Subject: Re: [PATCH 2/7] [POWERPC] Xilinx: clear data caches.

From: Benjamin Herrenschmidt <[email-masked]>
Date: Fri, 14 Dec 2007 11:07:28 +1100

On Thu, 2007-12-13 at 15:43 -0800, Stephen Neuendorffer wrote:
> This code is needed to boot without a boot loader.
> 
> Grant:  I'm not sure where the right place to put this is.  I'm assuming we'll actually need some boot code that is not generic?  Also, note that there is a V4FX errata workaround in arch/ppc/boot/head.S, which probably also needs to get pulled to powerpc.
> 
> Signed-off-by: Stephen Neuendorffer <[email-masked]>
> ---
>  arch/powerpc/boot/raw-platform.c |   22 ++++++++++++++++++++++
>  1 files changed, 22 insertions(+), 0 deletions(-)

This raw-platform.c file doesn't seem like a good place for code that is
totally platform specific ...

Ben.

> diff --git a/arch/powerpc/boot/raw-platform.c b/arch/powerpc/boot/raw-platform.c
> index b9caeee..2a5e493 100644
> --- a/arch/powerpc/boot/raw-platform.c
> +++ b/arch/powerpc/boot/raw-platform.c
> @@ -24,6 +24,28 @@ void platform_init(unsigned long r3, unsigned long r4, unsigned long r5,
>                     unsigned long r6, unsigned long r7)
>  {
>  	u64 memsize64 = memsize[0];
> +	static const unsigned long line_size = 32;
> +	static const unsigned long congruence_classes = 256;
> +	unsigned long addr;
> +	unsigned long dccr;
> +
> +	/*
> +	 * Invalidate the data cache if the data cache is turned off.
> +	 * - The 405 core does not invalidate the data cache on power-up
> +	 *   or reset but does turn off the data cache. We cannot assume
> +	 *   that the cache contents are valid.
> +	 * - If the data cache is turned on this must have been done by
> +	 *   a bootloader and we assume that the cache contents are
> +	 *   valid.
> +	 */
> +	__asm__("mfdccr %0": "=r" (dccr));
> +	if (dccr == 0) {
> +		for (addr = 0;
> +		     addr < (congruence_classes * line_size);
> +		     addr += line_size) {
> +			__asm__("dccci 0,%0": :"b"(addr));
> +		}
> +	}
>  
>  	if (mem_size_cells == 2) {
>  		memsize64 <<= 32;