[U-Boot] [PATCH v2 2/2] MIPS: add dma-mapping.h implementation

[Daniel Schwierzeck]

Am Mo., 10. Juni 2019 um 20:05 Uhr schrieb Ramon Fried <rfried.dev at gmail.com>:
>
> add implementation for dma_alloc_coherent(),
> dma_free_coherent(), dma_map_single() and dma_free_single()
>
> Signed-off-by: Ramon Fried <rfried.dev at 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.dev at 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