Due to electrical and mechanical constraints in certain platform designs
there may be likely interference of relatively high-powered harmonics of
the (G-)DDR memory clocks with local radio module frequency bands used
by Wifi 6/6e/7.
To mitigate this, AMD has introduced a mechanism that devices can use to
notify active use of particular frequencies so that other devices can make
relative internal adjustments as necessary to avoid this resonance.
Co-developed-by: Evan Quan <quanliangl@xxxxxxxxxxx>
Signed-off-by: Evan Quan <quanliangl@xxxxxxxxxxx>
Signed-off-by: Ma Jun <Jun.Ma2@xxxxxxx>
Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
--
v11:
- fix typo(Simon)
v12:
- Fix the code logic (Rafael)
- Move amd_wbrf.c to drivers/platform/x86/amd/wbrf.c
- Updated Evan's email because he's no longer at AMD.Thanks
for his work in earlier versions.
v13:
- Fix the format issue (IIpo Jarvinen)
- Add comment for some functions
v14:
- Use the apci_check_dsm and acpi_evaluate_dsm (Hans de Goede)
v15:
- Drop redundant functions and fix format issue (Hans de Goede)
- Fix the compile error
---
drivers/platform/x86/amd/Kconfig | 14 ++
drivers/platform/x86/amd/Makefile | 1 +
drivers/platform/x86/amd/wbrf.c | 317 ++++++++++++++++++++++++++++++
include/linux/acpi_amd_wbrf.h | 91 +++++++++
4 files changed, 423 insertions(+)
create mode 100644 drivers/platform/x86/amd/wbrf.c
create mode 100644 include/linux/acpi_amd_wbrf.h
diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
index 55f3a2fc6aec..54753213cc61 100644
--- a/drivers/platform/x86/amd/Kconfig
+++ b/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.
diff --git a/drivers/platform/x86/amd/Makefile b/drivers/platform/x86/amd/Makefile
index f04932b7a7d1..dcec0a46f8af 100644
--- a/drivers/platform/x86/amd/Makefile
+++ b/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
diff --git a/drivers/platform/x86/amd/wbrf.c b/drivers/platform/x86/amd/wbrf.c
new file mode 100644
index 000000000000..dd197b3aebe0
--- /dev/null
+++ b/drivers/platform/x86/amd/wbrf.c
@@ -0,0 +1,317 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Wifi Frequency Band Manage Interface
+ * Copyright (C) 2023 Advanced Micro Devices
+ */
+
+#include <linux/acpi.h>
+#include <linux/acpi_amd_wbrf.h>
+
+/*
+ * Functions bit vector for WBRF method
+ *
+ * Bit 0: WBRF supported.
+ * Bit 1: Function 1 (Add / Remove frequency) is supported.
+ * Bit 2: Function 2 (Get frequency list) is supported.
+ */
+#define WBRF_ENABLED 0x0
+#define WBRF_RECORD 0x1
+#define WBRF_RETRIEVE 0x2
+
+#define WBRF_REVISION 0x1
+
+/*
+ * The data structure used for WBRF_RETRIEVE is not naturally aligned.
+ * And unfortunately the design has been settled down.
+ */
+struct amd_wbrf_ranges_out {
+ u32 num_of_ranges;
+ struct freq_band_range band_list[MAX_NUM_OF_WBRF_RANGES];
+} __packed;
+
+static const guid_t wifi_acpi_dsm_guid =
+ GUID_INIT(0x7b7656cf, 0xdc3d, 0x4c1c,
+ 0x83, 0xe9, 0x66, 0xe7, 0x21, 0xde, 0x30, 0x70);
+
+/*
+ * Used to notify consumer (amdgpu driver currently) about
+ * the wifi frequency is change.
+ */
+static BLOCKING_NOTIFIER_HEAD(wbrf_chain_head);
+
+static int wbrf_record(struct acpi_device *adev, uint8_t action, struct wbrf_ranges_in_out *in)
+{
+ union acpi_object argv4;
+ union acpi_object *tmp;
+ union acpi_object *obj;
+ u32 num_of_ranges = 0;
+ u32 num_of_elements;
+ u32 arg_idx = 0;
+ int ret;
+ u32 i;
+
+ if (!in)
+ return -EINVAL;
+
+ for (i = 0; i < ARRAY_SIZE(in->band_list); i++) {
+ if (in->band_list[i].start && in->band_list[i].end)
+ num_of_ranges++;
+ }
+
+ /*
+ * The num_of_ranges value in the "in" object supplied by
+ * the caller is required to be equal to the number of
+ * entries in the band_list array in there.
