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// 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 (!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 = kcalloc(num_db, sizeof(struct pci_epf_doorbell_msg), GFP_KERNEL);
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);
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