From: Ivan Mikhaylov <i.mikhaylov@yadro.com>
To: Guenter Roeck <linux@roeck-us.net>,
Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org, linux-watchdog@vger.kernel.org,
linux-aspeed@lists.ozlabs.org, Andrew Jeffery <andrew@aj.id.au>,
openbmc@lists.ozlabs.org, Alexander Amelkin <a.amelkin@yadro.com>,
linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
Joel Stanley <joel@jms.id.au>,
Ivan Mikhaylov <i.mikhaylov@yadro.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 4/4] aspeed/watchdog: Add access_cs0 option for alt-boot
Date: Tue, 27 Aug 2019 19:54:26 +0300 [thread overview]
Message-ID: <20190827165426.17037-5-i.mikhaylov@yadro.com> (raw)
In-Reply-To: <20190827165426.17037-1-i.mikhaylov@yadro.com>
The option for the ast2400/2500 to get access to CS0 at runtime.
Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
---
.../ABI/testing/sysfs-class-watchdog | 34 +++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-class-watchdog b/Documentation/ABI/testing/sysfs-class-watchdog
index 6317ade5ad19..675f9b537661 100644
--- a/Documentation/ABI/testing/sysfs-class-watchdog
+++ b/Documentation/ABI/testing/sysfs-class-watchdog
@@ -72,3 +72,37 @@ Description:
It is a read/write file. When read, the currently assigned
pretimeout governor is returned. When written, it sets
the pretimeout governor.
+
+What: /sys/class/watchdog/watchdog1/access_cs0
+Date: August 2019
+Contact: Ivan Mikhaylov <i.mikhaylov@yadro.com>,
+ Alexander Amelkin <a.amelkin@yadro.com>
+Description:
+ It is a read/write file. This attribute exists only if the
+ system has booted from the alternate flash chip due to
+ expiration of a watchdog timer of AST2400/AST2500 when
+ alternate boot function was enabled with 'aspeed,alt-boot'
+ devicetree option for that watchdog or with an appropriate
+ h/w strapping (for WDT2 only).
+
+ At alternate flash the 'access_cs0' sysfs node provides:
+ ast2400: a way to get access to the primary SPI flash
+ chip at CS0 after booting from the alternate
+ chip at CS1.
+ ast2500: a way to restore the normal address mapping
+ from (CS0->CS1, CS1->CS0) to (CS0->CS0,
+ CS1->CS1).
+
+ Clearing the boot code selection and timeout counter also
+ resets to the initial state the chip select line mapping. When
+ the SoC is in normal mapping state (i.e. booted from CS0),
+ clearing those bits does nothing for both versions of the SoC.
+ For alternate boot mode (booted from CS1 due to wdt2
+ expiration) the behavior differs as described above.
+
+ This option can be used with wdt2 (watchdog1) only.
+
+ When read, the current status of the boot code selection is
+ shown. When written with any non-zero value, it clears
+ the boot code selection and the timeout counter, which results
+ in chipselect reset for AST2400/AST2500.
--
2.20.1
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prev parent reply other threads:[~2019-08-27 16:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 16:54 [PATCH v3 0/4] add dual-boot support Ivan Mikhaylov
2019-08-27 16:54 ` [PATCH v3 1/4] vesnin: add wdt2 section with alt-boot option Ivan Mikhaylov
2019-08-27 16:54 ` [PATCH v3 2/4] vesnin: add secondary SPI flash chip Ivan Mikhaylov
2019-08-27 16:54 ` [PATCH v3 3/4] watchdog/aspeed: add support for dual boot Ivan Mikhaylov
2019-08-27 17:21 ` Guenter Roeck
2019-08-27 16:54 ` Ivan Mikhaylov [this message]
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