Re: [PATCH v9 1/7] cdx: add the cdx bus driver

Greg KH
2023-03-09T13:08:10Z

On Tue, Mar 07, 2023 at 06:49:11PM +0530, Nipun Gupta wrote:
> Introduce AMD CDX bus, which provides a mechanism for scanning
> and probing CDX devices. These devices are memory mapped on
> system bus for Application Processors(APUs).
>
> CDX devices can be changed dynamically in the Fabric and CDX
> bus interacts with CDX controller to rescan the bus and
> rediscover the devices.
>
> Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
> Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
> Tested-by: Nikhil Agarwal <nikhil.agarwal@amd.com>
> ---
> Documentation/ABI/testing/sysfs-bus-cdx | 12 +
> MAINTAINERS | 7 +
> drivers/Kconfig | 2 +
> drivers/Makefile | 1 +
> drivers/cdx/Kconfig | 17 +
> drivers/cdx/Makefile | 8 +
> drivers/cdx/cdx.c | 407 ++++++++++++++++++++++++
> drivers/cdx/cdx.h | 62 ++++
> include/linux/cdx/cdx_bus.h | 147 +++++++++
> include/linux/mod_devicetable.h | 15 +
> scripts/mod/devicetable-offsets.c | 4 +
> scripts/mod/file2alias.c | 12 +
> 12 files changed, 694 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-bus-cdx
> create mode 100644 drivers/cdx/Kconfig
> create mode 100644 drivers/cdx/Makefile
> create mode 100644 drivers/cdx/cdx.c
> create mode 100644 drivers/cdx/cdx.h
> create mode 100644 include/linux/cdx/cdx_bus.h
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-cdx b/Documentation/ABI/testing/sysfs-bus-cdx
> new file mode 100644
> index 000000000000..063d1a0dd866
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-cdx
> @@ -0,0 +1,12 @@
> +What: /sys/bus/cdx/rescan
> +Date: March 2023
> +Contact: nipun.gupta@amd.com
> +Description:
> + Writing a non-zero value to this file cause rescan of the bus
> + and devices on the CDX bus. Any new devices are scanned and
> + added to the list of Linux devices and any devices removed are
> + also deleted from Linux.
> +
> + For example::
> +
> + # echo 1 > /sys/bus/cdx/rescan

See my comments on patch 7/7 about "non-zero" not being a good idea.

thanks,

greg k-h