// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright IBM Corp. 2020
 *
 * Author(s):
 *   Niklas Schnelle <schnelle@linux.ibm.com>
 *
 */

#define pr_fmt(fmt) "zpci: " fmt

#include <linux/kernel.h>
#include <linux/pci.h>

#include "pci_iov.h"

static struct resource iov_res = {
        .name   = "PCI IOV res",
        .start  = 0,
        .end    = -1,
        .flags  = IORESOURCE_MEM,
};

void zpci_iov_map_resources(struct pci_dev *pdev)
{
        resource_size_t len;
        int i;

        for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
                int bar = i + PCI_IOV_RESOURCES;

                len = pci_resource_len(pdev, bar);
                if (!len)
                        continue;
                pdev->resource[bar].parent = &iov_res;
        }
}

void zpci_iov_remove_virtfn(struct pci_dev *pdev, int vfn)
{
        pci_lock_rescan_remove();
        /* Linux' vfid's start at 0 vfn at 1 */
        pci_iov_remove_virtfn(pdev->physfn, vfn - 1);
        pci_unlock_rescan_remove();
}

static int zpci_iov_link_virtfn(struct pci_dev *pdev, struct pci_dev *virtfn, int vfid)
{
        int rc;

        rc = pci_iov_sysfs_link(pdev, virtfn, vfid);
        if (rc)
                return rc;

        virtfn->is_virtfn = 1;
        virtfn->multifunction = 0;
        virtfn->physfn = pci_dev_get(pdev);

        return 0;
}

/**
 * zpci_iov_find_parent_pf - Find the parent PF, if any, of the given function
 * @zbus:       The bus that the PCI function is on, or would be added on
 * @zdev:       The PCI function
 *
 * Finds the parent PF, if it exists and is configured, of the given PCI function
 * and increments its refcount. Th PF is searched for on the provided bus so the
 * caller has to ensure that this is the correct bus to search. This function may
 * be used before adding the PCI function to a zbus.
 *
 * Return: Pointer to the struct pci_dev of the parent PF or NULL if it not
 * found. If the function is not a VF or has no RequesterID information,
 * NULL is returned as well.
 */
struct pci_dev *zpci_iov_find_parent_pf(struct zpci_bus *zbus, struct zpci_dev *zdev)
{
        int i, vfid, devfn, cand_devfn;
        struct pci_dev *pdev;

        if (!zbus->multifunction)
                return NULL;
        /* Non-VFs and VFs without RID available don't have a parent */
        if (!zdev->vfn || !zdev->rid_available)
                return NULL;
        /* Linux vfid starts at 0 vfn at 1 */
        vfid = zdev->vfn - 1;
        devfn = zdev->rid & ZPCI_RID_MASK_DEVFN;
        /*
         * If the parent PF for the given VF is also configured in the
         * instance, it must be on the same zbus.
         * We can then identify the parent PF by checking what
         * devfn the VF would have if it belonged to that PF using the PF's
         * stride and offset. Only if this candidate devfn matches the
         * actual devfn will we link both functions.
         */
        for (i = 0; i < ZPCI_FUNCTIONS_PER_BUS; i++) {
                zdev = zbus->function[i];
                if (zdev && zdev->is_physfn) {
                        pdev = pci_get_slot(zbus->bus, zdev->devfn);
                        if (!pdev)
                                continue;
                        cand_devfn = pci_iov_virtfn_devfn(pdev, vfid);
                        if (cand_devfn == devfn)
                                return pdev;
                        /* balance pci_get_slot() */
                        pci_dev_put(pdev);
                }
        }
        return NULL;
}

int zpci_iov_setup_virtfn(struct zpci_bus *zbus, struct pci_dev *virtfn, int vfn)
{
        struct zpci_dev *zdev = to_zpci(virtfn);
        struct pci_dev *pdev_pf;
        int rc = 0;

        pdev_pf = zpci_iov_find_parent_pf(zbus, zdev);
        if (pdev_pf) {
                /* Linux' vfids start at 0 while zdev->vfn starts at 1 */
                rc = zpci_iov_link_virtfn(pdev_pf, virtfn, zdev->vfn - 1);
                pci_dev_put(pdev_pf);
        }
        return rc;
}