Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 66 insertions, 0 deletions

diff --git a/Documentation/watchdog/mlx-wdt.rst b/Documentation/watchdog/mlx-wdt.rst
new file mode 100644
index 000000000..35e690dea
--- /dev/null
+++ b/Documentation/watchdog/mlx-wdt.rst
@@ -0,0 +1,66 @@
+=========================
+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 3:
+  Same as Type 2 with extended maximum timeout period.
+  Maximum timeout is 65535 sec.
+
+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.
+
+Type 3 HW watchdog implementation can exist on all Mellanox systems
+with new programmer logic device.
+It's differentiated by WD capability bit.
+Old systems still have only one main watchdog.
+
+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.
+Watchdog can be started during a probe, in this case it will be
+pinged by watchdog core before watchdog device will be opened by
+user space application.
+Watchdog can be initialised in nowayout way, i.e. oncse started
+it can't be stopped.
+
+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: nowayout and start_at_boot, hw watchdog
+version - type1 or type2.
+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.
+Programmable logic device registers have little-endian order.