Introduce New AMD Heterogeneous Core Driver

From: Perry Yuan <[email protected]>

Introduce a new documentation file, amd_hfi.rst, which delves into the implementation details of the AMD Hardware Feedback Interface and its associated driver, amd_hfi. This documentation describes how the driver provides hint to the OS scheduling which depends on the capability of core performance and efficiency ranking data.

This documentation describes
* The design of the driver
* How the driver provides hints to the OS scheduling
* How the driver interfaces with the kernel for efficiency ranking data.

Signed-off-by Perry Yuan <[email protected]>

---
  Documentation/arch/x86/amd-hfi.rst | 116 +++++++++++++++++++++++++++++
  Documentation/arch/x86/index.rst   |   1 +
  2 files changed, 117 insertions(+)

create mode 100644 Documentation/arch/x86/amd-hfi.rst

Documentation/arch/x86/amd-hfi.rst new file +116 -0

new file mode 100644
index 000000000000..351641ce2821
@@ -0,0 +1,116 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================================================================
+Hardware Feedback Interface For Hetero Core Scheduling On AMD Platform
+======================================================================
+
+:Copyright (C) 2024 Advanced Micro Devices, Inc. All Rights Reserved.
+
+:Author: Perry Yuan <[email protected]>
+
+Overview
+--------
+
+AMD Heterogeneous Core implementations are comprised of more than one
+architectural class and CPUs are comprised of cores of various efficiency
+and power capabilities. Power management strategies must be designed to accommodate
+the complexities introduced by incorporating different core types.
+Heterogeneous systems can also extend to more than two architectural classes as well.
+The purpose of the scheduling feedback mechanism is to provide information to
+the operating system scheduler in real time such that the scheduler can direct
+threads to the optimal core.
+
+``Classic cores`` are generally more performant and ``Dense cores`` are generally more
+efficient.
+The goal of AMD's heterogeneous architecture is to attain power benefit by sending
+background thread to the dense cores while sending high priority threads to the classic
+cores. From a performance perspective, sending background threads to dense cores can free
+up power headroom and allow the classic cores to optimally service demanding threads.
+Furthermore, the area optimized nature of the dense cores allows for an increasing
+number of physical cores. This improved core density will have positive multithreaded
+performance impact.
+
+AMD Heterogeneous Core Driver
+-----------------------------
+
+The ``amd_hfi`` driver delivers the operating system a performance and energy efficiency
+capability data for each CPU in the system. The scheduler can use the ranking data
+from the HFI driver to make task placement decisions.
+
+Thread Classification and Ranking Table Interaction
+----------------------------------------------------
+
+The thread classification is used to select into a ranking table that describes
+an efficiency and performance ranking for each classification.
+
+Threads are classified during runtime into enumerated classes. The classes represent
+thread performance/power characteristics that may benefit from special scheduling behaviors.
+The below table depicts an example of thread classification and a preference where a given thread
+should be scheduled based on its thread class. The real time thread classification is consumed
+by the operating system and is used to inform the scheduler of where the thread should be placed.
+
+Thread Classification Example Table
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
++----------+----------------+-------------------------------+---------------------+---------+
+| class ID | Classification | Preferred scheduling behavior | Preemption priority | Counter |
++----------+----------------+-------------------------------+---------------------+---------+
+| 0        | Default        | Performant                    | Highest             |         |
++----------+----------------+-------------------------------+---------------------+---------+
+| 1        | Non-scalable   | Efficient                     | Lowest              | PMCx1A1 |
++----------+----------------+-------------------------------+---------------------+---------+
+| 2        | I/O bound      | Efficient                     | Lowest              | PMCx044 |
++----------+----------------+-------------------------------+---------------------+---------+
+
+
+AMD Hardware Feedback Interface
+--------------------------------
+
+The Hardware Feedback Interface provides to the operating system information
+about the performance and energy efficiency of each CPU in the system. Each
+capability is given as a unit-less quantity in the range [0-255]. A higher
+performance value indicates higher performance capability, and a higher
+efficiency value indicates more efficiency. Energy efficiency and performance
+are reported in separate capabilities in the shared memory based ranking table.
+
+These capabilities may change at runtime as a result of changes in the
+operating conditions of the system or the action of external factors.
+Power Management FW is responsible for detecting events that would require
+a reordering of the performance and efficiency ranking. Table updates would
+happen relatively infrequently and occur on the time scale of seconds or more.
+
+The mechanism used to trigger a table update like below events:
+    * Thermal Stress Events
+    * Silent Compute
+    * Extreme Low Battery Scenarios
+
+The kernel or a userspace policy daemon can use these capabilities to modify
+task placement decisions. For instance, if either the performance or energy
+capabilities of a given logical processor becomes zero, it is an indication that
+the hardware recommends to the operating system to not schedule any tasks on
+that processor for performance or energy efficiency reasons, respectively.
+
+Implementation details for Linux
+--------------------------------
+
+The implementation of threads scheduling consists of the following steps:
+
+1. A thread is spawned and scheduled to the ideal core using the default
+   heterogeneous scheduling policy.
+2. The processor profiles thread execution and assigns an enumerated classification ID.
+   This classification is communicated to the OS via logical processor scope MSR.
+3. During the thread context switch out the operating system consumes the workload(WL)
+   classification which resides in a logical processor scope MSR.
+4. The OS triggers the hardware to clear its history by writing to an MSR,
+   after consuming the WL classification and before switching in the new thread.
+5. If due to the classification, ranking table, and processor availability,
+   the thread is not on its ideal processor, the OS will then consider scheduling
+   the thread on its ideal processor (if available).
+
+Ranking Table update
+---------------------------
+The power management firmware issues an platform interrupt after updating the ranking
+table and is ready for the operating system to consume it. CPUs receive such interrupt
+and read new ranking table from shared memory which PCCT table has provided, then
+``amd_hfi`` driver parse the new table to provide new consume data for scheduling decisions.
+
+

