Re: [PATCH v12 3/6] staging: vc04_services: vchiq_arm: Add new bus type and device type

Greg Kroah-Hartman
2023-10-05T08:03:15Z

On Sat, Sep 23, 2023 at 08:01:57PM +0530, 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_bus.c | 100 ++++++++++++++++++
> .../interface/vchiq_arm/vchiq_bus.h | 54 ++++++++++
> 3 files changed, 155 insertions(+)
> create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_bus.c
> create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_bus.h
>
> diff --git a/drivers/staging/vc04_services/Makefile b/drivers/staging/vc04_services/Makefile
> index 44794bdf6173..e8b897a7b9a6 100644
> --- a/drivers/staging/vc04_services/Makefile
> +++ b/drivers/staging/vc04_services/Makefile
> @@ -4,6 +4,7 @@ obj-$(CONFIG_BCM2835_VCHIQ) += vchiq.o
> vchiq-objs := \
> interface/vchiq_arm/vchiq_core.o \
> interface/vchiq_arm/vchiq_arm.o \
> + interface/vchiq_arm/vchiq_bus.o \
> interface/vchiq_arm/vchiq_debugfs.o \
> interface/vchiq_arm/vchiq_connected.o \
>
> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_bus.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_bus.c
> new file mode 100644
> index 000000000000..4ac3491efe45
> --- /dev/null
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_bus.c
> @@ -0,0 +1,100 @@
> +// 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_bus.h"
> +
> +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 true;
> +
> + return false;
> +}
> +
> +static int vchiq_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
> +{
> + const struct vchiq_device *device = container_of_const(dev, struct vchiq_device, dev);
> +
> + return add_uevent_var(env, "MODALIAS=%s", dev_name(&device->dev));
> +}
> +
> +static int vchiq_bus_probe(struct device *dev)
> +{
> + struct vchiq_device *device = to_vchiq_device(dev);
> + struct vchiq_driver *driver = to_vchiq_driver(dev->driver);
> +
> + return driver->probe(device);
> +}
> +
> +struct bus_type vchiq_bus_type = {
> + .name = "vchiq-bus",
> + .match = vchiq_bus_type_match,
> + .uevent = vchiq_bus_uevent,
> + .probe = vchiq_bus_probe,
> +};
> +
> +static void vchiq_device_release(struct device *dev)
> +{
> + struct vchiq_device *device = to_vchiq_device(dev);
> +
> + kfree(device);
> +}
> +
> +struct vchiq_device *
> +vchiq_device_register(struct device *parent, const char *name)
> +{
> + struct vchiq_device *device;
> + int ret;
> +
> + device = kzalloc(sizeof(*device), GFP_KERNEL);
> + if (!device)
> + return NULL;
> +
> + device->dev.init_name = name;
> + device->dev.parent = parent;
> + device->dev.bus = &vchiq_bus_type;
> + device->dev.dma_mask = &device->dev.coherent_dma_mask;
> + device->dev.release = vchiq_device_release;
> +
> + of_dma_configure(&device->dev, parent->of_node, true);
> +
> + ret = device_register(&device->dev);
> + if (ret) {
> + dev_err(parent, "Cannot register %s: %d\n", name, ret);
> + put_device(&device->dev);
> + kfree(device);

As per the documentation for the device_register() call, this kfree()
will crash. The call to put_device() is all you need here to free the
memory.

I'll take this series as it's been reviewed and tested, but can you send
a follow-on patch for this?

thanks,

greg k-h