linux-kernel - Re: [PATCH v2] memory: dfl-emif: add the DFL EMIF private feature driver

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Date:   Sun, 20 Sep 2020 18:35:38 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Xu Yilun <yilun.xu@...el.com>
Cc:     linux-kernel@...r.kernel.org, trix@...hat.com,
        matthew.gerlach@...ux.intel.com, russell.h.weight@...el.com,
        lgoncalv@...hat.com, hao.wu@...el.com, mdf@...nel.org
Subject: Re: [PATCH v2] memory: dfl-emif: add the DFL EMIF private feature
 driver

On Wed, Sep 16, 2020 at 01:37:02PM +0800, Xu Yilun wrote:
> This driver is for the EMIF private feature implemented under FPGA
> Device Feature List (DFL) framework. It is used to expose memory
> interface status information as well as memory clearing control.
> 
> The purpose of memory clearing block is to zero out all private memory
> when FPGA is to be reprogrammed. This gives users a reliable method to
> prevent potential data leakage.
> 
> Signed-off-by: Xu Yilun <yilun.xu@...el.com>
> Signed-off-by: Russ Weight <russell.h.weight@...el.com>
> ---
> v2: Adjust the position of this driver in Kconfig.
>     Improves the name of the Kconfig option.
>     Change the include dfl-bus.h to dfl.h, cause the previous patchset
>      renames the file.
>     Some minor fixes and comment improvement.
> ---
>  .../ABI/testing/sysfs-bus-dfl-devices-emif         |  25 +++
>  drivers/memory/Kconfig                             |   9 +
>  drivers/memory/Makefile                            |   2 +
>  drivers/memory/dfl-emif.c                          | 207 +++++++++++++++++++++
>  4 files changed, 243 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
>  create mode 100644 drivers/memory/dfl-emif.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif b/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> new file mode 100644
> index 0000000..56f97dc
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> @@ -0,0 +1,25 @@
> +What:		/sys/bus/dfl/devices/dfl_dev.X/infX_cal_fail
> +Date:		Sep 2020
> +KernelVersion:	5.10
> +Contact:	Xu Yilun <yilun.xu@...el.com>
> +Description:	Read-only. It indicates if the calibration failed on this
> +		memory interface. "1" for calibration failure, "0" for OK.
> +		Format: %u
> +
> +What:		/sys/bus/dfl/devices/dfl_dev.X/infX_init_done
> +Date:		Sep 2020
> +KernelVersion:	5.10
> +Contact:	Xu Yilun <yilun.xu@...el.com>
> +Description:	Read-only. It indicates if the initialization completed on
> +		this memory interface. "1" for initialization complete, "0"
> +		for not yet.
> +		Format: %u
> +
> +What:		/sys/bus/dfl/devices/dfl_dev.X/infX_clear
> +Date:		Sep 2020
> +KernelVersion:	5.10
> +Contact:	Xu Yilun <yilun.xu@...el.com>
> +Description:	Write-only. Writing "1" to this file will zero out all memory
> +		data in this memory interface. Writing of other values is
> +		invalid.
> +		Format: %u
> diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
> index 8072204..8dc819f 100644
> --- a/drivers/memory/Kconfig
> +++ b/drivers/memory/Kconfig
> @@ -136,6 +136,15 @@ config TI_EMIF_SRAM
>  	  sequence so this driver provides several relocatable PM functions
>  	  for the SoC PM code to use.
>  
> +config FPGA_DFL_EMIF
> +	tristate "FPGA DFL EMIF Driver"
> +	depends on FPGA_DFL && HAS_IOMEM
> +	help
> +	  This driver is for the EMIF private feature implemented under
> +	  FPGA Device Feature List (DFL) framework. It is used to expose
> +	  memory interface status information as well as memory clearing
> +	  control.
> +
>  config MVEBU_DEVBUS
>  	bool "Marvell EBU Device Bus Controller"
>  	default y if PLAT_ORION
> diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
> index e71cf7b..0afbf39 100644
> --- a/drivers/memory/Makefile
> +++ b/drivers/memory/Makefile
> @@ -39,3 +39,5 @@ $(obj)/ti-emif-asm-offsets.h: $(obj)/emif-asm-offsets.s FORCE
>  
>  targets += emif-asm-offsets.s
>  clean-files += ti-emif-asm-offsets.h
> +
> +obj-$(CONFIG_FPGA_DFL_EMIF)	+= dfl-emif.o

It there is going to be a resend: this as well has to go next to CONFIG_TI_EMIF_SRAM.

Otherwise I will fix it up while applying.

Best regards,
Krzysztof