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cc2a2d19f8
Convert those documents and prepare them to be part of the kernel API book, as most of the stuff there are related to the Kernel interfaces. Still, in the future, it would make sense to split the docs, as some of the stuff is clearly focused on sysadmin tasks. The conversion is actually: - add blank lines and identation in order to identify paragraphs; - fix tables markups; - add some lists markups; - mark literal blocks; - adjust title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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57 lines
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=========================
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Mellanox watchdog drivers
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=========================
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for x86 based system switches
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=============================
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This driver provides watchdog functionality for various Mellanox
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Ethernet and Infiniband switch systems.
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Mellanox watchdog device is implemented in a programmable logic device.
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There are 2 types of HW watchdog implementations.
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Type 1:
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Actual HW timeout can be defined as a power of 2 msec.
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e.g. timeout 20 sec will be rounded up to 32768 msec.
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The maximum timeout period is 32 sec (32768 msec.),
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Get time-left isn't supported
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Type 2:
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Actual HW timeout is defined in sec. and it's the same as
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a user-defined timeout.
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Maximum timeout is 255 sec.
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Get time-left is supported.
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Type 1 HW watchdog implementation exist in old systems and
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all new systems have type 2 HW watchdog.
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Two types of HW implementation have also different register map.
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Mellanox system can have 2 watchdogs: main and auxiliary.
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Main and auxiliary watchdog devices can be enabled together
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on the same system.
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There are several actions that can be defined in the watchdog:
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system reset, start fans on full speed and increase register counter.
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The last 2 actions are performed without a system reset.
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Actions without reset are provided for auxiliary watchdog device,
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which is optional.
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Watchdog can be started during a probe, in this case it will be
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pinged by watchdog core before watchdog device will be opened by
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user space application.
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Watchdog can be initialised in nowayout way, i.e. oncse started
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it can't be stopped.
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This mlx-wdt driver supports both HW watchdog implementations.
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Watchdog driver is probed from the common mlx_platform driver.
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Mlx_platform driver provides an appropriate set of registers for
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Mellanox watchdog device, identity name (mlx-wdt-main or mlx-wdt-aux),
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initial timeout, performed action in expiration and configuration flags.
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watchdog configuration flags: nowayout and start_at_boot, hw watchdog
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version - type1 or type2.
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The driver checks during initialization if the previous system reset
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was done by the watchdog. If yes, it makes a notification about this event.
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Access to HW registers is performed through a generic regmap interface.
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