[PATCH v1 3/3] Documentation/watchdog: Add documentation mlx-wdt driver

[michaelsh@mellanox.com]

From: Michael Shych <michaelsh@mellanox.com>

Add documentation with details of mellanox watchdog driver.

Signed-off-by: Michael Shych <michaelsh@mellanox.com>
---
 Documentation/watchdog/mlx-wdt.txt | 48 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/watchdog/mlx-wdt.txt

diff --git a/Documentation/watchdog/mlx-wdt.txt b/Documentation/watchdog/mlx-wdt.txt
new file mode 100644
index 000000000000..13123acc4195
--- /dev/null
+++ b/Documentation/watchdog/mlx-wdt.txt
@@ -0,0 +1,48 @@
+		Mellanox watchdog drivers
+		for x86 based system switches
+
+This driver provides watchdog functionality for various Mellanox
+Ethernet and Infiniband switch systems.
+
+Mellanox watchdog device is implemented in a programmable logic device.
+
+There are 2 types of HW watchdog implementations.
+
+Type 1:
+Actual HW timeout can be defined as a power of 2 msec.
+e.g. timeout 20 sec will be rounded up to 32768 msec.
+The maximum timeout period is 32 sec (32768 msec.),
+Get time-left isn't supported
+
+Type 2:
+Actual HW timeout is defined in sec. and it's the same as 
+a user-defined timeout.
+Maximum timeout is 255 sec.
+Get time-left is supported.
+
+Type 1 HW watchdog implementation exist in old systems and 
+all new systems have type 2 HW watchdog.
+Two types of HW implementation have also different register map.
+
+Mellanox system can have 2 watchdogs: main and auxiliary.
+Main and auxiliary watchdog devices can be enabled together 
+on the same system.
+There are several actions that can be defined in the watchdog:
+system reset, start fans on full speed and increase register counter.
+The last 2 actions are performed without a system reset.
+Actions without reset are provided for auxiliary watchdog device,
+which is optional.
+
+This mlx-wdt driver supports both HW watchdog implementations.
+
+Watchdog driver is probed from the common mlx_platform driver.
+Mlx_platform driver provides an appropriate set of registers for
+Mellanox watchdog device, identity name (mlx-wdt-main or mlx-wdt-aux),
+initial timeout, performed action in expiration and configuration flags.
+watchdog configuration flags: nostop_after_start i.e. nowayout and
+start_at_boot.
+The driver reports if watchdog set timeout is rounded in type1 HW watchdog.
+The driver checks during initialization if the previous system reset 
+was done by the watchdog. If yes, it makes a notification about this event.
+
+Access to HW registers is performed through a generic regmap interface.
-- 
2.11.0