// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2020 Intel Corporation. */
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <cxlmem.h>
#include <cxl.h>
#include "core.h"

/**
 * DOC: cxl pmem
 *
 * The core CXL PMEM infrastructure supports persistent memory
 * provisioning and serves as a bridge to the LIBNVDIMM subsystem. A CXL
 * 'bridge' device is added at the root of a CXL device topology if
 * platform firmware advertises at least one persistent memory capable
 * CXL window. That root-level bridge corresponds to a LIBNVDIMM 'bus'
 * device. Then for each cxl_memdev in the CXL device topology a bridge
 * device is added to host a LIBNVDIMM dimm object. When these bridges
 * are registered native LIBNVDIMM uapis are translated to CXL
 * operations, for example, namespace label access commands.
 */

static DEFINE_IDA(cxl_nvdimm_bridge_ida);

static void cxl_nvdimm_bridge_release(struct device *dev)
{
        struct cxl_nvdimm_bridge *cxl_nvb = to_cxl_nvdimm_bridge(dev);

        ida_free(&cxl_nvdimm_bridge_ida, cxl_nvb->id);
        kfree(cxl_nvb);
}

static const struct attribute_group *cxl_nvdimm_bridge_attribute_groups[] = {
        &cxl_base_attribute_group,
        NULL,
};

const struct device_type cxl_nvdimm_bridge_type = {
        .name = "cxl_nvdimm_bridge",
        .release = cxl_nvdimm_bridge_release,
        .groups = cxl_nvdimm_bridge_attribute_groups,
};

struct cxl_nvdimm_bridge *to_cxl_nvdimm_bridge(struct device *dev)
{
        if (dev_WARN_ONCE(dev, dev->type != &cxl_nvdimm_bridge_type,
                          "not a cxl_nvdimm_bridge device\n"))
                return NULL;
        return container_of(dev, struct cxl_nvdimm_bridge, dev);
}
EXPORT_SYMBOL_NS_GPL(to_cxl_nvdimm_bridge, CXL);

bool is_cxl_nvdimm_bridge(struct device *dev)
{
        return dev->type == &cxl_nvdimm_bridge_type;
}
EXPORT_SYMBOL_NS_GPL(is_cxl_nvdimm_bridge, CXL);

__mock int match_nvdimm_bridge(struct device *dev, const void *data)
{
        return is_cxl_nvdimm_bridge(dev);
}

struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_nvdimm *cxl_nvd)
{
        struct device *dev;

        dev = bus_find_device(&cxl_bus_type, NULL, cxl_nvd, match_nvdimm_bridge);
        if (!dev)
                return NULL;
        return to_cxl_nvdimm_bridge(dev);
}
EXPORT_SYMBOL_NS_GPL(cxl_find_nvdimm_bridge, CXL);

static struct cxl_nvdimm_bridge *
cxl_nvdimm_bridge_alloc(struct cxl_port *port)
{
        struct cxl_nvdimm_bridge *cxl_nvb;
        struct device *dev;
        int rc;

        cxl_nvb = kzalloc(sizeof(*cxl_nvb), GFP_KERNEL);
        if (!cxl_nvb)
                return ERR_PTR(-ENOMEM);

        rc = ida_alloc(&cxl_nvdimm_bridge_ida, GFP_KERNEL);
        if (rc < 0)
                goto err;
        cxl_nvb->id = rc;

        dev = &cxl_nvb->dev;
        cxl_nvb->port = port;
        cxl_nvb->state = CXL_NVB_NEW;
        device_initialize(dev);
        device_set_pm_not_required(dev);
        dev->parent = &port->dev;
        dev->bus = &cxl_bus_type;
        dev->type = &cxl_nvdimm_bridge_type;

        return cxl_nvb;

err:
        kfree(cxl_nvb);
        return ERR_PTR(rc);
}

static void unregister_nvb(void *_cxl_nvb)
{
        struct cxl_nvdimm_bridge *cxl_nvb = _cxl_nvb;
        bool flush;

        /*
         * If the bridge was ever activated then there might be in-flight state
         * work to flush. Once the state has been changed to 'dead' then no new
         * work can be queued by user-triggered bind.
         */
        device_lock(&cxl_nvb->dev);
        flush = cxl_nvb->state != CXL_NVB_NEW;
        cxl_nvb->state = CXL_NVB_DEAD;
        device_unlock(&cxl_nvb->dev);

