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From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
To:     Masahiro Yamada <yamada.masahiro@socionext.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Gao Xiang <xiang@kernel.org>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Linus Walleij <linus.walleij@linaro.org>,
        kernel@pengutronix.de, Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: [RFC PATCH 1/3] decompress/keepalive.h: prepare for watchdog keepalive during kernel decompression
Date:   Thu, 17 Oct 2019 13:49:04 +0200
Message-Id: <20191017114906.30302-2-linux@rasmusvillemoes.dk>
In-Reply-To: <20191017114906.30302-1-linux@rasmusvillemoes.dk>
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Some boards have a hardware watchdog that (a) cannot be disabled
and (b) has a timeout short enough that there's no chance for the
kernel to get through decompression, let alone reach the
initialization of the appropriate watchdog device driver.

In order to allow booting such boards, the decompression routine needs
to service the watchdog in its main loop. This adds a header making it
easy to wire up each decompressor - just include this header and add a
decompress_keepalive() in the main loop.

Outside of the pre-boot stage, this is always a no-op.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 include/linux/decompress/keepalive.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 include/linux/decompress/keepalive.h

diff --git a/include/linux/decompress/keepalive.h b/include/linux/decompress/keepalive.h
new file mode 100644
index 000000000000..39caa7693624
--- /dev/null
+++ b/include/linux/decompress/keepalive.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef DECOMPRESS_KEEPALIVE_H
+#define DECOMPRESS_KEEPALIVE_H
+
+#ifdef PREBOOT
+
+#endif
+
+#ifndef decompress_keepalive
+#define decompress_keepalive() do { } while (0)
+#endif
+
+#endif /* DECOMPRESS_KEEPALIVE_H */
-- 
2.20.1