Am Mo., 10. Juni 2019 um 20:05 Uhr schrieb Ramon Fried <rfried....@gmail.com>:
>
> add implementation for dma_alloc_coherent(),
> dma_free_coherent(), dma_map_single() and dma_free_single()
>
> Signed-off-by: Ramon Fried <rfried....@gmail.com>
> ---
> v2: fix warning caused by missing casts.
>
> arch/mips/include/asm/dma-mapping.h | 48 +++++++++++++++++++++++++++++
> 1 file changed, 48 insertions(+)
> create mode 100644 arch/mips/include/asm/dma-mapping.h
>
> diff --git a/arch/mips/include/asm/dma-mapping.h
> b/arch/mips/include/asm/dma-mapping.h
> new file mode 100644
> index 0000000000..387427c13b
> --- /dev/null
> +++ b/arch/mips/include/asm/dma-mapping.h
> @@ -0,0 +1,48 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * (C) Copyright 2019
> + * Ramon Fried <rfried....@gmail.com>
> + */
> +
> +#ifndef __ASM_MIPS_DMA_MAPPING_H
> +#define __ASM_MIPS_DMA_MAPPING_H
> +
> +#include <linux/dma-direction.h>
> +#include <asm/addrspace.h>
> +#define dma_mapping_error(x, y) 0
> +
> +static inline void *dma_alloc_coherent(size_t len, unsigned long *handle)
> +{
> + void *vaddr = memalign(ARCH_DMA_MINALIGN,
> + ROUND(len, ARCH_DMA_MINALIGN));
> +
> + *handle = CPHYSADDR((unsigned long)vaddr);
> + return (void *)(CKSEG1ADDR((unsigned long)vaddr));
> +}
> +
> +static inline void dma_free_coherent(void *addr)
> +{
> + free((void *)CPHYSADDR((unsigned long)addr));
> +}
> +
> +static inline unsigned long dma_map_single(volatile void *vaddr, size_t len,
> + enum dma_data_direction dir)
> +{
> + unsigned long dma_addr = CPHYSADDR((unsigned long)vaddr);
> +
> + if (dir == DMA_TO_DEVICE)
> + flush_dcache_range((unsigned long)vaddr,
> + (unsigned long)vaddr + len);
> + if (dir == DMA_FROM_DEVICE)
> + invalidate_dcache_range((unsigned long)vaddr,
> + (unsigned long)vaddr + len);
> +
> + return dma_addr;
> +}
> +
> +static inline void dma_unmap_single(volatile void *vaddr, size_t len,
> + unsigned long paddr)
> +{
> +}
> +
> +#endif /* __ASM_MIPS_DMA_MAPPING_H */
> --
> 2.21.0
>
this doesn't match all requirements for a generic MIPS DMA interface.
It doesn't handle 64 Bit, coherent DMA or different kinds of memory
mapping. I would rather fix the macb driver to use existing U-Boot
API.
Alternatively you could port the generic dma-mapping.h from Linux so
you could either have empty function bodies or an architecture can
optionally provide an implementation.
--
- Daniel
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