From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wolfgang Denk <wd@denx.de>
Date: Thu, 13 Mar 2008 13:04:55 +0100
Subject: [U-Boot-Users] [PATCH 2/8] SPARC: SPARC cfi-flash support for
	64-bit reads
In-Reply-To: Your message of "Thu, 13 Mar 2008 10:38:50 +0100."
	<47D8F62A.2000108@gaisler.com>
Message-ID: <20080313120455.6ECA8247AF@gemini.denx.de>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

In message <47D8F62A.2000108@gaisler.com> you wrote:
> For current SPARC architectures (LEON2 and LEON3) each read from the
> FLASH must lead to a cache miss. This is because FLASH can not be set
> non-cacheable since program code resides there, and alternatively disabling
> cache is poor from performance view, or doing a cache flush between each 
> read
> is even poorer.
> 
> Forcing a cache miss on a SPARC is done by a special instruction "lda" -
> load alternative space, the alternative space number (ASI) is processor
> implementation spcific and can be found by including <asm/processor.h>.
> 
> SPARC has implemented __raw_readq, it reads 64-bit from any 32-bit address.
> 
> Best Regards,
> Daniel Hellstrom
> 
> 
>  drivers/mtd/cfi_flash.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> 
> diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c
> index 439c950..6fc6bc4 100644
> --- a/drivers/mtd/cfi_flash.c
> +++ b/drivers/mtd/cfi_flash.c
> @@ -241,8 +241,12 @@ static u32 flash_read32(void *addr)
>  
>  static u64 flash_read64(void *addr)
>  {
> +#ifdef CONFIG_SPARC
> +    return __raw_readq(addr);
> +#else
>      /* No architectures currently implement __raw_readq() */
>      return *(volatile u64 *)addr;
> +#endif
>  }

Instead of #ifdef'fing this code,  you  should  implement  a  private
(SPARC  specific)  version  of  flash_read64()  and probably make the
existing  one  "weak"  so  it  can  be  overwritten  by  such  custom
definitions.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
If I can have honesty, it's easier to overlook mistakes.
	-- Kirk, "Space Seed", stardate 3141.9