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It can be useful to delay setting the nowayout feature for a watchdog device. Moreover, not every driver (notably gpio_wdt) implements a nowayout module parameter/otherwise respects CONFIG_WATCHDOG_NOWAYOUT, and modifying those drivers carries a risk of causing a regression for someone who has two watchdog devices, sets CONFIG_WATCHDOG_NOWAYOUT and somehow relies on the gpio_wdt driver being ignorant of that (i.e., allowing one to gracefully close a gpio_wdt but not the other watchdog in the system). So instead, simply make the nowayout sysfs file writable. Obviously, setting nowayout is a one-way street. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20191105205118.11359-1-linux@rasmusvillemoes.dk Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
114 lines
4.0 KiB
Plaintext
114 lines
4.0 KiB
Plaintext
What: /sys/class/watchdog/watchdogn/bootstatus
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Date: August 2015
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It contains status of the watchdog
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device at boot. It is equivalent to WDIOC_GETBOOTSTATUS of
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ioctl interface.
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What: /sys/class/watchdog/watchdogn/identity
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Date: August 2015
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It contains identity string of
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watchdog device.
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What: /sys/class/watchdog/watchdogn/nowayout
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Date: August 2015
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read/write file. While reading, it gives '1'
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if the device has the nowayout feature set, otherwise
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it gives '0'. Writing a '1' to the file enables the
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nowayout feature. Once set, the nowayout feature
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cannot be disabled, so writing a '0' either has no
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effect (if the feature was already disabled) or
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results in a permission error.
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What: /sys/class/watchdog/watchdogn/state
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Date: August 2015
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It gives active/inactive status of
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watchdog device.
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What: /sys/class/watchdog/watchdogn/status
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Date: August 2015
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It contains watchdog device's
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internal status bits. It is equivalent to WDIOC_GETSTATUS
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of ioctl interface.
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What: /sys/class/watchdog/watchdogn/timeleft
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Date: August 2015
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It contains value of time left for
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reset generation. It is equivalent to WDIOC_GETTIMELEFT of
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ioctl interface.
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What: /sys/class/watchdog/watchdogn/timeout
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Date: August 2015
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It is read to know about current
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value of timeout programmed.
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What: /sys/class/watchdog/watchdogn/pretimeout
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Date: December 2016
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It specifies the time in seconds before
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timeout when the pretimeout interrupt is delivered. Pretimeout
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is an optional feature.
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What: /sys/class/watchdog/watchdogn/pretimeout_avaialable_governors
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Date: February 2017
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read only file. It shows the pretimeout governors
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available for this watchdog.
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What: /sys/class/watchdog/watchdogn/pretimeout_governor
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Date: February 2017
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Contact: Wim Van Sebroeck <wim@iguana.be>
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Description:
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It is a read/write file. When read, the currently assigned
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pretimeout governor is returned. When written, it sets
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the pretimeout governor.
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What: /sys/class/watchdog/watchdog1/access_cs0
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Date: August 2019
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Contact: Ivan Mikhaylov <i.mikhaylov@yadro.com>,
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Alexander Amelkin <a.amelkin@yadro.com>
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Description:
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It is a read/write file. This attribute exists only if the
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system has booted from the alternate flash chip due to
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expiration of a watchdog timer of AST2400/AST2500 when
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alternate boot function was enabled with 'aspeed,alt-boot'
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devicetree option for that watchdog or with an appropriate
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h/w strapping (for WDT2 only).
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At alternate flash the 'access_cs0' sysfs node provides:
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ast2400: a way to get access to the primary SPI flash
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chip at CS0 after booting from the alternate
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chip at CS1.
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ast2500: a way to restore the normal address mapping
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from (CS0->CS1, CS1->CS0) to (CS0->CS0,
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CS1->CS1).
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Clearing the boot code selection and timeout counter also
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resets to the initial state the chip select line mapping. When
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the SoC is in normal mapping state (i.e. booted from CS0),
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clearing those bits does nothing for both versions of the SoC.
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For alternate boot mode (booted from CS1 due to wdt2
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expiration) the behavior differs as described above.
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This option can be used with wdt2 (watchdog1) only.
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When read, the current status of the boot code selection is
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shown. When written with any non-zero value, it clears
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the boot code selection and the timeout counter, which results
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in chipselect reset for AST2400/AST2500.
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