[PATCH v8 04/28] spi: spi-mem: add spi_mem_dtr_supports_op()

[Sean Anderson <seanga2@gmail.com>]

On 4/1/21 3:31 PM, Pratyush Yadav wrote:
> spi_mem_default_supports_op() rejects DTR ops by default to ensure that
> the controller drivers that haven't been updated with DTR support
> continue to reject them. It also makes sure that controllers that don't
> support DTR mode at all (which is most of them at the moment) also
> reject them.
> 
> This means that controller drivers that want to support DTR mode can't
> use spi_mem_default_supports_op(). Driver authors have to roll their own
> supports_op() function and mimic the buswidth checks. See
> spi-cadence-quadspi.c for example. Or even worse, driver authors might
> skip it completely or get it wrong.
> 
> Add spi_mem_dtr_supports_op(). It provides a basic sanity check for DTR
> ops and performs the buswidth requirement check. Move the logic for
> checking buswidth in spi_mem_default_supports_op() to a separate
> function so the logic is not repeated twice.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> ---
>   drivers/spi/spi-mem.c | 22 +++++++++++++++++++---
>   include/spi-mem.h     |  2 ++
>   2 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index 541cd0e5a7..be1737a2c6 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -145,8 +145,8 @@ static int spi_check_buswidth_req(struct spi_slave *slave, u8 buswidth, bool tx)
>   	return -ENOTSUPP;
>   }
>   
> -bool spi_mem_default_supports_op(struct spi_slave *slave,
> -				 const struct spi_mem_op *op)
> +static bool spi_mem_check_buswidth(struct spi_slave *slave,
> +				   const struct spi_mem_op *op)
>   {
>   	if (spi_check_buswidth_req(slave, op->cmd.buswidth, true))
>   		return false;
> @@ -164,13 +164,29 @@ bool spi_mem_default_supports_op(struct spi_slave *slave,
>   				   op->data.dir == SPI_MEM_DATA_OUT))
>   		return false;
>   
> +	return true;
> +}
> +
> +bool spi_mem_dtr_supports_op(struct spi_slave *slave,
> +			     const struct spi_mem_op *op)
> +{
> +	if (op->cmd.nbytes != 2)
> +		return false;

Why does the command bytes need to be 2?

--Sean

> +
> +	return spi_mem_check_buswidth(slave, op);
> +}
> +EXPORT_SYMBOL_GPL(spi_mem_dtr_supports_op);
> +
> +bool spi_mem_default_supports_op(struct spi_slave *slave,
> +				 const struct spi_mem_op *op)
> +{
>   	if (op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr)
>   		return false;
>   
>   	if (op->cmd.nbytes != 1)
>   		return false;>   
> -	return true;
> +	return spi_mem_check_buswidth(slave, op);
>   }
>   EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
>   
> diff --git a/include/spi-mem.h b/include/spi-mem.h
> index dc53b517c1..37a9128c5b 100644
> --- a/include/spi-mem.h
> +++ b/include/spi-mem.h
> @@ -249,6 +249,8 @@ spi_controller_dma_unmap_mem_op_data(struct spi_controller *ctlr,
>   int spi_mem_adjust_op_size(struct spi_slave *slave, struct spi_mem_op *op);
>   
>   bool spi_mem_supports_op(struct spi_slave *slave, const struct spi_mem_op *op);
> +bool spi_mem_dtr_supports_op(struct spi_slave *slave,
> +			     const struct spi_mem_op *op);
>   
>   bool spi_mem_default_supports_op(struct spi_slave *slave,
>   				 const struct spi_mem_op *op);
>