linux-kernel - Re: [PATCH v9 10/17] PCI: endpoint: Allow user to create sub-directory of 'EPF Device' directory

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Date:   Tue, 19 Jan 2021 12:34:05 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Arnd Bergmann <arnd@...db.de>, Jon Mason <jdmason@...zu.us>,
        Dave Jiang <dave.jiang@...el.com>,
        Allen Hubbe <allenbh@...il.com>,
        Tom Joseph <tjoseph@...ence.com>,
        Rob Herring <robh@...nel.org>, linux-pci@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-ntb@...glegroups.com
Subject: Re: [PATCH v9 10/17] PCI: endpoint: Allow user to create
 sub-directory of 'EPF Device' directory

[cc->to Greg]

On Mon, Jan 04, 2021 at 08:59:02PM +0530, Kishon Vijay Abraham I wrote:
> Documentation/PCI/endpoint/pci-endpoint-cfs.rst explains how a user
> has to create a directory in-order to create a 'EPF Device' that
> can be configured/probed by 'EPF Driver'.
> 
> Allow user to create a sub-directory of 'EPF Device' directory for
> any function specific attributes that has to be exposed to the user.

Maybe add an example sysfs path in the commit log?

Seems like there's restriction on hierarchy depth in sysfs, but I
don't remember the details.  Moved Greg to "to" in case he wants to
comment.

> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> ---
>  drivers/pci/endpoint/pci-ep-cfs.c | 23 +++++++++++++++++++++++
>  include/linux/pci-epf.h           |  3 +++
>  2 files changed, 26 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
> index 8f750961d6ab..f3a8b833b479 100644
> --- a/drivers/pci/endpoint/pci-ep-cfs.c
> +++ b/drivers/pci/endpoint/pci-ep-cfs.c
> @@ -490,7 +490,29 @@ static struct configfs_item_operations pci_epf_ops = {
>  	.release		= pci_epf_release,
>  };
>  
> +static struct config_group *pci_epf_type_make(struct config_group *group,
> +					      const char *name)
> +{
> +	struct pci_epf_group *epf_group = to_pci_epf_group(&group->cg_item);
> +	struct config_group *epf_type_group;
> +
> +	epf_type_group = pci_epf_type_add_cfs(epf_group->epf, group);
> +	return epf_type_group;
> +}
> +
> +static void pci_epf_type_drop(struct config_group *group,
> +			      struct config_item *item)
> +{
> +	config_item_put(item);
> +}
> +
> +static struct configfs_group_operations pci_epf_type_group_ops = {
> +	.make_group     = &pci_epf_type_make,
> +	.drop_item      = &pci_epf_type_drop,
> +};
> +
>  static const struct config_item_type pci_epf_type = {
> +	.ct_group_ops	= &pci_epf_type_group_ops,
>  	.ct_item_ops	= &pci_epf_ops,
>  	.ct_attrs	= pci_epf_attrs,
>  	.ct_owner	= THIS_MODULE,
> @@ -553,6 +575,7 @@ static struct config_group *pci_epf_make(struct config_group *group,
>  		goto free_name;
>  	}
>  
> +	epf->group = &epf_group->group;
>  	epf_group->epf = epf;
>  
>  	kfree(epf_name);
> diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
> index b241e7dd171f..6833e2160ef1 100644
> --- a/include/linux/pci-epf.h
> +++ b/include/linux/pci-epf.h
> @@ -9,6 +9,7 @@
>  #ifndef __LINUX_PCI_EPF_H
>  #define __LINUX_PCI_EPF_H
>  
> +#include <linux/configfs.h>
>  #include <linux/device.h>
>  #include <linux/mod_devicetable.h>
>  #include <linux/pci.h>
> @@ -128,6 +129,7 @@ struct pci_epf_bar {
>   *   EPC device
>   * @sec_epc_bar: represents the BAR of EPF device associated with secondary EPC
>   * @sec_epc_func_no: unique (physical) function number within the secondary EPC
> + * @group: configfs group associated with the EPF device
>   */
>  struct pci_epf {
>  	struct device		dev;
> @@ -150,6 +152,7 @@ struct pci_epf {
>  	struct list_head	sec_epc_list;
>  	struct pci_epf_bar	sec_epc_bar[6];
>  	u8			sec_epc_func_no;
> +	struct config_group	*group;
>  };
>  
>  /**
> -- 
> 2.17.1
>