}
+
+/**
+ * Read PCI Enhanced Allocation BAR equivalent value
+ *
+ * @v pci		PCI device
+ * @v bei		BAR equivalent indicator
+ * @v low_offset	Offset to low dword of value
+ * @ret value		BAR equivalent value
+ */
+static unsigned long pciea_bar_value ( struct pci_device *pci, unsigned int bei,
+				       unsigned int low_offset ) {
+	uint32_t low;
+	uint32_t high;
+	int offset;
+
+	/* Locate Enhanced Allocation offset for this BEI */
+	offset = pciea_offset ( pci, bei );
+	if ( offset < 0 )
+		return 0;
+
+	/* Read BAR equivalent */
+	offset += low_offset;
+	pci_read_config_dword ( pci, offset, &low );
+	if ( low & PCIEA_LOW_ATTR_64BIT ) {
+		offset += PCIEA_LOW_HIGH;
+		pci_read_config_dword ( pci, offset, &high );
+		if ( high ) {
+			if ( sizeof ( unsigned long ) > sizeof ( uint32_t ) ) {
+				return ( ( ( uint64_t ) high << 32 ) | low );
+			} else {
+				DBGC ( pci, PCI_FMT " unhandled 64-bit EA BAR "
+				       "%08x%08x\n",
+				       PCI_ARGS ( pci ), high, low );
+				return 0;
+			}
+		}
+	}
+	return low;
+}
+
+/**
+ * Find the start of a PCI Enhanced Allocation BAR equivalent
+ *
+ * @v pci		PCI device
+ * @v bei		BAR equivalent indicator
+ * @ret start		BAR start address
+ *
+ * If the address exceeds the size of an unsigned long (i.e. if a
+ * 64-bit BAR has a non-zero high dword on a 32-bit machine), the
+ * return value will be zero.
+ */
+unsigned long pciea_bar_start ( struct pci_device *pci, unsigned int bei ) {
+	unsigned long base;
+
+	base = pciea_bar_value ( pci, bei, PCIEA_LOW_BASE );
+	return ( base & ~PCIEA_LOW_ATTR_MASK );
+}
+
+/**
+ * Find the size of a PCI Enhanced Allocation BAR equivalent
+ *
+ * @v pci		PCI device
+ * @v bei		BAR equivalent indicator
+ * @ret size		BAR size
+ */
+unsigned long pciea_bar_size ( struct pci_device *pci, unsigned int bei ) {
+	unsigned long limit;
+
+	limit = pciea_bar_value ( pci, bei, PCIEA_LOW_LIMIT );
+	return ( limit ? ( ( limit | PCIEA_LOW_ATTR_MASK ) + 1 ) : 0 );
+}