Re: [PATCH v4 5/7] riscv: mm: dma-noncoherent: Pass direction and operation to ALT_CMO_OP()

Heiko Stübner
2022-11-24T18:29:58Z

Am Donnerstag, 24. November 2022, 18:22:05 CET schrieb Prabhakar:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
>
> Pass direction and operation to ALT_CMO_OP() macro.
>
> This is in preparation for adding errata for the Andes CPU core.

can you provide more explanation why that is necessary please?
I guess you want to use different cache operations for some cases?

Thanks
Heiko

> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> ---
> RFC v3 -> v4
> * New patch
> ---
> arch/riscv/include/asm/cacheflush.h | 4 ++++
> arch/riscv/include/asm/errata_list.h | 8 ++++++--
> arch/riscv/mm/dma-noncoherent.c | 15 ++++++++++-----
> 3 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
> index f6fbe7042f1c..4a04d1be7c67 100644
> --- a/arch/riscv/include/asm/cacheflush.h
> +++ b/arch/riscv/include/asm/cacheflush.h
> @@ -8,6 +8,10 @@
>
> #include <linux/mm.h>
>
> +#define NON_COHERENT_SYNC_DMA_FOR_DEVICE 0
> +#define NON_COHERENT_SYNC_DMA_FOR_CPU 1
> +#define NON_COHERENT_DMA_PREP 2
> +
> static inline void local_flush_icache_all(void)
> {
> asm volatile ("fence.i" ::: "memory");
> diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
> index 2ba7e6e74540..48e899a8e7a9 100644
> --- a/arch/riscv/include/asm/errata_list.h
> +++ b/arch/riscv/include/asm/errata_list.h
> @@ -124,7 +124,7 @@ asm volatile(ALTERNATIVE( \
> #define THEAD_flush_A0 ".long 0x0275000b"
> #define THEAD_SYNC_S ".long 0x0190000b"
>
> -#define ALT_CMO_OP(_op, _start, _size, _cachesize) \
> +#define ALT_CMO_OP(_op, _start, _size, _cachesize, _dir, _ops) \
> asm volatile(ALTERNATIVE_2( \
> __nops(6), \
> "mv a0, %1\n\t" \
> @@ -146,7 +146,11 @@ asm volatile(ALTERNATIVE_2( \
> ERRATA_THEAD_CMO, CONFIG_ERRATA_THEAD_CMO) \
> : : "r"(_cachesize), \
> "r"((unsigned long)(_start) & ~((_cachesize) - 1UL)), \
> - "r"((unsigned long)(_start) + (_size)) \
> + "r"((unsigned long)(_start) + (_size)), \
> + "r"((unsigned long)(_start)), \
> + "r"((unsigned long)(_size)), \
> + "r"((unsigned long)(_dir)), \
> + "r"((unsigned long)(_ops)) \
> : "a0")
>
> #define THEAD_C9XX_RV_IRQ_PMU 17
> diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
> index d919efab6eba..e2b82034f504 100644
> --- a/arch/riscv/mm/dma-noncoherent.c
> +++ b/arch/riscv/mm/dma-noncoherent.c
> @@ -19,13 +19,16 @@ void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
>
> switch (dir) {
> case DMA_TO_DEVICE:
> - ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
> + ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size,
> + dir, NON_COHERENT_SYNC_DMA_FOR_DEVICE);
> break;
> case DMA_FROM_DEVICE:
> - ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
> + ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size,
> + dir, NON_COHERENT_SYNC_DMA_FOR_DEVICE);
> break;
> case DMA_BIDIRECTIONAL:
> - ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
> + ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size,
> + dir, NON_COHERENT_SYNC_DMA_FOR_DEVICE);
> break;
> default:
> break;
> @@ -42,7 +45,8 @@ void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
> break;
> case DMA_FROM_DEVICE:
> case DMA_BIDIRECTIONAL:
> - ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
> + ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size,
> + dir, NON_COHERENT_SYNC_DMA_FOR_CPU);
> break;
> default:
> break;
> @@ -53,7 +57,8 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
> {
> void *flush_addr = page_address(page);
>
> - ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
> + ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size,
> + 0, NON_COHERENT_DMA_PREP);
> }
>
> void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>