[PATCH V8 2/9] drivers core: add ACPI based WBRF mechanism introduced by AMD

Evan Quan
2023-08-10T07:40:03Z

AMD has introduced an ACPI based mechanism to support WBRF for some
platforms with AMD dGPU + WLAN. This needs support from BIOS equipped
with necessary AML implementations and dGPU firmwares.

For those systems without the ACPI mechanism and developing solutions,
user can use/fall-back the generic WBRF solution for diagnosing potential
interference issues.

And for the platform which does not equip with the necessary AMD ACPI
implementations but with CONFIG_WBRF_AMD_ACPI built as 'y', it will
fall back to generic WBRF solution if the `wbrf` is set as "on".

Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Co-developed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Evan Quan <evan.quan@amd.com>
--
v4->v5:
- promote this to be a more generic solution with input argument taking
`struct device` and provide better scalability to support non-ACPI
scenarios(Andrew)
- update the APIs naming and some other minor fixes(Rafael)
v5->v6:
- make the code more readable and some other fixes(Andrew)
v6->v8:
- drop CONFIG_WBRF_GENERIC(Mario)
- add `wbrf` kernel parameter for policy control(Mario)
---
drivers/acpi/Makefile | 2 +
drivers/acpi/amd_wbrf.c | 294 ++++++++++++++++++++++++++++++++++
drivers/base/Kconfig | 20 +++
drivers/base/wbrf.c | 135 +++++++++++++---
include/linux/acpi_amd_wbrf.h | 25 +++
5 files changed, 452 insertions(+), 24 deletions(-)
create mode 100644 drivers/acpi/amd_wbrf.c
create mode 100644 include/linux/acpi_amd_wbrf.h

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 3fc5a0d54f6e..9185d16e4495 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -133,3 +133,5 @@ obj-$(CONFIG_ARM64) += arm64/
obj-$(CONFIG_ACPI_VIOT) += viot.o

