// 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)
 */

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

struct aer_broadcast_data {
        enum pci_channel_state state;
        enum pci_ers_result result;
};

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, void *data)
{
        pci_ers_result_t vote;
        const struct pci_error_handlers *err_handler;
        struct aer_broadcast_data *result_data;

        result_data = (struct aer_broadcast_data *) data;

        device_lock(&dev->dev);
        dev->error_state = result_data->state;

        if (!dev->driver ||
                !dev->driver->err_handler ||
                !dev->driver->err_handler->error_detected) {
                if (result_data->state == pci_channel_io_frozen &&
                        dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
                        /*
                         * In case of fatal recovery, if one of down-
                         * stream device has no driver. We might be
                         * unable to recover because a later insmod
                         * of a driver for this device is unaware of
                         * its hw state.
                         */
                        pci_printk(KERN_DEBUG, dev, "device has %s\n",
                                   dev->driver ?
                                   "no AER-aware driver" : "no driver");
                }

                /*
                 * If there's any device in the subtree that does not
                 * have an error_detected callback, returning
                 * PCI_ERS_RESULT_NO_AER_DRIVER prevents calling of
                 * the subsequent mmio_enabled/slot_reset/resume
                 * callbacks of "any" device in the subtree. All the
                 * devices in the subtree are left in the error state
                 * without recovery.
                 */

                if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE)
                        vote = PCI_ERS_RESULT_NO_AER_DRIVER;
                else
                        vote = PCI_ERS_RESULT_NONE;
        } else {
                err_handler = dev->driver->err_handler;
                vote = err_handler->error_detected(dev, result_data->state);
                pci_uevent_ers(dev, PCI_ERS_RESULT_NONE);
        }

        result_data->result = merge_result(result_data->result, vote);
        device_unlock(&dev->dev);
        return 0;
}

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

        result_data = (struct aer_broadcast_data *) data;

        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_data->result = merge_result(result_data->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;
        const struct pci_error_handlers *err_handler;
        struct aer_broadcast_data *result_data;

        result_data = (struct aer_broadcast_data *) data;

        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_data->result = merge_result(result_data->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);
        dev->error_state = pci_channel_io_normal;

        if (!dev->driver ||
                !dev->driver->err_handler ||
                !dev->driver->err_handler->resume)
                goto out;

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

/**
 * default_reset_link - default reset function
 * @dev: pointer to pci_dev data structure
 *
 * Invoked when performing link reset on a Downstream Port or a
 * Root Port with no aer driver.
 */
static pci_ers_result_t default_reset_link(struct pci_dev *dev)
{
        int rc;

        rc = pci_bridge_secondary_bus_reset(dev);
        pci_printk(KERN_DEBUG, dev, "downstream link has been reset\n");
        return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
}

static pci_ers_result_t reset_link(struct pci_dev *dev, u32 service)
{
        struct pci_dev *udev;
        pci_ers_result_t status;
        struct pcie_port_service_driver *driver = NULL;

        if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
                /* Reset this port for all subordinates */
                udev = dev;
        } else {
                /* Reset the upstream component (likely downstream port) */
                udev = dev->bus->self;
        }

        /* Use the aer driver of the component firstly */
        driver = pcie_port_find_service(udev, service);

        if (driver && driver->reset_link) {
                status = driver->reset_link(udev);
        } else if (udev->has_secondary_link) {
                status = default_reset_link(udev);
        } else {
                pci_printk(KERN_DEBUG, dev, "no link-reset support at upstream device %s\n",
                        pci_name(udev));
                return PCI_ERS_RESULT_DISCONNECT;
        }

        if (status != PCI_ERS_RESULT_RECOVERED) {
                pci_printk(KERN_DEBUG, dev, "link reset at upstream device %s failed\n",
                        pci_name(udev));
                return PCI_ERS_RESULT_DISCONNECT;
        }

        return status;
}

/**
 * broadcast_error_message - handle message broadcast to downstream drivers
 * @dev: pointer to from where in a hierarchy message is broadcasted down
 * @state: error state
 * @error_mesg: message to print
 * @cb: callback to be broadcasted
 *
 * Invoked during error recovery process. Once being invoked, the content
 * of error severity will be broadcasted to all downstream drivers in a
 * hierarchy in question.
 */
static pci_ers_result_t broadcast_error_message(struct pci_dev *dev,
        enum pci_channel_state state,
        char *error_mesg,
        int (*cb)(struct pci_dev *, void *))
{
        struct aer_broadcast_data result_data;

