[U-Boot] [RFC] command/cache: Add flush_cache command

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi York,

On Tue, 19 Mar 2013 13:29:52 -0700, York Sun <yorksun@freescale.com>
wrote:

> When we need the copied code/data in the main memory, we can flush the
> cache now. It uses the existing function flush_cache. Syntax is
> 
> flush_cache <addr> <size>
> 
> The addr and size are given in hexadecimal. Like memory command, there is
> no sanity check for the parameters.
> 
> Signed-off-by: York Sun <yorksun@freescale.com>
> ---
>  common/cmd_cache.c |   30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/common/cmd_cache.c b/common/cmd_cache.c
> index 5512f92..93b7337 100644
> --- a/common/cmd_cache.c
> +++ b/common/cmd_cache.c
> @@ -94,6 +94,29 @@ int do_dcache(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
>  	return 0;
>  }
>  
> +void __weak flush_cache(ulong addr, ulong size)
> +{
> +	puts("No arch specific flush_cache available!\n");
> +	/* please define arch specific flush_cache */
> +}
> +
> +int do_flush_cache(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
> +{
> +	ulong addr, size;
> +
> +	switch (argc) {
> +	case 3:
> +		addr = simple_strtoul(argv[1], NULL, 16);
> +		size = simple_strtoul(argv[2], NULL, 16);
> +		flush_cache(addr, size);
> +		break;
> +	default:
> +		return cmd_usage(cmdtp);
> +	}
> +	return 0;
> +
> +}
> +
>  static int parse_argv(const char *s)
>  {
>  	if (strcmp(s, "flush") == 0)
> @@ -120,3 +143,10 @@ U_BOOT_CMD(
>  	"[on, off, flush]\n"
>  	"    - enable, disable, or flush data (writethrough) cache"
>  );
> +
> +U_BOOT_CMD(
> +	flush_cache,   3,   0,     do_flush_cache,
> +	"flush cache for a range",
> +	"<addr> <size>\n"
> +	"    - flush cache for specificed range"
> +);

What's the point of this command exactly? I can see the point of range
flushes (and invalidates) in the code for drivers that use DMA, but as a
shell command, I fail to see the interest of it.

Amicalement,
-- 
Albert.