67 lines
2.5 KiB
ReStructuredText
67 lines
2.5 KiB
ReStructuredText
=========================
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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 3:
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Same as Type 2 with extended maximum timeout period.
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Maximum timeout is 65535 sec.
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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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Type 3 HW watchdog implementation can exist on all Mellanox systems
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with new programmer logic device.
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It's differentiated by WD capability bit.
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Old systems still have only one main watchdog.
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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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Programmable logic device registers have little-endian order.
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