1 files changed, 96 insertions, 0 deletions
diff --git a/src/interface/linux/linux_sysfs.c b/src/interface/linux/linux_sysfs.c
new file mode 100644
index 000000000..4f0027cd4
--- /dev/null
+++ b/src/interface/linux/linux_sysfs.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2021 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., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <string.h>
+#include <errno.h>
+#include <ipxe/umalloc.h>
+#include <ipxe/linux_api.h>
+#include <ipxe/linux.h>
+#include <ipxe/linux_sysfs.h>
+
+/** @file
+ *
+ * Linux sysfs files
+ *
+ */
+
+/** Read blocksize */
+#define LINUX_SYSFS_BLKSIZE 4096
+
+/**
+ * Read file from sysfs
+ *
+ * @v filename		Filename
+ * @v data		Data to fill in
+ * @ret len		Length read, or negative error
+ */
+int linux_sysfs_read ( const char *filename, userptr_t *data ) {
+	userptr_t tmp;
+	ssize_t read;
+	size_t len;
+	int fd;
+	int rc;
+
+	/* Open file */
+	fd = linux_open ( filename, O_RDONLY );
+	if ( fd < 0 ) {
+		rc = -ELINUX ( linux_errno );
+		DBGC ( filename, "LINUX could not open %s: %s\n",
+		       filename, linux_strerror ( linux_errno ) );
+		goto err_open;
+	}
+
+	/* Read file */
+	for ( *data = UNULL, len = 0 ; ; len += read ) {
+
+		/* (Re)allocate space */
+		tmp = urealloc ( *data, ( len + LINUX_SYSFS_BLKSIZE ) );
+		if ( ! tmp ) {
+			rc = -ENOMEM;
+			goto err_alloc;
+		}
+		*data = tmp;
+
+		/* Read from file */
+		read = linux_read ( fd, user_to_virt ( *data, len ),
+				    LINUX_SYSFS_BLKSIZE );
+		if ( read == 0 )
+			break;
+		if ( read < 0 ) {
+			DBGC ( filename, "LINUX could not read %s: %s\n",
+			       filename, linux_strerror ( linux_errno ) );
+			goto err_read;
+		}
+	}
+
+	/* Close file */
+	linux_close ( fd );
+
+	DBGC ( filename, "LINUX read %s\n", filename );
+	return len;
+
+ err_read:
+ err_alloc:
+	ufree ( *data );
+	linux_close ( fd );
+ err_open:
+	return rc;
+}