// SPDX-License-Identifier: GPL-2.0
/*
 * Root Complex Event Collector Support
 *
 * Authors:
 *  Sean V Kelley <sean.v.kelley@intel.com>
 *  Qiuxu Zhuo <qiuxu.zhuo@intel.com>
 *
 * Copyright (C) 2020 Intel Corp.
 */

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

#include "../pci.h"

struct walk_rcec_data {
        struct pci_dev *rcec;
        int (*user_callback)(struct pci_dev *dev, void *data);
        void *user_data;
};

static bool rcec_assoc_rciep(struct pci_dev *rcec, struct pci_dev *rciep)
{
        unsigned long bitmap = rcec->rcec_ea->bitmap;
        unsigned int devn;

        /* An RCiEP found on a different bus in range */
        if (rcec->bus->number != rciep->bus->number)
                return true;

        /* Same bus, so check bitmap */
        for_each_set_bit(devn, &bitmap, 32)
                if (devn == PCI_SLOT(rciep->devfn))
                        return true;

        return false;
}

static int link_rcec_helper(struct pci_dev *dev, void *data)
{
        struct walk_rcec_data *rcec_data = data;
        struct pci_dev *rcec = rcec_data->rcec;

        if ((pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) &&
            rcec_assoc_rciep(rcec, dev)) {
                dev->rcec = rcec;
                pci_dbg(dev, "PME & error events signaled via %s\n",
                        pci_name(rcec));
        }

        return 0;
}

static int walk_rcec_helper(struct pci_dev *dev, void *data)
{
        struct walk_rcec_data *rcec_data = data;
        struct pci_dev *rcec = rcec_data->rcec;

        if ((pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) &&
            rcec_assoc_rciep(rcec, dev))
                rcec_data->user_callback(dev, rcec_data->user_data);

        return 0;
}

static void walk_rcec(int (*cb)(struct pci_dev *dev, void *data),
                      void *userdata)
{
        struct walk_rcec_data *rcec_data = userdata;
        struct pci_dev *rcec = rcec_data->rcec;
        u8 nextbusn, lastbusn;
        struct pci_bus *bus;
        unsigned int bnr;

        if (!rcec->rcec_ea)
                return;

        /* Walk own bus for bitmap based association */
        pci_walk_bus(rcec->bus, cb, rcec_data);

        nextbusn = rcec->rcec_ea->nextbusn;
        lastbusn = rcec->rcec_ea->lastbusn;

        /* All RCiEP devices are on the same bus as the RCEC */
        if (nextbusn == 0xff && lastbusn == 0x00)
                return;

        for (bnr = nextbusn; bnr <= lastbusn; bnr++) {
                /* No association indicated (PCIe 5.0-1, 7.9.10.3) */
                if (bnr == rcec->bus->number)
                        continue;

                bus = pci_find_bus(pci_domain_nr(rcec->bus), bnr);
                if (!bus)
                        continue;

                /* Find RCiEP devices on the given bus ranges */
                pci_walk_bus(bus, cb, rcec_data);
        }
}

/**
 * pcie_link_rcec - Link RCiEP devices associated with RCEC.
 * @rcec: RCEC whose RCiEP devices should be linked.
 *
 * Link the given RCEC to each RCiEP device found.
 */
void pcie_link_rcec(struct pci_dev *rcec)
{
        struct walk_rcec_data rcec_data;

        if (!rcec->rcec_ea)
                return;

        rcec_data.rcec = rcec;
        rcec_data.user_callback = NULL;
        rcec_data.user_data = NULL;

        walk_rcec(link_rcec_helper, &rcec_data);
}

/**
 * pcie_walk_rcec - Walk RCiEP devices associating with RCEC and call callback.
 * @rcec:       RCEC whose RCiEP devices should be walked
 * @cb:         Callback to be called for each RCiEP device found
 * @userdata:   Arbitrary pointer to be passed to callback
 *
 * Walk the given RCEC. Call the callback on each RCiEP found.
 *
 * If @cb returns anything other than 0, break out.
 */
void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
                    void *userdata)
{
        struct walk_rcec_data rcec_data;

        if (!rcec->rcec_ea)
                return;

        rcec_data.rcec = rcec;
        rcec_data.user_callback = cb;
        rcec_data.user_data = userdata;

        walk_rcec(walk_rcec_helper, &rcec_data);
}

void pci_rcec_init(struct pci_dev *dev)
{
        struct rcec_ea *rcec_ea;
        u32 rcec, hdr, busn;
        u8 ver;

        /* Only for Root Complex Event Collectors */
        if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC)
                return;

        rcec = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_RCEC);
        if (!rcec)
                return;

        rcec_ea = kzalloc_obj(*rcec_ea);
        if (!rcec_ea)
                return;

        pci_read_config_dword(dev, rcec + PCI_RCEC_RCIEP_BITMAP,
                              &rcec_ea->bitmap);

        /* Check whether RCEC BUSN register is present */
        pci_read_config_dword(dev, rcec, &hdr);
        ver = PCI_EXT_CAP_VER(hdr);
        if (ver >= PCI_RCEC_BUSN_REG_VER) {
                pci_read_config_dword(dev, rcec + PCI_RCEC_BUSN, &busn);
                rcec_ea->nextbusn = PCI_RCEC_BUSN_NEXT(busn);
                rcec_ea->lastbusn = PCI_RCEC_BUSN_LAST(busn);
        } else {
                /* Avoid later ver check by setting nextbusn */
                rcec_ea->nextbusn = 0xff;
                rcec_ea->lastbusn = 0x00;
        }

        dev->rcec_ea = rcec_ea;
}

void pci_rcec_exit(struct pci_dev *dev)
{
        kfree(dev->rcec_ea);
        dev->rcec_ea = NULL;
}