[PATCH v7 0/5] staging: vc04_services: vchiq: Register devices with a custom bus_type

[PATCH v7 0/5] staging: vc04_services: vchiq: Register devices with a custom bus_type

[Umang Jain]

The patch series added a new bus type vchiq_bus_type and registers
child devices in order to move them away from using platform
device/driver.

Patch 1/5 and 2/5 adds a new bus_type and registers them to vchiq
interface

Patch 3/5 and 4/5 moves the bcm2835-camera and bcm2835-audio
to the new bus respectively

Patch 5/5 removes a platform registeration helper which is no
longer required.

Changes in v7:
(5 out of 6 patches from v6 merged)
- Split the main patch (6/6) as requested.
- Use struct vchiq_device * instead of struct device * in
  all bus functions.
- Drop additional name attribute displayed in sysfs (redundant info)
- Document vchiq_interface doesn't enumerate device discovery
- remove EXPORT_SYMBOL_GPL(vchiq_bus_type)

Changes in v6:
- Split struct device and struct driver wrappers in vchiq_device.[ch]
- Move vchiq_bus_type definition to vchiq_device.[ch] as well
- return error on bus_register() failure
- drop dma_set_mask_and_coherent
- trivial variable name change

Changes in v5:
- Fixup missing "staging: " in commits' subject line
- No code changes from v4

Changes in v4:
- Introduce patches to drop include directives from Makefile

Changes in v3:
- Rework entirely to replace platform devices/driver model

-v2:
https://lore.kernel.org/all/20221222191500.515795-1-umang.jain@ideasonboard.com/

-v1:
https://lore.kernel.org/all/20221220084404.19280-1-umang.jain@ideasonboard.com/

Umang Jain (5):
  staging: vc04_services: vchiq_arm: Add new bus type and device type
  staging: vc04_services: vchiq_arm: Register vchiq_bus_type
  staging: bcm2835-camera: Register bcm2835-camera with vchiq_bus_type
  staging: bcm2835-audio: Register bcm2835-audio with vchiq_bus_type
  staging: vc04_services: vchiq_arm: Remove vchiq_register_child()

 drivers/staging/vc04_services/Makefile        |  1 +
 .../vc04_services/bcm2835-audio/bcm2835.c     | 17 ++--
 .../bcm2835-camera/bcm2835-camera.c           | 16 ++--
 .../interface/vchiq_arm/vchiq_arm.c           | 56 +++++++------
 .../interface/vchiq_arm/vchiq_device.c        | 78 +++++++++++++++++++
 .../interface/vchiq_arm/vchiq_device.h        | 43 ++++++++++
 6 files changed, 165 insertions(+), 46 deletions(-)
 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

-- 
2.39.1

[PATCH v7 1/5] staging: vc04_services: vchiq_arm: Add new bus type and device type

[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        | 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..e16279a25126
--- /dev/null
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * 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;
+	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;
+	}
+
+	return 0;
+}
+
+int vchiq_device_unregister(struct device *dev, void *data)
+{
+	device_unregister(dev);
+	return 0;
+}
+
+int vchiq_driver_register(struct vchiq_driver *vchiq_drv)
+{
+	vchiq_drv->driver.bus = &vchiq_bus_type;
+
+	return driver_register(&vchiq_drv->driver);
+}
+EXPORT_SYMBOL_GPL(vchiq_driver_register);
+
+void vchiq_driver_unregister(struct vchiq_driver *vchiq_drv)
+{
+	driver_unregister(&vchiq_drv->driver);
+}
+EXPORT_SYMBOL_GPL(vchiq_driver_unregister);
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.h b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.h
new file mode 100644
index 000000000000..55d242b230f9
--- /dev/null
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
+/*
+ * Copyright (c) 2023 Ideas On Board Oy
+ */
+
+#ifndef _VCHIQ_DEVICE_H
+#define _VCHIQ_DEVICE_H
+
+#include <linux/device.h>
+
+struct vchiq_device {
+	struct device dev;
+};
+
+struct vchiq_driver {
+        int                     (*probe)(struct vchiq_device *device);
+        void                    (*remove)(struct vchiq_device *device);
+        int                     (*resume)(struct vchiq_device *device);
+        int                     (*suspend)(struct vchiq_device *device,
+					   pm_message_t state);
+	struct device_driver driver;
+};
+
+extern struct bus_type vchiq_bus_type;
+
+int vchiq_device_register(struct device *parent, const char *name);
+int vchiq_device_unregister(struct device *dev, void *data);
+
+int vchiq_driver_register(struct vchiq_driver *vchiq_drv);
+void vchiq_driver_unregister(struct vchiq_driver *vchiq_drv);
+
+/**
+ * module_vchiq_driver() - Helper macro for registering a vchiq driver
+ * @__vchiq_driver: vchiq driver struct
+ *
+ * Helper macro for vchiq drivers which do not do anything special in
+ * module init/exit. This eliminates a lot of boilerplate. Each module may only
+ * use this macro once, and calling it replaces module_init() and module_exit()
+ */
+#define module_vchiq_driver(__vchiq_driver) \
+	module_driver(__vchiq_driver, vchiq_driver_register, vchiq_driver_unregister)
+
+#endif /* _VCHIQ_DEVICE_H */
-- 
2.39.1