obj-$(CONFIG_RISCV) += riscv/
+
+obj-$(CONFIG_WBRF_AMD_ACPI) += amd_wbrf.o
diff --git a/drivers/acpi/amd_wbrf.c b/drivers/acpi/amd_wbrf.c
new file mode 100644
index 000000000000..a3390d91cbea
--- /dev/null
+++ b/drivers/acpi/amd_wbrf.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Wifi Band Exclusion Interface (AMD ACPI Implementation)
+ * Copyright (C) 2023 Advanced Micro Devices
+ *
+ */
+
+#include <linux/acpi.h>
+#include <linux/acpi_amd_wbrf.h>
+
+#define ACPI_AMD_WBRF_METHOD "\\WBRF"
+
+/*
+ * Functions bit vector for WBRF method
+ *
+ * Bit 0: Supported for any functions other than function 0.
+ * 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
+
+/* record actions */
+#define WBRF_RECORD_ADD 0x0
+#define WBRF_RECORD_REMOVE 0x1
+
+#define WBRF_REVISION 0x1
+
+/*
+ * The data structure used for WBRF_RETRIEVE is not natually aligned.
+ * And unfortunately the design has been settled down.
+ */
+struct amd_wbrf_ranges_out {
+ u32 num_of_ranges;
+ struct exclusion_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);
+
+static int wbrf_dsm(struct acpi_device *adev, u8 fn,
+ union acpi_object *argv4,
+ union acpi_object **out)
+{
+ union acpi_object *obj;
+ int rc;
+
+ obj = acpi_evaluate_dsm(adev->handle, &wifi_acpi_dsm_guid,
+ WBRF_REVISION, fn, argv4);
+ if (!obj)
+ return -ENXIO;
+
+ switch (obj->type) {
+ case ACPI_TYPE_BUFFER:
+ *out = obj;
+ return 0;
+
+ case ACPI_TYPE_INTEGER:
+ rc = obj->integer.value ? -EINVAL : 0;
+ break;
+
+ default:
+ rc = -EOPNOTSUPP;
+ }
+
+ ACPI_FREE(obj);
+
+ return rc;
+}
+
+static int wbrf_record(struct acpi_device *adev, uint8_t action,
+ struct wbrf_ranges_in *in)
+{
+ union acpi_object argv4;
+ union acpi_object *tmp;
+ u32 num_of_ranges = 0;
+ u32 num_of_elements;
+ u32 arg_idx = 0;
+ u32 loop_idx;
+ int ret;
+
+ if (!in)
+ return -EINVAL;
+
+ for (loop_idx = 0; loop_idx < ARRAY_SIZE(in->band_list);
+ loop_idx++)
+ if (in->band_list[loop_idx].start &&
+ in->band_list[loop_idx].end)
+ num_of_ranges++;
+
+ /*
+ * Every range comes with two end points(start and end) and
+ * each of them 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 + 1 + 1;
+
+ 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;
+
+ tmp[arg_idx].integer.type = ACPI_TYPE_INTEGER;
+ tmp[arg_idx++].integer.value = num_of_ranges;
+ tmp[arg_idx].integer.type = ACPI_TYPE_INTEGER;
+ tmp[arg_idx++].integer.value = action;
+
+ for (loop_idx = 0; loop_idx < ARRAY_SIZE(in->band_list);
+ loop_idx++) {
+ if (!in->band_list[loop_idx].start ||
+ !in->band_list[loop_idx].end)
+ continue;
+
+ tmp[arg_idx].integer.type = ACPI_TYPE_INTEGER;
+ tmp[arg_idx++].integer.value = in->band_list[loop_idx].start;
+ tmp[arg_idx].integer.type = ACPI_TYPE_INTEGER;
+ tmp[arg_idx++].integer.value = in->band_list[loop_idx].end;
+ }
+
+ ret = wbrf_dsm(adev, WBRF_RECORD, &argv4, NULL);
+
+ kfree(tmp);
+
+ return ret;
+}
+
+int acpi_amd_wbrf_add_exclusion(struct device *dev,
+ struct wbrf_ranges_in *in)
+{
+ struct acpi_device *adev = ACPI_COMPANION(dev);
+
+ if (!adev)
+ return -ENODEV;
+
+ return wbrf_record(adev, WBRF_RECORD_ADD, in);
+}
+
+int acpi_amd_wbrf_remove_exclusion(struct device *dev,
