tty,serial: Unify UPF_* and ASYNC_* flag definitions
The userspace-defined ASYNC_* flags in include/uapi/linux/tty_flags.h
are the authoritative bit definitions for the serial_struct flags,
and thus for any derivative values or fields.
Although the serial core provides the TIOCSSERIAL and TIOCGSERIAL
ioctls to set and retrieve these flags from userspace, it defines these
bits independently, as UPF_* macros.
Define the UPF_* macros which are userspace-modifiable directly from
the ASYNC_* symbolic constants. Add compile-time test to ensure the
bits changeable by TIOCSSERIAL match the defined range in the uapi
header.
Add ASYNCB_MAGIC_MULTIPLIER to the uapi header since this bit is
programmable by userspace.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/uapi/linux/tty_flags.h b/include/uapi/linux/tty_flags.h
index eefcb48..7b516f7 100644
--- a/include/uapi/linux/tty_flags.h
+++ b/include/uapi/linux/tty_flags.h
@@ -6,6 +6,8 @@
* shared by the tty_port flags structures.
*
* Define ASYNCB_* for convenient use with {test,set,clear}_bit.
+ *
+ * Bits [0..ASYNCB_LAST_USER] are userspace defined/visible/changeable
*/
#define ASYNCB_HUP_NOTIFY 0 /* Notify getty on hangups and closes
* on the callout port */
@@ -26,7 +28,8 @@
#define ASYNCB_BUGGY_UART 14 /* This is a buggy UART, skip some safety
* checks. Note: can be dangerous! */
#define ASYNCB_AUTOPROBE 15 /* Port was autoprobed by PCI or PNP code */
-#define ASYNCB_LAST_USER 15
+#define ASYNCB_MAGIC_MULTIPLIER 16 /* Use special CLK or divisor */
+#define ASYNCB_LAST_USER 16
/* Internal flags used only by kernel */
#define ASYNCB_INITIALIZED 31 /* Serial port was initialized */
@@ -57,6 +60,7 @@
#define ASYNC_LOW_LATENCY (1U << ASYNCB_LOW_LATENCY)
#define ASYNC_BUGGY_UART (1U << ASYNCB_BUGGY_UART)
#define ASYNC_AUTOPROBE (1U << ASYNCB_AUTOPROBE)
+#define ASYNC_MAGIC_MULTIPLIER (1U << ASYNCB_MAGIC_MULTIPLIER)
#define ASYNC_FLAGS ((1U << (ASYNCB_LAST_USER + 1)) - 1)
#define ASYNC_USR_MASK (ASYNC_SPD_MASK|ASYNC_CALLOUT_NOHUP| \