Re: [PATCH v7 1/5] staging: vc04_services: vchiq_arm: Add new bus type and device type

[Greg KH]

On Tue, Jun 20, 2023 at 07:11:48PM +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_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..e16279a25126
> --- /dev/null
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> @@ -0,0 +1,78 @@
> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause

Code that directly interacts with the driver core can, for obvious
reasons, not be BSD-3 licensed, sorry.

Also, why is any of this dual licensed?  What good is any of that?  In
order for me to accept new dual-licensed code, it needs to be documented
in the changelog very very well as to exactly why this is required, as
the legal issues involved in maintaining dual-licensed code like this is
tricky and easy to get wrong (as proven here already in this patch...)

thanks,

greg k-h

Re: [PATCH v7 1/5] staging: vc04_services: vchiq_arm: Add new bus type and device type

[Laurent Pinchart]

On Tue, Jun 20, 2023 at 04:17:05PM +0200, Greg KH wrote:
> On Tue, Jun 20, 2023 at 07:11:48PM +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_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..e16279a25126
> > --- /dev/null
> > +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> > @@ -0,0 +1,78 @@
> > +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> 
> Code that directly interacts with the driver core can, for obvious
> reasons, not be BSD-3 licensed, sorry.
> 
> Also, why is any of this dual licensed?  What good is any of that?  In
> order for me to accept new dual-licensed code, it needs to be documented
> in the changelog very very well as to exactly why this is required, as
> the legal issues involved in maintaining dual-licensed code like this is
> tricky and easy to get wrong (as proven here already in this patch...)

The whole vchiq_arm layer is dual licensed GPL-2.0 + BSD-3. I assume
this is why Umang used the same licensing terms. We can use GPL-2.0 only
if this patch qualifies as original work and not derived work of the
existing code.

This being said, I have no objection changing the license of the whole
vchiq_arm layer to GPL-2.0 only. Dave, any opinion on this ?

-- 
Regards,

Laurent Pinchart

Re: [PATCH v7 1/5] staging: vc04_services: vchiq_arm: Add new bus type and device type

[Greg KH]

On Tue, Jun 20, 2023 at 09:20:54PM +0300, Laurent Pinchart wrote:
> On Tue, Jun 20, 2023 at 04:17:05PM +0200, Greg KH wrote:
> > On Tue, Jun 20, 2023 at 07:11:48PM +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_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..e16279a25126
> > > --- /dev/null
> > > +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> > > @@ -0,0 +1,78 @@
> > > +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> > 
> > Code that directly interacts with the driver core can, for obvious
> > reasons, not be BSD-3 licensed, sorry.
> > 
> > Also, why is any of this dual licensed?  What good is any of that?  In
> > order for me to accept new dual-licensed code, it needs to be documented
> > in the changelog very very well as to exactly why this is required, as
> > the legal issues involved in maintaining dual-licensed code like this is
> > tricky and easy to get wrong (as proven here already in this patch...)
> 
> The whole vchiq_arm layer is dual licensed GPL-2.0 + BSD-3. I assume
> this is why Umang used the same licensing terms. We can use GPL-2.0 only
> if this patch qualifies as original work and not derived work of the
> existing code.

