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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Common ACPI functions for hot plug platforms4 *5 * Copyright (C) 2006 Intel Corporation6 *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 firmware35 *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 else52 dbg("%s:%s OSHP not found\n",53 __func__, (char *)string.pointer);54 else55 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_firmware64 * @pdev: the pci_dev of the bridge that has a hotplug controller65 *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 compiled78 * 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 manage88 * 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 the99 * firmware can transfer control to the OS, e.g., direct interrupts100 * to the OS instead of to the firmware.101 *102 * N.B. The PCI Firmware Spec (r3.2, sec 4.8) does not endorse103 * 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 name109 * 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_pci_check_ejectable - check if handle is ejectable ACPI PCI slot161 * @pbus: the PCI bus of the PCI slot corresponding to 'handle'162 * @handle: ACPI handle to check163 *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_status182check_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 slots194 * @handle: handle of the PCI bus to scan195 *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