// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * AMD 3D V-Cache Performance Optimizer Driver
 *
 * Copyright (c) 2024, Advanced Micro Devices, Inc.
 * All Rights Reserved.
 *
 * Authors: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
 *          Perry Yuan <perry.yuan@amd.com>
 *          Mario Limonciello <mario.limonciello@amd.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/acpi.h>
#include <linux/array_size.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/sysfs.h>
#include <linux/uuid.h>

static char *x3d_mode = "frequency";
module_param(x3d_mode, charp, 0);
MODULE_PARM_DESC(x3d_mode, "Initial 3D-VCache mode; 'frequency' (default) or 'cache'");

#define DSM_REVISION_ID                 0
#define DSM_SET_X3D_MODE                1

static guid_t x3d_guid = GUID_INIT(0xdff8e55f, 0xbcfd, 0x46fb, 0xba, 0x0a,
                                   0xef, 0xd0, 0x45, 0x0f, 0x34, 0xee);

enum amd_x3d_mode_type {
        MODE_INDEX_FREQ,
        MODE_INDEX_CACHE,
};

static const char * const amd_x3d_mode_strings[] = {
        [MODE_INDEX_FREQ] = "frequency",
        [MODE_INDEX_CACHE] = "cache",
};

struct amd_x3d_dev {
        struct device *dev;
        acpi_handle ahandle;
        /* To protect x3d mode setting */
        struct mutex lock;
        enum amd_x3d_mode_type curr_mode;
};

static int amd_x3d_get_mode(struct amd_x3d_dev *data)
{
        guard(mutex)(&data->lock);

        return data->curr_mode;
}

static int amd_x3d_mode_switch(struct amd_x3d_dev *data, int new_state)
{
        union acpi_object *out, argv;

        guard(mutex)(&data->lock);
        argv.type = ACPI_TYPE_INTEGER;
        argv.integer.value = new_state;

        out = acpi_evaluate_dsm(data->ahandle, &x3d_guid, DSM_REVISION_ID,
                                DSM_SET_X3D_MODE, &argv);
        if (!out) {
                dev_err(data->dev, "failed to evaluate _DSM\n");
                return -EINVAL;
        }

        data->curr_mode = new_state;

        kfree(out);

        return 0;
}

static ssize_t amd_x3d_mode_store(struct device *dev, struct device_attribute *attr,
                                  const char *buf, size_t count)
{
        struct amd_x3d_dev *data = dev_get_drvdata(dev);
        int ret;

        ret = sysfs_match_string(amd_x3d_mode_strings, buf);
        if (ret < 0)
                return ret;

        ret = amd_x3d_mode_switch(data, ret);
        if (ret < 0)
                return ret;

        return count;
}

static ssize_t amd_x3d_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct amd_x3d_dev *data = dev_get_drvdata(dev);
        int mode = amd_x3d_get_mode(data);

        return sysfs_emit(buf, "%s\n", amd_x3d_mode_strings[mode]);
}
static DEVICE_ATTR_RW(amd_x3d_mode);

static struct attribute *amd_x3d_attrs[] = {
        &dev_attr_amd_x3d_mode.attr,
        NULL
};
ATTRIBUTE_GROUPS(amd_x3d);

static int amd_x3d_resume_handler(struct device *dev)
{
        struct amd_x3d_dev *data = dev_get_drvdata(dev);
        int ret = amd_x3d_get_mode(data);

        return amd_x3d_mode_switch(data, ret);
}

static DEFINE_SIMPLE_DEV_PM_OPS(amd_x3d_pm, NULL, amd_x3d_resume_handler);

static const struct acpi_device_id amd_x3d_acpi_ids[] = {
        {"AMDI0101"},
        { },
};
MODULE_DEVICE_TABLE(acpi, amd_x3d_acpi_ids);

static int amd_x3d_probe(struct platform_device *pdev)
{
        struct amd_x3d_dev *data;
        acpi_handle handle;
        int ret;

        handle = ACPI_HANDLE(&pdev->dev);
        if (!handle)
                return -ENODEV;

        if (!acpi_check_dsm(handle, &x3d_guid, DSM_REVISION_ID, BIT(DSM_SET_X3D_MODE)))
                return -ENODEV;

        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->dev = &pdev->dev;

        ret = devm_mutex_init(data->dev, &data->lock);
        if (ret)
                return ret;

        data->ahandle = handle;
        platform_set_drvdata(pdev, data);

        ret = match_string(amd_x3d_mode_strings, ARRAY_SIZE(amd_x3d_mode_strings), x3d_mode);
        if (ret < 0)
                return dev_err_probe(&pdev->dev, -EINVAL, "invalid mode %s\n", x3d_mode);

        return amd_x3d_mode_switch(data, ret);
}

static struct platform_driver amd_3d_vcache_driver = {
        .driver = {
                .name = "amd_x3d_vcache",
                .dev_groups = amd_x3d_groups,
                .acpi_match_table = amd_x3d_acpi_ids,
                .pm = pm_sleep_ptr(&amd_x3d_pm),
        },
        .probe = amd_x3d_probe,
};
module_platform_driver(amd_3d_vcache_driver);

MODULE_DESCRIPTION("AMD 3D V-Cache Performance Optimizer Driver");
MODULE_LICENSE("GPL");