+ struct wbrf_ranges_in *in)
+{
+ struct acpi_device *adev = ACPI_COMPANION(dev);
+
+ if (!adev)
+ return -ENODEV;
+
+ return wbrf_record(adev, WBRF_RECORD_REMOVE, in);
+}
+
+bool acpi_amd_wbrf_supported_system(void)
+{
+ acpi_status status;
+ acpi_handle handle;
+
+ status = acpi_get_handle(NULL, ACPI_AMD_WBRF_METHOD, &handle);
+
+ return ACPI_SUCCESS(status);
+}
+
+bool acpi_amd_wbrf_supported_producer(struct device *dev)
+{
+ struct acpi_device *adev = ACPI_COMPANION(dev);
+
+ if (!adev)
+ return false;
+
+ return acpi_check_dsm(adev->handle, &wifi_acpi_dsm_guid,
+ WBRF_REVISION,
+ BIT(WBRF_RECORD));
+}
+
+static union acpi_object *
+acpi_evaluate_wbrf(acpi_handle handle, u64 rev, u64 func)
+{
+ acpi_status ret;
+ struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
+ union acpi_object params[4];
+ struct acpi_object_list input = {
+ .count = 4,
+ .pointer = params,
+ };
+
+ params[0].type = ACPI_TYPE_INTEGER;
+ params[0].integer.value = rev;
+ params[1].type = ACPI_TYPE_INTEGER;
+ params[1].integer.value = func;
+ params[2].type = ACPI_TYPE_PACKAGE;
+ params[2].package.count = 0;
+ params[2].package.elements = NULL;
+ params[3].type = ACPI_TYPE_STRING;
+ params[3].string.length = 0;
+ params[3].string.pointer = NULL;
+
+ ret = acpi_evaluate_object(handle, "WBRF", &input, &buf);
+ if (ACPI_SUCCESS(ret))
+ return (union acpi_object *)buf.pointer;
+
+ return NULL;
+}
+
+static bool check_acpi_wbrf(acpi_handle handle, u64 rev, u64 funcs)
+{
+ int i;
+ u64 mask = 0;
+ union acpi_object *obj;
+
+ if (funcs == 0)
+ return false;
+
+ obj = acpi_evaluate_wbrf(handle, rev, 0);
+ if (!obj)
+ return false;
+
+ if (obj->type != ACPI_TYPE_BUFFER)
+ return false;
+
+ /*
+ * Bit vector providing supported functions information.
+ * Each bit marks support for one specific function of the WBRF method.
+ */
+ for (i = 0; i < obj->buffer.length && i < 8; i++)
+ mask |= (((u64)obj->buffer.pointer[i]) << (i * 8));
+
+ ACPI_FREE(obj);
+
+ if ((mask & BIT(WBRF_ENABLED)) &&
+ (mask & funcs) == funcs)
+ return true;
+
+ return false;
+}
+
+bool acpi_amd_wbrf_supported_consumer(struct device *dev)
+{
+ struct acpi_device *adev = ACPI_COMPANION(dev);
+
+ if (!adev)
+ return false;
+
+ return check_acpi_wbrf(adev->handle,
+ WBRF_REVISION,
+ BIT(WBRF_RETRIEVE));
+}
+
+int acpi_amd_wbrf_retrieve_exclusions(struct device *dev,
+ struct wbrf_ranges_out *out)
+{
+ struct acpi_device *adev = ACPI_COMPANION(dev);
+ struct amd_wbrf_ranges_out acpi_out = {0};
+ union acpi_object *obj;
+
+ if (!adev)
+ return -ENODEV;
+
+ obj = acpi_evaluate_wbrf(adev->handle,
+ WBRF_REVISION,
+ WBRF_RETRIEVE);
+ 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, "BIOS FUBAR, ignoring wrong sized WBRT information");
+ ACPI_FREE(obj);
+ return -EINVAL;
+ }
+ 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));
+
+ ACPI_FREE(obj);
+
+ return 0;
+}
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 2b8fd6bb7da0..feb6f5625728 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -242,4 +242,24 @@ config FW_DEVLINK_SYNC_STATE_TIMEOUT
command line option on every system/board your kernel is expected to
work on.