Documentation/arch/x86/index.rst +1 -0

index 8ac64d7de4dc..7f47229f3104 100644
@@ -43,3 +43,4 @@ x86-specific Documentation
     features
     elf_auxvec
     xstate
+   amd_hfi

From: Perry Yuan <[email protected]>

Introduce the amd_hfi driver into the MAINTAINERS file. The driver will support AMD Heterogeneous Core design which provides hardware feedback to the OS scheduler.

Moving forward, Perry and Mario will be responsible for the maintenance and review of patches related to this driver.

Signed-off-by Perry Yuan <[email protected]>

---
  MAINTAINERS | 9 +++++++++
  1 file changed, 9 insertions(+)

MAINTAINERS +9 -0

index 03090276a416..3ccc782095f9 100644
@@ -1039,6 +1039,15 @@ F:	arch/x86/include/asm/amd_hsmp.h
  F:	arch/x86/include/uapi/asm/amd_hsmp.h
  F:	drivers/platform/x86/amd/hsmp.c
 
+AMD HETERO CORE HARDWARE FEEDBACK DRIVER
+M:	Perry Yuan <[email protected]>
+M:	Mario Limonciello <[email protected]>
+L:	[email protected]
+S:	Supported
+B:	https://gitlab.freedesktop.org/drm/amd/-/issues
+F:	drivers/platform/x86/amd/hfi/
+F:	Documentation/arch/x86/amd-hfi.rst
+
  AMD IOMMU (AMD-VI)
  M:	Joerg Roedel <[email protected]>
  R:	Suravee Suthikulpanit <[email protected]>

From: Perry Yuan <[email protected]>

The AMD Heterogeneous core design and Hardware Feedback Interface (HFI) provide behavioral classification and a dynamically updated ranking table for the scheduler to use when choosing cores for tasks.

There are two CPU core types defined: Classic Core and Dense Core. "Classic" cores are the standard performance cores, while "Dense" cores are optimized for area and efficiency.

Heterogeneous compute refers to CPU implementations that are comprised of more than one architectural class, each with two capabilities. This means each CPU reports two separate capabilities: "perf" and "eff".

Each capability lists all core ranking numbers between 0 and 255, where a higher number represents a higher capability.

Heterogeneous systems can also extend to more than two architectural classes.

The purpose of the scheduling feedback mechanism is to provide information to the operating system scheduler in real time, allowing the scheduler to direct threads to the optimal core during task scheduling.

All core ranking data are provided by the BIOS via a shared memory ranking table, which the driver reads and uses to update core capabilities to the scheduler. When the hardware updates the table, it generates a platform interrupt to notify the OS to read the new ranking table.

