Re: [PATCH 12/13] ARM: ARM64: implement dma_alloc_writecombine()

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 26.09.24 15:15, Sascha Hauer wrote:
> We currently only have dma_alloc_writecombine() for aarch32. Implement
> it for aarch64 as it is useful for mapping framebuffer memory.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

Thanks,
Ahmad

> ---
>  arch/arm/cpu/mmu_64.c | 11 ++++++++++-
>  arch/arm/cpu/mmu_64.h | 15 ++++++---------
>  2 files changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c
> index 7c7834201b..7854f71f4c 100644
> --- a/arch/arm/cpu/mmu_64.c
> +++ b/arch/arm/cpu/mmu_64.c
> @@ -24,6 +24,8 @@
>  
>  #include "mmu_64.h"
>  
> +#define ARCH_MAP_WRITECOMBINE  ((unsigned)-1)
> +
>  static uint64_t *get_ttb(void)
>  {
>  	return (uint64_t *)get_ttbr(current_el());
> @@ -172,9 +174,11 @@ static unsigned long get_pte_attrs(unsigned flags)
>  	case MAP_CACHED:
>  		return CACHED_MEM;
>  	case MAP_UNCACHED:
> -		return attrs_uncached_mem();
> +		return attrs_xn() | UNCACHED_MEM;
>  	case MAP_FAULT:
>  		return 0x0;
> +	case ARCH_MAP_WRITECOMBINE:
> +		return attrs_xn() | MEM_ALLOC_WRITECOMBINE;
>  	default:
>  		return ~0UL;
>  	}
> @@ -295,6 +299,11 @@ void dma_flush_range(void *ptr, size_t size)
>  	v8_flush_dcache_range(start, end);
>  }
>  
> +void *dma_alloc_writecombine(size_t size, dma_addr_t *dma_handle)
> +{
> +	return dma_alloc_map(size, dma_handle, ARCH_MAP_WRITECOMBINE);
> +}
> +
>  static void init_range(size_t total_level0_tables)
>  {
>  	uint64_t *ttb = get_ttb();
> diff --git a/arch/arm/cpu/mmu_64.h b/arch/arm/cpu/mmu_64.h
> index e3959e4407..d3c39dabb5 100644
> --- a/arch/arm/cpu/mmu_64.h
> +++ b/arch/arm/cpu/mmu_64.h
> @@ -8,22 +8,19 @@
>  #define UNCACHED_MEM    (PTE_BLOCK_MEMTYPE(MT_DEVICE_nGnRnE) | \
>  			 PTE_BLOCK_OUTER_SHARE | \
>  			 PTE_BLOCK_AF)
> +#define MEM_ALLOC_WRITECOMBINE	(PTE_BLOCK_MEMTYPE(MT_NORMAL_NC) | \
> +				 PTE_BLOCK_OUTER_SHARE | \
> +				 PTE_BLOCK_AF)
>  
> -static inline unsigned long attrs_uncached_mem(void)
> +static inline unsigned long attrs_xn(void)
>  {
> -	unsigned long attrs = UNCACHED_MEM;
> -
>  	switch (current_el()) {
>  	case 3:
>  	case 2:
> -		attrs |= PTE_BLOCK_UXN;
> -		break;
> +		return PTE_BLOCK_UXN;
>  	default:
> -		attrs |= PTE_BLOCK_UXN | PTE_BLOCK_PXN;
> -		break;
> +		return PTE_BLOCK_UXN | PTE_BLOCK_PXN;
>  	}
> -
> -	return attrs;
>  }
>  
>  /*
> 


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