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author | Michael Shych <michaelsh@mellanox.com> | 2019-02-24 20:26:31 +0300 |
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committer | Wim Van Sebroeck <wim@linux-watchdog.org> | 2019-03-02 17:28:20 +0300 |
commit | 9d489ad121927609d6e51df1a755707966945a53 (patch) | |
tree | 3dabcc902f5ecebe64a70c37ee162f7e9b0b22e9 /Documentation/watchdog/mlx-wdt.txt | |
parent | c60923dd5feedc337b1450e3f4c6e19ffa305439 (diff) | |
download | linux-9d489ad121927609d6e51df1a755707966945a53.tar.xz |
Documentation/watchdog: Add documentation mlx-wdt driver
Add documentation with details of Mellanox watchdog driver.
Signed-off-by: Michael Shych <michaelsh@mellanox.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Diffstat (limited to 'Documentation/watchdog/mlx-wdt.txt')
-rw-r--r-- | Documentation/watchdog/mlx-wdt.txt | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/watchdog/mlx-wdt.txt b/Documentation/watchdog/mlx-wdt.txt new file mode 100644 index 000000000000..66eeb78505c3 --- /dev/null +++ b/Documentation/watchdog/mlx-wdt.txt @@ -0,0 +1,52 @@ + 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. +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. |