This is most certainly original work, not related to the original code
here, and can never work in a BSD-3 licensed environment.

thanks,

greg k-h

[PATCH v7 2/5] staging: vc04_services: vchiq_arm: Register vchiq_bus_type

[Umang Jain]

Register the vchiq_bus_type bus with the vchiq interface.
The bcm2835-camera nad bcm2835_audio will be registered to this bus type
going ahead.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
---
 .../vc04_services/interface/vchiq_arm/vchiq_arm.c        | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index aa2313f3bcab..e8d40f891449 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -12,6 +12,7 @@
 #include <linux/cdev.h>
 #include <linux/fs.h>
 #include <linux/device.h>
+#include <linux/device/bus.h>
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
@@ -34,6 +35,7 @@
 #include "vchiq_ioctl.h"
 #include "vchiq_arm.h"
 #include "vchiq_debugfs.h"
+#include "vchiq_device.h"
 #include "vchiq_connected.h"
 #include "vchiq_pagelist.h"
 
@@ -1870,6 +1872,12 @@ static int __init vchiq_driver_init(void)
 {
 	int ret;
 
+	ret = bus_register(&vchiq_bus_type);
+	if (ret) {
+		pr_err("Failed to register %s\n", vchiq_bus_type.name);
+		return ret;
+	}
+
 	ret = platform_driver_register(&vchiq_driver);
 	if (ret)
 		pr_err("Failed to register vchiq driver\n");
@@ -1880,6 +1888,7 @@ module_init(vchiq_driver_init);
 
 static void __exit vchiq_driver_exit(void)
 {
+	bus_unregister(&vchiq_bus_type);
 	platform_driver_unregister(&vchiq_driver);
 }
 module_exit(vchiq_driver_exit);
-- 
2.39.1

[PATCH v7 3/5] staging: bcm2835-camera: Register bcm2835-camera with vchiq_bus_type

[Umang Jain]

Register the bcm2835-camera with the vchiq_bus_type instead of using
platform driver/device.

Also the VCHIQ firmware doesn't support device enumeration, hence
one has to maintain a list of devices to be registered in the interface.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
---
 .../bcm2835-camera/bcm2835-camera.c           | 16 +++++++-------
 .../interface/vchiq_arm/vchiq_arm.c           | 21 ++++++++++++++++---
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
index 346d00df815a..f37b2a881d92 100644
--- a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
+++ b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
@@ -24,8 +24,9 @@
 #include <media/v4l2-event.h>
 #include <media/v4l2-common.h>
 #include <linux/delay.h>
-#include <linux/platform_device.h>
 
+#include "../interface/vchiq_arm/vchiq_arm.h"
+#include "../interface/vchiq_arm/vchiq_device.h"
 #include "../vchiq-mmal/mmal-common.h"
 #include "../vchiq-mmal/mmal-encodings.h"
 #include "../vchiq-mmal/mmal-vchiq.h"
@@ -1841,7 +1842,7 @@ static struct v4l2_format default_v4l2_format = {
 	.fmt.pix.sizeimage = 1024 * 768,
 };
 
-static int bcm2835_mmal_probe(struct platform_device *pdev)
+static int bcm2835_mmal_probe(struct vchiq_device *device)
 {
 	int ret;
 	struct bcm2835_mmal_dev *dev;
@@ -1896,7 +1897,7 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
 						       &camera_instance);
 		ret = v4l2_device_register(NULL, &dev->v4l2_dev);
 		if (ret) {
-			dev_err(&pdev->dev, "%s: could not register V4L2 device: %d\n",
+			dev_err(&device->dev, "%s: could not register V4L2 device: %d\n",
 				__func__, ret);
 			goto free_dev;
 		}
@@ -1976,7 +1977,7 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static void bcm2835_mmal_remove(struct platform_device *pdev)
+static void bcm2835_mmal_remove(struct vchiq_device *device)
 {
 	int camera;
 	struct vchiq_mmal_instance *instance = gdev[0]->instance;
@@ -1988,17 +1989,16 @@ static void bcm2835_mmal_remove(struct platform_device *pdev)
 	vchiq_mmal_finalise(instance);
 }
 
-static struct platform_driver bcm2835_camera_driver = {
+static struct vchiq_driver bcm2835_camera_driver = {
 	.probe		= bcm2835_mmal_probe,
-	.remove_new	= bcm2835_mmal_remove,
+	.remove		= bcm2835_mmal_remove,
 	.driver		= {
 		.name	= "bcm2835-camera",
 	},
 };
 
-module_platform_driver(bcm2835_camera_driver)
+module_vchiq_driver(bcm2835_camera_driver)
 
 MODULE_DESCRIPTION("Broadcom 2835 MMAL video capture");
 MODULE_AUTHOR("Vincent Sanders");
 MODULE_LICENSE("GPL");
-MODULE_ALIAS("platform:bcm2835-camera");
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index e8d40f891449..79d4d0eeb5fb 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -67,7 +67,6 @@ int vchiq_susp_log_level = VCHIQ_LOG_ERROR;
 DEFINE_SPINLOCK(msg_queue_spinlock);
 struct vchiq_state g_state;
 
