[U-Boot] [PATCH 3/3 v2] ARM: ARM926EJS - Add cache operations

[Aneesh V]

Hi Hong,

On Friday 19 August 2011 02:53 PM, Hong Xu wrote:
> Add a new file arch/arm/cpu/arm926ejs/cache.c and put cache operations
> into this file.
> 
> Signed-off-by: Hong Xu <hong.xu at atmel.com>
> Tested-by: Elen Song <elen.song at atmel.com>
> CC: Albert Aribaud <albert.u.boot at aribaud.net>
> ---
> Since V1
>     Modified copyright line
>     Fix for compiling warnings
>     Changed the way to use CONFIG_SYS_CACHELINE_SIZE
>     When unaligned buffer detected, emit ERROR instead of WARNING
> 
>     Do not make a common v5,v6 cache file. It seems arm946 is lack of
>     Test-and-Clean DCache operation. And maybe more differents...
> 
>  arch/arm/cpu/arm926ejs/Makefile |    2 +-
>  arch/arm/cpu/arm926ejs/cache.c  |  135 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 136 insertions(+), 1 deletions(-)
>  create mode 100644 arch/arm/cpu/arm926ejs/cache.c
> 
> diff --git a/arch/arm/cpu/arm926ejs/Makefile b/arch/arm/cpu/arm926ejs/Makefile
> index 930e0d1..5b5f330 100644
> --- a/arch/arm/cpu/arm926ejs/Makefile
> +++ b/arch/arm/cpu/arm926ejs/Makefile
> @@ -26,7 +26,7 @@ include $(TOPDIR)/config.mk
>  LIB	= $(obj)lib$(CPU).o
>  
>  START	= start.o
> -COBJS	= cpu.o
> +COBJS	= cpu.o cache.o
>  
>  SRCS	:= $(START:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c)
>  OBJS	:= $(addprefix $(obj),$(COBJS) $(SOBJS))
> diff --git a/arch/arm/cpu/arm926ejs/cache.c b/arch/arm/cpu/arm926ejs/cache.c
> new file mode 100644
> index 0000000..756c9b1
> --- /dev/null
> +++ b/arch/arm/cpu/arm926ejs/cache.c
> @@ -0,0 +1,135 @@
> +/*
> + * (C) Copyright 2011 Atmel Corporation
> + *
> + * See file CREDITS for list of people who contributed to this
> + * project.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + * MA 02111-1307 USA
> + */
> +
> +#include <common.h>
> +
> +#define FLUSH_CACHE_OP		0
> +#define INVALIDATE_CACHE_OP	1
> +
> +#ifndef CONFIG_SYS_CACHELINE_SIZE
> +/*
> + * ARM926EJ-S Technical Reference Manual, Chap 2.3.1 Table 2-9
> + * only b'10, aka. 32 bytes cache line len is valid
> + */
> +#define CONFIG_SYS_CACHELINE_SIZE 32
> +#endif
> +
> +#ifndef CONFIG_SYS_DCACHE_OFF
> +/*
> + * Flush or Invalidate DCache respectively
> + */
> +static void cache_range_op(unsigned long start, unsigned long stop, int op)
> +{
> +	unsigned long mva;
> +
> +	if (op > INVALIDATE_CACHE_OP) {
> +		printf("ERROR: %s - Invalid cache operation, op: %d!\n",
> +			__func__, op);
> +		return;
> +	}
> +
> +	mva = start;
> +	if ((mva & (CONFIG_SYS_CACHELINE_SIZE - 1)) != 0) {
> +		printf("ERROR: %s op: %d - start address 0x%08lx not aligned "
> +			"to cache line size(%d bytes)\n", __func__, op, start,
> +			CONFIG_SYS_CACHELINE_SIZE);
> +		/* Round up starting address */
> +		mva = (mva | (CONFIG_SYS_CACHELINE_SIZE - 1)) + 1;
> +	}
> +	if ((stop & (CONFIG_SYS_CACHELINE_SIZE - 1)) != 0) {
> +		printf("ERROR: %s op: %d - stop address 0x%08lx not aligned "
> +			"to cache line size(%d bytes)\n", __func__, op, stop,
> +			CONFIG_SYS_CACHELINE_SIZE);
> +		/* Round down ending address */
> +		stop &= ~(CONFIG_SYS_CACHELINE_SIZE - 1);
> +	}
> +
> +	while (mva < stop) {
> +		if (op == FLUSH_CACHE_OP)
> +			asm("mcr p15, 0, %0, c7, c14, 1\n" : : "r"(mva));
> +		else
> +			asm("mcr p15, 0, %0, c7, c6, 1\n" : : "r"(mva));
> +
> +		mva += CONFIG_SYS_CACHELINE_SIZE;
> +	}
> +
> +	/* Drain WB if necessary */
> +	if (op == FLUSH_CACHE_OP)
> +		asm("mcr p15, 0, %0, c7, c10, 4\n" : : "r" (0));
> +}
> +
> +/*
> + * The buffer range to be flushed is [start, stop)
> + */
> +void flush_dcache_range(unsigned long start, unsigned long stop)
> +{
> +	cache_range_op(start, stop, FLUSH_CACHE_OP);
> +}
> +
> +void flush_dcache_all(void)
> +{
> +	/*
> +	 * ARM926EJ-S Technical Reference Manual, Chap 2.3.8
> +	 * Clean & Invalidate the entire DCache
> +	 */
> +	asm("0: mrc p15, 0, r15, c7, c14, 3\n\t" "bne 0b\n" : : : "memory");
> +	/* Drain WB */
> +	asm("mcr p15, 0, %0, c7, c10, 4\n" : : "r" (0));

While looking at the manuals for the armv5 compatibility I stumbled
upon the following in Chapter 2.3.8. Are you sure your flush_dcache_all
implementation is correct? I suspect the above is flushing only one
line?

"The test, clean, and invalidate DCache instruction is the same as test
and clean DCache,
except that when the entire cache has been cleaned, it is invalidated.
This means that
you can use the following loop to clean and invalidate the entire
DCache:

tci_loop:     MRC p15, 0, r15, c7, c14, 3
              BNE tci_loop
"
best regards,
Aneesh