LXR linux/drivers/pci/hotplug/acpi

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Common ACPI functions for hot plug platforms
   4 *
   5 * Copyright (C) 2006 Intel Corporation
   6 *
   7 * All rights reserved.
   8 *
   9 * Send feedback to <kristen.c.accardi@intel.com>
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/moduleparam.h>
  14#include <linux/kernel.h>
  15#include <linux/types.h>
  16#include <linux/pci.h>
  17#include <linux/pci_hotplug.h>
  18#include <linux/acpi.h>
  19#include <linux/pci-acpi.h>
  20#include <linux/slab.h>
  21
  22#define MY_NAME "acpi_pcihp"
  23
  24#define dbg(fmt, arg...) do { if (debug_acpi) printk(KERN_DEBUG "%s: %s: " fmt, MY_NAME, __func__, ## arg); } while (0)
  25#define err(format, arg...) printk(KERN_ERR "%s: " format, MY_NAME, ## arg)
  26#define info(format, arg...) printk(KERN_INFO "%s: " format, MY_NAME, ## arg)
  27#define warn(format, arg...) printk(KERN_WARNING "%s: " format, MY_NAME, ## arg)
  28
  29#define METHOD_NAME__SUN        "_SUN"
  30#define METHOD_NAME_OSHP        "OSHP"
  31
  32static bool debug_acpi;
  33
  34/* acpi_run_oshp - get control of hotplug from the firmware
  35 *
  36 * @handle - the handle of the hotplug controller.
  37 */
  38static acpi_status acpi_run_oshp(acpi_handle handle)
  39{
  40        acpi_status             status;
  41        struct acpi_buffer      string = { ACPI_ALLOCATE_BUFFER, NULL };
  42
  43        acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
  44
  45        /* run OSHP */
  46        status = acpi_evaluate_object(handle, METHOD_NAME_OSHP, NULL, NULL);
  47        if (ACPI_FAILURE(status))
  48                if (status != AE_NOT_FOUND)
  49                        printk(KERN_ERR "%s:%s OSHP fails=0x%x\n",
  50                               __func__, (char *)string.pointer, status);
  51                else
  52                        dbg("%s:%s OSHP not found\n",
  53                            __func__, (char *)string.pointer);
  54        else
  55                pr_debug("%s:%s OSHP passes\n", __func__,
  56                        (char *)string.pointer);
  57
  58        kfree(string.pointer);
  59        return status;
  60}
  61
  62/**
  63 * acpi_get_hp_hw_control_from_firmware
  64 * @dev: the pci_dev of the bridge that has a hotplug controller
  65 *
  66 * Attempt to take hotplug control from firmware.
  67 */
  68int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
  69{
  70        const struct pci_host_bridge *host;
  71        const struct acpi_pci_root *root;
  72        acpi_status status;
  73        acpi_handle chandle, handle;
  74        struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
  75
  76        /*
  77         * If there's no ACPI host bridge (i.e., ACPI support is compiled
  78         * into the kernel but the hardware platform doesn't support ACPI),
  79         * there's nothing to do here.
  80         */
  81        host = pci_find_host_bridge(pdev->bus);
  82        root = acpi_pci_find_root(ACPI_HANDLE(&host->dev));
  83        if (!root)
  84                return 0;
  85
  86        /*
  87         * If _OSC exists, it determines whether we're allowed to manage
  88         * the SHPC.  We executed it while enumerating the host bridge.
  89         */
  90        if (root->osc_support_set) {
  91                if (host->native_shpc_hotplug)
  92                        return 0;
  93                return -ENODEV;
  94        }
  95
  96        /*
  97         * In the absence of _OSC, we're always allowed to manage the SHPC.
  98         * However, if an OSHP method is present, we must execute it so the
  99         * firmware can transfer control to the OS, e.g., direct interrupts
 100         * to the OS instead of to the firmware.
 101         *
 102         * N.B. The PCI Firmware Spec (r3.2, sec 4.8) does not endorse
 103         * searching up the ACPI hierarchy, so the loops below are suspect.