Link https://bugzilla.kernel.org/show_bug.cgi?id=206537

Signed-off-by Perry Yuan <[email protected]>

---
  drivers/platform/x86/amd/Kconfig      |   1 +
  drivers/platform/x86/amd/Makefile     |   1 +
  drivers/platform/x86/amd/hfi/Kconfig  |  21 +++
  drivers/platform/x86/amd/hfi/Makefile |   7 +
  drivers/platform/x86/amd/hfi/hfi.c    | 209 ++++++++++++++++++++++++++
  5 files changed, 239 insertions(+)

create mode 100644 drivers/platform/x86/amd/hfi/Kconfig create mode 100644 drivers/platform/x86/amd/hfi/Makefile create mode 100644 drivers/platform/x86/amd/hfi/hfi.c

drivers/platform/x86/amd/Kconfig +1 -0

index f88682d36447..c3f69dbe3037 100644
@@ -5,6 +5,7 @@
 
  source "drivers/platform/x86/amd/pmf/Kconfig"
  source "drivers/platform/x86/amd/pmc/Kconfig"
+source "drivers/platform/x86/amd/hfi/Kconfig"
 
  config AMD_HSMP
  	tristate "AMD HSMP Driver"

drivers/platform/x86/amd/Makefile +1 -0

index dcec0a46f8af..2676fc81fee5 100644
@@ -9,3 +9,4 @@ amd_hsmp-y			:= hsmp.o
  obj-$(CONFIG_AMD_HSMP)		+= amd_hsmp.o
  obj-$(CONFIG_AMD_PMF)		+= pmf/
  obj-$(CONFIG_AMD_WBRF)		+= wbrf.o
+obj-$(CONFIG_AMD_HFI)		+= hfi/

drivers/platform/x86/amd/hfi/Kconfig new file +0 -0

new file mode 100644
index 000000000000..4671cc1037a0

drivers/platform/x86/amd/hfi/Kconfig new file +11 -0

+	help
+	 Select this option to enable the AMD Heterogeneous Core Hardware Feedback Interface. If
+	 selected, hardware provides runtime thread classification guidance to the operating system
+	 on the performance and energy efficiency capabilities of each heterogeneous CPU core.
+	 These capabilities may vary due to the inherent differences in the core types and can
+	 also change as a result of variations in the operating conditions of the system such
+	 as power and thermal limits. If selected, the kernel relays updates in heterogeneous
+	 CPUs' capabilities to userspace, allowing for more optimal task scheduling and
+	 resource allocation, leveraging the diverse set of cores available.
+
+

drivers/platform/x86/amd/hfi/Makefile new file +7 -0

new file mode 100644
index 000000000000..672c6ac106e9
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# AMD Hardware Feedback Interface Driver
+#
+
+obj-$(CONFIG_AMD_HFI) += amd_hfi.o
+amd_hfi-objs := hfi.o

