drivers/pci/hotplug/acpi_pcihp.c

   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
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/kernel.h>
  16 #include <linux/types.h>
  17 #include <linux/pci.h>
  18 #include <linux/pci_hotplug.h>
  19 #include <linux/acpi.h>
  20 #include <linux/pci-acpi.h>
  21 #include <linux/slab.h>
  22
  23 #define MY_NAME "acpi_pcihp"
  24
  25 #define dbg(fmt, arg...) do { if (debug_acpi) printk(KERN_DEBUG "%s: %s: " fmt, MY_NAME, __func__, ## arg); } while (0)
  26 #define err(format, arg...) printk(KERN_ERR "%s: " format, MY_NAME, ## arg)
  27 #define info(format, arg...) printk(KERN_INFO "%s: " format, MY_NAME, ## arg)
  28 #define warn(format, arg...) printk(KERN_WARNING "%s: " format, MY_NAME, ## arg)
  29
  30 #define METHOD_NAME__SUN        "_SUN"
  31 #define METHOD_NAME_OSHP        "OSHP"
  32
  33 static bool debug_acpi;
  34
  35 /* acpi_run_oshp - get control of hotplug from the firmware
  36  *
  37  * @handle - the handle of the hotplug controller.
  38  */
  39 static acpi_status acpi_run_oshp(acpi_handle handle)
  40 {
  41         acpi_status             status;
  42         struct acpi_buffer      string = { ACPI_ALLOCATE_BUFFER, NULL };
  43
  44         acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
  45
  46         /* run OSHP */
  47         status = acpi_evaluate_object(handle, METHOD_NAME_OSHP, NULL, NULL);
  48         if (ACPI_FAILURE(status))
  49                 if (status != AE_NOT_FOUND)
  50                         printk(KERN_ERR "%s:%s OSHP fails=0x%x\n",
  51                                __func__, (char *)string.pointer, status);
  52                 else
  53                         dbg("%s:%s OSHP not found\n",
  54                             __func__, (char *)string.pointer);
  55         else
  56                 pr_debug("%s:%s OSHP passes\n", __func__,
  57                         (char *)string.pointer);
  58
  59         kfree(string.pointer);
  60         return status;
  61 }
  62
  63 /**
  64  * acpi_get_hp_hw_control_from_firmware
  65  * @dev: the pci_dev of the bridge that has a hotplug controller
  66  * @flags: requested control bits for _OSC
  67  *
  68  * Attempt to take hotplug control from firmware.
  69  */
  70 int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev, u32 flags)
  71 {
  72         acpi_status status;
  73         acpi_handle chandle, handle;
  74         struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
  75
  76         flags &= OSC_PCI_SHPC_NATIVE_HP_CONTROL;
  77         if (!flags) {
  78                 err("Invalid flags %u specified!\n", flags);
  79                 return -EINVAL;
  80         }
  81
  82         /*
  83          * Per PCI firmware specification, we should run the ACPI _OSC
  84          * method to get control of hotplug hardware before using it. If
  85          * an _OSC is missing, we look for an OSHP to do the same thing.
  86          * To handle different BIOS behavior, we look for _OSC on a root
  87          * bridge preferentially (according to PCI fw spec). Later for
  88          * OSHP within the scope of the hotplug controller and its parents,
  89          * up to the host bridge under which this controller exists.
  90          */
  91         handle = acpi_find_root_bridge_handle(pdev);
  92         if (handle) {
  93                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
  94                 dbg("Trying to get hotplug control for %s\n",
  95                                 (char *)string.pointer);
  96                 status = acpi_pci_osc_control_set(handle, &flags, flags);
  97                 if (ACPI_SUCCESS(status))
  98                         goto got_one;
  99                 if (status == AE_SUPPORT)
 100                         goto no_control;
 101                 kfree(string.pointer);
 102                 string = (struct acpi_buffer){ ACPI_ALLOCATE_BUFFER, NULL };
 103         }
 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                 dbg("Trying to get hotplug control for %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 no_control:
 134         dbg("Cannot get control of hotplug hardware for pci %s\n",
 135             pci_name(pdev));
 136         kfree(string.pointer);
 137         return -ENODEV;
 138 got_one:
 139         dbg("Gained control for hotplug HW for pci %s (%s)\n",
 140             pci_name(pdev), (char *)string.pointer);
 141         kfree(string.pointer);
 142         return 0;
 143 }
 144 EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
 145
 146 static int pcihp_is_ejectable(acpi_handle handle)
 147 {
 148         acpi_status status;
 149         unsigned long long removable;
 150         if (!acpi_has_method(handle, "_ADR"))
 151                 return 0;
 152         if (acpi_has_method(handle, "_EJ0"))
 153                 return 1;
 154         status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
 155         if (ACPI_SUCCESS(status) && removable)
 156                 return 1;
 157         return 0;
 158 }
 159
 160 /**
 161  * acpi_pcihp_check_ejectable - check if handle is ejectable ACPI PCI slot
 162  * @pbus: the PCI bus of the PCI slot corresponding to 'handle'
 163  * @handle: ACPI handle to check
 164  *
 165  * Return 1 if handle is ejectable PCI slot, 0 otherwise.
 166  */
 167 int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle)
 168 {
 169         acpi_handle bridge_handle, parent_handle;
 170
 171         bridge_handle = acpi_pci_get_bridge_handle(pbus);
 172         if (!bridge_handle)
 173                 return 0;
 174         if ((ACPI_FAILURE(acpi_get_parent(handle, &parent_handle))))
 175                 return 0;
 176         if (bridge_handle != parent_handle)
 177                 return 0;
 178         return pcihp_is_ejectable(handle);
 179 }
 180 EXPORT_SYMBOL_GPL(acpi_pci_check_ejectable);
 181
 182 static acpi_status
 183 check_hotplug(acpi_handle handle, u32 lvl, void *context, void **rv)
 184 {
 185         int *found = (int *)context;
 186         if (pcihp_is_ejectable(handle)) {
 187                 *found = 1;
 188                 return AE_CTRL_TERMINATE;
 189         }
 190         return AE_OK;
 191 }
 192
 193 /**
 194  * acpi_pci_detect_ejectable - check if the PCI bus has ejectable slots
 195  * @handle - handle of the PCI bus to scan
 196  *
 197  * Returns 1 if the PCI bus has ACPI based ejectable slots, 0 otherwise.
 198  */
 199 int acpi_pci_detect_ejectable(acpi_handle handle)
 200 {
 201         int found = 0;
 202
 203         if (!handle)
 204                 return found;
 205
 206         acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
 207                             check_hotplug, NULL, (void *)&found, NULL);
 208         return found;
 209 }
 210 EXPORT_SYMBOL_GPL(acpi_pci_detect_ejectable);
 211
 212 module_param(debug_acpi, bool, 0644);
 213 MODULE_PARM_DESC(debug_acpi, "Debugging mode for ACPI enabled or not");