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Date:   Wed, 21 May 2014 15:34:07 +0200
From:   Ralf Baechle <ralf@linux-mips.org>
To:     Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc:     linux-mips@linux-mips.org, David Daney <ddaney.cavm@gmail.com>,
        James Hogan <james.hogan@imgtec.com>, kvm@vger.kernel.org,
        David Daney <david.daney@cavium.com>
Subject: Re: [PATCH 11/15] MIPS: paravirt: Add pci controller for virtio
Message-ID: <20140521133407.GS10287@linux-mips.org>
References: <1400597236-11352-1-git-send-email-andreas.herrmann@caviumnetworks.com>
 <1400597236-11352-12-git-send-email-andreas.herrmann@caviumnetworks.com>
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On Tue, May 20, 2014 at 04:47:12PM +0200, Andreas Herrmann wrote:

> +
> +union pci_config_address {
> +	struct {
> +#ifdef __LITTLE_ENDIAN
> +		unsigned	register_number	: 8;		/* 7  .. 0  */
> +		unsigned	devfn_number	: 8;		/* 15 .. 8  */
> +		unsigned	bus_number	: 8;		/* 23 .. 16 */
> +		unsigned	reserved	: 7;		/* 30 .. 24 */
> +		unsigned	enable_bit	: 1;		/* 31       */
> +#else
> +		unsigned	enable_bit	: 1;		/* 31       */
> +		unsigned	reserved	: 7;		/* 30 .. 24 */
> +		unsigned	bus_number	: 8;		/* 23 .. 16 */
> +		unsigned	devfn_number	: 8;		/* 15 .. 8  */
> +		unsigned	register_number	: 8;		/* 7  .. 0  */
> +#endif

For this kind of endianess dependency there is a more elegant way of
defining things in linux-next's <uapi/asm/bitfield.h> like:

#include <uapi/asm/bitfield.h>
...

struct {
	__BITFIELD_FIELD(unsigned	enable_bit	: 1,		/* 31       */
	__BITFIELD_FIELD(unsigned	reserved	: 7,		/* 30 .. 24 */
	__BITFIELD_FIELD(unsigned	bus_number	: 8,		/* 23 .. 16 */
	__BITFIELD_FIELD(unsigned	devfn_number	: 8,		/* 15 .. 8  */
	__BITFIELD_FIELD(unsigned	register_number	: 8,		/* 7  .. 0  */
	)))));
};

No ifdef, no duplication!

  Ralf