drivers/platform/x86/amd/hfi/hfi.c new file +209 -0

new file mode 100644
index 000000000000..914390682fef
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AMD Hardware Feedback Interface Driver
+ *
+ * Copyright (C) 2024 Advanced Micro Devices, Inc. All Rights Reserved.
+ *
+ * Author: Perry Yuan <[email protected]>
+ *
+ */
+
+#define pr_fmt(fmt)  "amd-hfi: " fmt
+
+#include <linux/acpi.h>
+#include <linux/bitops.h>
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/gfp.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/smp.h>
+#include <linux/string.h>
+
+#define AMD_HFI_DRIVER		"amd_hfi"
+#define AMD_HETERO_CPUID_27	0x80000027
+static struct platform_device *device;
+
+struct amd_hfi_data {
+	const char	*name;
+	struct device	*dev;
+	struct mutex	lock;
+	acpi_handle	dhandle;
+};
+
+struct amd_hfi_classes {
+	u32	perf;
+	u32	eff;
+} __packed;
+
+/**
+ * struct amd_hfi_cpuinfo - HFI workload class info per CPU
+ * @cpu:		cpu index
+ * @cpus:		cpu mask of cpus
+ * @class_index:	workload class ID index
+ * @nr_classa:		max number of workload class supported
+ * @amd_hfi_classes:	current cpu workload class ranking data
+ *
+ * Parameters of a logical processor linked with hardware feedback class
+ */
+struct amd_hfi_cpuinfo {
+	int		cpu;
+	cpumask_var_t	cpus;
+	s16		class_index;
+	u8		nr_class;
+	struct amd_hfi_classes	*amd_hfi_classes;
+};
+
+static DEFINE_PER_CPU(struct amd_hfi_cpuinfo, amd_hfi_cpuinfo) = {.class_index = -1};
+
+static int amd_hfi_alloc_class_data(struct platform_device *pdev)
+{
+	struct amd_hfi_cpuinfo *hfi_cpuinfo;
+	struct device *dev = &pdev->dev;
+	int idx;
+	int nr_class_id;
+
+	nr_class_id = cpuid_eax(AMD_HETERO_CPUID_27);
+	if (nr_class_id < 0 || nr_class_id > 255) {
+		dev_warn(dev, "failed to get supported class number from CPUID %d\n",
+				AMD_HETERO_CPUID_27);
+		return -EINVAL;
+	}
+
+	for_each_possible_cpu(idx) {
+		hfi_cpuinfo = per_cpu_ptr(&amd_hfi_cpuinfo, idx);
+		hfi_cpuinfo->amd_hfi_classes = devm_kmalloc(dev, nr_class_id *
+				sizeof(struct amd_hfi_classes), GFP_KERNEL);
+		if (!hfi_cpuinfo->amd_hfi_classes) {
+			pr_err("failed to allocate memory\n");
+			return -ENOMEM;
+		}
+
+		hfi_cpuinfo->nr_class = nr_class_id;
+	}
+
+	return 0;
+}
+
+static void amd_hfi_remove(struct platform_device *pdev)
+{
+	struct amd_hfi_data *dev = platform_get_drvdata(pdev);
+
+	mutex_destroy(&dev->lock);
+}
+
+static const struct acpi_device_id amd_hfi_platform_match[] = {
+	{ "AMDI0104", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, amd_hfi_platform_match);
+
+static int amd_hfi_probe(struct platform_device *pdev)
+{
+	struct amd_hfi_data *amd_hfi_data;
+	const struct acpi_device_id *id;
+	struct acpi_device *acpi_dev;
+	acpi_handle dhandle;
+	int ret;
+
+	id = acpi_match_device(amd_hfi_platform_match, &pdev->dev);
+	if (!id)
+		return -ENODEV;
+
+	amd_hfi_data = devm_kzalloc(&pdev->dev,
+			sizeof(*amd_hfi_data), GFP_KERNEL);
+	if (!amd_hfi_data)
+		return -ENOMEM;
+
+	amd_hfi_data->dev = &pdev->dev;
+	dhandle = ACPI_HANDLE(&pdev->dev);
+	if (!dhandle) {
+		dev_err(&pdev->dev, "dhandle is null\n");
+		return -ENODEV;
+	}
+
+	acpi_dev = acpi_fetch_acpi_dev(dhandle);
+	if (!acpi_dev)
+		return -ENODEV;
+
+	amd_hfi_data->dhandle = dhandle;
+	mutex_init(&amd_hfi_data->lock);
+	platform_set_drvdata(pdev, amd_hfi_data);
+
+	/* alloc data array for hardware feedback class data */
+	ret = amd_hfi_alloc_class_data(pdev);
+	if (ret)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static struct platform_driver amd_hfi_driver = {
+	.driver = {
+		.name = AMD_HFI_DRIVER,
+		.owner = THIS_MODULE,
+		.acpi_match_table = ACPI_PTR(amd_hfi_platform_match),
+	},
+	.probe = amd_hfi_probe,
+	.remove_new = amd_hfi_remove,
+};
+
+static int amd_platform_hfi_init(void)
+{
+	struct platform_device *pdev;
+	int ret;
+
+	pdev = platform_device_register_simple(AMD_HFI_DRIVER, -1, NULL, 0);
+	if (IS_ERR(pdev)) {
+		pr_err("unable to register hfi platform device\n");
+		return PTR_ERR(pdev);
+	}
+
+	ret = platform_driver_register(&amd_hfi_driver);
+	if (ret) {
+		pr_err("Failed to register hfi driver\n");
+	}
+
+	return ret;
+}
+
+static int __init amd_hfi_init(void)
+{
+	int ret;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	if (!boot_cpu_has(X86_FEATURE_HETERO_CORE_TOPOLOGY)) {
+		pr_debug("amd Hetero Core feature reporting not supported!\n");
+		return -ENODEV;
+	}
+
+	if (!boot_cpu_has(X86_FEATURE_WORKLOAD_CLASS)) {
+		pr_debug("workload class reporting not supported!\n");
+		return -ENODEV;
+	}
+
+	/* platform PCC Subspace Type 4 driver init */
+	ret = amd_platform_hfi_init();
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static __exit void amd_hfi_exit(void)
+{
+	platform_device_unregister(device);
+	platform_driver_unregister(&amd_hfi_driver);
+}
+module_init(amd_hfi_init);
+module_exit(amd_hfi_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("AMD Hardware Feedback Interface Driver");

From: Perry Yuan <[email protected]>

When amd_hfi driver is loaded, it will use PCCT subspace type 4 table to retrieve the shared memory address which contains the CPU core ranking table. This table includes a header that specifies the number of ranking data entries to be parsed and rank each CPU core with the Performance and Energy Efficiency capability as implemented by the CPU power management firmware.

