// SPDX-License-Identifier: GPL-2.0
/*
 * PCI Error Disconnect Recover support
 * Author: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
 *
 * Copyright (C) 2020 Intel Corp.
 */

#define dev_fmt(fmt) "EDR: " fmt

#include <linux/pci.h>
#include <linux/pci-acpi.h>

#include "portdrv.h"
#include "../pci.h"

#define EDR_PORT_DPC_ENABLE_DSM         0x0C
#define EDR_PORT_LOCATE_DSM             0x0D
#define EDR_OST_SUCCESS                 0x80
#define EDR_OST_FAILED                  0x81

/*
 * _DSM wrapper function to enable/disable DPC
 * @pdev   : PCI device structure
 *
 * returns 0 on success or errno on failure.
 */
static int acpi_enable_dpc(struct pci_dev *pdev)
{
        struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
        union acpi_object *obj, argv4, req;
        int status = 0;

        /*
         * Behavior when calling unsupported _DSM functions is undefined,
         * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
         */
        if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
                            1ULL << EDR_PORT_DPC_ENABLE_DSM))
                return 0;

        req.type = ACPI_TYPE_INTEGER;
        req.integer.value = 1;

        argv4.type = ACPI_TYPE_PACKAGE;
        argv4.package.count = 1;
        argv4.package.elements = &req;

        /*
         * Per Downstream Port Containment Related Enhancements ECN to PCI
         * Firmware Specification r3.2, sec 4.6.12, EDR_PORT_DPC_ENABLE_DSM is
         * optional.  Return success if it's not implemented.
         */
        obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
                                EDR_PORT_DPC_ENABLE_DSM, &argv4);
        if (!obj)
                return 0;

        if (obj->type != ACPI_TYPE_INTEGER) {
                pci_err(pdev, FW_BUG "Enable DPC _DSM returned non integer\n");
                status = -EIO;
        }

        if (obj->integer.value != 1) {
                pci_err(pdev, "Enable DPC _DSM failed to enable DPC\n");
                status = -EIO;
        }

        ACPI_FREE(obj);

        return status;
}

/*
 * _DSM wrapper function to locate DPC port
 * @pdev   : Device which received EDR event
 *
 * Returns pci_dev or NULL.  Caller is responsible for dropping a reference
 * on the returned pci_dev with pci_dev_put().
 */
static struct pci_dev *acpi_dpc_port_get(struct pci_dev *pdev)
{
        struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
        union acpi_object *obj;
        u16 port;

        /*
         * Behavior when calling unsupported _DSM functions is undefined,
         * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
         */
        if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
                            1ULL << EDR_PORT_LOCATE_DSM))
                return pci_dev_get(pdev);

        obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
                                EDR_PORT_LOCATE_DSM, NULL);
        if (!obj)
                return pci_dev_get(pdev);

        if (obj->type != ACPI_TYPE_INTEGER) {
                ACPI_FREE(obj);
                pci_err(pdev, FW_BUG "Locate Port _DSM returned non integer\n");
                return NULL;
        }

        /*
         * Firmware returns DPC port BDF details in following format:
         *      15:8 = bus
         *       7:3 = device
         *       2:0 = function
         */
        port = obj->integer.value;

        ACPI_FREE(obj);

        return pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
                                           PCI_BUS_NUM(port), port & 0xff);
}

/*
 * _OST wrapper function to let firmware know the status of EDR event
 * @pdev   : Device used to send _OST
 * @edev   : Device which experienced EDR event
 * @status : Status of EDR event
 */
static int acpi_send_edr_status(struct pci_dev *pdev, struct pci_dev *edev,
                                u16 status)
{
        struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
        u32 ost_status;

        pci_dbg(pdev, "Status for %s: %#x\n", pci_name(edev), status);

        ost_status = PCI_DEVID(edev->bus->number, edev->devfn) << 16;
        ost_status |= status;

        status = acpi_evaluate_ost(adev->handle, ACPI_NOTIFY_DISCONNECT_RECOVER,
                                   ost_status, NULL);
        if (ACPI_FAILURE(status))
                return -EINVAL;

        return 0;
}

static void edr_handle_event(acpi_handle handle, u32 event, void *data)
{
        struct pci_dev *pdev = data, *edev;
        pci_ers_result_t estate = PCI_ERS_RESULT_DISCONNECT;
        u16 status;

        if (event != ACPI_NOTIFY_DISCONNECT_RECOVER)
                return;

        pci_info(pdev, "EDR event received\n");

        /* Locate the port which issued EDR event */
        edev = acpi_dpc_port_get(pdev);
        if (!edev) {
                pci_err(pdev, "Firmware failed to locate DPC port\n");
                return;
        }

        pci_dbg(pdev, "Reported EDR dev: %s\n", pci_name(edev));

        /* If port does not support DPC, just send the OST */
        if (!edev->dpc_cap) {
                pci_err(edev, FW_BUG "This device doesn't support DPC\n");
                goto send_ost;
        }

        /* Check if there is a valid DPC trigger */
        pci_read_config_word(edev, edev->dpc_cap + PCI_EXP_DPC_STATUS, &status);
        if (!(status & PCI_EXP_DPC_STATUS_TRIGGER)) {
                pci_err(edev, "Invalid DPC trigger %#010x\n", status);
                goto send_ost;
        }

        dpc_process_error(edev);
        pci_aer_raw_clear_status(edev);

        /*
         * Irrespective of whether the DPC event is triggered by ERR_FATAL
         * or ERR_NONFATAL, since the link is already down, use the FATAL
         * error recovery path for both cases.
         */
        estate = pcie_do_recovery(edev, pci_channel_io_frozen, dpc_reset_link);

send_ost:

        /*
         * If recovery is successful, send _OST(0xF, BDF << 16 | 0x80)
         * to firmware. If not successful, send _OST(0xF, BDF << 16 | 0x81).
         */
        if (estate == PCI_ERS_RESULT_RECOVERED) {
                pci_dbg(edev, "DPC port successfully recovered\n");
                acpi_send_edr_status(pdev, edev, EDR_OST_SUCCESS);
        } else {
                pci_dbg(edev, "DPC port recovery failed\n");
                acpi_send_edr_status(pdev, edev, EDR_OST_FAILED);
        }

        pci_dev_put(edev);
}

void pci_acpi_add_edr_notifier(struct pci_dev *pdev)
{
        struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
        acpi_status status;

        if (!adev) {
                pci_dbg(pdev, "No valid ACPI node, skipping EDR init\n");
                return;
        }

        status = acpi_install_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
                                             edr_handle_event, pdev);
        if (ACPI_FAILURE(status)) {
                pci_err(pdev, "Failed to install notify handler\n");
                return;
        }

        if (acpi_enable_dpc(pdev))
                acpi_remove_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
                                           edr_handle_event);
        else
                pci_dbg(pdev, "Notify handler installed\n");
}

void pci_acpi_remove_edr_notifier(struct pci_dev *pdev)
{
        struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);

        if (!adev)
                return;

        acpi_remove_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
                                   edr_handle_event);
        pci_dbg(pdev, "Notify handler removed\n");
}