[U-Boot-Users] [PATCH] SPARC: CFI flash_read64 is defined a weak function.

Hello Wolfgang and Stefan,
SPARC has implemented __raw_readq, it reads 64-bit from any 32-bit address. SPARC CPUs implement flash_read64 which calls __raw_readq.
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>.
This patch is also available at ftp://ftp.gaisler.com/gaisler.com/uboot/patches.
Best Regards, Daniel Hellstrom
Signed-off-by: Daniel Hellstrom daniel@gaisler.com --- drivers/mtd/cfi_flash.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c index f04c72d..a55afc9 100644 --- a/drivers/mtd/cfi_flash.c +++ b/drivers/mtd/cfi_flash.c @@ -239,12 +239,14 @@ static u32 flash_read32(void *addr) return __raw_readl(addr); }
-static u64 flash_read64(void *addr) +static u64 __flash_read64(void *addr) { /* No architectures currently implement __raw_readq() */ return *(volatile u64 *)addr; }
+u64 flash_read64(void *addr)__attribute__((weak, alias("__flash_read64"))); + /*----------------------------------------------------------------------- */ #if defined(CFG_ENV_IS_IN_FLASH) || defined(CFG_ENV_ADDR_REDUND) || (CFG_MONITOR_BASE >= CFG_FLASH_BASE)

On Friday 28 March 2008, Daniel Hellstrom wrote:
SPARC has implemented __raw_readq, it reads 64-bit from any 32-bit address. SPARC CPUs implement flash_read64 which calls __raw_readq.
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>.
Added to cfi-flash repository. Thanks.
Best regards, Stefan
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participants (2)
-
Daniel Hellstrom
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Stefan Roese