Once the table has been parsed, each CPU is assigned a ranking score within its class. Subsequently, when the scheduler selects cores, it chooses from the ranking list based on the assigned scores in each class, thereby ensuring the optimal selection of CPU cores according to their predefined classifications and priorities.

Signed-off-by Perry Yuan <[email protected]>

---
 drivers/platform/x86/amd/hfi/hfi.c | 267 +++++++++++++++++++++++++++++
 1 file changed, 267 insertions(+)

drivers/platform/x86/amd/hfi/hfi.c +85 -0

index 914390682fef..50f6ca9c148a 100644
@@ -19,23 +19,108 @@
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/mailbox_client.h>
 #include <linux/mutex.h>
+#include <linux/percpu-defs.h>
 #include <linux/platform_device.h>
 #include <linux/printk.h>
 #include <linux/smp.h>
 #include <linux/string.h>
+#include <linux/topology.h>
+#include <linux/workqueue.h>
+
+#include <asm/cpu_device_id.h>
+
+#include <acpi/pcc.h>
+#include <acpi/cppc_acpi.h>
 
 #define AMD_HFI_DRIVER		"amd_hfi"
 #define AMD_HETERO_CPUID_27	0x80000027
+#define AMD_HETERO_RANKING_TABLE_VER	2
 static struct platform_device *device;
 
+/**
+ * struct amd_core_rank_table - HFI capabilities for the logical
+ * processors in the memory mappep table.
+ *
+ * @signature:	The PCC signature. The signature of a subspace is computed by
+ *		a bitwise of the value 0x50434300 with the subspace ID.
+ * @flags:	Notify on completion
+ * @length:	Length of payload being transmitted including command field
+ * @command:	Command being sent over the subspace
+ * @version_number:		Version number of the table
+ * @n_logical_processors:	Number of logical processors
+ * @n_capabilities:		Number of ranking dimensions (performance, efficiency, etc)
+ * @table_update_context:	Command being sent over the subspace
+ * @n_bitmaps:			Number of 32-bit bitmaps to enumerate all the APIC IDs
+ *				This is based on the maximum apic ID enumerated in the system
+ * @reserved:			The 24bit spare
+ * @bitmap_of_apic_id0:		Bit Map of enabled logical processors APIC ID for 31:0
+ * @bitmap_of_apic_id1:		Bit Map of enabled logical processors APIC ID for 64:32
+ * @n_classes:			Number of workload class
+ * @dynamic_rank_feature:	Table update mode
+ * @diagnostics:		Reserved space for diagnostics
+ * @timestamp:			Timestamp for last table update
+ * @table_size:			Table length of shared memory
+ * @shmem_info:			The table data read from shared memory
+ * @bitmap_data:		Bitmap data read from table
+ * @max_index:			The max data array in the table
+ *
+ * A memory mapped table is used to express the capabilities of each logical
+ * processor for each thread classification. with dynamic table update feature
+ * supported, the table will be notified to update for all the cores while system
+ * running, each table update can reorder the cores for much better performance and
+ * power efficiency.
+ *
+ */
+struct amd_hfi_metadata {
+	u32	signature;
+	u32	flags:1;
+	u32	length;
+	u32	command;
+	u8	version_number;
+	u8	n_logical_processors;
+	u8	n_capabilities;
+	u8	table_update_context;
+	u8	n_bitmaps;
+	u32	reserved:24;
+	u32	bitmap_of_apic_id0;
+	u32	bitmap_of_apic_id1;
+	u8	n_classes;
+	bool	dynamic_rank_feature;
+	int	diagnostics;
+	u64	timestamp;
+	u64	table_size;
+	u32	shmem_info[64];
+	u32	bitmap_data;
+	u32	max_index;
+};
+
 struct amd_hfi_data {
 	const char	*name;
 	struct device	*dev;
 	struct mutex	lock;
 	acpi_handle	dhandle;
+
+	/* PCCT table related*/
+	int		plat_irq;
+	struct pcc_mbox_chan	*pcc_chan;
+	void __iomem		*pcc_comm_addr;
+	struct completion	done;
+	struct mbox_client	cl;
+	raw_spinlock_t		table_lock;
+	struct acpi_subtable_header	*pcct_entry;
+	struct amd_hfi_metadata		*hfi_meta;
 };
 
