// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2023 Advanced Micro Devices, Inc. */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/pci.h>
#include <linux/types.h>
#include <linux/vfio.h>

#include <linux/pds/pds_common.h>
#include <linux/pds/pds_core_if.h>
#include <linux/pds/pds_adminq.h>

#include "vfio_dev.h"
#include "pci_drv.h"
#include "cmds.h"

#define PDS_VFIO_DRV_DESCRIPTION        "AMD/Pensando VFIO Device Driver"
#define PCI_VENDOR_ID_PENSANDO          0x1dd8

static void pds_vfio_recovery(struct pds_vfio_pci_device *pds_vfio)
{
        /*
         * Documentation states that the kernel migration driver must not
         * generate asynchronous device state transitions outside of
         * manipulation by the user or the VFIO_DEVICE_RESET ioctl.
         *
         * Since recovery is an asynchronous event received from the device,
         * initiate a reset in the following situations:
         *   1. Migration is in progress, which will cause the next step of
         *      the migration to fail.
         *   2. If the device is in a state that will be set to
         *      VFIO_DEVICE_STATE_RUNNING on the next action (i.e. VM is
         *      shutdown and device is in VFIO_DEVICE_STATE_STOP).
         */
        mutex_lock(&pds_vfio->state_mutex);
        if ((pds_vfio->state != VFIO_DEVICE_STATE_RUNNING &&
             pds_vfio->state != VFIO_DEVICE_STATE_ERROR) ||
            (pds_vfio->state == VFIO_DEVICE_STATE_RUNNING &&
             pds_vfio_dirty_is_enabled(pds_vfio)))
                pds_vfio_reset(pds_vfio, VFIO_DEVICE_STATE_ERROR);
        mutex_unlock(&pds_vfio->state_mutex);
}

static int pds_vfio_pci_notify_handler(struct notifier_block *nb,
                                       unsigned long ecode, void *data)
{
        struct pds_vfio_pci_device *pds_vfio =
                container_of(nb, struct pds_vfio_pci_device, nb);
        struct device *dev = pds_vfio_to_dev(pds_vfio);
        union pds_core_notifyq_comp *event = data;

        dev_dbg(dev, "%s: event code %lu\n", __func__, ecode);

        /*
         * We don't need to do anything for RESET state==0 as there is no notify
         * or feedback mechanism available, and it is possible that we won't
         * even see a state==0 event since the pds_core recovery is pending.
         *
         * Any requests from VFIO while state==0 will fail, which will return
         * error and may cause migration to fail.
         */
        if (ecode == PDS_EVENT_RESET) {
                dev_info(dev, "%s: PDS_EVENT_RESET event received, state==%d\n",
                         __func__, event->reset.state);
                /*
                 * pds_core device finished recovery and sent us the
                 * notification (state == 1) to allow us to recover
                 */
                if (event->reset.state == 1)
                        pds_vfio_recovery(pds_vfio);
        }

        return 0;
}

static int
pds_vfio_pci_register_event_handler(struct pds_vfio_pci_device *pds_vfio)
{
        struct device *dev = pds_vfio_to_dev(pds_vfio);
        struct notifier_block *nb = &pds_vfio->nb;
        int err;

        if (!nb->notifier_call) {
                nb->notifier_call = pds_vfio_pci_notify_handler;
                err = pdsc_register_notify(nb);
                if (err) {
                        nb->notifier_call = NULL;
                        dev_err(dev,
                                "failed to register pds event handler: %pe\n",
                                ERR_PTR(err));
                        return -EINVAL;
                }
                dev_dbg(dev, "pds event handler registered\n");
        }

        return 0;
}

static void
pds_vfio_pci_unregister_event_handler(struct pds_vfio_pci_device *pds_vfio)
{
        if (pds_vfio->nb.notifier_call) {
                pdsc_unregister_notify(&pds_vfio->nb);
                pds_vfio->nb.notifier_call = NULL;
        }
}

static int pds_vfio_pci_probe(struct pci_dev *pdev,
                              const struct pci_device_id *id)
{
        struct pds_vfio_pci_device *pds_vfio;
        int err;

        pds_vfio = vfio_alloc_device(pds_vfio_pci_device, vfio_coredev.vdev,
                                     &pdev->dev, pds_vfio_ops_info());
        if (IS_ERR(pds_vfio))
                return PTR_ERR(pds_vfio);

        dev_set_drvdata(&pdev->dev, &pds_vfio->vfio_coredev);

        err = vfio_pci_core_register_device(&pds_vfio->vfio_coredev);
        if (err)
                goto out_put_vdev;

        err = pds_vfio_register_client_cmd(pds_vfio);
        if (err) {
                dev_err(&pdev->dev, "failed to register as client: %pe\n",
                        ERR_PTR(err));
                goto out_unregister_coredev;
        }

        err = pds_vfio_pci_register_event_handler(pds_vfio);
        if (err)
                goto out_unregister_client;

        return 0;

out_unregister_client:
        pds_vfio_unregister_client_cmd(pds_vfio);
out_unregister_coredev:
        vfio_pci_core_unregister_device(&pds_vfio->vfio_coredev);
out_put_vdev:
        vfio_put_device(&pds_vfio->vfio_coredev.vdev);
        return err;
}

static void pds_vfio_pci_remove(struct pci_dev *pdev)
{
        struct pds_vfio_pci_device *pds_vfio = pds_vfio_pci_drvdata(pdev);

        pds_vfio_pci_unregister_event_handler(pds_vfio);
        pds_vfio_unregister_client_cmd(pds_vfio);
        vfio_pci_core_unregister_device(&pds_vfio->vfio_coredev);
        vfio_put_device(&pds_vfio->vfio_coredev.vdev);
}

static const struct pci_device_id pds_vfio_pci_table[] = {
        { PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_PENSANDO, 0x1003) }, /* Ethernet VF */
        { 0, }
};
MODULE_DEVICE_TABLE(pci, pds_vfio_pci_table);

static void pds_vfio_pci_aer_reset_done(struct pci_dev *pdev)
{
        struct pds_vfio_pci_device *pds_vfio = pds_vfio_pci_drvdata(pdev);

        mutex_lock(&pds_vfio->state_mutex);
        pds_vfio_reset(pds_vfio, VFIO_DEVICE_STATE_RUNNING);
        mutex_unlock(&pds_vfio->state_mutex);
}

static const struct pci_error_handlers pds_vfio_pci_err_handlers = {
        .reset_done = pds_vfio_pci_aer_reset_done,
        .error_detected = vfio_pci_core_aer_err_detected,
};

static struct pci_driver pds_vfio_pci_driver = {
        .name = KBUILD_MODNAME,
        .id_table = pds_vfio_pci_table,
        .probe = pds_vfio_pci_probe,
        .remove = pds_vfio_pci_remove,
        .err_handler = &pds_vfio_pci_err_handlers,
        .driver_managed_dma = true,
};

module_pci_driver(pds_vfio_pci_driver);

MODULE_IMPORT_NS("IOMMUFD");
MODULE_DESCRIPTION(PDS_VFIO_DRV_DESCRIPTION);
MODULE_AUTHOR("Brett Creeley <brett.creeley@amd.com>");
MODULE_LICENSE("GPL");