drivers: base: Add generic cross-process locking API
Add a generic locking API for situations where multiple user-space
processes and/or kernel drivers need to cooordinate access to a
shared resource such as a graphics buffer.
Change-Id: Ic0dedbad74b970d7bd1a6624a845b5b1b9847443
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
diff --git a/include/linux/genlock.h b/include/linux/genlock.h
new file mode 100644
index 0000000..2e9f9d6
--- /dev/null
+++ b/include/linux/genlock.h
@@ -0,0 +1,45 @@
+#ifndef _GENLOCK_H_
+#define _GENLOCK_H_
+
+#ifdef __KERNEL__
+
+struct genlock;
+struct genlock_handle;
+
+struct genlock_handle *genlock_get_handle(void);
+struct genlock_handle *genlock_get_handle_fd(int fd);
+void genlock_put_handle(struct genlock_handle *handle);
+struct genlock *genlock_create_lock(struct genlock_handle *);
+struct genlock *genlock_attach_lock(struct genlock_handle *, int fd);
+int genlock_wait(struct genlock_handle *handle, u32 timeout);
+void genlock_release_lock(struct genlock_handle *);
+int genlock_lock(struct genlock_handle *handle, int op, int flags,
+ u32 timeout);
+#endif
+
+#define GENLOCK_UNLOCK 0
+#define GENLOCK_WRLOCK 1
+#define GENLOCK_RDLOCK 2
+
+#define GENLOCK_NOBLOCK (1 << 0)
+
+struct genlock_lock {
+ int fd;
+ int op;
+ int flags;
+ int timeout;
+};
+
+#define GENLOCK_IOC_MAGIC 'G'
+
+#define GENLOCK_IOC_NEW _IO(GENLOCK_IOC_MAGIC, 0)
+#define GENLOCK_IOC_EXPORT _IOR(GENLOCK_IOC_MAGIC, 1, \
+ struct genlock_lock)
+#define GENLOCK_IOC_ATTACH _IOW(GENLOCK_IOC_MAGIC, 2, \
+ struct genlock_lock)
+#define GENLOCK_IOC_LOCK _IOW(GENLOCK_IOC_MAGIC, 3, \
+ struct genlock_lock)
+#define GENLOCK_IOC_RELEASE _IO(GENLOCK_IOC_MAGIC, 4)
+#define GENLOCK_IOC_WAIT _IOW(GENLOCK_IOC_MAGIC, 5, \
+ struct genlock_lock)
+#endif