[linux] Add support for accessing PCI configuration space via /proc/bus/pci

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

1 files changed, 185 insertions, 0 deletions

diff --git a/src/interface/linux/linux_pci.c b/src/interface/linux/linux_pci.c
new file mode 100644
index 00000000..cbd825c1
--- /dev/null
+++ b/src/interface/linux/linux_pci.c
@@ -0,0 +1,185 @@
+/*
+ * 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 <byteswap.h>
+#include <linux_api.h>
+#include <ipxe/linux.h>
+#include <ipxe/pci.h>
+
+/** @file
+ *
+ * iPXE PCI API for Linux
+ *
+ */
+
+/**
+ * Open PCI configuration space
+ *
+ * @v pci		PCI device
+ * @v flags		Access mode flags
+ * @v where		Address within configuration space
+ * @ret fd		File handle, or negative error
+ */
+static int linux_pci_open ( struct pci_device *pci, int flags,
+			    unsigned long where ) {
+	char filename[ 22 /* "/proc/bus/pci/xx/xx.x" + NUL */ ];
+	int fd;
+	int rc;
+
+	/* Construct filename */
+	snprintf ( filename, sizeof ( filename ), "/proc/bus/pci/%02x/%02x.%x",
+		   PCI_BUS ( pci->busdevfn ), PCI_SLOT ( pci->busdevfn ),
+		   PCI_FUNC ( pci->busdevfn ) );
+
+	/* Open file */
+	fd = linux_open ( filename, flags );
+	if ( fd < 0 ) {
+		DBGC ( pci, "PCI could not open %s: %s\n", filename,
+		       linux_strerror ( linux_errno ) );
+		rc = -ELINUX ( linux_errno );
+		goto err_open;
+	}
+
+	/* Seek to location */
+	if ( linux_lseek ( fd, where, SEEK_SET ) < 0 ) {
+		DBGC ( pci, "PCI could not seek to %s offset %#02lx: %s\n",
+		       filename, where, linux_strerror ( linux_errno ) );
+		rc = -ELINUX ( linux_errno );
+		goto err_seek;
+	}
+
+	return fd;
+
+ err_seek:
+	linux_close ( fd );
+ err_open:
+	return rc;
+}
+
+/**
+ * Read from PCI configuration space
+ *
+ * @v pci		PCI device
+ * @v where		Address within configuration space
+ * @v value		Data buffer
+ * @v len		Length to read
+ * @ret rc		Return status code
+ */
+int linux_pci_read ( struct pci_device *pci, unsigned long where,
+		     unsigned long *value, size_t len ) {
+	uint32_t tmp = 0;
+	int fd;
+	int check_len;
+	int rc;
+
+	/* Return "missing device" in case of error */
+	*value = -1UL;
+
+	/* Open configuration space */
+	fd = linux_pci_open ( pci, O_RDONLY, where );
+	if ( fd < 0 ) {
+		rc = fd;
+		goto err_open;
+	}
+
+	/* Read value */
+	check_len = linux_read ( fd, &tmp, len );
+	if ( check_len < 0 ) {
+		DBGC ( pci, "PCI could not read from " PCI_FMT " %#02lx+%#zx: "
+		       "%s\n", PCI_ARGS ( pci ), where, len,
+		       linux_strerror ( linux_errno ) );
+		rc = -ELINUX ( linux_errno );
+		goto err_read;
+	}
+	if ( ( size_t ) check_len != len ) {
+		DBGC ( pci, "PCI read only %#x bytes from " PCI_FMT
+		       " %#02lx+%#zx\n", check_len, PCI_ARGS ( pci ),
+		       where, len );
+		rc = -EIO;
+		goto err_read;
+	}
+
+	/* Return value */
+	*value = le32_to_cpu ( tmp );
+
+	/* Success */
+	rc = 0;
+
+ err_read:
+	linux_close ( fd );
+ err_open:
+	return rc;
+}
+
+/**
+ * Write to PCI configuration space
+ *
+ * @v pci		PCI device
+ * @v where		Address within configuration space
+ * @v value		Value to write
+ * @v len		Length of value
+ * @ret rc		Return status code
+ */
+int linux_pci_write ( struct pci_device *pci, unsigned long where,
+		      unsigned long value, size_t len ) {
+	uint32_t tmp;
+	int fd;
+	int check_len;
+	int rc;
+
+	/* Open configuration space */
+	fd = linux_pci_open ( pci, O_WRONLY, where );
+	if ( fd < 0 ) {
+		rc = fd;
+		goto err_open;
+	}
+
+	/* Prepare value for writing */
+	tmp = cpu_to_le32 ( value );
+	assert ( len <= sizeof ( tmp ) );
+
+	/* Write value */
+	check_len = linux_write ( fd, &tmp, len );
+	if ( check_len < 0 ) {
+		DBGC ( pci, "PCI could not write to " PCI_FMT " %#02lx+%#zx: "
+		       "%s\n", PCI_ARGS ( pci ), where, len,
+		       linux_strerror ( linux_errno ) );
+		rc = -ELINUX ( linux_errno );
+		goto err_write;
+	}
+	if ( ( size_t ) check_len != len ) {
+		DBGC ( pci, "PCI wrote only %#x bytes to " PCI_FMT
+		       " %#02lx+%#zx\n", check_len, PCI_ARGS ( pci ),
+		       where, len );
+		rc = -EIO;
+		goto err_write;
+	}
+
+	/* Success */
+	rc = 0;
+
+ err_write:
+	linux_close ( fd );
+ err_open:
+	return rc;
+}