-static struct platform_device *bcm2835_camera;
 static struct platform_device *bcm2835_audio;
 
 struct vchiq_drvdata {
@@ -134,6 +133,15 @@ struct vchiq_pagelist_info {
 	unsigned int scatterlist_mapped;
 };
 
+/*
+ * The devices implemented in the VCHIQ firmware are not discoverable,
+ * so we need to maintain a list of them in order to register them with
+ * the interface.
+ */
+static const char *const vchiq_devices[] = {
+	"bcm2835-camera",
+};
+
 static void __iomem *g_regs;
 /* This value is the size of the L2 cache lines as understood by the
  * VPU firmware, which determines the required alignment of the
@@ -1798,6 +1806,7 @@ static int vchiq_probe(struct platform_device *pdev)
 	struct device_node *fw_node;
 	const struct of_device_id *of_id;
 	struct vchiq_drvdata *drvdata;
+	unsigned int i;
 	int err;
 
 	of_id = of_match_node(vchiq_of_match, pdev->dev.of_node);
@@ -1840,9 +1849,15 @@ static int vchiq_probe(struct platform_device *pdev)
 		goto error_exit;
 	}
 
-	bcm2835_camera = vchiq_register_child(pdev, "bcm2835-camera");
 	bcm2835_audio = vchiq_register_child(pdev, "bcm2835_audio");
 
+	for (i = 0; i < ARRAY_SIZE(vchiq_devices); i++) {
+		err = vchiq_device_register(&pdev->dev, vchiq_devices[i]);
+		if (err)
+			dev_err(&pdev->dev, "Failed to register %s vchiq device\n",
+			vchiq_devices[i]);
+	}
+
 	return 0;
 
 failed_platform_init:
@@ -1854,7 +1869,7 @@ static int vchiq_probe(struct platform_device *pdev)
 static void vchiq_remove(struct platform_device *pdev)
 {
 	platform_device_unregister(bcm2835_audio);
-	platform_device_unregister(bcm2835_camera);
+	bus_for_each_dev(&vchiq_bus_type, NULL, NULL, vchiq_device_unregister);
 	vchiq_debugfs_deinit();
 	vchiq_deregister_chrdev();
 }
-- 
2.39.1

[PATCH v7 4/5] staging: bcm2835-audio: Register bcm2835-audio with vchiq_bus_type

[Umang Jain]

Similar to how bcm2385-camera device is registered, register the
bcm2835-audio with vchiq_bus_type as well.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
---
 .../vc04_services/bcm2835-audio/bcm2835.c       | 17 ++++++++---------
 .../interface/vchiq_arm/vchiq_arm.c             |  6 +-----
 2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c b/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c
index 00bc898b0189..f81a9a4fbd5d 100644
--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c
@@ -1,12 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright 2011 Broadcom Corporation.  All rights reserved. */
 
-#include <linux/platform_device.h>
-
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 
+#include "../interface/vchiq_arm/vchiq_arm.h"
+#include "../interface/vchiq_arm/vchiq_device.h"
 #include "bcm2835.h"
 
 static bool enable_hdmi;
@@ -268,9 +268,9 @@ static int snd_add_child_devices(struct device *device, u32 numchans)
 	return 0;
 }
 
-static int snd_bcm2835_alsa_probe(struct platform_device *pdev)
+static int snd_bcm2835_alsa_probe(struct vchiq_device *device)
 {
-	struct device *dev = &pdev->dev;
+	struct device *dev = &device->dev;
 	int err;
 
 	if (num_channels <= 0 || num_channels > MAX_SUBSTREAMS) {
@@ -292,20 +292,20 @@ static int snd_bcm2835_alsa_probe(struct platform_device *pdev)
 
 #ifdef CONFIG_PM
 
-static int snd_bcm2835_alsa_suspend(struct platform_device *pdev,
+static int snd_bcm2835_alsa_suspend(struct vchiq_device *device,
 				    pm_message_t state)
 {
 	return 0;
 }
 
-static int snd_bcm2835_alsa_resume(struct platform_device *pdev)
+static int snd_bcm2835_alsa_resume(struct vchiq_device *device)
 {
 	return 0;
 }
 
