// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * AMD Hardware Feedback Interface Driver
 *
 * Copyright (C) 2025 Advanced Micro Devices, Inc. All Rights Reserved.
 *
 * Authors: Perry Yuan <Perry.Yuan@amd.com>
 *          Mario Limonciello <mario.limonciello@amd.com>
 */

#define pr_fmt(fmt)  "amd-hfi: " fmt

#include <linux/acpi.h>
#include <linux/cpu.h>
#include <linux/debugfs.h>
#include <linux/gfp.h>
#include <linux/init.h>
#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/smp.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_HFI_MAILBOX_COUNT           1
#define AMD_HETERO_RANKING_TABLE_VER    2

#define AMD_HETERO_CPUID_27     0x80000027

static struct platform_device *device;

/**
 * struct amd_shmem_info - Shared memory table for AMD HFI
 *
 * @header:     The PCCT table header including signature, length flags and command.
 * @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:                   24 bit spare
 * @table_data:                 Bit Map(s) of enabled logical processors
 *                              Followed by the ranking data for each logical processor
 */
struct amd_shmem_info {
        struct acpi_pcct_ext_pcc_shared_memory header;
        u32     version_number          :8,
                n_logical_processors    :8,
                n_capabilities          :8,
                table_update_context    :8;
        u32     n_bitmaps               :8,
                reserved                :24;
        u32     table_data[];
};

struct amd_hfi_data {
        const char      *name;
        struct device   *dev;

        /* PCCT table related */
        struct pcc_mbox_chan    *pcc_chan;
        void __iomem            *pcc_comm_addr;
        struct acpi_subtable_header     *pcct_entry;
        struct amd_shmem_info   *shmem;

        struct dentry *dbgfs_dir;
};

/**
 * struct amd_hfi_classes - HFI class capabilities per CPU
 * @perf:       Performance capability
 * @eff:        Power efficiency capability
 *
 * Capabilities of a logical processor in the ranking table. These capabilities
 * are unitless and specific to each HFI class.
 */
struct amd_hfi_classes {
        u32     perf;
        u32     eff;
};

/**
 * struct amd_hfi_cpuinfo - HFI workload class info per CPU
 * @cpu:                CPU index
 * @apic_id:            APIC id of the current CPU
 * @class_index:        workload class ID index
 * @nr_class:           max number of workload class supported
 * @ipcc_scores:        ipcc scores for each class
 * @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;
        u32             apic_id;
        s16             class_index;
        u8              nr_class;
        int             *ipcc_scores;
        struct amd_hfi_classes  *amd_hfi_classes;
};

static DEFINE_PER_CPU(struct amd_hfi_cpuinfo, amd_hfi_cpuinfo) = {.class_index = -1};

static DEFINE_MUTEX(hfi_cpuinfo_lock);

static void amd_hfi_sched_itmt_work(struct work_struct *work)
{
        sched_set_itmt_support();
}
static DECLARE_WORK(sched_amd_hfi_itmt_work, amd_hfi_sched_itmt_work);

static int find_cpu_index_by_apicid(unsigned int target_apicid)
{
        int cpu_index;

        for_each_possible_cpu(cpu_index) {
                struct cpuinfo_x86 *info = &cpu_data(cpu_index);

                if (info->topo.apicid == target_apicid) {
                        pr_debug("match APIC id %u for CPU index: %d\n",
                                 info->topo.apicid, cpu_index);
                        return cpu_index;
                }
        }

        return -ENODEV;
}

static int amd_hfi_fill_metadata(struct amd_hfi_data *amd_hfi_data)
{
        struct acpi_pcct_ext_pcc_slave *pcct_ext =
                (struct acpi_pcct_ext_pcc_slave *)amd_hfi_data->pcct_entry;
        void __iomem *pcc_comm_addr;
        u32 apic_start = 0;

        pcc_comm_addr = acpi_os_ioremap(amd_hfi_data->pcc_chan->shmem_base_addr,
                                        amd_hfi_data->pcc_chan->shmem_size);
        if (!pcc_comm_addr) {
                dev_err(amd_hfi_data->dev, "failed to ioremap PCC common region mem\n");
                return -ENOMEM;
        }

