1 files changed, 136 insertions, 0 deletions
diff --git a/drivers/staging/meilhaus/meslock.c b/drivers/staging/meilhaus/meslock.c
new file mode 100644
index 00000000000..5230b89b45b
--- /dev/null
+++ b/drivers/staging/meilhaus/meslock.c
@@ -0,0 +1,136 @@
+/**
+ * @file meslock.c
+ *
+ * @brief Implements the subdevice lock class.
+ * @note Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
+ * @author Guenter Gebhardt
+ */
+
+/*
+ * Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
+ *
+ * This file 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/spinlock.h>
+
+#include "medefines.h"
+#include "meerror.h"
+
+#include "medebug.h"
+#include "meslock.h"
+
+int me_slock_enter(struct me_slock *slock, struct file *filep)
+{
+	PDEBUG_LOCKS("executed.\n");
+
+	spin_lock(&slock->spin_lock);
+
+	if ((slock->filep) != NULL && (slock->filep != filep)) {
+		PERROR("Subdevice is locked by another process.\n");
+		spin_unlock(&slock->spin_lock);
+		return ME_ERRNO_LOCKED;
+	}
+
+	slock->count++;
+
+	spin_unlock(&slock->spin_lock);
+
+	return ME_ERRNO_SUCCESS;
+}
+
+int me_slock_exit(struct me_slock *slock, struct file *filep)
+{
+	PDEBUG_LOCKS("executed.\n");
+
+	spin_lock(&slock->spin_lock);
+	slock->count--;
+	spin_unlock(&slock->spin_lock);
+
+	return ME_ERRNO_SUCCESS;
+}
+
+int me_slock_lock(struct me_slock *slock, struct file *filep, int lock)
+{
+	PDEBUG_LOCKS("executed.\n");
+
+	switch (lock) {
+
+	case ME_LOCK_RELEASE:
+		spin_lock(&slock->spin_lock);
+
+		if (slock->filep == filep)
+			slock->filep = NULL;
+
+		spin_unlock(&slock->spin_lock);
+
+		break;
+
+	case ME_LOCK_SET:
+		spin_lock(&slock->spin_lock);
+
+		if (slock->count) {
+			spin_unlock(&slock->spin_lock);
+			PERROR("Subdevice is used by another process.\n");
+			return ME_ERRNO_USED;
+		} else if (slock->filep == NULL)
+			slock->filep = filep;
+		else if (slock->filep != filep) {
+			spin_unlock(&slock->spin_lock);
+			PERROR("Subdevice is locked by another process.\n");
+			return ME_ERRNO_LOCKED;
+		}
+
+		spin_unlock(&slock->spin_lock);
+
+		break;
+
+	case ME_LOCK_CHECK:
+		spin_lock(&slock->spin_lock);
+
+		if (slock->count) {
+			spin_unlock(&slock->spin_lock);
+			return ME_ERRNO_USED;
+		} else if ((slock->filep != NULL) && (slock->filep != filep)) {
+			spin_unlock(&slock->spin_lock);
+			return ME_ERRNO_LOCKED;
+		}
+
+		spin_unlock(&slock->spin_lock);
+
+		break;
+
+	default:
+		break;
+	}
+
+	return ME_ERRNO_SUCCESS;
+}
+
+void me_slock_deinit(struct me_slock *slock)
+{
+	PDEBUG_LOCKS("executed.\n");
+}
+
+int me_slock_init(me_slock_t * slock)
+{
+	PDEBUG_LOCKS("executed.\n");
+
+	slock->filep = NULL;
+	slock->count = 0;
+	spin_lock_init(&slock->spin_lock);
+
+	return 0;
+}