 #endif
 
-static struct platform_driver bcm2835_alsa_driver = {
+static struct vchiq_driver bcm2835_alsa_driver = {
 	.probe = snd_bcm2835_alsa_probe,
 #ifdef CONFIG_PM
 	.suspend = snd_bcm2835_alsa_suspend,
@@ -315,9 +315,8 @@ static struct platform_driver bcm2835_alsa_driver = {
 		.name = "bcm2835_audio",
 	},
 };
-module_platform_driver(bcm2835_alsa_driver);
+module_vchiq_driver(bcm2835_alsa_driver);
 
 MODULE_AUTHOR("Dom Cobley");
 MODULE_DESCRIPTION("Alsa driver for BCM2835 chip");
 MODULE_LICENSE("GPL");
-MODULE_ALIAS("platform:bcm2835_audio");
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 79d4d0eeb5fb..75da37fa6372 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -67,8 +67,6 @@ int vchiq_susp_log_level = VCHIQ_LOG_ERROR;
 DEFINE_SPINLOCK(msg_queue_spinlock);
 struct vchiq_state g_state;
 
-static struct platform_device *bcm2835_audio;
-
 struct vchiq_drvdata {
 	const unsigned int cache_line_size;
 	struct rpi_firmware *fw;
@@ -139,6 +137,7 @@ struct vchiq_pagelist_info {
  * the interface.
  */
 static const char *const vchiq_devices[] = {
+	"bcm2835_audio",
 	"bcm2835-camera",
 };
 
@@ -1849,8 +1848,6 @@ static int vchiq_probe(struct platform_device *pdev)
 		goto error_exit;
 	}
 
-	bcm2835_audio = vchiq_register_child(pdev, "bcm2835_audio");
-
 	for (i = 0; i < ARRAY_SIZE(vchiq_devices); i++) {
 		err = vchiq_device_register(&pdev->dev, vchiq_devices[i]);
 		if (err)
@@ -1868,7 +1865,6 @@ static int vchiq_probe(struct platform_device *pdev)
 
 static void vchiq_remove(struct platform_device *pdev)
 {
-	platform_device_unregister(bcm2835_audio);
 	bus_for_each_dev(&vchiq_bus_type, NULL, NULL, vchiq_device_unregister);
 	vchiq_debugfs_deinit();
 	vchiq_deregister_chrdev();
-- 
2.39.1

[PATCH v7 5/5] staging: vc04_services: vchiq_arm: Remove vchiq_register_child()

[Umang Jain]

vchiq_register_child() is used to registered child devices as platform
devices. Now that the child devices are migrated to use the
vchiq_bus_type instead, they will be registered to that. Hence, drop
vchiq_register_child() as it is no more required.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
---
 .../interface/vchiq_arm/vchiq_arm.c           | 22 -------------------
 1 file changed, 22 deletions(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 75da37fa6372..3c52b09c49ea 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -1778,28 +1778,6 @@ static const struct of_device_id vchiq_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, vchiq_of_match);
 
-static struct platform_device *
-vchiq_register_child(struct platform_device *pdev, const char *name)
-{
-	struct platform_device_info pdevinfo;
-	struct platform_device *child;
-
-	memset(&pdevinfo, 0, sizeof(pdevinfo));
-
-	pdevinfo.parent = &pdev->dev;
-	pdevinfo.name = name;
-	pdevinfo.id = PLATFORM_DEVID_NONE;
-	pdevinfo.dma_mask = DMA_BIT_MASK(32);
-
-	child = platform_device_register_full(&pdevinfo);
-	if (IS_ERR(child)) {
-		dev_warn(&pdev->dev, "%s not registered\n", name);
-		child = NULL;
-	}
-
-	return child;
-}
-
 static int vchiq_probe(struct platform_device *pdev)
 {
 	struct device_node *fw_node;
-- 
2.39.1

Re: [PATCH v7 0/5] staging: vc04_services: vchiq: Register devices with a custom bus_type

[Greg KH]

On Tue, Jun 20, 2023 at 07:11:47PM +0530, Umang Jain wrote:
> The patch series added a new bus type vchiq_bus_type and registers
> child devices in order to move them away from using platform
> device/driver.
> 
> Patch 1/5 and 2/5 adds a new bus_type and registers them to vchiq
> interface
> 
> Patch 3/5 and 4/5 moves the bcm2835-camera and bcm2835-audio
> to the new bus respectively
> 
> Patch 5/5 removes a platform registeration helper which is no
> longer required.

License issues asside, this looks very good, thanks for doing this!

greg k-h