        /*
         * Even though the device core will trigger device_release_driver()
         * before the unregister, it does not know about the fact that
         * cxl_nvdimm_bridge_driver defers ->remove() work. So, do the driver
         * release not and flush it before tearing down the nvdimm device
         * hierarchy.
         */
        device_release_driver(&cxl_nvb->dev);
        if (flush)
                flush_work(&cxl_nvb->state_work);
        device_unregister(&cxl_nvb->dev);
}

/**
 * devm_cxl_add_nvdimm_bridge() - add the root of a LIBNVDIMM topology
 * @host: platform firmware root device
 * @port: CXL port at the root of a CXL topology
 *
 * Return: bridge device that can host cxl_nvdimm objects
 */
struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host,
                                                     struct cxl_port *port)
{
        struct cxl_nvdimm_bridge *cxl_nvb;
        struct device *dev;
        int rc;

        if (!IS_ENABLED(CONFIG_CXL_PMEM))
                return ERR_PTR(-ENXIO);

        cxl_nvb = cxl_nvdimm_bridge_alloc(port);
        if (IS_ERR(cxl_nvb))
                return cxl_nvb;

        dev = &cxl_nvb->dev;
        rc = dev_set_name(dev, "nvdimm-bridge%d", cxl_nvb->id);
        if (rc)
                goto err;

        rc = device_add(dev);
        if (rc)
                goto err;

        rc = devm_add_action_or_reset(host, unregister_nvb, cxl_nvb);
        if (rc)
                return ERR_PTR(rc);

        return cxl_nvb;

err:
        put_device(dev);
        return ERR_PTR(rc);
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_add_nvdimm_bridge, CXL);

static void cxl_nvdimm_release(struct device *dev)
{
        struct cxl_nvdimm *cxl_nvd = to_cxl_nvdimm(dev);

        kfree(cxl_nvd);
}

static const struct attribute_group *cxl_nvdimm_attribute_groups[] = {
        &cxl_base_attribute_group,
        NULL,
};

const struct device_type cxl_nvdimm_type = {
        .name = "cxl_nvdimm",
        .release = cxl_nvdimm_release,
        .groups = cxl_nvdimm_attribute_groups,
};

bool is_cxl_nvdimm(struct device *dev)
{
        return dev->type == &cxl_nvdimm_type;
}
EXPORT_SYMBOL_NS_GPL(is_cxl_nvdimm, CXL);

struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev)
{
        if (dev_WARN_ONCE(dev, !is_cxl_nvdimm(dev),
                          "not a cxl_nvdimm device\n"))
                return NULL;
        return container_of(dev, struct cxl_nvdimm, dev);
}
EXPORT_SYMBOL_NS_GPL(to_cxl_nvdimm, CXL);

static struct cxl_nvdimm *cxl_nvdimm_alloc(struct cxl_memdev *cxlmd)
{
        struct cxl_nvdimm *cxl_nvd;
        struct device *dev;

        cxl_nvd = kzalloc(sizeof(*cxl_nvd), GFP_KERNEL);
        if (!cxl_nvd)
                return ERR_PTR(-ENOMEM);

        dev = &cxl_nvd->dev;
        cxl_nvd->cxlmd = cxlmd;
        device_initialize(dev);
        device_set_pm_not_required(dev);
        dev->parent = &cxlmd->dev;
        dev->bus = &cxl_bus_type;
        dev->type = &cxl_nvdimm_type;

        return cxl_nvd;
}

static void cxl_nvd_unregister(void *dev)
{
        device_unregister(dev);
}

/**
 * devm_cxl_add_nvdimm() - add a bridge between a cxl_memdev and an nvdimm
 * @host: same host as @cxlmd
 * @cxlmd: cxl_memdev instance that will perform LIBNVDIMM operations
 *
 * Return: 0 on success negative error code on failure.
 */
int devm_cxl_add_nvdimm(struct device *host, struct cxl_memdev *cxlmd)
{
        struct cxl_nvdimm *cxl_nvd;
        struct device *dev;
        int rc;

        cxl_nvd = cxl_nvdimm_alloc(cxlmd);
        if (IS_ERR(cxl_nvd))
                return PTR_ERR(cxl_nvd);

        dev = &cxl_nvd->dev;
        rc = dev_set_name(dev, "pmem%d", cxlmd->id);
        if (rc)
                goto err;

        rc = device_add(dev);
        if (rc)
                goto err;

        dev_dbg(host, "%s: register %s\n", dev_name(dev->parent),
                dev_name(dev));

        return devm_add_action_or_reset(host, cxl_nvd_unregister, dev);

err:
        put_device(dev);
        return rc;
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_add_nvdimm, CXL);