Re: [PATCH v2] MIPS: c-r4k: Invalidate BMIPS5000 ZSCM prefetch lines

Florian Fainelli
2020-03-11T20:54:32Z

On 2/7/20 2:33 PM, Kamal Dasu wrote:
> Zephyr secondary cache is 256KB, 128B lines. 32B sectors. A secondary cache
> line can contain two instruction cache lines (64B), or four data cache
> lines (32B). Hardware prefetch Cache detects stream access, and prefetches
> ahead of processor access. Add support to invalidate BMIPS5000 cpu zephyr
> secondary cache module (ZSCM) on DMA from device so that data returned is
> coherent during DMA read operations.
>
> Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>

Thomas can review and apply this patch? Thank you!

> ---
> arch/mips/mm/c-r4k.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
> index 5f3d0103b95d..acd9ef383e97 100644
> --- a/arch/mips/mm/c-r4k.c
> +++ b/arch/mips/mm/c-r4k.c
> @@ -901,6 +901,31 @@ static void r4k_dma_cache_wback_inv(unsigned long addr, unsigned long size)
> __sync();
> }
>
> +static void prefetch_cache_inv(unsigned long addr, unsigned long size)
> +{
> + unsigned int linesz = cpu_scache_line_size();
> + unsigned long addr0 = addr, addr1;
> +
> + addr0 &= ~(linesz - 1);
> + addr1 = (addr0 + size - 1) & ~(linesz - 1);
> +
> + protected_writeback_scache_line(addr0);
> + if (likely(addr1 != addr0))
> + protected_writeback_scache_line(addr1);
> + else
> + return;
> +
> + addr0 += linesz;
> + if (likely(addr1 != addr0))
> + protected_writeback_scache_line(addr0);
> + else
> + return;
> +
> + addr1 -= linesz;
> + if (likely(addr1 > addr0))
> + protected_writeback_scache_line(addr0);
> +}
> +
> static void r4k_dma_cache_inv(unsigned long addr, unsigned long size)
> {
> /* Catch bad driver code */
> @@ -908,6 +933,10 @@ static void r4k_dma_cache_inv(unsigned long addr, unsigned long size)
> return;
>
> preempt_disable();
> +
> + if (current_cpu_type() == CPU_BMIPS5000)
> + prefetch_cache_inv(addr, size);
> +
> if (cpu_has_inclusive_pcaches) {
> if (size >= scache_size) {
> if (current_cpu_type() != CPU_LOONGSON64)
>

--
Florian