linux-kernel - [PATCH] FDDI: defza: Include linux/io-64-nonatomic-lo-hi.h

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Message-ID: <20190620221224.27352-1-paul.burton@mips.com>
Date:   Thu, 20 Jun 2019 22:13:58 +0000
From:   Paul Burton <paul.burton@...s.com>
To:     "Maciej W. Rozycki" <macro@...ux-mips.org>,
        "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Paul Burton <pburton@...ecomp.com>,
        Serge Semin <Sergey.Semin@...latforms.ru>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] FDDI: defza: Include linux/io-64-nonatomic-lo-hi.h

Currently arch/mips/include/asm/io.h provides 64b memory accessor
functions such as readq & writeq even on MIPS32 platforms where those
accessors cannot actually perform a 64b memory access. They instead
BUG(). This is unfortunate for drivers which either #ifdef on the
presence of these accessors, or can function with non-atomic
implementations of them found in either linux/io-64-nonatomic-lo-hi.h or
linux/io-64-nonatomic-hi-lo.h. As such we're preparing to remove the
definitions of these 64b accessor functions for MIPS32 kernels.

In preparation for this, include linux/io-64-nonatomic-lo-hi.h in
defza.c in order to provide a non-atomic implementation of the
readq_relaxed & writeq_relaxed functions that are used by this code. In
practice this will have no runtime effect, since use of the 64b accessor
functions is conditional upon sizeof(unsigned long) == 8, ie. upon
CONFIG_64BIT=y. This means the calls to these non-atomic readq & writeq
implementations will be optimized out anyway, but we need their
definitions to keep the compiler happy.

For 64bit kernels using this code this change should also have no effect
because asm/io.h will continue to provide the definitions of
readq_relaxed & writeq_relaxed, which linux/io-64-nonatomic-lo-hi.h
checks for before defining itself.

Signed-off-by: Paul Burton <paul.burton@...s.com>
Cc: Serge Semin <Sergey.Semin@...latforms.ru>
Cc: "Maciej W. Rozycki" <macro@...ux-mips.org>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Cc: linux-mips@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
Maciej, David, if you'd be happy to provide an Ack so that I can take
this through the mips-next branch that would be great; that'll let me
apply it prior to the asm/io.h change.
---
 drivers/net/fddi/defza.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/fddi/defza.c b/drivers/net/fddi/defza.c
index c5cae8e74dc4..060712c666bf 100644
--- a/drivers/net/fddi/defza.c
+++ b/drivers/net/fddi/defza.c
@@ -33,6 +33,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
-- 
2.22.0