Re: [PATCH v4 1/2] mtd: spi-nor: split spi_nor_spimem_xfer_data()

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 27 Jan 2020 23:28:05 +0300
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> wrote:

> spi_nor_spimem_xfer_data() being a helper function for the data reads/
> writes contains 3 fragments that depend on the data direction; and I'm
> going to add another one to call the SPI dirmap API...
> I think this function should be split so that the common fragments are
> put into 2 functions, spi_nor_spimem_bounce() and spi_nor_spimem_exec_op()
> called from spi_nor_spimem_{read|write}_data(), and the data direction
> dependent bits moved back into those read/write functions -- that way we
> would be able to avoid *goto*s otherwise needed in the next patch adding
> the  SPI dirmap support...
> 
> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> 
> ---
> Changes in version 4:
> - new patch.
> 
>  drivers/mtd/spi-nor/spi-nor.c |   91 +++++++++++++++++++++++-------------------
>  1 file changed, 51 insertions(+), 40 deletions(-)
> 
> Index: linux/drivers/mtd/spi-nor/spi-nor.c
> ===================================================================
> --- linux.orig/drivers/mtd/spi-nor/spi-nor.c
> +++ linux/drivers/mtd/spi-nor/spi-nor.c
> @@ -246,55 +246,45 @@ struct flash_info {
>  #define JEDEC_MFR(info)	((info)->id[0])
>  
>  /**
> - * spi_nor_spimem_xfer_data() - helper function to read/write data to
> - *                              flash's memory region
> + * spi_nor_spimem_bounce() - check if a bounce buffer is needed for the data
> + *                           transfer
>   * @nor:        pointer to 'struct spi_nor'
>   * @op:         pointer to 'struct spi_mem_op' template for transfer
>   *
> - * Return: number of bytes transferred on success, -errno otherwise
> + * If we have to use the bounce buffer, the data field in @op will be updated.
> + *
> + * Return: true if the bounce buffer is needed, false if not
>   */
> -static ssize_t spi_nor_spimem_xfer_data(struct spi_nor *nor,
> -					struct spi_mem_op *op)
> +static bool spi_nor_spimem_bounce(struct spi_nor *nor, struct spi_mem_op *op)
>  {
> -	bool usebouncebuf = false;
> -	void *rdbuf = NULL;
> -	const void *buf;
> -	int ret;
> -
> -	if (op->data.dir == SPI_MEM_DATA_IN)
> -		buf = op->data.buf.in;
> -	else
> -		buf = op->data.buf.out;
> -
> -	if (object_is_on_stack(buf) || !virt_addr_valid(buf))
> -		usebouncebuf = true;
> -
> -	if (usebouncebuf) {
> +	/* op->data.buf.in occupies the same memory as op->data.buf.out */
> +	if (object_is_on_stack(op->data.buf.in) ||
> +	    !virt_addr_valid(op->data.buf.in)) {
>  		if (op->data.nbytes > nor->bouncebuf_size)
>  			op->data.nbytes = nor->bouncebuf_size;
> -
> -		if (op->data.dir == SPI_MEM_DATA_IN) {
> -			rdbuf = op->data.buf.in;
> -			op->data.buf.in = nor->bouncebuf;
> -		} else {
> -			op->data.buf.out = nor->bouncebuf;
> -			memcpy(nor->bouncebuf, buf,
> -			       op->data.nbytes);
> -		}
> +		op->data.buf.in = nor->bouncebuf;
> +		return true;
>  	}
>  
> -	ret = spi_mem_adjust_op_size(nor->spimem, op);
> -	if (ret)
> -		return ret;
> -
> -	ret = spi_mem_exec_op(nor->spimem, op);
> -	if (ret)
> -		return ret;
> +	return false;
> +}
> +
> +/**
> + * spi_nor_spimem_exec_op() - execute a memory operation
> + * @nor:        pointer to 'struct spi_nor'
> + * @op:         pointer to 'struct spi_mem_op' template for transfer
> + *
> + * Return: 0 on success, -error otherwise.
> + */
> +static int spi_nor_spimem_exec_op(struct spi_nor *nor, struct spi_mem_op *op)
> +{
> +	int error;
>  
> -	if (usebouncebuf && op->data.dir == SPI_MEM_DATA_IN)
> -		memcpy(rdbuf, nor->bouncebuf, op->data.nbytes);
> +	error = spi_mem_adjust_op_size(nor->spimem, op);
> +	if (error)
> +		return error;
>  
> -	return op->data.nbytes;
> +	return spi_mem_exec_op(nor->spimem, op);
>  }
>  
>  /**
> @@ -315,6 +305,8 @@ static ssize_t spi_nor_spimem_read_data(
>  			   SPI_MEM_OP_ADDR(nor->addr_width, from, 1),
>  			   SPI_MEM_OP_DUMMY(nor->read_dummy, 1),
>  			   SPI_MEM_OP_DATA_IN(len, buf, 1));
> +	bool usebouncebuf;
> +	int error;
>  
>  	/* get transfer protocols. */
>  	op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(nor->read_proto);
> @@ -325,7 +317,16 @@ static ssize_t spi_nor_spimem_read_data(
>  	/* convert the dummy cycles to the number of bytes */
>  	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
>  
> -	return spi_nor_spimem_xfer_data(nor, &op);
> +	usebouncebuf = spi_nor_spimem_bounce(nor, &op);
> +
> +	error = spi_nor_spimem_exec_op(nor, &op);
> +	if (error)
> +		return error;
> +
> +	if (usebouncebuf)
> +		memcpy(buf, op.data.buf.in, op.data.nbytes);
> +
> +	return op.data.nbytes;
>  }
>  
>  /**
> @@ -364,6 +365,8 @@ static ssize_t spi_nor_spimem_write_data
>  			   SPI_MEM_OP_ADDR(nor->addr_width, to, 1),
>  			   SPI_MEM_OP_NO_DUMMY,
>  			   SPI_MEM_OP_DATA_OUT(len, buf, 1));
> +	bool usebouncebuf;
> +	int error;
>  
>  	op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(nor->write_proto);
>  	op.addr.buswidth = spi_nor_get_protocol_addr_nbits(nor->write_proto);
> @@ -372,7 +375,15 @@ static ssize_t spi_nor_spimem_write_data
>  	if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
>  		op.addr.nbytes = 0;
>  
> -	return spi_nor_spimem_xfer_data(nor, &op);
> +	usebouncebuf = spi_nor_spimem_bounce(nor, &op);
> +	if (usebouncebuf)
> +		memcpy(nor->bouncebuf, buf, op.data.nbytes);
> +
> +	error = spi_nor_spimem_exec_op(nor, &op);
> +	if (error)
> +		return error;
> +
> +	return op.data.nbytes;
>  }
>  
>  /**
> 
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