platform/x86/amd: Add support for AMD ACPI based Wifi band RFI mitigation feature

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@hotmail.com>
Signed-off-by: Evan Quan <quanliangl@hotmail.com>
Signed-off-by: Ma Jun <Jun.Ma2@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 91 insertions, 0 deletions

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 */