+ */
+ if (num_of_ranges != in->num_of_ranges)
+ return -EINVAL;
+
+ /*
+ * Every input frequency band comes with two end points(start/end)
+ * and each is accounted as an element. Meanwhile the range count
+ * and action type are accounted as an element each.
+ * So, the total element count = 2 * num_of_ranges + 1 + 1.
+ */
+ num_of_elements = 2 * num_of_ranges + 2;
+
+ tmp = kcalloc(num_of_elements, sizeof(*tmp), GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ argv4.package.type = ACPI_TYPE_PACKAGE;
+ argv4.package.count = num_of_elements;
+ argv4.package.elements = tmp;
+
+ /* save the number of ranges*/
+ tmp[0].integer.type = ACPI_TYPE_INTEGER;
+ tmp[0].integer.value = num_of_ranges;
+
+ /* save the action(WBRF_RECORD_ADD/REMOVE/RETRIEVE) */
+ tmp[1].integer.type = ACPI_TYPE_INTEGER;
+ tmp[1].integer.value = action;
+
+ arg_idx = 2;
+ for (i = 0; i < ARRAY_SIZE(in->band_list); i++) {
+ if (!in->band_list[i].start || !in->band_list[i].end)
+ continue;
+
+ tmp[arg_idx].integer.type = ACPI_TYPE_INTEGER;
+ tmp[arg_idx++].integer.value = in->band_list[i].start;
+ tmp[arg_idx].integer.type = ACPI_TYPE_INTEGER;
+ tmp[arg_idx++].integer.value = in->band_list[i].end;
+ }
+
+ obj = acpi_evaluate_dsm(adev->handle, &wifi_acpi_dsm_guid,
+ WBRF_REVISION, WBRF_RECORD, &argv4);
+
+ if (!obj)
+ return -EINVAL;
+
+ if (obj->type != ACPI_TYPE_INTEGER) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = obj->integer.value;
+ if (ret)
+ ret = -EINVAL;
+
+out:
+ ACPI_FREE(obj);
+ kfree(tmp);
+
+ return ret;
+}
+
+/**
+ * acpi_amd_wbrf_add_remove - add or remove the frequency band the device is using
+ *
+ * @dev: device pointer
+ * @action: remove or add the frequency band into bios
+ * @in: input structure containing the frequency band the device is using
+ *
+ * Broadcast to other consumers the frequency band the device starts
+ * to use. Underneath the surface the information is cached into an
+ * internal buffer first. Then a notification is sent to all those
+ * registered consumers. So then they can retrieve that buffer to
+ * know the latest active frequency bands. Consumers that haven't
+ * yet been registered can retrieve the information from the cache
+ * when they register.
+ *
+ * Return:
+ * 0 for success add/remove wifi frequency band.
+ * Returns a negative error code for failure.
+ */
+int acpi_amd_wbrf_add_remove(struct device *dev, uint8_t action, struct wbrf_ranges_in_out *in)
+{
+ struct acpi_device *adev;
+ int ret;
+
+ adev = ACPI_COMPANION(dev);
+ if (!adev)
+ return -ENODEV;
+
+ ret = wbrf_record(adev, action, in);
+ if (ret)
+ return ret;
+
+ blocking_notifier_call_chain(&wbrf_chain_head, WBRF_CHANGED, NULL);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_amd_wbrf_add_remove);
+
+/**
+ * acpi_amd_wbrf_supported_producer - determine if the WBRF can be enabled
+ * for the device as a producer
+ *
+ * @dev: device pointer
+ *
+ * Check if the platform equipped with necessary implementations to
+ * support WBRF for the device as a producer.