 104         */
 105        handle = ACPI_HANDLE(&pdev->dev);
 106        if (!handle) {
 107                /*
 108                 * This hotplug controller was not listed in the ACPI name
 109                 * space at all. Try to get ACPI handle of parent PCI bus.
 110                 */
 111                struct pci_bus *pbus;
 112                for (pbus = pdev->bus; pbus; pbus = pbus->parent) {
 113                        handle = acpi_pci_get_bridge_handle(pbus);
 114                        if (handle)
 115                                break;
 116                }
 117        }
 118
 119        while (handle) {
 120                acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
 121                pci_info(pdev, "Requesting control of SHPC hotplug via OSHP (%s)\n",
 122                         (char *)string.pointer);
 123                status = acpi_run_oshp(handle);
 124                if (ACPI_SUCCESS(status))
 125                        goto got_one;
 126                if (acpi_is_root_bridge(handle))
 127                        break;
 128                chandle = handle;
 129                status = acpi_get_parent(chandle, &handle);
 130                if (ACPI_FAILURE(status))
 131                        break;
 132        }
 133
 134        pci_info(pdev, "Cannot get control of SHPC hotplug\n");
 135        kfree(string.pointer);
 136        return -ENODEV;
 137got_one:
 138        pci_info(pdev, "Gained control of SHPC hotplug (%s)\n",
 139                 (char *)string.pointer);
 140        kfree(string.pointer);
 141        return 0;
 142}
 143EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
 144
 145static int pcihp_is_ejectable(acpi_handle handle)
 146{
 147        acpi_status status;
 148        unsigned long long removable;
 149        if (!acpi_has_method(handle, "_ADR"))
 150                return 0;
 151        if (acpi_has_method(handle, "_EJ0"))
 152                return 1;
 153        status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
 154        if (ACPI_SUCCESS(status) && removable)
 155                return 1;
 156        return 0;
 157}
 158
 159/**
 160 * acpi_pcihp_check_ejectable - check if handle is ejectable ACPI PCI slot
 161 * @pbus: the PCI bus of the PCI slot corresponding to 'handle'
 162 * @handle: ACPI handle to check
 163 *
 164 * Return 1 if handle is ejectable PCI slot, 0 otherwise.
 165 */
 166int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle)
 167{
 168        acpi_handle bridge_handle, parent_handle;
 169
 170        bridge_handle = acpi_pci_get_bridge_handle(pbus);
 171        if (!bridge_handle)
 172                return 0;
 173        if ((ACPI_FAILURE(acpi_get_parent(handle, &parent_handle))))
 174                return 0;
 175        if (bridge_handle != parent_handle)
 176                return 0;
 177        return pcihp_is_ejectable(handle);
 178}
 179EXPORT_SYMBOL_GPL(acpi_pci_check_ejectable);
 180
 181static acpi_status
 182check_hotplug(acpi_handle handle, u32 lvl, void *context, void **rv)
 183{
 184        int *found = (int *)context;
 185        if (pcihp_is_ejectable(handle)) {
 186                *found = 1;
 187                return AE_CTRL_TERMINATE;
 188        }
 189        return AE_OK;
 190}
 191
 192/**
 193 * acpi_pci_detect_ejectable - check if the PCI bus has ejectable slots
 194 * @handle - handle of the PCI bus to scan
 195 *
 196 * Returns 1 if the PCI bus has ACPI based ejectable slots, 0 otherwise.
 197 */
 198int acpi_pci_detect_ejectable(acpi_handle handle)
 199{
 200        int found = 0;
 201
 202        if (!handle)
 203                return found;
 204
 205        acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
 206                            check_hotplug, NULL, (void *)&found, NULL);
 207        return found;
 208}
 209EXPORT_SYMBOL_GPL(acpi_pci_detect_ejectable);
 210
 211module_param(debug_acpi, bool, 0644);
 212MODULE_PARM_DESC(debug_acpi, "Debugging mode for ACPI enabled or not");
 213