        memcpy_fromio(amd_hfi_data->shmem, pcc_comm_addr, pcct_ext->length);
        iounmap(pcc_comm_addr);

        if (amd_hfi_data->shmem->header.signature != PCC_SIGNATURE) {
                dev_err(amd_hfi_data->dev, "invalid signature in shared memory\n");
                return -EINVAL;
        }
        if (amd_hfi_data->shmem->version_number != AMD_HETERO_RANKING_TABLE_VER) {
                dev_err(amd_hfi_data->dev, "invalid version %d\n",
                        amd_hfi_data->shmem->version_number);
                return -EINVAL;
        }

        for (unsigned int i = 0; i < amd_hfi_data->shmem->n_bitmaps; i++) {
                u32 bitmap = amd_hfi_data->shmem->table_data[i];

                for (unsigned int j = 0; j < BITS_PER_TYPE(u32); j++) {
                        u32 apic_id = i * BITS_PER_TYPE(u32) + j;
                        struct amd_hfi_cpuinfo *info;
                        int cpu_index, apic_index;

                        if (!(bitmap & BIT(j)))
                                continue;

                        cpu_index = find_cpu_index_by_apicid(apic_id);
                        if (cpu_index < 0) {
                                dev_warn(amd_hfi_data->dev, "APIC ID %u not found\n", apic_id);
                                continue;
                        }

                        info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu_index);
                        info->apic_id = apic_id;

                        /* Fill the ranking data for each logical processor */
                        info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu_index);
                        apic_index = apic_start * info->nr_class * 2;
                        for (unsigned int k = 0; k < info->nr_class; k++) {
                                u32 *table = amd_hfi_data->shmem->table_data +
                                             amd_hfi_data->shmem->n_bitmaps +
                                             i * info->nr_class;

                                info->amd_hfi_classes[k].eff = table[apic_index + 2 * k];
                                info->amd_hfi_classes[k].perf = table[apic_index + 2 * k + 1];
                        }
                        apic_start++;
                }
        }

        return 0;
}

static int amd_hfi_alloc_class_data(struct platform_device *pdev)
{
        struct amd_hfi_cpuinfo *hfi_cpuinfo;
        struct device *dev = &pdev->dev;
        u32 nr_class_id;
        int idx;

        nr_class_id = cpuid_eax(AMD_HETERO_CPUID_27);
        if (nr_class_id > 255) {
                dev_err(dev, "number of supported classes too large: %d\n",
                        nr_class_id);
                return -EINVAL;
        }

        for_each_possible_cpu(idx) {
                struct amd_hfi_classes *classes;
                int *ipcc_scores;

                classes = devm_kcalloc(dev,
                                       nr_class_id,
                                       sizeof(struct amd_hfi_classes),
                                       GFP_KERNEL);
                if (!classes)
                        return -ENOMEM;
                ipcc_scores = devm_kcalloc(dev, nr_class_id, sizeof(int), GFP_KERNEL);
                if (!ipcc_scores)
                        return -ENOMEM;
                hfi_cpuinfo = per_cpu_ptr(&amd_hfi_cpuinfo, idx);
                hfi_cpuinfo->amd_hfi_classes = classes;
                hfi_cpuinfo->ipcc_scores = ipcc_scores;
                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);

        debugfs_remove_recursive(dev->dbgfs_dir);
}

static int amd_set_hfi_ipcc_score(struct amd_hfi_cpuinfo *hfi_cpuinfo, int cpu)
{
        for (int i = 0; i < hfi_cpuinfo->nr_class; i++)
                WRITE_ONCE(hfi_cpuinfo->ipcc_scores[i],
                           hfi_cpuinfo->amd_hfi_classes[i].perf);

        sched_set_itmt_core_prio(hfi_cpuinfo->ipcc_scores[0], cpu);

        return 0;
}

static int amd_hfi_set_state(unsigned int cpu, bool state)
{
        int ret;

