firmware: tegra: bpmp: Add MBWT sysfs interface

Different workloads can place different memory-bandwidth demands on the
system. Selecting an appropriate bandwidth limit depends on the runtime
workload mix and on the devices carrying that traffic, such as PCIe
traffic or GPU traffic connected over the chip-to-chip link (NVCLINK).
That information is not available to the kernel.

BPMP firmware of some Tegra platforms provides Memory Bandwidth
Throttler (MBWT) controls for PCIe and GPU traffic connected over
NVCLINK on the path to DRAM. Each PCIe bandwidth group has a single
shared cap for all traffic in that group. Bandwidth for a group can be
set per traffic type.

Describe the available bandwidth groups and traffic types in platform
data. Each entry maps a sysfs name to the corresponding firmware
instance and VC type so that these values can vary between platforms.

Add sysfs attributes on the tegra-bpmp platform device to expose a
narrow userspace interface for MBWT control. The attributes are arranged
as mbwt/<bandwidth-group>/<traffic-type>/bandwidth. The directory names
come from platform data. The current platform description uses pcie0
through pcie5 for bandwidth groups and pcie_read, pcie_write and
nvclink for traffic types.

Reading a bandwidth attribute queries firmware for the selected bandwidth
group and traffic type. Writing an integer programs the target bandwidth
cap in GB/s for that bandwidth group and traffic type.

Register the attributes only when BPMP firmware reports support for the
MBWT GET_BW and SET_BW requests through its query ABI.

Signed-off-by: Aniruddha Rao <anrao@nvidia.com>
[treding@nvidia.com: minor stylistic changes]
Signed-off-by: Thierry Reding <treding@nvidia.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/soc/tegra/bpmp.h b/include/soc/tegra/bpmp.h
index a33582590a3b..f55db918ccb1 100644
--- a/include/soc/tegra/bpmp.h
+++ b/include/soc/tegra/bpmp.h
@@ -16,6 +16,7 @@
 #include <soc/tegra/bpmp-abi.h>
 
 struct tegra_bpmp_clk;
+struct tegra_bpmp_mbwt_soc;
 struct tegra_bpmp_ops;
 
 struct tegra_bpmp_soc {
@@ -28,6 +29,7 @@ struct tegra_bpmp_soc {
 	} channels;
 
 	const struct tegra_bpmp_ops *ops;
+	const struct tegra_bpmp_mbwt_soc *mbwt;
 	unsigned int num_resets;
 };