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From: Timur Tabi <timur@freescale.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>,
	linuxppc-dev@ozlabs.org, sl@powerlinux.fr,
	Philippe Lachenal <philippe.lachenal@hotmail.fr>
Subject: Re: MPC8349ea Random Device Generator driver
Date: Wed, 06 Jun 2007 17:19:26 -0500	[thread overview]
Message-ID: <466732EE.8080306@freescale.com> (raw)
In-Reply-To: <200706070011.43347.arnd@arndb.de>

Arnd Bergmann wrote:

> The only code that is allowed to dereference an __iomem pointer is the
> implementation of readl/writel and similar functions.
> The code you gave as an example gives you a warning when building with
> make C=1 using sparse, and missed barriers.

Well, that's why I said "or something like that".

Anyway, there's a more fundamental problem.  I can't find any 64-bit versions of the 
in_be/out_be/read/write functions.  Because the registers are big-endian, then we have a 
few choices:

1) Create 64-bit versions of these functions.  Can someone tell me why they don't exist 
already?

2) Do something stupid like u32 v = in_be32(((void *) &rng->rngisr) + 4);

3) Change the struct like this:

struct sec_rng {
	__be32	rngmr_hi;
	__be32	rngmr_lo;
	u8 res1[8];
	__be32 rngdsr_hi;
	__be32 rngdsr_lo;
	__be32 rngrcr_hi;
	__be32 rngrcr_lo;
...

Comments?

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

  reply	other threads:[~2007-06-06 22:19 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-05 15:42 MPC8349ea Random Device Generator driver Philippe Lachenal
2007-06-06 14:15 ` Arnd Bergmann
2007-06-07 11:29   ` MPC8349ea Random Number " Philippe Lachenal
2007-06-07 14:03     ` Arnd Bergmann
2007-06-06 21:57 ` MPC8349ea Random Device " Timur Tabi
2007-06-06 22:09   ` Olof Johansson
2007-06-06 22:07     ` Timur Tabi
2007-06-06 22:11       ` Arnd Bergmann
2007-06-06 22:19         ` Timur Tabi [this message]
2007-06-06 22:35           ` Arnd Bergmann
2007-06-06 22:38             ` Timur Tabi
2007-06-06 22:24       ` Olof Johansson
2007-06-06 22:32         ` Timur Tabi
2007-06-06 23:54           ` Olof Johansson
2007-06-07 14:23             ` Timur Tabi
2007-06-07 15:20               ` Olof Johansson
2007-06-07 15:20                 ` Timur Tabi
2007-06-07 15:36                   ` Olof Johansson
2007-06-06 22:48         ` Timur Tabi
2007-06-07  0:00           ` Olof Johansson
2007-06-07  2:55 ` Kim Phillips

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