Re: [U-Boot] [PATCH] armv7:cache: D cache line size read method

Hi Lukasz,

On 12/08/2011 10:24, Lukasz Majewski wrote:

This commit adds support for reading the D cache line size for armv7 architecture.

The get_dcache_line_size() function is supposed to work in conjunction with memalign call to provide D cache aligned DMA buffers.

Signed-off-by: Lukasz Majewskil.majewski@samsung.com Signed-off-by: Kyungmin Parkkyungmin.park@samsung.com CC: Aneesh Vaneesh@ti.com CC: Albert ARIBAUDalbert.u.boot@aribaud.net

---

arch/arm/cpu/armv7/cache_v7.c | 25 +++++++++++++++++++++++++ include/common.h | 1 + 2 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/arch/arm/cpu/armv7/cache_v7.c b/arch/arm/cpu/armv7/cache_v7.c index 3e1e1bf..bd0b1a8 100644 --- a/arch/arm/cpu/armv7/cache_v7.c +++ b/arch/arm/cpu/armv7/cache_v7.c @@ -246,6 +246,21 @@ static void v7_inval_tlb(void) CP15ISB; }

+/* Read the cache line size (bytes) */ +static int v7_dcache_line_size(void) +{

• u32 ccsidr, log2_line_len;
• ccsidr = get_ccsidr();
• log2_line_len = ((ccsidr& CCSIDR_LINE_SIZE_MASK)>>

• 		CCSIDR_LINE_SIZE_OFFSET) + 2;
  

• /* Converting from words to bytes */
• log2_line_len += 2;
• return 1<< log2_line_len;

+}

• void invalidate_dcache_all(void) { v7_maint_dcache_all(ARMV7_DCACHE_INVAL_ALL);

@@ -303,6 +318,11 @@ void flush_cache(unsigned long start, unsigned long size) { flush_dcache_range(start, start + size); }

+int get_dcache_line_size(void) +{

• return v7_dcache_line_size();

+} #else /* #ifndef CONFIG_SYS_DCACHE_OFF */ void invalidate_dcache_all(void) { @@ -327,6 +347,11 @@ void arm_init_before_mmu(void) void flush_cache(unsigned long start, unsigned long size) { }

+int get_dcache_line_size(void) +{

• return 0;

+} #endif /* #ifndef CONFIG_SYS_DCACHE_OFF */

#ifndef CONFIG_SYS_ICACHE_OFF diff --git a/include/common.h b/include/common.h index 12a1074..b535300 100644 --- a/include/common.h +++ b/include/common.h @@ -622,6 +622,7 @@ void flush_dcache_range(unsigned long start, unsigned long stop); void invalidate_dcache_range(unsigned long start, unsigned long stop); void invalidate_dcache_all(void); void invalidate_icache_all(void); +int get_dcache_line_size(void);

/* arch/$(ARCH)/lib/ticks.S */ unsigned long long get_ticks(void);

I like the idea of a global cache line accessor, but:

1) Does it have to be a function? I don't know cache implementations where line size is not a constant, and a function might be overkill.

2) If it has to be a function, then I'd rather have the function introduced in arch/arm/lib/cache.c as a weak function returning 32, with armv7 providing a replacement.

Aneesh, that patch could affect your patch series as the magic 32 could then come from this weak function rather than be hard-coded.

Amicalement,