Re: [PATCH 12/14] dma: mxs: Add header file to be shared with gpmi nand driver

[Vinod Koul <vkoul@kernel.org>]

On 09-04-19, 13:34, Sascha Hauer wrote:
> The mxs dma driver can do PIO transfers. A pointer to the PIO words
> to transfer is passed in the struct scatterlist * argument of
> dmaengine_prep_slave_sg(). It's quite ugly and non obvious to cast
> u32 * to struct scatterlist * each time when calling
> dmaengine_prep_slave_sg(), so add a static inline wrapper function
> to be called by the user along with a description what is going on.

Again after fixing subsystem tag to dmanegine: 

Acked-by: Vinod Koul <vkoul@kernel.org>

> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  drivers/dma/mxs-dma.c                      |  1 +
>  drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 36 +++++++++-------------
>  include/linux/dma/mxs-dma.h                | 21 +++++++++++++
>  3 files changed, 36 insertions(+), 22 deletions(-)
>  create mode 100644 include/linux/dma/mxs-dma.h
> 
> diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
> index ce92a3626ea4..62ee9328aea1 100644
> --- a/drivers/dma/mxs-dma.c
> +++ b/drivers/dma/mxs-dma.c
> @@ -24,6 +24,7 @@
>  #include <linux/of_device.h>
>  #include <linux/of_dma.h>
>  #include <linux/list.h>
> +#include <linux/dma/mxs-dma.h>
>  
>  #include <asm/irq.h>
>  
> diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> index a6e769afc89a..cf016ec0b1c6 100644
> --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> @@ -15,6 +15,7 @@
>  #include <linux/of.h>
>  #include <linux/of_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/dma/mxs-dma.h>
>  #include "gpmi-nand.h"
>  #include "gpmi-regs.h"
>  #include "bch-regs.h"
> @@ -913,9 +914,8 @@ static int gpmi_send_command(struct gpmi_nand_data *this)
>  		| BM_GPMI_CTRL0_ADDRESS_INCREMENT
>  		| BF_GPMI_CTRL0_XFER_COUNT(this->command_length);
>  	pio[1] = pio[2] = 0;
> -	desc = dmaengine_prep_slave_sg(channel,
> -					(struct scatterlist *)pio,
> -					ARRAY_SIZE(pio), DMA_TRANS_NONE, 0);
> +	desc = mxs_dmaengine_prep_pio(channel, pio, ARRAY_SIZE(pio),
> +				      DMA_TRANS_NONE, 0);
>  	if (!desc)
>  		return -EINVAL;
>  
> @@ -988,8 +988,8 @@ static int gpmi_send_data(struct gpmi_nand_data *this, const void *buf,
>  		| BF_GPMI_CTRL0_ADDRESS(address)
>  		| BF_GPMI_CTRL0_XFER_COUNT(len);
>  	pio[1] = 0;
> -	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)pio,
> -					ARRAY_SIZE(pio), DMA_TRANS_NONE, 0);
> +	desc = mxs_dmaengine_prep_pio(channel, pio, ARRAY_SIZE(pio),
> +				      DMA_TRANS_NONE, 0);
>  	if (!desc)
>  		return -EINVAL;
>  
> @@ -1025,9 +1025,8 @@ static int gpmi_read_data(struct gpmi_nand_data *this, void *buf, int len)
>  		| BF_GPMI_CTRL0_ADDRESS(BV_GPMI_CTRL0_ADDRESS__NAND_DATA)
>  		| BF_GPMI_CTRL0_XFER_COUNT(len);
>  	pio[1] = 0;
> -	desc = dmaengine_prep_slave_sg(channel,
> -					(struct scatterlist *)pio,
> -					ARRAY_SIZE(pio), DMA_TRANS_NONE, 0);
