[PATCH V2 1/5] common: bouncebuf: Permit passing custom alignment check function

[Jaehoon Chung]

On 4/4/20 7:45 PM, Marek Vasut wrote:
> Add extended version of the bounce_buffer_start(), which permits passing in
> a custom alignment checker function for the buffer. This is useful e.g. on
> systems with various DMA restrictions and where the checker function might
> be more complex than a simple CPU cache alignment check.
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas at gmail.com>
> Cc: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
> Cc: Masahiro Yamada <yamada.masahiro at socionext.com>
> Cc: Peng Fan <peng.fan at nxp.com>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Tom Rini <trini at konsulko.com>
> ---
> V2: No change
> ---
>  common/bouncebuf.c  | 20 +++++++++++++++-----
>  include/bouncebuf.h | 15 +++++++++++++++
>  2 files changed, 30 insertions(+), 5 deletions(-)
> 
> diff --git a/common/bouncebuf.c b/common/bouncebuf.c
> index 614eb36c78..0ace152b98 100644
> --- a/common/bouncebuf.c
> +++ b/common/bouncebuf.c
> @@ -31,17 +31,19 @@ static int addr_aligned(struct bounce_buffer *state)
>  	return 1;
>  }
>  
> -int bounce_buffer_start(struct bounce_buffer *state, void *data,
> -			size_t len, unsigned int flags)
> +int bounce_buffer_start_extalign(struct bounce_buffer *state, void *data,
> +				 size_t len, unsigned int flags,
> +				 size_t alignment,
> +				 int (*addr_is_aligned)(struct bounce_buffer *state))
>  {
>  	state->user_buffer = data;
>  	state->bounce_buffer = data;
>  	state->len = len;
> -	state->len_aligned = roundup(len, ARCH_DMA_MINALIGN);
> +	state->len_aligned = roundup(len, alignment);
>  	state->flags = flags;
>  
> -	if (!addr_aligned(state)) {
> -		state->bounce_buffer = memalign(ARCH_DMA_MINALIGN,
> +	if (!addr_is_aligned(state)) {

how about checking condition whether addr_is_aligned function is present or not at here?

Best Regards,
Jaehoon Chung

> +		state->bounce_buffer = memalign(alignment,
>  						state->len_aligned);
>  		if (!state->bounce_buffer)
>  			return -ENOMEM;
> @@ -62,6 +64,14 @@ int bounce_buffer_start(struct bounce_buffer *state, void *data,
>  	return 0;
>  }
>  
> +int bounce_buffer_start(struct bounce_buffer *state, void *data,
> +			size_t len, unsigned int flags)
> +{
> +	return bounce_buffer_start_extalign(state, data, len, flags,
> +					    ARCH_DMA_MINALIGN,
> +					    addr_aligned);
> +}
> +
>  int bounce_buffer_stop(struct bounce_buffer *state)
>  {
>  	if (state->flags & GEN_BB_WRITE) {
> diff --git a/include/bouncebuf.h b/include/bouncebuf.h
> index fd9b0f3b28..7427bd12e2 100644
> --- a/include/bouncebuf.h
> +++ b/include/bouncebuf.h
> @@ -62,6 +62,21 @@ struct bounce_buffer {
>   */
>  int bounce_buffer_start(struct bounce_buffer *state, void *data,
>  			size_t len, unsigned int flags);
> +
> +/**
> + * bounce_buffer_start() -- Start the bounce buffer session with external align check function
> + * state:	stores state passed between bounce_buffer_{start,stop}
> + * data:	pointer to buffer to be aligned
> + * len:		length of the buffer
> + * flags:	flags describing the transaction, see above.
> + * alignment:	alignment of the newly allocated bounce buffer
> + * addr_is_aligned: function for checking the alignment instead of the default one
> + */
> +int bounce_buffer_start_extalign(struct bounce_buffer *state, void *data,
> +				 size_t len, unsigned int flags,
> +				 size_t alignment,
> +				 int (*addr_is_aligned)(struct bounce_buffer *state));
> +
>  /**
>   * bounce_buffer_stop() -- Finish the bounce buffer session
>   * state:	stores state passed between bounce_buffer_{start,stop}
>