// SPDX-License-Identifier: GPL-2.0+
/*
 * Common ACPI functions for hot plug platforms
 *
 * Copyright (C) 2006 Intel Corporation
 *
 * All rights reserved.
 *
 * Send feedback to <kristen.c.accardi@intel.com>
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <linux/acpi.h>
#include <linux/pci-acpi.h>
#include <linux/slab.h>

#define MY_NAME "acpi_pcihp"

#define dbg(fmt, arg...) do { if (debug_acpi) printk(KERN_DEBUG "%s: %s: " fmt, MY_NAME, __func__, ## arg); } while (0)
#define err(format, arg...) printk(KERN_ERR "%s: " format, MY_NAME, ## arg)
#define info(format, arg...) printk(KERN_INFO "%s: " format, MY_NAME, ## arg)
#define warn(format, arg...) printk(KERN_WARNING "%s: " format, MY_NAME, ## arg)

#define METHOD_NAME__SUN        "_SUN"
#define METHOD_NAME_OSHP        "OSHP"

static bool debug_acpi;

/* acpi_run_oshp - get control of hotplug from the firmware
 *
 * @handle - the handle of the hotplug controller.
 */
static acpi_status acpi_run_oshp(acpi_handle handle)
{
        acpi_status             status;
        struct acpi_buffer      string = { ACPI_ALLOCATE_BUFFER, NULL };

        acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);

        /* run OSHP */
        status = acpi_evaluate_object(handle, METHOD_NAME_OSHP, NULL, NULL);
        if (ACPI_FAILURE(status))
                if (status != AE_NOT_FOUND)
                        printk(KERN_ERR "%s:%s OSHP fails=0x%x\n",
                               __func__, (char *)string.pointer, status);
                else
                        dbg("%s:%s OSHP not found\n",
                            __func__, (char *)string.pointer);
        else
                pr_debug("%s:%s OSHP passes\n", __func__,
                        (char *)string.pointer);

        kfree(string.pointer);
        return status;
}

/**
 * acpi_get_hp_hw_control_from_firmware
 * @pdev: the pci_dev of the bridge that has a hotplug controller
 *
 * Attempt to take hotplug control from firmware.
 */
int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
{
        const struct pci_host_bridge *host;
        const struct acpi_pci_root *root;
        acpi_status status;
        acpi_handle chandle, handle;
        struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };

        /*
         * If there's no ACPI host bridge (i.e., ACPI support is compiled
         * into the kernel but the hardware platform doesn't support ACPI),
         * there's nothing to do here.
         */
        host = pci_find_host_bridge(pdev->bus);
        root = acpi_pci_find_root(ACPI_HANDLE(&host->dev));
        if (!root)
                return 0;

        /*
         * If _OSC exists, it determines whether we're allowed to manage
         * the SHPC.  We executed it while enumerating the host bridge.
         */
        if (root->osc_support_set) {
                if (host->native_shpc_hotplug)
                        return 0;
                return -ENODEV;
        }

        /*
         * In the absence of _OSC, we're always allowed to manage the SHPC.
         * However, if an OSHP method is present, we must execute it so the
         * firmware can transfer control to the OS, e.g., direct interrupts
         * to the OS instead of to the firmware.
         *
         * N.B. The PCI Firmware Spec (r3.2, sec 4.8) does not endorse
         * searching up the ACPI hierarchy, so the loops below are suspect.
         */
        handle = ACPI_HANDLE(&pdev->dev);
        if (!handle) {
                /*
                 * This hotplug controller was not listed in the ACPI name
                 * space at all. Try to get ACPI handle of parent PCI bus.
                 */
                struct pci_bus *pbus;
                for (pbus = pdev->bus; pbus; pbus = pbus->parent) {
                        handle = acpi_pci_get_bridge_handle(pbus);
                        if (handle)
                                break;
                }
        }

        while (handle) {
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
                pci_info(pdev, "Requesting control of SHPC hotplug via OSHP (%s)\n",
                         (char *)string.pointer);
                status = acpi_run_oshp(handle);
                if (ACPI_SUCCESS(status))
                        goto got_one;
                if (acpi_is_root_bridge(handle))
                        break;
                chandle = handle;
                status = acpi_get_parent(chandle, &handle);
                if (ACPI_FAILURE(status))
                        break;
        }

        pci_info(pdev, "Cannot get control of SHPC hotplug\n");
        kfree(string.pointer);
        return -ENODEV;
got_one:
        pci_info(pdev, "Gained control of SHPC hotplug (%s)\n",
                 (char *)string.pointer);
        kfree(string.pointer);
        return 0;
}
EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);

static int pcihp_is_ejectable(acpi_handle handle)
{
        acpi_status status;
        unsigned long long removable;
        if (!acpi_has_method(handle, "_ADR"))
                return 0;
        if (acpi_has_method(handle, "_EJ0"))
                return 1;
        status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
        if (ACPI_SUCCESS(status) && removable)
                return 1;
        return 0;
}

/**
 * acpi_pci_check_ejectable - check if handle is ejectable ACPI PCI slot
 * @pbus: the PCI bus of the PCI slot corresponding to 'handle'
 * @handle: ACPI handle to check
 *
 * Return 1 if handle is ejectable PCI slot, 0 otherwise.
 */
int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle)
{
        acpi_handle bridge_handle, parent_handle;

        bridge_handle = acpi_pci_get_bridge_handle(pbus);
        if (!bridge_handle)
                return 0;
        if ((ACPI_FAILURE(acpi_get_parent(handle, &parent_handle))))
                return 0;
        if (bridge_handle != parent_handle)
                return 0;
        return pcihp_is_ejectable(handle);
}
EXPORT_SYMBOL_GPL(acpi_pci_check_ejectable);

static acpi_status
check_hotplug(acpi_handle handle, u32 lvl, void *context, void **rv)
{
        int *found = (int *)context;
        if (pcihp_is_ejectable(handle)) {
                *found = 1;
                return AE_CTRL_TERMINATE;
        }
        return AE_OK;
}

/**
 * acpi_pci_detect_ejectable - check if the PCI bus has ejectable slots
 * @handle: handle of the PCI bus to scan
 *
 * Returns 1 if the PCI bus has ACPI based ejectable slots, 0 otherwise.
 */
int acpi_pci_detect_ejectable(acpi_handle handle)
{
        int found = 0;

        if (!handle)
                return found;

        acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
                            check_hotplug, NULL, (void *)&found, NULL);
        return found;
}
EXPORT_SYMBOL_GPL(acpi_pci_detect_ejectable);

module_param(debug_acpi, bool, 0644);
MODULE_PARM_DESC(debug_acpi, "Debugging mode for ACPI enabled or not");