        ret = wrmsrq_on_cpu(cpu, MSR_AMD_WORKLOAD_CLASS_CONFIG, state ? 1 : 0);
        if (ret)
                return ret;

        return wrmsrq_on_cpu(cpu, MSR_AMD_WORKLOAD_HRST, 0x1);
}

/**
 * amd_hfi_online() - Enable workload classification on @cpu
 * @cpu: CPU in which the workload classification will be enabled
 *
 * Return: 0 on success, negative error code on failure.
 */
static int amd_hfi_online(unsigned int cpu)
{
        struct amd_hfi_cpuinfo *hfi_info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu);
        struct amd_hfi_classes *hfi_classes;
        int ret;

        if (WARN_ON_ONCE(!hfi_info))
                return -EINVAL;

        /*
         * Check if @cpu as an associated, initialized and ranking data must
         * be filled.
         */
        hfi_classes = hfi_info->amd_hfi_classes;
        if (!hfi_classes)
                return -EINVAL;

        guard(mutex)(&hfi_cpuinfo_lock);

        ret = amd_hfi_set_state(cpu, true);
        if (ret)
                pr_err("WCT enable failed for CPU %u\n", cpu);

        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.
 *
 * Return: 0 on success, negative error code on failure
 */
static int amd_hfi_offline(unsigned int cpu)
{
        struct amd_hfi_cpuinfo *hfi_info = &per_cpu(amd_hfi_cpuinfo, cpu);
        int ret;

        if (WARN_ON_ONCE(!hfi_info))
                return -EINVAL;

        guard(mutex)(&hfi_cpuinfo_lock);

        ret = amd_hfi_set_state(cpu, false);
        if (ret)
                pr_err("WCT disable failed for CPU %u\n", cpu);

        return ret;
}

static int update_hfi_ipcc_scores(void)
{
        int cpu;
        int ret;

        for_each_possible_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;
        }

        return 0;
}

static int amd_hfi_metadata_parser(struct platform_device *pdev,
                                   struct amd_hfi_data *amd_hfi_data)
{
        struct acpi_pcct_ext_pcc_slave *pcct_ext;
        struct acpi_subtable_header *pcct_entry;
        struct mbox_chan *pcc_mbox_channels;
        struct acpi_table_header *pcct_tbl;
        struct pcc_mbox_chan *pcc_chan;
        acpi_status status;
        int ret;

        pcc_mbox_channels = devm_kcalloc(&pdev->dev, AMD_HFI_MAILBOX_COUNT,
                                         sizeof(*pcc_mbox_channels), GFP_KERNEL);
        if (!pcc_mbox_channels)
                return -ENOMEM;

        pcc_chan = devm_kcalloc(&pdev->dev, AMD_HFI_MAILBOX_COUNT,
                                sizeof(*pcc_chan), GFP_KERNEL);
        if (!pcc_chan)
                return -ENOMEM;

        status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
        if (ACPI_FAILURE(status) || !pcct_tbl)
                return -ENODEV;

        /* get pointer to the first PCC subspace entry */
        pcct_entry = (struct acpi_subtable_header *) (
                        (unsigned long)pcct_tbl + sizeof(struct acpi_table_pcct));

        pcc_chan->mchan = &pcc_mbox_channels[0];

        amd_hfi_data->pcc_chan = pcc_chan;
        amd_hfi_data->pcct_entry = pcct_entry;
        pcct_ext = (struct acpi_pcct_ext_pcc_slave *)pcct_entry;

        if (pcct_ext->length <= 0) {
                ret = -EINVAL;
                goto out;
        }

        amd_hfi_data->shmem = devm_kzalloc(amd_hfi_data->dev, pcct_ext->length, GFP_KERNEL);
        if (!amd_hfi_data->shmem) {
                ret = -ENOMEM;
                goto out;
        }

        pcc_chan->shmem_base_addr = pcct_ext->base_address;
        pcc_chan->shmem_size = pcct_ext->length;