+menu "Wifi band RF mitigation mechanism"
+
+config WBRF_AMD_ACPI
+ bool "ACPI based mechanism introduced by AMD"
+ depends on ACPI
+ help
+ Wifi band RF mitigation mechanism allows multiple drivers from
+ different domains to notify the frequencies in use so that hardware
+ can be reconfigured to avoid harmonic conflicts.
+
+ AMD has introduced an ACPI based mechanism to support WBRF for some
+ platforms with AMD dGPU and WLAN. This needs support from BIOS equipped
+ with necessary AML implementations and dGPU firmwares.
+
+ Before enabling this ACPI based mechanism, it is suggested to confirm
+ with the hardware designer/provider first whether your platform
+ equipped with necessary BIOS and firmwares.
+
+endmenu
+
endmenu
diff --git a/drivers/base/wbrf.c b/drivers/base/wbrf.c
index 678f245c12c6..751e252d0039 100644
--- a/drivers/base/wbrf.c
+++ b/drivers/base/wbrf.c
@@ -6,9 +6,25 @@
*/

#include <linux/wbrf.h>
+#include <linux/acpi_amd_wbrf.h>

static BLOCKING_NOTIFIER_HEAD(wbrf_chain_head);
+
static DEFINE_MUTEX(wbrf_mutex);
+
+static struct exclusion_range_pool {
+ struct exclusion_range band_list[MAX_NUM_OF_WBRF_RANGES];
+ u64 ref_counter[MAX_NUM_OF_WBRF_RANGES];
+} wbrf_pool;
+
+enum WBRF_SUPPORT_CHECK {
+ WBRF_SUPPORT_UNCHECKED,
+ WBRF_SUPPORT_NONE,
+ WBRF_SUPPORT_GENERIC,
+ WBRF_SUPPORT_OTHERS,
+};
+static atomic_t wbrf_support_check = ATOMIC_INIT(WBRF_SUPPORT_UNCHECKED);
+
static enum WBRF_POLICY_MODE {
WBRF_POLICY_FORCE_DISABLE,
WBRF_POLICY_AUTO,
@@ -30,11 +46,6 @@ static int __init parse_wbrf_policy_mode(char *p)
}
early_param("wbrf", parse_wbrf_policy_mode);

-static struct exclusion_range_pool {
- struct exclusion_range band_list[MAX_NUM_OF_WBRF_RANGES];
- u64 ref_counter[MAX_NUM_OF_WBRF_RANGES];
-} wbrf_pool;
-
static int _wbrf_add_exclusion_ranges(struct wbrf_ranges_in *in)
{
int i, j;
@@ -121,20 +132,45 @@ static int _wbrf_retrieve_exclusion_ranges(struct wbrf_ranges_out *out)
*
* WBRF is used to mitigate devices that cause harmonic interference.
* This function will determine if the platform is able to support the
- * WBRF features.
+ * WBRF features. For example, for AMD ACPI implementation it should say
+ * true only when the necessary AML code/logic supporting wbrf feature
+ * available.
*/
-static bool wbrf_supported_system(void)
+static enum WBRF_SUPPORT_CHECK wbrf_supported_system(void)
{
+ enum WBRF_SUPPORT_CHECK support_check;
+
+ support_check = atomic_read(&wbrf_support_check);
+ if (support_check != WBRF_SUPPORT_UNCHECKED)
+ return support_check;
+
+ support_check = WBRF_SUPPORT_NONE;
+
switch (wbrf_policy) {
case WBRF_POLICY_FORCE_ENABLE:
- return true;
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+ if (acpi_amd_wbrf_supported_system()) {
+ support_check = WBRF_SUPPORT_OTHERS;
+ break;
+ }
+ pr_warn_once("Force WBRF w/o acpi_amd_wbrf support\n");
+ pr_warn_once("Fall back to generic version\n");
+#endif
+ support_check = WBRF_SUPPORT_GENERIC;
+ break;
case WBRF_POLICY_FORCE_DISABLE:
- return false;
+ break;
case WBRF_POLICY_AUTO:
- return false;
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+ if (acpi_amd_wbrf_supported_system())
+ support_check = WBRF_SUPPORT_OTHERS;
+#endif
+ break;
}

- return false;
+ atomic_set(&wbrf_support_check, support_check);
+
+ return support_check;
}

/**
@@ -144,13 +180,22 @@ static bool wbrf_supported_system(void)
*
* WBRF is used to mitigate devices that cause harmonic interference.
* This function will determine if this device should report such frequencies.
+ * For example, for AMD ACPI implementation it should say true only when the
+ * necessary AML code/logic supporting wbrf feature available for this device.
*/
bool wbrf_supported_producer(struct device *dev)
{
- if (!wbrf_supported_system())
+ switch (wbrf_supported_system()) {
+ case WBRF_SUPPORT_GENERIC:
+ return true;
+ case WBRF_SUPPORT_OTHERS:
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+ return acpi_amd_wbrf_supported_producer(dev);
+#endif
+ fallthrough;
+ default:
return false;
-
- return true;
+ }
}
EXPORT_SYMBOL_GPL(wbrf_supported_producer);

@@ -166,11 +211,22 @@ EXPORT_SYMBOL_GPL(wbrf_supported_producer);
int wbrf_add_exclusion(struct device *dev,
struct wbrf_ranges_in *in)
{
- int r;
+ int r = -ENODEV;

mutex_lock(&wbrf_mutex);