+/**
+ * struct amd_hfi_classes - HFI class capabilities per CPU
+ * @perf:		Performance capability
+ * @eff:		Power efficiency capability
+ *
+ * Capabilities of a logical processor in the rank table. These capabilities are
+ * unitless and specific to each HFI class.
+ */
 struct amd_hfi_classes {
 	u32	perf;
 	u32	eff;

@@ -61,6 +146,118 @@ struct amd_hfi_cpuinfo {
 
 static DEFINE_PER_CPU(struct amd_hfi_cpuinfo, amd_hfi_cpuinfo) = {.class_index = -1};

drivers/platform/x86/amd/hfi/hfi.c +29 -0

+			return cpu_index;
+		}
+	}
+
+	return -ENODEV;
+}
+
+static int amd_hfi_fill_metadata(struct amd_hfi_data *amd_hfi_data)
+{
+	struct pcc_mbox_chan *pcc_chan = amd_hfi_data->pcc_chan;
+	struct acpi_subtable_header *pcct_entry = amd_hfi_data->pcct_entry;
+	struct acpi_pcct_ext_pcc_slave *pcct_ext =
+		(struct acpi_pcct_ext_pcc_slave *)pcct_entry;
+	struct amd_hfi_metadata *meta = amd_hfi_data->hfi_meta;
+	u32 header_index = 0, data_index = 0;
+	struct amd_hfi_cpuinfo *info;
+	u32 offset, offset_begin;
+	void __iomem *pcc_comm_addr;
+	int idx, ret, length;
+	u32 *shmem_info;
+
+	length = pcct_ext->length;
+	if (length <= 0) {
+		pr_err("length is less than min table length required\n");
+		return -EINVAL;
+	}
+
+	shmem_info = devm_kmalloc_array(amd_hfi_data->dev, length, sizeof(u32), GFP_KERNEL);
+	if (!shmem_info) {

drivers/platform/x86/amd/hfi/hfi.c +14 -0

+			if (cpu_index < 0) {
+				ret = -ENODEV;
+				goto err_map;
+			}
+
+			info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu_index);
+
+			offset = data_index * 6 + offset_begin;
+			for (int i = 0; i < meta->n_classes; i++) {
+				info->amd_hfi_classes[i].eff = shmem_info[offset + 2 * i];
+				info->amd_hfi_classes[i].perf = shmem_info[offset + 2 * i + 1];
+			}
+		} else {
+			continue;

drivers/platform/x86/amd/hfi/hfi.c +3 -0

+	return ret;
+}
+
 static int amd_hfi_alloc_class_data(struct platform_device *pdev)
 {
 	struct amd_hfi_cpuinfo *hfi_cpuinfo;

@@ -96,6 +293,56 @@ static void amd_hfi_remove(struct platform_device *pdev)
 
 	mutex_destroy(&dev->lock);
 }

drivers/platform/x86/amd/hfi/hfi.c +24 -0

+
+	pcc_chan->mchan = &pcc_mbox_channels[0];
+
+	amd_hfi_data->pcc_chan = pcc_chan;
+	amd_hfi_data->pcct_entry = pcct_entry;
+
+	/* parse the shared memory info from the pcct table */
+	ret = amd_hfi_fill_metadata(amd_hfi_data);
+	if (ret) {
+		pr_err("failed to parse core ranking table\n");
+		ret = -ENODATA;
+	}
+
+exit_err:
+	acpi_put_table(pcct_tbl);
+	return ret;
+}
 
 static const struct acpi_device_id amd_hfi_platform_match[] = {
 	{ "AMDI0104", 0},

@@ -120,6 +367,10 @@ static int amd_hfi_probe(struct platform_device *pdev)
 	if (!amd_hfi_data)
 		return -ENOMEM;
 
+	amd_hfi_data->hfi_meta = devm_kzalloc(&pdev->dev,
+					sizeof(*amd_hfi_data->hfi_meta), GFP_KERNEL);
+	if (!amd_hfi_data->hfi_meta)
+		return -ENOMEM;
 	amd_hfi_data->dev = &pdev->dev;
 	dhandle = ACPI_HANDLE(&pdev->dev);
 	if (!dhandle) {

@@ -132,7 +383,10 @@ static int amd_hfi_probe(struct platform_device *pdev)
 		return -ENODEV;
 
 	amd_hfi_data->dhandle = dhandle;
+
+	raw_spin_lock_init(&amd_hfi_data->table_lock);
 	mutex_init(&amd_hfi_data->lock);
+
 	platform_set_drvdata(pdev, amd_hfi_data);
 
 	/* alloc data array for hardware feedback class data */

@@ -140,7 +394,20 @@ static int amd_hfi_probe(struct platform_device *pdev)
 	if (ret)

drivers/platform/x86/amd/hfi/hfi.c +0 -0

 }
 
 static struct platform_driver amd_hfi_driver = {

From: Perry Yuan <[email protected]>

Initialize per cpu score amd_hfi_ipcc_scores which store energy score and performance score data for each class.

