// 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 == 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 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);
}

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(sizeof(*rcec_ea), GFP_KERNEL);
	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;
}