- r = _wbrf_add_exclusion_ranges(in);
+ switch (wbrf_supported_system()) {
+ case WBRF_SUPPORT_OTHERS:
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+ r = acpi_amd_wbrf_add_exclusion(dev, in);
+#endif
+ break;
+ case WBRF_SUPPORT_GENERIC:
+ r = _wbrf_add_exclusion_ranges(in);
+ break;
+ default:
+ break;
+ }

mutex_unlock(&wbrf_mutex);
if (r)
@@ -194,11 +250,22 @@ EXPORT_SYMBOL_GPL(wbrf_add_exclusion);
int wbrf_remove_exclusion(struct device *dev,
struct wbrf_ranges_in *in)
{
- int r;
+ int r = -ENODEV;

mutex_lock(&wbrf_mutex);

- r = _wbrf_remove_exclusion_ranges(in);
+ switch (wbrf_supported_system()) {
+ case WBRF_SUPPORT_OTHERS:
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+ r = acpi_amd_wbrf_remove_exclusion(dev, in);
+#endif
+ break;
+ case WBRF_SUPPORT_GENERIC:
+ r = _wbrf_remove_exclusion_ranges(in);
+ break;
+ default:
+ break;
+ }

mutex_unlock(&wbrf_mutex);
if (r)
@@ -217,14 +284,23 @@ EXPORT_SYMBOL_GPL(wbrf_remove_exclusion);
*
* WBRF is used to mitigate devices that cause harmonic interference.
* This function will determine if this device should react to reports from
- * other devices for such frequencies.
+ * other devices for such frequencies. For example, for AMD ACPI implementation
+ * it should say true only when the necessary AML code/logic supporting wbrf
+ * feature available for this device.
*/
bool wbrf_supported_consumer(struct device *dev)
{
- if (!wbrf_supported_system())
+ switch (wbrf_supported_system()) {
+ case WBRF_SUPPORT_GENERIC:
+ return true;
+ case WBRF_SUPPORT_OTHERS:
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+ return acpi_amd_wbrf_supported_consumer(dev);
+#endif
+ fallthrough;
+ default:
return false;
-
- return true;
+ }
}
EXPORT_SYMBOL_GPL(wbrf_supported_consumer);

@@ -267,11 +343,22 @@ EXPORT_SYMBOL_GPL(wbrf_unregister_notifier);
int wbrf_retrieve_exclusions(struct device *dev,
struct wbrf_ranges_out *out)
{
- int r;
+ int r = -ENODEV;

mutex_lock(&wbrf_mutex);

- r = _wbrf_retrieve_exclusion_ranges(out);
+ switch (wbrf_supported_system()) {
+ case WBRF_SUPPORT_OTHERS:
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+ r = acpi_amd_wbrf_retrieve_exclusions(dev, out);
+#endif
+ break;
+ case WBRF_SUPPORT_GENERIC:
+ r = _wbrf_retrieve_exclusion_ranges(out);
+ break;
+ default:
+ break;
+ }

mutex_unlock(&wbrf_mutex);

diff --git a/include/linux/acpi_amd_wbrf.h b/include/linux/acpi_amd_wbrf.h
new file mode 100644
index 000000000000..40c59e9f626d
--- /dev/null
+++ b/include/linux/acpi_amd_wbrf.h
@@ -0,0 +1,25 @@
+// 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/wbrf.h>
+
+#if IS_ENABLED(CONFIG_WBRF_AMD_ACPI)
+bool acpi_amd_wbrf_supported_system(void);
+bool acpi_amd_wbrf_supported_consumer(struct device *dev);
+bool acpi_amd_wbrf_supported_producer(struct device *dev);
+int acpi_amd_wbrf_remove_exclusion(struct device *dev,
+ struct wbrf_ranges_in *in);
+int acpi_amd_wbrf_add_exclusion(struct device *dev,
+ struct wbrf_ranges_in *in);
+int acpi_amd_wbrf_retrieve_exclusions(struct device *dev,
+ struct wbrf_ranges_out *out);
+#endif
+
+#endif /* _ACPI_AMD_WBRF_H */
--
2.34.1