Multidrop mode differentiates the data characters and the address
characters. Data is transmitted with the parity bit to 0 and addresses
are transmitted with the parity bit to 1. However this usually slow
down communication by adding a delay between the first byte and the
others.
This patch defines two non-stadard bits PARMD (that enables multidrop)
and SENDA (that marks the next transmitted byte as address) that can
be used to completely remove the delay during transmission by
correctly managing the parity bit generation in hardware.
Signed-off-by: Rodolfo Giometti <giometti@xxxxxxxx>
---
include/linux/tty.h | 2 ++
include/uapi/asm-generic/termbits.h | 2 ++
2 files changed, 4 insertions(+)
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 83b264c..85238ff 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -166,6 +166,8 @@ struct tty_bufhead {
#define C_CIBAUD(tty) _C_FLAG((tty), CIBAUD)
#define C_CRTSCTS(tty) _C_FLAG((tty), CRTSCTS)
#define C_CMSPAR(tty) _C_FLAG((tty), CMSPAR)
+#define C_PARMD(tty) _C_FLAG((tty), PARMD)
+#define C_SENDA(tty) _C_FLAG((tty), SENDA)
#define L_ISIG(tty) _L_FLAG((tty), ISIG)
#define L_ICANON(tty) _L_FLAG((tty), ICANON)
diff --git a/include/uapi/asm-generic/termbits.h b/include/uapi/asm-generic/termbits.h
index 232b478..7e82859 100644
--- a/include/uapi/asm-generic/termbits.h
+++ b/include/uapi/asm-generic/termbits.h
@@ -140,6 +140,8 @@ struct ktermios {
#define HUPCL 0002000
#define CLOCAL 0004000
#define CBAUDEX 0010000
+#define PARMD 0100000
+#define SENDA 0200000
#define BOTHER 0010000
#define B57600 0010001
#define B115200 0010002
--
2.7.4
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