        pci_printk(KERN_DEBUG, dev, "broadcast %s message\n", error_mesg);
        result_data.state = state;
        if (cb == report_error_detected)
                result_data.result = PCI_ERS_RESULT_CAN_RECOVER;
        else
                result_data.result = PCI_ERS_RESULT_RECOVERED;

        if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
                /*
                 * If the error is reported by a bridge, we think this error
                 * is related to the downstream link of the bridge, so we
                 * do error recovery on all subordinates of the bridge instead
                 * of the bridge and clear the error status of the bridge.
                 */
                if (cb == report_error_detected)
                        dev->error_state = state;
                pci_walk_bus(dev->subordinate, cb, &result_data);
                if (cb == report_resume) {
                        pci_aer_clear_device_status(dev);
                        pci_cleanup_aer_uncorrect_error_status(dev);
                        dev->error_state = pci_channel_io_normal;
                }
        } else {
                /*
                 * If the error is reported by an end point, we think this
                 * error is related to the upstream link of the end point.
                 * The error is non fatal so the bus is ok; just invoke
                 * the callback for the function that logged the error.
                 */
                cb(dev, &result_data);
        }

        return result_data.result;
}

/**
 * pcie_do_fatal_recovery - handle fatal error recovery process
 * @dev: pointer to a pci_dev data structure of agent detecting an error
 *
 * Invoked when an error is fatal. Once being invoked, removes the devices
 * beneath this AER agent, followed by reset link e.g. secondary bus reset
 * followed by re-enumeration of devices.
 */
void pcie_do_fatal_recovery(struct pci_dev *dev, u32 service)
{
        struct pci_dev *udev;
        struct pci_bus *parent;
        struct pci_dev *pdev, *temp;
        pci_ers_result_t result;

        if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
                udev = dev;
        else
                udev = dev->bus->self;

        parent = udev->subordinate;
        pci_walk_bus(parent, pci_dev_set_disconnected, NULL);

        pci_lock_rescan_remove();
        pci_dev_get(dev);
        list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
                                         bus_list) {
                pci_stop_and_remove_bus_device(pdev);
        }

        result = reset_link(udev, service);

        if ((service == PCIE_PORT_SERVICE_AER) &&
            (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)) {
                /*
                 * If the error is reported by a bridge, we think this error
                 * is related to the downstream link of the bridge, so we
                 * do error recovery on all subordinates of the bridge instead
                 * of the bridge and clear the error status of the bridge.
                 */
                pci_aer_clear_fatal_status(dev);
                pci_aer_clear_device_status(dev);
        }

        if (result == PCI_ERS_RESULT_RECOVERED) {
                if (pcie_wait_for_link(udev, true))
                        pci_rescan_bus(udev->bus);
                pci_info(dev, "Device recovery from fatal error successful\n");
        } else {
                pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
                pci_info(dev, "Device recovery from fatal error failed\n");
        }

        pci_dev_put(dev);
        pci_unlock_rescan_remove();
}

/**
 * pcie_do_nonfatal_recovery - handle nonfatal error recovery process
 * @dev: pointer to a pci_dev data structure of agent detecting an error
 *
 * Invoked when an error is nonfatal/fatal. Once being invoked, broadcast
 * error detected message to all downstream drivers within a hierarchy in
 * question and return the returned code.
 */
void pcie_do_nonfatal_recovery(struct pci_dev *dev)
{
        pci_ers_result_t status;
        enum pci_channel_state state;

        state = pci_channel_io_normal;

        status = broadcast_error_message(dev,
                        state,
                        "error_detected",
                        report_error_detected);

        if (status == PCI_ERS_RESULT_CAN_RECOVER)
                status = broadcast_error_message(dev,
                                state,
                                "mmio_enabled",
                                report_mmio_enabled);

        if (status == PCI_ERS_RESULT_NEED_RESET) {
                /*
                 * TODO: Should call platform-specific
                 * functions to reset slot before calling
                 * drivers' slot_reset callbacks?
                 */
                status = broadcast_error_message(dev,
                                state,
                                "slot_reset",
                                report_slot_reset);
        }

        if (status != PCI_ERS_RESULT_RECOVERED)
                goto failed;

        broadcast_error_message(dev,
                                state,
                                "resume",
                                report_resume);

        pci_info(dev, "AER: Device recovery successful\n");
        return;

failed:
        pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);

        /* TODO: Should kernel panic here? */
        pci_info(dev, "AER: Device recovery failed\n");
}