platform/raspberrypi: Destage VCHIQ interface

Destage the VCHIQ interface driver to drivers/platform/raspberrypi.

There is still the remaining TODO item of improving the documentation,
which can be handled post destaging.

Secondly, multimedia drivers like codec and ISP that rely on this
interface need to be upstreamed. And lastly, the drivers that facilitate
the shared memory between VideoCore and Linux, like the vc-sm-cma driver
and vc_mem char driver also need to be upstreamed.

Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com>
Link: https://patch.msgid.link/20251029-vchiq-destage-v3-6-da8d6c83c2c5@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jailuthra

MAINTAINERS

@@ -4828,6 +4828,7 @@ S:	Maintained
 T:	git https://github.com/broadcom/stblinux.git
 F:	Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml
 F:	drivers/pci/controller/pcie-brcmstb.c
+F:	drivers/platform/raspberrypi/vchiq-*
 F:	drivers/staging/vc04_services
 F:	include/linux/raspberrypi/vchiq*
 N:	bcm2711

drivers/platform/Kconfig

@@ -18,3 +18,5 @@ source "drivers/platform/surface/Kconfig"
 source "drivers/platform/x86/Kconfig"
 
 source "drivers/platform/arm64/Kconfig"
+
+source "drivers/platform/raspberrypi/Kconfig"

drivers/platform/Makefile

@@ -13,3 +13,4 @@ obj-$(CONFIG_CHROME_PLATFORMS)	+= chrome/
 obj-$(CONFIG_CZNIC_PLATFORMS)	+= cznic/
 obj-$(CONFIG_SURFACE_PLATFORMS)	+= surface/
 obj-$(CONFIG_ARM64_PLATFORM_DEVICES)	+= arm64/
+obj-$(CONFIG_BCM2835_VCHIQ)	+= raspberrypi/

drivers/platform/raspberrypi/Kconfig

@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menuconfig BCM_VIDEOCORE
+	tristate "Broadcom VideoCore support"
+	depends on OF
+	depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
+	default y
+	help
+		Support for Broadcom VideoCore services including
+		the BCM2835 family of products which is used
+		by the Raspberry PI.
+
+if BCM_VIDEOCORE
+
+config BCM2835_VCHIQ
+	tristate "BCM2835 VCHIQ"
+	depends on HAS_DMA
+	imply VCHIQ_CDEV
+	help
+		Broadcom BCM2835 and similar SoCs have a VPU called VideoCore.
+		This config enables the VCHIQ driver, which implements a
+		messaging interface between the kernel and the firmware running
+		on VideoCore. Other drivers use this interface to communicate to
+		the VPU. More specifically, the VCHIQ driver is used by
+		audio/video and camera drivers as well as for implementing MMAL
+		API, which is in turn used by several multimedia services on the
+		BCM2835 family of SoCs.
+
+		Defaults to Y when the Broadcom Videocore services are included
+		in the build, N otherwise.
+
+if BCM2835_VCHIQ
+
+config VCHIQ_CDEV
+	bool "VCHIQ Character Driver"
+	help
+		Enable the creation of VCHIQ character driver. The cdev exposes
+		ioctls used by userspace libraries and testing tools to interact
+		with VideoCore, via the VCHIQ core driver (Check BCM2835_VCHIQ
+		for more info).
+
+		This can be set to 'N' if the VideoCore communication is not
+		needed by userspace but only by other kernel modules
+		(like bcm2835-audio).
+
+		If not sure, set this to 'Y'.
+
+endif
+
+endif

drivers/platform/raspberrypi/Makefile

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_BCM2835_VCHIQ)	+= vchiq.o
+
+vchiq-objs := \
+   vchiq-interface/vchiq_core.o  \
+   vchiq-interface/vchiq_arm.o \
+   vchiq-interface/vchiq_bus.o \
+   vchiq-interface/vchiq_debugfs.o \
+
+ifdef CONFIG_VCHIQ_CDEV
+vchiq-objs += vchiq-interface/vchiq_dev.o
+endif
+