// SPDX-License-Identifier: GPL-2.0
/*
 * This file implements the error recovery as a core part of PCIe error
 * reporting. When a PCIe error is delivered, an error message will be
 * collected and printed to console, then, an error recovery procedure
 * will be executed by following the PCI error recovery rules.
 *
 * Copyright (C) 2006 Intel Corp.
 *      Tom Long Nguyen (tom.l.nguyen@intel.com)
 *      Zhang Yanmin (yanmin.zhang@intel.com)
 */

#define dev_fmt(fmt) "AER: " fmt

#include <linux/pci.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/aer.h>
#include "portdrv.h"
#include "../pci.h"

static pci_ers_result_t merge_result(enum pci_ers_result orig,
                                  enum pci_ers_result new)
{
        if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
                return PCI_ERS_RESULT_NO_AER_DRIVER;

        if (new == PCI_ERS_RESULT_NONE)
                return orig;

        switch (orig) {
        case PCI_ERS_RESULT_CAN_RECOVER:
        case PCI_ERS_RESULT_RECOVERED:
                orig = new;
                break;
        case PCI_ERS_RESULT_DISCONNECT:
                if (new == PCI_ERS_RESULT_NEED_RESET)
                        orig = PCI_ERS_RESULT_NEED_RESET;
                break;
        default:
                break;
        }

        return orig;
}

static int report_error_detected(struct pci_dev *dev,
                                 pci_channel_state_t state,
                                 enum pci_ers_result *result)
{
        pci_ers_result_t vote;
        const struct pci_error_handlers *err_handler;

        device_lock(&dev->dev);
        if (!pci_dev_set_io_state(dev, state) ||
                !dev->driver ||
                !dev->driver->err_handler ||
                !dev->driver->err_handler->error_detected) {
                /*
                 * If any device in the subtree does not have an error_detected
                 * callback, PCI_ERS_RESULT_NO_AER_DRIVER prevents subsequent
                 * error callbacks of "any" device in the subtree, and will
                 * exit in the disconnected error state.
                 */
                if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
                        vote = PCI_ERS_RESULT_NO_AER_DRIVER;
                        pci_info(dev, "can't recover (no error_detected callback)\n");
                } else {
                        vote = PCI_ERS_RESULT_NONE;
                }
        } else {
                err_handler = dev->driver->err_handler;
                vote = err_handler->error_detected(dev, state);
        }
        pci_uevent_ers(dev, vote);
        *result = merge_result(*result, vote);
        device_unlock(&dev->dev);
        return 0;
}

static int report_frozen_detected(struct pci_dev *dev, void *data)
{
        return report_error_detected(dev, pci_channel_io_frozen, data);
}

static int report_normal_detected(struct pci_dev *dev, void *data)
{
        return report_error_detected(dev, pci_channel_io_normal, data);
}

static int report_mmio_enabled(struct pci_dev *dev, void *data)
{
        pci_ers_result_t vote, *result = data;
        const struct pci_error_handlers *err_handler;

        device_lock(&dev->dev);
        if (!dev->driver ||
                !dev->driver->err_handler ||
                !dev->driver->err_handler->mmio_enabled)
                goto out;

        err_handler = dev->driver->err_handler;
        vote = err_handler->mmio_enabled(dev);
        *result = merge_result(*result, vote);
out:
        device_unlock(&dev->dev);
        return 0;
}

static int report_slot_reset(struct pci_dev *dev, void *data)
{
        pci_ers_result_t vote, *result = data;
        const struct pci_error_handlers *err_handler;

        device_lock(&dev->dev);
        if (!dev->driver ||
                !dev->driver->err_handler ||
                !dev->driver->err_handler->slot_reset)
                goto out;

        err_handler = dev->driver->err_handler;
        vote = err_handler->slot_reset(dev);
        *result = merge_result(*result, vote);
out:
        device_unlock(&dev->dev);
        return 0;
}

static int report_resume(struct pci_dev *dev, void *data)
{
        const struct pci_error_handlers *err_handler;

        device_lock(&dev->dev);
        if (!pci_dev_set_io_state(dev, pci_channel_io_normal) ||
                !dev->driver ||
                !dev->driver->err_handler ||
                !dev->driver->err_handler->resume)
                goto out;

        err_handler = dev->driver->err_handler;
        err_handler->resume(dev);
out:
        pci_uevent_ers(dev, PCI_ERS_RESULT_RECOVERED);
        device_unlock(&dev->dev);
        return 0;
}

