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Date:   Sun, 17 Sep 2023 10:40:53 +0200
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Subject: Re: [PATCH v11 1/5] staging: vc04_services: vchiq_arm: Add new bus
 type and device type
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To:     Umang Jain <umang.jain@ideasonboard.com>,
        linux-staging@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org,
        linux-rpi-kernel@lists.infradead.org, linux-media@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Stefan Wahren <stefan.wahren@i2se.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Adrien Thierry <athierry@redhat.com>,
        Dan Carpenter <error27@gmail.com>,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Kieran Bingham <kieran.bingham@ideasonboard.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>
References: <20230913195354.835884-1-umang.jain@ideasonboard.com>
 <20230913195354.835884-2-umang.jain@ideasonboard.com>
From:   Stefan Wahren <wahrenst@gmx.net>
In-Reply-To: <20230913195354.835884-2-umang.jain@ideasonboard.com>
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Precedence: bulk

Hi Umang,

Am 13.09.23 um 21:53 schrieb Umang Jain:
> The devices that the vchiq interface registers (bcm2835-audio,
> bcm2835-camera) are implemented and exposed by the VC04 firmware.
> The device tree describes the VC04 itself with the resources required
> to communicate with it through a mailbox interface. However, the
> vchiq interface registers these devices as platform devices. This
> also means the specific drivers for these devices are getting
> registered as platform drivers. This is not correct and a blatant
> abuse of platform device/driver.
>
> Add a new bus type, vchiq_bus_type and device type (struct vchiq_device)
> which will be used to migrate child devices that the vchiq interfaces
> creates/registers from the platform device/driver.
>
> Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
> ---
>   drivers/staging/vc04_services/Makefile        |   1 +
>   .../interface/vchiq_arm/vchiq_device.c        | 111 ++++++++++++++++++
>   .../interface/vchiq_arm/vchiq_device.h        |  54 +++++++++
>   3 files changed, 166 insertions(+)
>   create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/v=
chiq_device.c
sorry for not noticing this before, but there is already a vchiq_dev.c
file which represent the character device.

In order to avoid confusion how about renaming vchiq_device.c to
vchiq_bus.c ? This also matches the function names better.
>   create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/v=
chiq_device.h
>
> diff --git a/drivers/staging/vc04_services/Makefile b/drivers/staging/vc=
04_services/Makefile
> index 44794bdf6173..2d071e55e175 100644
> --- a/drivers/staging/vc04_services/Makefile
> +++ b/drivers/staging/vc04_services/Makefile
> @@ -5,6 +5,7 @@ vchiq-objs :=3D \
>      interface/vchiq_arm/vchiq_core.o  \
>      interface/vchiq_arm/vchiq_arm.o \
>      interface/vchiq_arm/vchiq_debugfs.o \
> +   interface/vchiq_arm/vchiq_device.o \
>      interface/vchiq_arm/vchiq_connected.o \
>
>   ifdef CONFIG_VCHIQ_CDEV
> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev=
ice.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> new file mode 100644
> index 000000000000..aad55c461905
> --- /dev/null
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> @@ -0,0 +1,111 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * vchiq_device.c - VCHIQ generic device and bus-type
> + *
> + * Copyright (c) 2023 Ideas On Board Oy
> + */
> +
> +#include <linux/device/bus.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/of_device.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +
> +#include "vchiq_device.h"
> +
> +static int vchiq_bus_type_match(struct device *dev, struct device_drive=
r *drv)
> +{
> +	if (dev->bus =3D=3D &vchiq_bus_type &&
> +	    strcmp(dev_name(dev), drv->name) =3D=3D 0)
> +		return 1;
> +
> +	return 0;
> +}
> +
>