[PATCH v3 3/4] tty: documentation: abi: add ttyvs null modem driver sysfs nodes

[Rishi Gupta]

The ttyvs driver exposes sysfs file called event to emulate
various serial port events. This commit document this file.
User space application writes various codes to this file.

Signed-off-by: Rishi Gupta <gupt21@xxxxxxxxx>
---
Changes in v3:
- Rebased on top of v5.7-rc1

Changes in v2:
- Updated path to /sys/class/tty/ttyvsN/event
- Used Documentation/ABI/testing/sysfs-tty, previously new file was created

 Documentation/ABI/testing/sysfs-tty | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty
index e157130..c17b49d 100644
--- a/Documentation/ABI/testing/sysfs-tty
+++ b/Documentation/ABI/testing/sysfs-tty
@@ -161,3 +161,18 @@ Contact:	Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
 Description:
 		 Allows user to detach or attach back the given device as
 		 kernel console. It shows and accepts a boolean variable.
+
+What:		/sys/class/tty/ttyvsN/event
+Date:		February 2020
+Contact:	Rishi Gupta <gupt21@xxxxxxxxx>
+Description:
+		The ttyvs driver will emulate serial port event; parity error,
+		framing error, overrun error, asserting/de-asserting break
+		condition and ring indication when user space application
+		writes an event code on this sysfs file.
+
+		Write 1 to emulate framing error, write 2 for parity error,
+		write 3 for overrun error, write 4 to set ring indication,
+		write 5 to clear ring indication, write 6 to emulate a break
+		condition detected, write 7 to emulate a faulty cable and
+		write 8 to remove faulty cable condition.
-- 
2.7.4