[26.04_linux-nvidia-bos] BPMP ACPI + SoC Hub MBWT sysfs for T410/NVL72

Documentation/ABI/testing/sys-platform-tegra-bpmp

@@ -0,0 +1,51 @@
+What:           /sys/bus/platform/devices/<bpmp-device>/mbwt_control/pcie_instance_id
+What:           /sys/bus/platform/devices/<bpmp-device>/mbwt_control/vc_type
+What:           /sys/bus/platform/devices/<bpmp-device>/mbwt_control/bandwidth
+Date:           March 2026
+KernelVersion:  6.18
+Contact:        Aniruddha TVS Rao <anrao@nvidia.com>
+Description:
+               On ACPI-based Tegra systems the BPMP driver does not use the
+               device-tree mailbox path; firmware interaction is via AML. This sysfs
+               interface is a userspace tuning knob for memory bandwidth throttler
+               (MBWT) settings.
+
+               On Tegra410, the PCIe bandwidth control path exposes QoS that caps
+               aggregate bandwidth for PCIe and for GPU traffic over UPHY. Each PCIe
+               bandwidth group has a single shared cap for all traffic in that group.
+               A group may contain only PCIe devices, only a GPU on UPHY, or PCIe and
+               GPU together in a bifurcated topology.
+
+               Following attributes appear under a kobject named mbwt_control on the
+               tegra-bpmp platform device (the same struct device as the driver
+               binds to), only when that device has an ACPI companion and BPMP
+               firmware reports support for both MBWT_GET and MBWT_SET via the MBWT
+               QUERY probe.
+
+               pcie_instance_id (RW):
+                       PCIe bandwidth group index: 0 = pcie0, 1 = pcie1, ..., 5 = pcie5.
+
+               vc_type (RW):
+                       Traffic type to cap for that group:
+                       0 = PCIe read
+                       1 = PCIe write
+                       2 = GPU UPHY read plus write (combined)
+
+               bandwidth (RW):
+                       Target bandwidth cap in GB/s for the pcie_instance_id and vc_type
+                       currently stored in the other two attributes. Intended range is
+                       1-110 GB/s; firmware validates the request (via MRQ MBWT_SET).
+
+                       When read, issues a MBWT_GET for that same pcie_instance_id and vc_type
+                       and returns one line of three decimal fields separated by ASCII
+                       space: PCIe instance ID, vc_type, and the bandwidth value in GB/s
+                       returned by firmware.
+
+               Example:
+                       echo 0 > .../mbwt_control/pcie_instance_id
+                       echo 1 > .../mbwt_control/vc_type
+                       echo 100 > .../mbwt_control/bandwidth
+                       cat .../mbwt_control/bandwidth
+
+Users:         Customer tuning of PCIe and GPU UPHY bandwidth caps on
+               ACPI-based Tegra410 systems.

drivers/firmware/tegra/Makefile

@@ -7,4 +7,5 @@ tegra-bpmp-$(CONFIG_ARCH_TEGRA_234_SOC)	+= bpmp-tegra186.o
 tegra-bpmp-$(CONFIG_ARCH_TEGRA_264_SOC)	+= bpmp-tegra186.o
 tegra-bpmp-$(CONFIG_DEBUG_FS)	+= bpmp-debugfs.o
 obj-$(CONFIG_TEGRA_BPMP)	+= tegra-bpmp.o
+obj-$(CONFIG_TEGRA_BPMP)       += bpmp-tegra-sysfs.o
 obj-$(CONFIG_TEGRA_IVC)		+= ivc.o

drivers/firmware/tegra/bpmp-debugfs.c

@@ -2,6 +2,7 @@
 /*
  * Copyright (c) 2017, NVIDIA CORPORATION.  All rights reserved.
  */
+#include <linux/acpi.h>
 #include <linux/debugfs.h>
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
@@ -771,6 +772,8 @@ static int bpmp_populate_debugfs_shmem(struct tegra_bpmp *bpmp)
 
 int tegra_bpmp_init_debugfs(struct tegra_bpmp *bpmp)
 {
+	const char *root_name = "bpmp";
+	char *acpi_root_name = NULL;
 	struct dentry *root;
 	bool inband;
 	int err;
@@ -780,13 +783,23 @@ int tegra_bpmp_init_debugfs(struct tegra_bpmp *bpmp)
 	if (!inband && !tegra_bpmp_mrq_is_supported(bpmp, MRQ_DEBUGFS))
 		return 0;
 
-	root = debugfs_create_dir("bpmp", NULL);
+	if (ACPI_HANDLE(bpmp->dev)) {
+		acpi_root_name = kasprintf(GFP_KERNEL, "bpmp-%s",
+					   dev_name(bpmp->dev));
+		if (!acpi_root_name)
+			return -ENOMEM;
+
+		root_name = acpi_root_name;
+	}
+
+	root = debugfs_create_dir(root_name, NULL);
+	kfree(acpi_root_name);
 	if (IS_ERR(root))
-		return -ENOMEM;
+		return PTR_ERR(root);
 
 	bpmp->debugfs_mirror = debugfs_create_dir("debug", root);
 	if (IS_ERR(bpmp->debugfs_mirror)) {
-		err = -ENOMEM;
+		err = PTR_ERR(bpmp->debugfs_mirror);
 		goto out;
 	}
 

drivers/firmware/tegra/bpmp-private.h

@@ -26,4 +26,12 @@ struct tegra_bpmp_ops {
 extern const struct tegra_bpmp_ops tegra186_bpmp_ops;
 extern const struct tegra_bpmp_ops tegra210_bpmp_ops;
 
+#define TEGRA_BPMP_ACPI_BMRQ_DATA_SZ   3960U
+
+struct tegra_bpmp_acpi_message {
+	u64 status;
+	u8 *data_ptr;
+	u8 data[TEGRA_BPMP_ACPI_BMRQ_DATA_SZ];
+};
+
 #endif