linux-kernel - Re: [PATCH V1 4/6] DCC: Added the sysfs entries for DCC(Data Capture and Compare) driver

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Message-ID: <YElWLqemavtXGlPd@builder.lan>
Date:   Wed, 10 Mar 2021 17:28:46 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Souradeep Chowdhury <schowdhu@...eaurora.org>
Cc:     Rob Herring <robh+dt@...nel.org>, Andy Gross <agross@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        sibis@...eaurora.org, saiprakash.ranjan@...eaurora.org,
        Rajendra Nayak <rnayak@...eaurora.org>, vkoul@...nel.org
Subject: Re: [PATCH V1 4/6] DCC: Added the sysfs entries for DCC(Data Capture
 and Compare) driver

On Wed 10 Mar 10:46 CST 2021, Souradeep Chowdhury wrote:

> The DCC is a DMA engine designed to store register values either in
> case of a system crash or in case of software triggers manually done
> by the user. Using DCC hardware and the sysfs interface of the driver
> the user can exploit various functionalities of DCC. The user can specify
> the register addresses, the values of which is stored by DCC in it's
> dedicated SRAM. The register addresses can be used either to read from,
> write to, first read and store value and then write or to loop. All these
> options can be exploited using the sysfs interface given to the user.
> Following are the sysfs interfaces exposed in DCC driver which are
> documented
> 1)trigger
> 2)config
> 3)config_write
> 4)config_reset
> 5)enable
> 6)rd_mod_wr
> 7)loop
> 
> Signed-off-by: Souradeep Chowdhury <schowdhu@...eaurora.org>
> ---
>  Documentation/ABI/testing/sysfs-driver-dcc | 74 ++++++++++++++++++++++++++++++
>  1 file changed, 74 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-driver-dcc
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-dcc b/Documentation/ABI/testing/sysfs-driver-dcc
> new file mode 100644
> index 0000000..7a855ca
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-dcc
> @@ -0,0 +1,74 @@
> +What:           /sys/bus/platform/devices/.../trigger
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file allows the software trigger to be enabled
> +		by the user through the sysfs interface.Through this
> +		interface the user can manually start a software trigger
> +		in dcc where by the dcc driver stores the current status
> +		of the specified registers in dcc sram.
> +
> +What:           /sys/bus/platform/devices/.../enable
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file allows the user to manually enable or
> +		disable dcc driver.The dcc hardware needs to be
> +		enabled before use.
> +
> +What:           /sys/bus/platform/devices/.../config
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file allows user to configure the register values
> +		along with addresses to the dcc driver.This register
> +		addresses are used to read from,write or loop through.
> +		To enable all these options separate sysfs files have
> +		are created.

Please describe the expected content of this file.

> +
> +What:           /sys/bus/platform/devices/.../config_write
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file allows user to write a value to the register
> +		address given as argument.The values are entered in the
> +		form of <register_address> <value>.

So it's just a generic 'write some user defined data to some user
defined register'? This doesn't sound like the typical way things are
exposed in sysfs.

> +
> +What:           /sys/bus/platform/devices/.../config_reset
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file is used to reset the configuration of
> +		a dcc driver to the default configuration.
> +
> +What:           /sys/bus/platform/devices/.../loop
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file is used to enter the loop count as dcc
> +		driver gives the option to loop multiple times on
> +		the same register and store the values for each
> +		loop.
> +
> +What:           /sys/bus/platform/devices/.../rd_mod_wr
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file is used to read the value of the register
> +		and then write the value given as an argument to the
> +		register address in config.The address argument should
> +		be given of the form <mask> <value>.
> +
> +What:           /sys/bus/platform/devices/.../ready
> +Date:           February 2021
> +Contact:        Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file is used to check the status of the dcc
> +		hardware if it's ready to take the inputs.
> +
> +What:		/sys/bus/platform/devices/.../curr_list
> +Date:		February 2021
> +Contact:	Souradeep Chowdhury <schowdhu@...eaurora.org>
> +Description:
> +		This file is used to configure the linkedlist data
> +		to be used while configuring addresses.

Please describe the format of this attr. Is it read/write?

Regards,
Bjorn

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