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2024-10-22 8ac6c7a54ed1b98d142dce24b11c6de6a1e239a5 
 kernel/Documentation/ABI/testing/sysfs-class-watchdog
....@@ -17,8 +17,13 @@
1717 Date:		August 2015
1818 Contact:	Wim Van Sebroeck <wim@iguana.be>
1919 Description:
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-		It is a read only file. While reading, it gives '1' if that
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-		device supports nowayout feature else, it gives '0'.
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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.
2227 
2328 What:		/sys/class/watchdog/watchdogn/state
2429 Date:		August 2015
....@@ -49,3 +54,63 @@
4954 Description:
5055 		It is a read only file. It is read to know about current
5156 		value of timeout programmed.
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+
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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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+
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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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+
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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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+
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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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+
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+		At alternate flash the 'access_cs0' sysfs node provides:
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+
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+			ast2400:
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+				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:
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+				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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+
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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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+
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+		This option can be used with wdt2 (watchdog1) only.
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+
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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.