Date:   Wed, 13 Sep 2017 16:38:09 -0700 (PDT)
From:   matthew.gerlach@...ux.intel.com
To:     Alan Tull <atull@...nel.org>
cc:     Moritz Fischer <mdf@...nel.org>, linux-kernel@...r.kernel.org,
        linux-fpga@...r.kernel.org
Subject: Re: [PATCH v4 01/18] fpga: bridge: support getting bridge from
 device


Hi Alan,

Two minor nits below.

Matthew Gerlach

On Wed, 13 Sep 2017, Alan Tull wrote:

> Add two functions for getting the FPGA bridge from the device
> rather than device tree node.  This is to enable writing code
> that will support using FPGA bridges without device tree.
> Rename one old function to make it clear that it is device
> tree-ish.  This leaves us with 3 functions for getting a bridge:
>
> * fpga_bridge_get
>  Get the bridge given the device.
>
> * fpga_bridges_get_to_list
>  Given the device, get the bridge and add it to a list.
>
> * of_fpga_bridges_get_to_list
>  Renamed from priviously existing fpga_bridges_get_to_list.
>  Given the device node, get the bridge and add it to a list.
>
> Signed-off-by: Alan Tull <atull@...nel.org>
> ---
> v2: use list_for_each_entry
>    static the bridge_list_lock
>    update copyright and author email
> v3: no change to this patch in this version of patchset
> v4: no change to this patch in this version of patchset
> ---
> drivers/fpga/fpga-bridge.c       | 110 +++++++++++++++++++++++++++++++--------
> drivers/fpga/fpga-region.c       |  11 ++--
> include/linux/fpga/fpga-bridge.h |   7 ++-
> 3 files changed, 100 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c
> index fcd2bd3..af6d97e 100644
> --- a/drivers/fpga/fpga-bridge.c
> +++ b/drivers/fpga/fpga-bridge.c
> @@ -2,6 +2,7 @@
>  * FPGA Bridge Framework Driver
>  *
>  *  Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
> + *  Copyright (C) 2017 Intel Corporation
>  *
>  * This program is free software; you can redistribute it and/or modify it
>  * under the terms and conditions of the GNU General Public License,
> @@ -70,29 +71,12 @@ int fpga_bridge_disable(struct fpga_bridge *bridge)
> }
> EXPORT_SYMBOL_GPL(fpga_bridge_disable);
>
> -/**
> - * of_fpga_bridge_get - get an exclusive reference to a fpga bridge
> - *
> - * @np: node pointer of a FPGA bridge
> - * @info: fpga image specific information
> - *
> - * Return fpga_bridge struct if successful.
> - * Return -EBUSY if someone already has a reference to the bridge.
> - * Return -ENODEV if @np is not a FPGA Bridge.
> - */
> -struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
> -				       struct fpga_image_info *info)
> -
> +struct fpga_bridge *__fpga_bridge_get(struct device *dev,
> +				      struct fpga_image_info *info)

Should this be a static function?

I was recently told by mtd maintainers that function names prefixed with
__ should be avoided.


