nvidia-oot: tegra_bpmp: add dummy driver support

For some of the kernel tegra_bpmp is part of core kernel and
hence it is nto required to use the OOT tegra_bpmp driver.

However, some packaging still expect the tegra_bpmp.ko from
the OOT path. To trick the packaging file, add dummy tegra_bpmp
driver which does not have anything other than module_init/module_exit.

Bug 4551265

Change-Id: Ifae52acb63be009029c820b0ba7b15da6ea7a12e
Signed-off-by: Manish Bhardwaj <mbhardwaj@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3198304
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
Reviewed-by: Laxman Dewangan <ldewangan@nvidia.com>
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>

configs/Makefile.config.oot

@@ -5,3 +5,4 @@
 
 export NV_OOT_IVC_EXT_SKIP_BUILD=y
 export NV_OOT_TEGRA_HV_SKIP_BUILD=y
+export NV_OOT_TEGRA_BPMP_SKIP_BUILD=y

drivers/firmware/tegra/Makefile

@@ -11,9 +11,15 @@ else
 obj-m		+= ivc_ext.o
 ivc_ext-objs := ivc_ext_dummy.o
 endif
+
+ifneq ($(NV_OOT_TEGRA_BPMP_SKIP_BUILD),y)
 tegra_bpmp-y	+= ../../clk/tegra/clk-bpmp.o
 tegra_bpmp-y	+= ../../reset/tegra/reset-bpmp.o
 tegra_bpmp-y	+= ../../soc/tegra/powergate-bpmp.o
 tegra_bpmp-$(CONFIG_DEBUG_FS)	+= bpmp-debugfs.o
 tegra_bpmp-y	+= bpmp-tegra186-hv.o
 obj-m 		+= tegra_bpmp.o
+else
+obj-m 		+= tegra_bpmp.o
+tegra_bpmp-objs	+= tegra_bpmp_dummy.o
+endif

drivers/firmware/tegra/tegra_bpmp_dummy.c

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+
+#include <linux/module.h>
+
+static int __init tegra_bpmp_dummy_init(void)
+{
+	pr_info("Inserting dummy tegra_bpmp.ko module");
+	return 0;
+}
+module_init(tegra_bpmp_dummy_init);
+
+static void __exit tegra_bpmp_dummy_exit(void)
+{
+	pr_info("Removing dummy tegra_bpmp.ko module");
+}
+module_exit(tegra_bpmp_dummy_exit);
+
+MODULE_AUTHOR("Manish Bhardwaj <mbhardwaj@nvidia.com>");
+MODULE_DESCRIPTION("Tegra BPMP Dummy Driver");
+MODULE_LICENSE("GPL v2");