> +	desc = mxs_dmaengine_prep_pio(channel, pio, ARRAY_SIZE(pio),
> +				      DMA_TRANS_NONE, 0);
>  	if (!desc)
>  		return -EINVAL;
>  
> @@ -1083,10 +1082,8 @@ static int gpmi_send_page(struct gpmi_nand_data *this,  dma_addr_t payload,
>  	pio[4] = payload;
>  	pio[5] = auxiliary;
>  
> -	desc = dmaengine_prep_slave_sg(channel,
> -					(struct scatterlist *)pio,
> -					ARRAY_SIZE(pio), DMA_TRANS_NONE,
> -					DMA_CTRL_ACK);
> +	desc = mxs_dmaengine_prep_pio(channel, pio, ARRAY_SIZE(pio),
> +				      DMA_TRANS_NONE, DMA_CTRL_ACK);
>  	if (!desc)
>  		return -EINVAL;
>  
> @@ -1117,9 +1114,7 @@ static int gpmi_read_page(struct gpmi_nand_data *this,
>  		| BF_GPMI_CTRL0_ADDRESS(address)
>  		| BF_GPMI_CTRL0_XFER_COUNT(0);
>  	pio[1] = 0;
> -	desc = dmaengine_prep_slave_sg(channel,
> -				(struct scatterlist *)pio, 2,
> -				DMA_TRANS_NONE, 0);
> +	desc = mxs_dmaengine_prep_pio(channel, pio, 2, DMA_TRANS_NONE, 0);
>  	if (!desc)
>  		return -EINVAL;
>  
> @@ -1144,10 +1139,8 @@ static int gpmi_read_page(struct gpmi_nand_data *this,
>  	pio[3] = geo->page_size;
>  	pio[4] = payload;
>  	pio[5] = auxiliary;
> -	desc = dmaengine_prep_slave_sg(channel,
> -					(struct scatterlist *)pio,
> -					ARRAY_SIZE(pio), DMA_TRANS_NONE,
> -					DMA_CTRL_ACK);
> +	desc = mxs_dmaengine_prep_pio(channel, pio, ARRAY_SIZE(pio),
> +				      DMA_TRANS_NONE, DMA_CTRL_ACK);
>  	if (!desc)
>  		return -EINVAL;
>  
> @@ -1163,9 +1156,8 @@ static int gpmi_read_page(struct gpmi_nand_data *this,
>  		| BF_GPMI_CTRL0_XFER_COUNT(geo->page_size);
>  	pio[1] = 0;
>  	pio[2] = 0; /* clear GPMI_HW_GPMI_ECCCTRL, disable the BCH. */
> -	desc = dmaengine_prep_slave_sg(channel,
> -				(struct scatterlist *)pio, 3,
> -				DMA_TRANS_NONE, DMA_CTRL_ACK);
> +	desc = mxs_dmaengine_prep_pio(channel, pio, 3, DMA_TRANS_NONE,
> +				      DMA_CTRL_ACK);
>  	if (!desc)
>  		return -EINVAL;
>  
> diff --git a/include/linux/dma/mxs-dma.h b/include/linux/dma/mxs-dma.h
> new file mode 100644
> index 000000000000..092b2a7b92ac
> --- /dev/null
> +++ b/include/linux/dma/mxs-dma.h
> @@ -0,0 +1,21 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _MXS_DMA_H_
> +#define _MXS_DMA_H_
> +
> +#include <linux/dmaengine.h>
> +
> +/*
> + * The mxs dmaengine can do PIO transfers. We pass a pointer to the PIO words
> + * in the second argument to dmaengine_prep_slave_sg when the direction is
> + * set to DMA_TRANS_NONE. To make this clear and to prevent users from doing
> + * the error prone casting we have this wrapper function
> + */
> +static inline struct dma_async_tx_descriptor *mxs_dmaengine_prep_pio(
> +        struct dma_chan *chan, u32 *pio, unsigned int npio,
> +        enum dma_transfer_direction dir, unsigned long flags)
> +{
> +	return dmaengine_prep_slave_sg(chan, (struct scatterlist *)pio, npio,
> +				       dir, flags);
> +}
> +
> +#endif /* _MXS_DMA_H_ */
> -- 
> 2.20.1

-- 
~Vinod

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/