+ *
+ * Return:
+ * true if WBRF is supported, otherwise returns false
+ */
+bool acpi_amd_wbrf_supported_producer(struct device *dev)
+{
+ struct acpi_device *adev;
+
+ adev = ACPI_COMPANION(dev);
+ if (!adev)
+ return false;
+
+ return acpi_check_dsm(adev->handle, &wifi_acpi_dsm_guid,
+ WBRF_REVISION, BIT(WBRF_RECORD));
+}
+EXPORT_SYMBOL_GPL(acpi_amd_wbrf_supported_producer);
+
+/**
+ * acpi_amd_wbrf_supported_consumer - determine if the WBRF can be enabled
+ * for the device as a consumer
+ *
+ * @dev: device pointer
+ *
+ * Determine if the platform equipped with necessary implementations to
+ * support WBRF for the device as a consumer.
+ *
+ * Return:
+ * true if WBRF is supported, otherwise returns false.
+ */
+bool acpi_amd_wbrf_supported_consumer(struct device *dev)
+{
+ struct acpi_device *adev;
+
+ adev = ACPI_COMPANION(dev);
+ if (!adev)
+ return false;
+
+ return acpi_check_dsm(adev->handle, &wifi_acpi_dsm_guid,
+ WBRF_REVISION, BIT(WBRF_RETRIEVE));
+}
+EXPORT_SYMBOL_GPL(acpi_amd_wbrf_supported_consumer);
+
+/**
+ * amd_wbrf_retrieve_freq_band - retrieve current active frequency bands
+ *
+ * @dev: device pointer
+ * @out: output structure containing all the active frequency bands
+ *
+ * Retrieve the current active frequency bands which were broadcasted
+ * by other producers. The consumer who calls this API should take
+ * proper actions if any of the frequency band may cause RFI with its
+ * own frequency band used.
+ *
+ * Return:
+ * 0 for getting wifi freq band successfully.
+ * Returns a negative error code for failure.
+ */
+int amd_wbrf_retrieve_freq_band(struct device *dev, struct wbrf_ranges_in_out *out)
+{
+ struct amd_wbrf_ranges_out acpi_out = {0};
+ struct acpi_device *adev;
+ union acpi_object *obj;
+ union acpi_object param;
+ int ret = 0;
+
+ adev = ACPI_COMPANION(dev);
+ if (!adev)
+ return -ENODEV;
+
+ param.type = ACPI_TYPE_STRING;
+ param.string.length = 0;
+ param.string.pointer = NULL;
+
+ obj = acpi_evaluate_dsm(adev->handle, &wifi_acpi_dsm_guid,
+ WBRF_REVISION, WBRF_RETRIEVE, ¶m);
+ if (!obj)
+ return -EINVAL;
+
+ /*
+ * The return buffer is with variable length and the format below:
+ * number_of_entries(1 DWORD): Number of entries
+ * start_freq of 1st entry(1 QWORD): Start frequency of the 1st entry
+ * end_freq of 1st entry(1 QWORD): End frequency of the 1st entry
+ * ...
+ * ...
+ * start_freq of the last entry(1 QWORD)
+ * end_freq of the last entry(1 QWORD)
+ *
+ * Thus the buffer length is determined by the number of entries.
+ * - For zero entry scenario, the buffer length will be 4 bytes.
+ * - For one entry scenario, the buffer length will be 20 bytes.
+ */
+ if (obj->buffer.length > sizeof(acpi_out) || obj->buffer.length < 4) {
+ dev_err(dev, "Wrong sized WBRT information");
+ ret = -EINVAL;
+ goto out;
+ }
+ memcpy(&acpi_out, obj->buffer.pointer, obj->buffer.length);
+
+ out->num_of_ranges = acpi_out.num_of_ranges;
+ memcpy(out->band_list, acpi_out.band_list, sizeof(acpi_out.band_list));
+
+out:
+ ACPI_FREE(obj);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(amd_wbrf_retrieve_freq_band);
+
+/**
+ * amd_wbrf_register_notifier - register for notifications of frequency
+ * band update
+ *
+ * @nb: driver notifier block
+ *
+ * The consumer should register itself via this API so that it can get
+ * notified on the frequency band updates from other producers.
+ *
+ * Return:
+ * 0 for registering a consumer driver successfully.
+ * Returns a negative error code for failure.