> {
> -	struct device *dev;
> 	struct fpga_bridge *bridge;
> 	int ret = -ENODEV;
>
> -	dev = class_find_device(fpga_bridge_class, NULL, np,
> -				fpga_bridge_of_node_match);
> -	if (!dev)
> -		goto err_dev;
> -
> 	bridge = to_fpga_bridge(dev);
> 	if (!bridge)
> 		goto err_dev;
> @@ -117,8 +101,58 @@ struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
> 	put_device(dev);
> 	return ERR_PTR(ret);
> }
> +
> +/**
> + * of_fpga_bridge_get - get an exclusive reference to a fpga bridge
> + *
> + * @np: node pointer of a FPGA bridge
> + * @info: fpga image specific information
> + *
> + * Return fpga_bridge struct if successful.
> + * Return -EBUSY if someone already has a reference to the bridge.
> + * Return -ENODEV if @np is not a FPGA Bridge.
> + */
> +struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
> +				       struct fpga_image_info *info)
> +{
> +	struct device *dev;
> +
> +	dev = class_find_device(fpga_bridge_class, NULL, np,
> +				fpga_bridge_of_node_match);
> +	if (!dev)
> +		return ERR_PTR(-ENODEV);
> +
> +	return __fpga_bridge_get(dev, info);
> +}
> EXPORT_SYMBOL_GPL(of_fpga_bridge_get);
>
> +static int fpga_bridge_dev_match(struct device *dev, const void *data)
> +{
> +	return dev->parent == data;
> +}
> +
> +/**
> + * fpga_bridge_get - get an exclusive reference to a fpga bridge
> + * @dev:	parent device that fpga bridge was registered with
> + *
> + * Given a device, get an exclusive reference to a fpga bridge.
> + *
> + * Return: fpga manager struct or IS_ERR() condition containing error code.
> + */
> +struct fpga_bridge *fpga_bridge_get(struct device *dev,
> +				    struct fpga_image_info *info)
> +{
> +	struct device *bridge_dev;
> +
> +	bridge_dev = class_find_device(fpga_bridge_class, NULL, dev,
> +				       fpga_bridge_dev_match);
> +	if (!bridge_dev)
> +		return ERR_PTR(-ENODEV);
> +
> +	return __fpga_bridge_get(bridge_dev, info);
> +}
> +EXPORT_SYMBOL_GPL(fpga_bridge_get);
> +
> /**
>  * fpga_bridge_put - release a reference to a bridge
>  *
> @@ -206,7 +240,7 @@ void fpga_bridges_put(struct list_head *bridge_list)
> EXPORT_SYMBOL_GPL(fpga_bridges_put);
>
> /**
> - * fpga_bridges_get_to_list - get a bridge, add it to a list
> + * of_fpga_bridge_get_to_list - get a bridge, add it to a list
>  *
>  * @np: node pointer of a FPGA bridge
>  * @info: fpga image specific information
> @@ -216,14 +250,44 @@ EXPORT_SYMBOL_GPL(fpga_bridges_put);
>  *
>  * Return 0 for success, error code from of_fpga_bridge_get() othewise.
>  */
> -int fpga_bridge_get_to_list(struct device_node *np,
> +int of_fpga_bridge_get_to_list(struct device_node *np,
> +			       struct fpga_image_info *info,
> +			       struct list_head *bridge_list)
> +{
> +	struct fpga_bridge *bridge;
> +	unsigned long flags;
> +
> +	bridge = of_fpga_bridge_get(np, info);
> +	if (IS_ERR(bridge))
> +		return PTR_ERR(bridge);
> +
> +	spin_lock_irqsave(&bridge_list_lock, flags);
> +	list_add(&bridge->node, bridge_list);
> +	spin_unlock_irqrestore(&bridge_list_lock, flags);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(of_fpga_bridge_get_to_list);
> +
> +/**
> + * fpga_bridge_get_to_list - given device, get a bridge, add it to a list
> + *
> + * @dev: FPGA bridge device
> + * @info: fpga image specific information
> + * @bridge_list: list of FPGA bridges
> + *
> + * Get an exclusive reference to the bridge and and it to the list.
> + *
> + * Return 0 for success, error code from fpga_bridge_get() othewise.
> + */
> +int fpga_bridge_get_to_list(struct device *dev,
> 			    struct fpga_image_info *info,
> 			    struct list_head *bridge_list)
> {
> 	struct fpga_bridge *bridge;
> 	unsigned long flags;
>
> -	bridge = of_fpga_bridge_get(np, info);
> +	bridge = fpga_bridge_get(dev, info);
> 	if (IS_ERR(bridge))
> 		return PTR_ERR(bridge);
>
> @@ -381,7 +445,7 @@ static void __exit fpga_bridge_dev_exit(void)
> }
>
> MODULE_DESCRIPTION("FPGA Bridge Driver");
> -MODULE_AUTHOR("Alan Tull <atull@...nsource.altera.com>");
> +MODULE_AUTHOR("Alan Tull <atull@...nel.org>");
> MODULE_LICENSE("GPL v2");
>
> subsys_initcall(fpga_bridge_dev_init);
> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
> index d9ab7c7..91755562 100644
> --- a/drivers/fpga/fpga-region.c
> +++ b/drivers/fpga/fpga-region.c
> @@ -183,11 +183,14 @@ static int fpga_region_get_bridges(struct fpga_region *region,
> 	int i, ret;
>
> 	/* If parent is a bridge, add to list */
> -	ret = fpga_bridge_get_to_list(region_np->parent, region->info,
> -				      &region->bridge_list);
> +	ret = of_fpga_bridge_get_to_list(region_np->parent, region->info,
> +					 &region->bridge_list);
> +
> +	/* -EBUSY means parent is a bridge that is under use. Give up. */
> 	if (ret == -EBUSY)
> 		return ret;
>
> +	/* Zero return code means parent was a bridge and was added to list. */
> 	if (!ret)
> 		parent_br = region_np->parent;
>
> @@ -207,8 +210,8 @@ static int fpga_region_get_bridges(struct fpga_region *region,
> 			continue;
>
> 		/* If node is a bridge, get it and add to list */
> -		ret = fpga_bridge_get_to_list(br, region->info,
> -					      &region->bridge_list);
> +		ret = of_fpga_bridge_get_to_list(br, region->info,
> +						 &region->bridge_list);
>
> 		/* If any of the bridges are in use, give up */
> 		if (ret == -EBUSY) {
> diff --git a/include/linux/fpga/fpga-bridge.h b/include/linux/fpga/fpga-bridge.h
> index dba6e3c..9f6696b 100644
> --- a/include/linux/fpga/fpga-bridge.h
> +++ b/include/linux/fpga/fpga-bridge.h
> @@ -42,6 +42,8 @@ struct fpga_bridge {
>
> struct fpga_bridge *of_fpga_bridge_get(struct device_node *node,
> 				       struct fpga_image_info *info);
> +struct fpga_bridge *fpga_bridge_get(struct device *dev,
> +				    struct fpga_image_info *info);
> void fpga_bridge_put(struct fpga_bridge *bridge);
> int fpga_bridge_enable(struct fpga_bridge *bridge);
> int fpga_bridge_disable(struct fpga_bridge *bridge);
> @@ -49,9 +51,12 @@ int fpga_bridge_disable(struct fpga_bridge *bridge);
> int fpga_bridges_enable(struct list_head *bridge_list);
> int fpga_bridges_disable(struct list_head *bridge_list);
> void fpga_bridges_put(struct list_head *bridge_list);
> -int fpga_bridge_get_to_list(struct device_node *np,
> +int fpga_bridge_get_to_list(struct device *dev,
> 			    struct fpga_image_info *info,
> 			    struct list_head *bridge_list);
> +int of_fpga_bridge_get_to_list(struct device_node *np,
> +			       struct fpga_image_info *info,
> +			       struct list_head *bridge_list);
>
> int fpga_bridge_register(struct device *dev, const char *name,
> 			 const struct fpga_bridge_ops *br_ops, void *priv);
> -- 
> 2.7.4
>
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