/**
 * pci_walk_bridge - walk bridges potentially AER affected
 * @bridge:     bridge which may be a Port, an RCEC, or an RCiEP
 * @cb:         callback to be called for each device found
 * @userdata:   arbitrary pointer to be passed to callback
 *
 * If the device provided is a bridge, walk the subordinate bus, including
 * any bridged devices on buses under this bus.  Call the provided callback
 * on each device found.
 *
 * If the device provided has no subordinate bus, e.g., an RCEC or RCiEP,
 * call the callback on the device itself.
 */
static void pci_walk_bridge(struct pci_dev *bridge,
                            int (*cb)(struct pci_dev *, void *),
                            void *userdata)
{
        if (bridge->subordinate)
                pci_walk_bus(bridge->subordinate, cb, userdata);
        else
                cb(bridge, userdata);
}

pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
                pci_channel_state_t state,
                pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev))
{
        int type = pci_pcie_type(dev);
        struct pci_dev *bridge;
        pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
        struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);

        /*
         * If the error was detected by a Root Port, Downstream Port, RCEC,
         * or RCiEP, recovery runs on the device itself.  For Ports, that
         * also includes any subordinate devices.
         *
         * If it was detected by another device (Endpoint, etc), recovery
         * runs on the device and anything else under the same Port, i.e.,
         * everything under "bridge".
         */
        if (type == PCI_EXP_TYPE_ROOT_PORT ||
            type == PCI_EXP_TYPE_DOWNSTREAM ||
            type == PCI_EXP_TYPE_RC_EC ||
            type == PCI_EXP_TYPE_RC_END)
                bridge = dev;
        else
                bridge = pci_upstream_bridge(dev);

        pci_dbg(bridge, "broadcast error_detected message\n");
        if (state == pci_channel_io_frozen) {
                pci_walk_bridge(bridge, report_frozen_detected, &status);
                if (reset_subordinates(bridge) != PCI_ERS_RESULT_RECOVERED) {
                        pci_warn(bridge, "subordinate device reset failed\n");
                        goto failed;
                }
        } else {
                pci_walk_bridge(bridge, report_normal_detected, &status);
        }

        if (status == PCI_ERS_RESULT_CAN_RECOVER) {
                status = PCI_ERS_RESULT_RECOVERED;
                pci_dbg(bridge, "broadcast mmio_enabled message\n");
                pci_walk_bridge(bridge, report_mmio_enabled, &status);
        }

        if (status == PCI_ERS_RESULT_NEED_RESET) {
                /*
                 * TODO: Should call platform-specific
                 * functions to reset slot before calling
                 * drivers' slot_reset callbacks?
                 */
                status = PCI_ERS_RESULT_RECOVERED;
                pci_dbg(bridge, "broadcast slot_reset message\n");
                pci_walk_bridge(bridge, report_slot_reset, &status);
        }

        if (status != PCI_ERS_RESULT_RECOVERED)
                goto failed;

        pci_dbg(bridge, "broadcast resume message\n");
        pci_walk_bridge(bridge, report_resume, &status);

        /*
         * If we have native control of AER, clear error status in the device
         * that detected the error.  If the platform retained control of AER,
         * it is responsible for clearing this status.  In that case, the
         * signaling device may not even be visible to the OS.
         */
        if (host->native_aer || pcie_ports_native) {
                pcie_clear_device_status(dev);
                pci_aer_clear_nonfatal_status(dev);
        }
        pci_info(bridge, "device recovery successful\n");
        return status;

failed:
        pci_uevent_ers(bridge, PCI_ERS_RESULT_DISCONNECT);

        /* TODO: Should kernel panic here? */
        pci_info(bridge, "device recovery failed\n");

        return status;
}