Classic core and Dense core are ranked according to those values as energy efficiency capability or performance capability.
OS scheduler will pick cores from the ranking list on each class ID for the thread which provide the class id got from hardware feedback interface.

Signed-off-by Perry Yuan <[email protected]>

---
 drivers/platform/x86/amd/hfi/hfi.c | 65 ++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

drivers/platform/x86/amd/hfi/hfi.c +3 -0

index 50f6ca9c148a..cd5f2b708ebf 100644
@@ -111,6 +111,7 @@ struct amd_hfi_data {
 	raw_spinlock_t		table_lock;
 	struct acpi_subtable_header	*pcct_entry;
 	struct amd_hfi_metadata		*hfi_meta;
+	raw_spinlock_t		hfi_data_lock;
 };
 
 /**

@@ -130,6 +131,7 @@ struct amd_hfi_classes {
  * struct amd_hfi_cpuinfo - HFI workload class info per CPU
  * @cpu:		cpu index
  * @cpus:		cpu mask of cpus
+ * @apic_id:		apic id of the current cpu
  * @class_index:	workload class ID index
  * @nr_classa:		max number of workload class supported
  * @amd_hfi_classes:	current cpu workload class ranking data

@@ -139,6 +141,7 @@ struct amd_hfi_classes {
 struct amd_hfi_cpuinfo {
 	int		cpu;
 	cpumask_var_t	cpus;
+	u32		apic_id;
 	s16		class_index;
 	u8		nr_class;
 	struct amd_hfi_classes	*amd_hfi_classes;

drivers/platform/x86/amd/hfi/hfi.c +12 -0

+	for_each_online_cpu(cpu) {
+		struct amd_hfi_cpuinfo *hfi_cpuinfo = per_cpu_ptr(&amd_hfi_cpuinfo, cpu);
+
+		ret = amd_set_hfi_ipcc_score(hfi_cpuinfo, cpu);
+		if (ret)
+			return ret;
+	}
+	raw_spin_unlock_irq(&amd_hfi_data->hfi_data_lock);
+
+	return 0;
+}
+
 static int amd_hfi_metadata_parser(struct platform_device *pdev,
 		struct amd_hfi_data *amd_hfi_data)
 {

drivers/platform/x86/amd/hfi/hfi.c +15 -0

+	if (WARN_ON(!amd_hfi_ipcc_scores))
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct acpi_device_id amd_hfi_platform_match[] = {
 	{ "AMDI0104", 0},
 	{ }

@@ -385,6 +441,7 @@ static int amd_hfi_probe(struct platform_device *pdev)
 	amd_hfi_data->dhandle = dhandle;
 
 	raw_spin_lock_init(&amd_hfi_data->table_lock);
+	raw_spin_lock_init(&amd_hfi_data->hfi_data_lock);
 	mutex_init(&amd_hfi_data->lock);
 
 	platform_set_drvdata(pdev, amd_hfi_data);

@@ -402,6 +459,14 @@ static int amd_hfi_probe(struct platform_device *pdev)
 
 	amd_hfi_data->hfi_meta->dynamic_rank_feature =
 					cpuid_ebx(AMD_HETERO_CPUID_27) & 0xF;
+
+	if (alloc_amd_hfi_ipcc_scores(amd_hfi_data))
+		goto err_exit;
+
+	ret = update_hfi_ipcc_scores(amd_hfi_data);
+	if (ret)
+		goto err_exit;
+
 	dev_dbg(&pdev->dev, "%s driver registered.\n", pdev->name);
 
 	return 0;

From: Perry Yuan <[email protected]>

There are some firmware parameters that need to be configured when a CPU core is brought online or offline.

when CPU is online, it will initialize the workload classification parameters to CPU firmware which will trigger the workload class ID updating function.

Once the CPU is going to offline, it will need to disable the workload classification function and clear the history.

