Re: [PATCH v2 2/3] dmaengine: qcom: bam_dma: wrapper functions for command descriptor

[Abhishek Sahu]

On 2017-07-19 15:39, Vinod Koul wrote:
> On Mon, Jun 26, 2017 at 06:19:28PM +0530, Abhishek Sahu wrote:
> > QCOM BAM also supports command descriptor which allows the SW to
> > create descriptors of type command which does not generate any
> > data transmissions but configures registers in the peripheral.
> > In command descriptor the 32bit address point to the start of
> > the command block which holds the command elements and the
> > 16bit size define the size of the command block.
> >
> > Each Command Element is structured by 4 words:
> >     Write command: address + cmd
> >                    register data
> >                    register mask
> >                    reserved
> >
> >     Read command: address + cmd
> >                   read data result address,
> >                   reserved
> >                   reserved
> >
> > This patch creates a new header file for BAM driver which contains the
> > structures and wrapper functions for command descriptor. This file 
> > will
> > be used by different QCOM peripheral drivers for forming the command
> > descriptor
> >
> > Signed-off-by: Abhishek Sahu <absahu@xxxxxxxxxxxxxx>
> > ---
> >  include/linux/dma/qcom_bam_dma.h | 79 
> > ++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 79 insertions(+)
> >  create mode 100644 include/linux/dma/qcom_bam_dma.h
> >
> > diff --git a/include/linux/dma/qcom_bam_dma.h 
> > b/include/linux/dma/qcom_bam_dma.h
> > new file mode 100644
> > index 0000000..077d43a
> > --- /dev/null
> > +++ b/include/linux/dma/qcom_bam_dma.h
> > @@ -0,0 +1,79 @@
> > +/*
> > + * Copyright (c) 2016-2017, The Linux Foundation. All rights 
> > reserved.
> > + *
> > + * This software is licensed under the terms of the GNU General 
> > Public
> > + * License version 2, as published by the Free Software Foundation, 
> > and
> > + * may be copied, distributed, and modified under those terms.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#ifndef _QCOM_BAM_DMA_H
> > +#define _QCOM_BAM_DMA_H
> > +
> > +#include <asm/byteorder.h>
> > +
> > +/*
> > + * This data type corresponds to the native Command Element
> > + * supported by BAM DMA Engine.
> > + *
> > + * @cmd_and_addr - upper 8 bits command and lower 24 bits register 
> > address.
> > + * @data - for write command: content to be written into peripheral 
> > register.
> > + *	   for read command: dest addr to write peripheral register value.
> > + * @mask - register mask.
> > + * @reserved - for future usage.
> > + *
> > + */
> > +struct bam_cmd_element {
> > +	__le32 cmd_and_addr;
> > +	__le32 data;
> > +	__le32 mask;
> > +	__le32 reserved;
> > +};
> > +
> > +/*
> > + * This enum indicates the command type in a command element
> > + */
> > +enum bam_command_type {
> > +	BAM_WRITE_COMMAND = 0,
> > +	BAM_READ_COMMAND,
> > +};
> > +
> > +/*
> > + * prep_bam_ce_le32 - Wrapper function to prepare a single BAM 
> > command
> > + * element with the data already in le32 format.
> > + *
> > + * @bam_ce: bam command element
> > + * @addr: target address
> > + * @cmd: BAM command
> > + * @data: actual data for write and dest addr for read in le32
> > + */
> > +static inline void
> > +bam_prep_ce_le32(struct bam_cmd_element *bam_ce, u32 addr,
> > +		 enum bam_command_type cmd, __le32 data)
> > +{
> > +	bam_ce->cmd_and_addr =
> > +		cpu_to_le32((addr & 0xffffff) | ((cmd & 0xff) << 24));
> > +	bam_ce->data = data;
> > +	bam_ce->mask = cpu_to_le32(0xffffffff);
> > +}
>
> Is this being used by clients?

 Yes Vinod. This wrapper function will be called by clients.
 NAND driver will call this function for reading/writing
 registers from BAM DMA.

 Following is the NAND client driver patch
 http://www.spinics.net/lists/devicetree/msg183713.html

> > +
> > +/*
> > + * bam_prep_ce - Wrapper function to prepare a single BAM command 
> > element
> > + * with the data.
> > + *
> > + * @bam_ce: BAM command element
> > + * @addr: target address
> > + * @cmd: BAM command
> > + * @data: actual data for write and dest addr for read
> > + */
> > +static inline void
> > +bam_prep_ce(struct bam_cmd_element *bam_ce, u32 addr,
> > +	    enum bam_command_type cmd, u32 data)
> > +{
> > +	bam_prep_ce_le32(bam_ce, addr, cmd, cpu_to_le32(data));
> > +}
> > +#endif
> > --
> > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a 
> > member of Code Aurora Forum, hosted by The Linux Foundation

--
Abhishek Sahu