linux-kernel - Re: [PATCH v2 13/13] nubus: Add support for the driver model

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Date:   Sat, 18 Nov 2017 11:21:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Finn Thain <fthain@...egraphics.com.au>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 13/13] nubus: Add support for the driver model

On Fri, Nov 17, 2017 at 09:30:11PM -0500, Finn Thain wrote:
> This patch brings basic support for the Linux Driver Model to the
> NuBus subsystem.
> 
> For flexibility, bus matching is left up to the drivers. This is also
> the approach taken by NetBSD NuBus drivers in matching cards.
> 
> Since a board may have many functions, drivers have to consider all of
> a board's functional resources, and potentially also the board resource.
> 
> However, this implementation does not support binding many drivers to
> one board. Apple's configuration ROM design is flexible enough to allow
> it but I don't see a need to support it as I don't see a need to support
> the "slot zero" (main logic board) ROM or proprietary drivers.
> 
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Tested-by: Stan Johnson <userm57@...oo.com>
> Signed-off-by: Finn Thain <fthain@...egraphics.com.au>
> 
> ---
> The conversion of Mac network drivers from the Space.c convention to
> the Driver Model takes place in a separate patch series, archived at
> https://lkml.org/lkml/2017/11/11/25
> That series motivates many of the definitions found here, such as
> 'for_each_board_func_rsrc'.
> ---
>  drivers/nubus/Makefile |  2 +-
>  drivers/nubus/bus.c    | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/nubus/nubus.c  |  3 ++
>  include/linux/nubus.h  | 39 +++++++++++++++++++++++
>  4 files changed, 128 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/nubus/bus.c
> 
> diff --git a/drivers/nubus/Makefile b/drivers/nubus/Makefile
> index 21bda2031e7e..6d063cde39d1 100644
> --- a/drivers/nubus/Makefile
> +++ b/drivers/nubus/Makefile
> @@ -2,6 +2,6 @@
>  # Makefile for the nubus specific drivers.
>  #
>  
> -obj-y   := nubus.o
> +obj-y := nubus.o bus.o
>  
>  obj-$(CONFIG_PROC_FS) += proc.o
> diff --git a/drivers/nubus/bus.c b/drivers/nubus/bus.c
> new file mode 100644
> index 000000000000..9ee7aa392ca1
> --- /dev/null
> +++ b/drivers/nubus/bus.c
> @@ -0,0 +1,85 @@
> +/*
> + * Bus implementation for the NuBus subsystem.
> + *
> + * Copyright (C) 2017 Finn Thain
> + *
> + * SPDX-License-Identifier: GPL-2.0
> + */
> +
> +#include <linux/nubus.h>
> +
> +#define to_nubus_board(d)       container_of(d, struct nubus_board, dev)
> +#define to_nubus_driver(d)      container_of(d, struct nubus_driver, driver)
> +
> +static int nubus_bus_match(struct device *dev, struct device_driver *driver)
> +{
> +	return 1;
> +}
> +
> +static int nubus_device_probe(struct device *dev)
> +{
> +	struct nubus_driver *ndrv = to_nubus_driver(dev->driver);
> +	int err = -ENODEV;
> +
> +	if (ndrv->probe)
> +		err = ndrv->probe(to_nubus_board(dev));
> +	return err;
> +}
> +
> +static int nubus_device_remove(struct device *dev)
> +{
> +	struct nubus_driver *ndrv = to_nubus_driver(dev->driver);
> +	int err = -ENODEV;
> +
> +	if (dev->driver && ndrv->remove)
> +		err = ndrv->remove(to_nubus_board(dev));
> +	return err;
> +}
> +
> +struct bus_type nubus_bus_type = {
> +	.name		= "nubus",
> +	.match		= nubus_bus_match,
> +	.probe		= nubus_device_probe,
> +	.remove		= nubus_device_remove,
> +};
> +EXPORT_SYMBOL(nubus_bus_type);

EXPORT_SYMBOL_GPL()?  I have to ask :)

And what happens when a device is removed from the system?  Or unbound?
You need to free up the memory allocated, and I don't see that happening
here.  Have you tested it out?  The kernel should yell at you for not
having a release function for your bus type.

thanks,

greg k-h