Re: [PATCH v8 1/5] staging: vc04_services: vchiq_arm: Add new bus type and device type

Greg KH
2023-07-03T13:29:12Z

On Tue, Jun 27, 2023 at 10:16:24PM +0200, Umang Jain wrote:
> 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 | 78 +++++++++++++++++++
> .../interface/vchiq_arm/vchiq_device.h | 43 ++++++++++
> 3 files changed, 122 insertions(+)
> create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.h
>
> diff --git a/drivers/staging/vc04_services/Makefile b/drivers/staging/vc04_services/Makefile
> index 44794bdf6173..2d071e55e175 100644
> --- a/drivers/staging/vc04_services/Makefile
> +++ b/drivers/staging/vc04_services/Makefile
> @@ -5,6 +5,7 @@ vchiq-objs := \
> 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_device.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> new file mode 100644
> index 000000000000..dff312e9735c
> --- /dev/null
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> @@ -0,0 +1,78 @@
> +// 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/slab.h>
> +#include <linux/string.h>
> +
> +#include "vchiq_device.h"
> +
> +static int vchiq_bus_type_match(struct device *dev, struct device_driver *drv);
> +
> +struct bus_type vchiq_bus_type = {
> + .name = "vchiq-bus",
> + .match = vchiq_bus_type_match,
> +};
> +
> +static int vchiq_bus_type_match(struct device *dev, struct device_driver *drv)
> +{
> + if (dev->bus == &vchiq_bus_type &&
> + strcmp(dev_name(dev), drv->name) == 0)
> + return 1;
> + return 0;
> +}
> +
> +static void vchiq_device_release(struct device *dev)
> +{
> + struct vchiq_device *device;
> +
> + device = container_of(dev, struct vchiq_device, dev);
> + kfree(device);
> +}
> +
> +int vchiq_device_register(struct device *parent, const char *name)
> +{
> + struct vchiq_device *device = NULL;

No need to set this to NULL.

> + int ret;
> +
> + device = kzalloc(sizeof(*device), GFP_KERNEL);
> + if (!device)
> + return -ENOMEM;
> +
> + device->dev.init_name = name;
> + device->dev.parent = parent;
> + device->dev.bus = &vchiq_bus_type;
> + device->dev.release = vchiq_device_release;
> +
> + ret = device_register(&device->dev);
> + if (ret) {
> + put_device(&device->dev);
> + return -EINVAL;

Why not return the error given to you?

> + }
> +
> + return 0;

You create a new device, shouldn't you return it? How is it going to be
looked up again?

> +}
> +
> +int vchiq_device_unregister(struct device *dev, void *data)

You should be passing in a sruct vchiq_device *device here, right?

And why the void pointer you do nothing with?

> +{
> + device_unregister(dev);
> + return 0;
> +}

No need to export this?

thanks,

greg k-h