On 2022-02-22 16:21, Christoph Hellwig wrote:
On Fri, Feb 18, 2022 at 01:39:45PM +0200, Mikko Perttunen wrote:
The context bus is a "dummy" bus that contains struct devices that
correspond to IOMMU contexts assigned through Host1x to processes.
Even when host1x itself is built as a module, the bus is registered
in built-in code so that the built-in ARM SMMU driver is able to
reference it.
Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
---
drivers/gpu/Makefile | 3 +--
drivers/gpu/host1x/Kconfig | 5 +++++
drivers/gpu/host1x/Makefile | 1 +
drivers/gpu/host1x/context_bus.c | 31 ++++++++++++++++++++++++++++++
include/linux/host1x_context_bus.h | 15 +++++++++++++++
5 files changed, 53 insertions(+), 2 deletions(-)
create mode 100644 drivers/gpu/host1x/context_bus.c
create mode 100644 include/linux/host1x_context_bus.h
diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
index 835c88318cec..8997f0096545 100644
--- a/drivers/gpu/Makefile
+++ b/drivers/gpu/Makefile
@@ -2,7 +2,6 @@
# drm/tegra depends on host1x, so if both drivers are built-in care must be
# taken to initialize them in the correct order. Link order is the only way
# to ensure this currently.
-obj-$(CONFIG_TEGRA_HOST1X) += host1x/
-obj-y += drm/ vga/
+obj-y += host1x/ drm/ vga/
obj-$(CONFIG_IMX_IPUV3_CORE) += ipu-v3/
obj-$(CONFIG_TRACE_GPU_MEM) += trace/
diff --git a/drivers/gpu/host1x/Kconfig b/drivers/gpu/host1x/Kconfig
index 6815b4db17c1..1861a8180d3f 100644
--- a/drivers/gpu/host1x/Kconfig
+++ b/drivers/gpu/host1x/Kconfig
@@ -1,8 +1,13 @@
# SPDX-License-Identifier: GPL-2.0-only
+
+config TEGRA_HOST1X_CONTEXT_BUS
+ bool
+
config TEGRA_HOST1X
tristate "NVIDIA Tegra host1x driver"
depends on ARCH_TEGRA || (ARM && COMPILE_TEST)
select DMA_SHARED_BUFFER
+ select TEGRA_HOST1X_CONTEXT_BUS
select IOMMU_IOVA
help
Driver for the NVIDIA Tegra host1x hardware.
diff --git a/drivers/gpu/host1x/Makefile b/drivers/gpu/host1x/Makefile
index d2b6f7de0498..c891a3e33844 100644
--- a/drivers/gpu/host1x/Makefile
+++ b/drivers/gpu/host1x/Makefile
@@ -18,3 +18,4 @@ host1x-y = \
hw/host1x07.o
obj-$(CONFIG_TEGRA_HOST1X) += host1x.o
+obj-$(CONFIG_TEGRA_HOST1X_CONTEXT_BUS) += context_bus.o
diff --git a/drivers/gpu/host1x/context_bus.c b/drivers/gpu/host1x/context_bus.c
new file mode 100644
index 000000000000..2625914f3c7d
--- /dev/null
+++ b/drivers/gpu/host1x/context_bus.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021, NVIDIA Corporation.
+ */
+
+#include <linux/device.h>
+#include <linux/of.h>
+
+struct bus_type host1x_context_device_bus_type = {
+ .name = "host1x-context",
+};
+EXPORT_SYMBOL(host1x_context_device_bus_type);
EXPORT_SYMBOL_GPL, please.
But the pattern that this copies in arm_smmu_bus_init is really
ugly. I think we need to figure out a way todo that without having
to export all the low-level bus types.
Yup, as it happens that was the first step on my mission :)
https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus
Still a way to go with the main meat of that work, though, so I was
figuring this could probably land as-is and I'll sweep it up in due course.
Robin.
