linux-kernel - Re: Do cpu-endian MMIO accessors exist?

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Message-Id: <200907221035.50025.arnd@arndb.de>
Date:	Wed, 22 Jul 2009 10:35:49 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	Pekka Paalanen <pq@....fi>, linux-kernel@...r.kernel.org,
	Christoph Hellwig <hch@...radead.org>, lethal@...ux-sh.org,
	linux-sh@...r.kernel.org
Subject: Re: Do cpu-endian MMIO accessors exist?

On Wednesday 22 July 2009, Jiri Slaby wrote:
> No, I should have written this explicitly. I meant read* have a barrier,
> whereas ioread* do not. Similarly for writes. Is this expected?
> 
> For example:
> #define __raw_readl(a) (__chk_io_ptr(a), *(volatile u32 __force *)(a))
> #define readl(a)       ({ u32 r_ = __raw_readl(a); mb(); r_; })
> #define ioread32(a)    __raw_readl(a)

No, this looks like a bug. I would have expected

#define ioread32(a)    readl(a)

in this case. Also, ioread32 should actually multiplex between
readl() and inl() based on the address token, as the code in
lib/iomap.c does. It's probably easy enough to enable
CONFIG_GENERIC_IOMAP on sh, and remove the ioread*/iowrite*
macros from arch/sh/include/asm/io.h.

	Arnd <><
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