Merge tag 'platform-drivers-x86-amd-wbrf-v6.8-1' into review-hans

Immutable branch between pdx86 amd wbrf branch and wifi / amdgpu due for the v6.8 merge window

platform-drivers-x86-amd-wbrf-v6.8-1: v6.7-rc1 + AMD WBRF support
for merging into the wifi subsys and amdgpu driver for 6.8.

Author: jwrdegoede

Documentation/driver-api/index.rst

@@ -115,6 +115,7 @@ available subsections can be seen below.
    hte/index
    wmi
    dpll
+   wbrf
 
 .. only::  subproject and html
 

Documentation/driver-api/wbrf.rst

@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+=================================
+WBRF - Wifi Band RFI Mitigations
+=================================
+
+Due to electrical and mechanical constraints in certain platform designs
+there may be likely interference of relatively high-powered harmonics of
+the GPU memory clocks with local radio module frequency bands used by
+certain Wifi bands.
+
+To mitigate possible RFI interference producers can advertise the
+frequencies in use and consumers can use this information to avoid using
+these frequencies for sensitive features.
+
+When a platform is known to have this issue with any contained devices,
+the platform designer will advertise the availability of this feature via
+ACPI devices with a device specific method (_DSM).
+* Producers with this _DSM will be able to advertise the frequencies in use.
+* Consumers with this _DSM will be able to register for notifications of
+frequencies in use.
+
+Some general terms
+==================
+
+Producer: such component who can produce high-powered radio frequency
+Consumer: such component who can adjust its in-use frequency in
+response to the radio frequencies of other components to mitigate the
+possible RFI.
+
+To make the mechanism function, those producers should notify active use
+of their particular frequencies so that other consumers can make relative
+internal adjustments as necessary to avoid this resonance.
+
+ACPI interface
+==============
+
+Although initially used by for wifi + dGPU use cases, the ACPI interface
+can be scaled to any type of device that a platform designer discovers
+can cause interference.
+
+The GUID used for the _DSM is 7B7656CF-DC3D-4C1C-83E9-66E721DE3070.
+
+3 functions are available in this _DSM:
+
+* 0: discover # of functions available
+* 1: record RF bands in use
+* 2: retrieve RF bands in use
+
+Driver programming interface
+============================
+
+.. kernel-doc:: drivers/platform/x86/amd/wbrf.c
+
+Sample Usage
+=============
+
+The expected flow for the producers:
+1. During probe, call `acpi_amd_wbrf_supported_producer` to check if WBRF
+can be enabled for the device.
+2. On using some frequency band, call `acpi_amd_wbrf_add_remove` with 'add'
+param to get other consumers properly notified.
+3. Or on stopping using some frequency band, call
+`acpi_amd_wbrf_add_remove` with 'remove' param to get other consumers notified.
+
+The expected flow for the consumers:
+1. During probe, call `acpi_amd_wbrf_supported_consumer` to check if WBRF
+can be enabled for the device.
+2. Call `amd_wbrf_register_notifier` to register for notification
+of frequency band change(add or remove) from other producers.
+3. Call the `amd_wbrf_retrieve_freq_band` initally to retrieve
+current active frequency bands considering some producers may broadcast
+such information before the consumer is up.
+4. On receiving a notification for frequency band change, run
+`amd_wbrf_retrieve_freq_band` again to retrieve the latest
+active frequency bands.
+5. During driver cleanup, call `amd_wbrf_unregister_notifier` to
+unregister the notifier.

drivers/platform/x86/amd/Kconfig

@@ -18,3 +18,17 @@ config AMD_HSMP
 
 	  If you choose to compile this driver as a module the module will be
 	  called amd_hsmp.
+
+config AMD_WBRF
+	bool "AMD Wifi RF Band mitigations (WBRF)"
+	depends on ACPI
+	help
+	  WBRF(Wifi Band RFI mitigation) mechanism allows Wifi drivers
+	  to notify the frequencies they are using so that other hardware
+	  can be reconfigured to avoid harmonic conflicts.
+
+	  AMD provides an ACPI based mechanism to support WBRF on platform with
+	  appropriate underlying support.
+
+	  This mechanism will only be activated on platforms that advertise a
+	  need for it.

drivers/platform/x86/amd/Makefile

@@ -8,3 +8,4 @@ obj-$(CONFIG_AMD_PMC)		+= pmc/
 amd_hsmp-y			:= hsmp.o
 obj-$(CONFIG_AMD_HSMP)		+= amd_hsmp.o
 obj-$(CONFIG_AMD_PMF)		+= pmf/
+obj-$(CONFIG_AMD_WBRF)		+= wbrf.o