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

Abhishek Sahu
2017-07-19T11:31:16Z

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@codeaurora.org>
>> ---
>> 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