+ */
+int amd_wbrf_register_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&wbrf_chain_head, nb);
+}
+EXPORT_SYMBOL_GPL(amd_wbrf_register_notifier);
+
+/**
+ * amd_wbrf_unregister_notifier - unregister for notifications of
+ * frequency band update
+ *
+ * @nb: driver notifier block
+ *
+ * The consumer should call this API when it is longer interested with
+ * the frequency band updates from other producers. Usually, this should
+ * be performed during driver cleanup.
+ *
+ * Return:
+ * 0 for unregistering a consumer driver.
+ * Returns a negative error code for failure.
+ */
+int amd_wbrf_unregister_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&wbrf_chain_head, nb);
+}
+EXPORT_SYMBOL_GPL(amd_wbrf_unregister_notifier);
diff --git a/include/linux/acpi_amd_wbrf.h b/include/linux/acpi_amd_wbrf.h
new file mode 100644
index 000000000000..898f31d536d4
--- /dev/null
+++ b/include/linux/acpi_amd_wbrf.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Wifi Band Exclusion Interface (AMD ACPI Implementation)
+ * Copyright (C) 2023 Advanced Micro Devices
+ */
+
+#ifndef _ACPI_AMD_WBRF_H
+#define _ACPI_AMD_WBRF_H
+
+#include <linux/device.h>
+#include <linux/notifier.h>
+
+/* The maximum number of frequency band ranges */
+#define MAX_NUM_OF_WBRF_RANGES 11
+
+/* Record actions */
+#define WBRF_RECORD_ADD 0x0
+#define WBRF_RECORD_REMOVE 0x1
+
+/**
+ * struct freq_band_range - Wifi frequency band range definition
+ * @start: start frequency point (in Hz)
+ * @end: end frequency point (in Hz)
+ */
+struct freq_band_range {
+ u64 start;
+ u64 end;
+};
+
+/**
+ * struct wbrf_ranges_in_out - wbrf ranges info
+ * @num_of_ranges: total number of band ranges in this struct
+ * @band_list: array of Wifi band ranges
+ */
+struct wbrf_ranges_in_out {
+ u64 num_of_ranges;
+ struct freq_band_range band_list[MAX_NUM_OF_WBRF_RANGES];
+};
+
+/**
+ * enum wbrf_notifier_actions - wbrf notifier actions index
+ * @WBRF_CHANGED: there was some frequency band updates. The consumers
+ * should retrieve the latest active frequency bands.
+ */
+enum wbrf_notifier_actions {
+ WBRF_CHANGED,
+};
+
+#if IS_ENABLED(CONFIG_AMD_WBRF)
+bool acpi_amd_wbrf_supported_producer(struct device *dev);
+int acpi_amd_wbrf_add_remove(struct device *dev, uint8_t action, struct wbrf_ranges_in_out *in);
+bool acpi_amd_wbrf_supported_consumer(struct device *dev);
+int amd_wbrf_retrieve_freq_band(struct device *dev, struct wbrf_ranges_in_out *out);
+int amd_wbrf_register_notifier(struct notifier_block *nb);
+int amd_wbrf_unregister_notifier(struct notifier_block *nb);
+#else
+static inline
+bool acpi_amd_wbrf_supported_consumer(struct device *dev)
+{
+ return false;
+}
+
+static inline
+int acpi_amd_wbrf_add_remove(struct device *dev, uint8_t action, struct wbrf_ranges_in_out *in)
+{
+ return -ENODEV;
+}
+
+static inline
+bool acpi_amd_wbrf_supported_producer(struct device *dev)
+{
+ return false;
+}
+static inline
+int amd_wbrf_retrieve_freq_band(struct device *dev, struct wbrf_ranges_in_out *out)
+{
+ return -ENODEV;
+}
+static inline
+int amd_wbrf_register_notifier(struct notifier_block *nb)
+{
+ return -ENODEV;
+}
+static inline
+int amd_wbrf_unregister_notifier(struct notifier_block *nb)
+{
+ return -ENODEV;
+}
+#endif /* CONFIG_AMD_WBRF */
+
+#endif /* _ACPI_AMD_WBRF_H */
--
2.34.1