        /* parse the shared memory info from the PCCT table */
        ret = amd_hfi_fill_metadata(amd_hfi_data);

out:
        /* Don't leak any ACPI memory */
        acpi_put_table(pcct_tbl);

        return ret;
}

static int class_capabilities_show(struct seq_file *s, void *unused)
{
        u32 cpu, idx;

        seq_puts(s, "CPU #\tWLC\tPerf\tEff\n");
        for_each_possible_cpu(cpu) {
                struct amd_hfi_cpuinfo *hfi_cpuinfo = per_cpu_ptr(&amd_hfi_cpuinfo, cpu);

                seq_printf(s, "%d", cpu);
                for (idx = 0; idx < hfi_cpuinfo->nr_class; idx++) {
                        seq_printf(s, "\t%u\t%u\t%u\n", idx,
                                   hfi_cpuinfo->amd_hfi_classes[idx].perf,
                                   hfi_cpuinfo->amd_hfi_classes[idx].eff);
                }
        }

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(class_capabilities);

static int amd_hfi_pm_resume(struct device *dev)
{
        int ret, cpu;

        for_each_online_cpu(cpu) {
                ret = amd_hfi_set_state(cpu, true);
                if (ret < 0) {
                        dev_err(dev, "failed to enable workload class config: %d\n", ret);
                        return ret;
                }
        }

        return 0;
}

static int amd_hfi_pm_suspend(struct device *dev)
{
        int ret, cpu;

        for_each_online_cpu(cpu) {
                ret = amd_hfi_set_state(cpu, false);
                if (ret < 0) {
                        dev_err(dev, "failed to disable workload class config: %d\n", ret);
                        return ret;
                }
        }

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(amd_hfi_pm_ops, amd_hfi_pm_suspend, amd_hfi_pm_resume);

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;
        int ret;

        if (!acpi_match_device(amd_hfi_platform_match, &pdev->dev))
                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;
        platform_set_drvdata(pdev, amd_hfi_data);

        ret = amd_hfi_alloc_class_data(pdev);
        if (ret)
                return ret;

        ret = amd_hfi_metadata_parser(pdev, amd_hfi_data);
        if (ret)
                return ret;

        ret = update_hfi_ipcc_scores();
        if (ret)
                return ret;

        /*
         * Tasks will already be running at the time this happens. This is
         * OK because rankings will be adjusted by the callbacks.
         */
        ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/amd_hfi:online",
                                amd_hfi_online, amd_hfi_offline);
        if (ret < 0)
                return ret;

        schedule_work(&sched_amd_hfi_itmt_work);

        amd_hfi_data->dbgfs_dir = debugfs_create_dir("amd_hfi", arch_debugfs_dir);
        debugfs_create_file("class_capabilities", 0644, amd_hfi_data->dbgfs_dir, pdev,
                            &class_capabilities_fops);

        return 0;
}

static struct platform_driver amd_hfi_driver = {
        .driver = {
                .name = AMD_HFI_DRIVER,
                .pm = &amd_hfi_pm_ops,
                .acpi_match_table = ACPI_PTR(amd_hfi_platform_match),
        },
        .probe = amd_hfi_probe,
        .remove = amd_hfi_remove,
};

static int __init amd_hfi_init(void)
{
        int ret;

        if (acpi_disabled ||
            !cpu_feature_enabled(X86_FEATURE_AMD_HTR_CORES) ||
            !cpu_feature_enabled(X86_FEATURE_AMD_WORKLOAD_CLASS))
                return -ENODEV;

        device = platform_device_register_simple(AMD_HFI_DRIVER, -1, NULL, 0);
        if (IS_ERR(device)) {
                pr_err("unable to register HFI platform device\n");
                return PTR_ERR(device);
        }

        ret = platform_driver_register(&amd_hfi_driver);
        if (ret)
                pr_err("failed to register HFI driver\n");

        return ret;
}

static __exit void amd_hfi_exit(void)
{
        platform_driver_unregister(&amd_hfi_driver);
        platform_device_unregister(device);
}
module_init(amd_hfi_init);
module_exit(amd_hfi_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("AMD Hardware Feedback Interface Driver");