tty: rework break handling
Some hardware needs to do break handling itself and may have partial
support only. Make break_ctl return an error code. Add a tty driver flag
so you can indicate driver hardware side break support.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index d2a0035..e1065ac 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -135,7 +135,7 @@
*
* Optional:
*
- * void (*break_ctl)(struct tty_stuct *tty, int state);
+ * int (*break_ctl)(struct tty_stuct *tty, int state);
*
* This optional routine requests the tty driver to turn on or
* off BREAK status on the RS-232 port. If state is -1,
@@ -146,6 +146,10 @@
* handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
* TIOCCBRK.
*
+ * If the driver sets TTY_DRIVER_HARDWARE_BREAK then the interface
+ * will also be called with actual times and the hardware is expected
+ * to do the delay work itself. 0 and -1 are still used for on/off.
+ *
* Optional: Required for TCSBRK/BRKP/etc handling.
*
* void (*wait_until_sent)(struct tty_struct *tty, int timeout);
@@ -192,7 +196,7 @@
void (*stop)(struct tty_struct *tty);
void (*start)(struct tty_struct *tty);
void (*hangup)(struct tty_struct *tty);
- void (*break_ctl)(struct tty_struct *tty, int state);
+ int (*break_ctl)(struct tty_struct *tty, int state);
void (*flush_buffer)(struct tty_struct *tty);
void (*set_ldisc)(struct tty_struct *tty);
void (*wait_until_sent)(struct tty_struct *tty, int timeout);
@@ -285,12 +289,18 @@
* TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
* use dynamic memory keyed through the devpts filesystem. This
* is only applicable to the pty driver.
+ *
+ * TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
+ * the requested timeout to the caller instead of using a simple
+ * on/off interface.
+ *
*/
#define TTY_DRIVER_INSTALLED 0x0001
#define TTY_DRIVER_RESET_TERMIOS 0x0002
#define TTY_DRIVER_REAL_RAW 0x0004
#define TTY_DRIVER_DYNAMIC_DEV 0x0008
#define TTY_DRIVER_DEVPTS_MEM 0x0010
+#define TTY_DRIVER_HARDWARE_BREAK 0x0020
/* tty driver types */
#define TTY_DRIVER_TYPE_SYSTEM 0x0001