Signed-off-by Perry Yuan <[email protected]>

---
 drivers/platform/x86/amd/hfi/hfi.c | 90 ++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)

drivers/platform/x86/amd/hfi/hfi.c +0 -0

index cd5f2b708ebf..57b642c4c522 100644

drivers/platform/x86/amd/hfi/hfi.c +13 -0

 static int find_cpu_index_by_apicid(unsigned int target_apicid)
 {

@@ -318,6 +319,87 @@ static int amd_set_hfi_ipcc_score(struct amd_hfi_cpuinfo *hfi_cpuinfo, int cpu)
 	return 0;
 }
 
+static int amd_hfi_set_state(unsigned int cpu, bool state)
+{
+	int ret;
+
+	ret = wrmsrl_on_cpu(cpu, AMD_WORKLOAD_CLASS_CONFIG, state);
+	if (ret)
+		return ret;
+
+	return wrmsrl_on_cpu(cpu, AMD_WORKLOAD_HRST, 0x1);
+}
+
+/*
+ * amd_hfi_online() - Enable workload classification on @cpu

drivers/platform/x86/amd/hfi/hfi.c +21 -0

+
+	mutex_unlock(&hfi_cpuinfo_lock);
+	return 0;
+
+unlock:
+	free_cpumask_var(hfi_info->cpus);
+	mutex_unlock(&hfi_cpuinfo_lock);
+	return ret;
+}
+
+/*
+ * amd_hfi_offline() - Disable workload classification on @cpu
+ * @cpu: CPU in which the workload classification will be disabled
+ *
+ * Remove @cpu from those covered by its HFI instance.
+ *
+ */
+static int amd_hfi_offline(unsigned int cpu)
+{
+	struct amd_hfi_cpuinfo *hfi_info = &per_cpu(amd_hfi_cpuinfo, cpu);
+	int ret;

drivers/platform/x86/amd/hfi/hfi.c +16 -0

+
+	mutex_unlock(&hfi_cpuinfo_lock);
+
+	free_cpumask_var(hfi_info->cpus);
+
+	return 0;
+}
+
 static int update_hfi_ipcc_scores(struct amd_hfi_data *amd_hfi_data)
 {
 	int cpu;

@@ -467,6 +549,14 @@ static int amd_hfi_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_exit;
 
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/amd_hfi:online",
+			amd_hfi_online,
+			amd_hfi_offline);
+	if (ret < 0) {
+		pr_warn("failed to setup cpuhp state! (%d)\n", ret);
+		return ret;
+	}
+
 	dev_dbg(&pdev->dev, "%s driver registered.\n", pdev->name);
 
 	return 0;

From: Perry Yuan <[email protected]>

Introduces power management callbacks for the amd_hfi driver. Specifically, the suspend and resume callbacks have been added to handle the necessary operations during system low power states and wake-up.

Signed-off-by Perry Yuan <[email protected]>

---
  drivers/platform/x86/amd/hfi/hfi.c | 34 ++++++++++++++++++++++++++++++
  1 file changed, 34 insertions(+)

drivers/platform/x86/amd/hfi/hfi.c +34 -0

index 57b642c4c522..c3da2edf8590 100644
@@ -304,6 +304,39 @@ static void amd_hfi_remove(struct platform_device *pdev)
  	mutex_destroy(&dev->lock);
  }
 
+static int amd_hfi_pm_resume(struct device *dev)
+{
+	int cpu, err;
+
+	for_each_present_cpu(cpu) {
+		err = amd_hfi_set_state(cpu, true);
+		if (err < 0) {
+			dev_err(dev, "failed to enable workload class config: %d\n", err);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int amd_hfi_pm_suspend(struct device *dev)
+{
+	int err, cpu;
+
+	for_each_possible_cpu(cpu) {
+		err = amd_hfi_set_state(cpu, false);
+		if (err < 0) {
+			dev_err(dev, "failed to disable workload class config: %d\n", err);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(amd_hfi_pm_ops,
+		amd_hfi_pm_suspend, amd_hfi_pm_resume);
+
  static int amd_set_hfi_ipcc_score(struct amd_hfi_cpuinfo *hfi_cpuinfo, int cpu)
  {
  	int i, *hfi_scores;

@@ -569,6 +602,7 @@ static struct platform_driver amd_hfi_driver = {
  	.driver = {
  		.name = AMD_HFI_DRIVER,
  		.owner = THIS_MODULE,
+		.pm	= &amd_hfi_pm_ops,
  		.acpi_match_table = ACPI_PTR(amd_hfi_platform_match),
  	},
  	.probe = amd_hfi_probe,