// SPDX-License-Identifier: GPL-2.0
/*
 * PCI Endpoint *Controller* (EPC) MSI library
 *
 * Copyright (C) 2025 NXP
 * Author: Frank Li <Frank.Li@nxp.com>
 */

#include <linux/device.h>
#include <linux/export.h>
#include <linux/irqdomain.h>
#include <linux/module.h>
#include <linux/msi.h>
#include <linux/of_irq.h>
#include <linux/pci-epc.h>
#include <linux/pci-epf.h>
#include <linux/pci-ep-cfs.h>
#include <linux/pci-ep-msi.h>
#include <linux/slab.h>

static void pci_epf_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
{
        struct pci_epc *epc;
        struct pci_epf *epf;

        epc = pci_epc_get(dev_name(msi_desc_to_dev(desc)));
        if (IS_ERR(epc))
                return;

        epf = list_first_entry_or_null(&epc->pci_epf, struct pci_epf, list);

        if (epf && epf->db_msg && desc->msi_index < epf->num_db)
                memcpy(&epf->db_msg[desc->msi_index].msg, msg, sizeof(*msg));

        pci_epc_put(epc);
}

int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 num_db)
{
        struct pci_epc *epc = epf->epc;
        struct device *dev = &epf->dev;
        struct irq_domain *domain;
        void *msg;
        int ret;
        int i;

        /* TODO: Multi-EPF support */
        if (list_first_entry_or_null(&epc->pci_epf, struct pci_epf, list) != epf) {
                dev_err(dev, "MSI doorbell doesn't support multiple EPF\n");
                return -EINVAL;
        }

        domain = of_msi_map_get_device_domain(epc->dev.parent, 0,
                                              DOMAIN_BUS_PLATFORM_MSI);
        if (!domain) {
                dev_err(dev, "Can't find MSI domain for EPC\n");
                return -ENODEV;
        }

        if (!irq_domain_is_msi_parent(domain))
                return -ENODEV;

        if (!irq_domain_is_msi_immutable(domain)) {
                dev_err(dev, "Mutable MSI controller not supported\n");
                return -ENODEV;
        }

        dev_set_msi_domain(epc->dev.parent, domain);

        msg = kzalloc_objs(struct pci_epf_doorbell_msg, num_db);
        if (!msg)
                return -ENOMEM;

        epf->num_db = num_db;
        epf->db_msg = msg;

        ret = platform_device_msi_init_and_alloc_irqs(epc->dev.parent, num_db,
                                                      pci_epf_write_msi_msg);
        if (ret) {
                dev_err(dev, "Failed to allocate MSI\n");
                kfree(msg);
                return ret;
        }

        for (i = 0; i < num_db; i++)
                epf->db_msg[i].virq = msi_get_virq(epc->dev.parent, i);

        return ret;
}
EXPORT_SYMBOL_GPL(pci_epf_alloc_doorbell);

void pci_epf_free_doorbell(struct pci_epf *epf)
{
        platform_device_msi_free_irqs_all(epf->epc->dev.parent);

        kfree(epf->db_msg);
        epf->db_msg = NULL;
        epf->num_db = 0;
}
EXPORT_SYMBOL_GPL(pci_epf_free_doorbell);