// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2023 Intel Corporation. All rights reserved. */
#include <linux/module.h>
#include <linux/dax.h>

#include "../cxl/cxl.h"
#include "bus.h"

static int cxl_dax_region_probe(struct device *dev)
{
        struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
        int nid = phys_to_target_node(cxlr_dax->hpa_range.start);
        struct cxl_region *cxlr = cxlr_dax->cxlr;
        struct dax_region *dax_region;
        struct dev_dax_data data;

        if (nid == NUMA_NO_NODE)
                nid = memory_add_physaddr_to_nid(cxlr_dax->hpa_range.start);

        dax_region = alloc_dax_region(dev, cxlr->id, &cxlr_dax->hpa_range, nid,
                                      PMD_SIZE, IORESOURCE_DAX_KMEM);
        if (!dax_region)
                return -ENOMEM;

        data = (struct dev_dax_data) {
                .dax_region = dax_region,
                .id = -1,
                .size = range_len(&cxlr_dax->hpa_range),
                .memmap_on_memory = true,
        };

        return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
}

static struct cxl_driver cxl_dax_region_driver = {
        .name = "cxl_dax_region",
        .probe = cxl_dax_region_probe,
        .id = CXL_DEVICE_DAX_REGION,
        .drv = {
                .suppress_bind_attrs = true,
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
};

static void cxl_dax_region_driver_register(struct work_struct *work)
{
        dax_hmem_flush_work();
        cxl_driver_register(&cxl_dax_region_driver);
}

static DECLARE_WORK(cxl_dax_region_driver_work, cxl_dax_region_driver_register);

static int __init cxl_dax_region_init(void)
{
        /*
         * Need to resolve a race with dax_hmem wanting to drive regions
         * instead of CXL
         */
        queue_work(system_long_wq, &cxl_dax_region_driver_work);
        return 0;
}
module_init(cxl_dax_region_init);

static void __exit cxl_dax_region_exit(void)
{
        flush_work(&cxl_dax_region_driver_work);
        cxl_driver_unregister(&cxl_dax_region_driver);
}
module_exit(cxl_dax_region_exit);

MODULE_ALIAS_CXL(CXL_DEVICE_DAX_REGION);
MODULE_DESCRIPTION("CXL DAX: direct access to CXL regions");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Intel Corporation");
MODULE_IMPORT_NS("CXL");