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  *
  67  * Attempt to take hotplug control from firmware.
  68  */
  69 int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
  70 {
  71         const struct pci_host_bridge *host;
  72         const struct acpi_pci_root *root;
  73         acpi_status status;
  74         acpi_handle chandle, handle;
  75         struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
  76
  77         /*
  78          * Per PCI firmware specification, we should run the ACPI _OSC
  79          * method to get control of hotplug hardware before using it. If
  80          * an _OSC is missing, we look for an OSHP to do the same thing.
  81          * To handle different BIOS behavior, we look for _OSC on a root
  82          * bridge preferentially (according to PCI fw spec). Later for
  83          * OSHP within the scope of the hotplug controller and its parents,
  84          * up to the host bridge under which this controller exists.
  85          */
  86         if (shpchp_is_native(pdev))
  87                 return 0;
  88
  89         /* If _OSC exists, we should not evaluate OSHP */
  90         host = pci_find_host_bridge(pdev->bus);
  91         root = acpi_pci_find_root(ACPI_HANDLE(&host->dev));
  92         if (root->osc_support_set)
  93                 goto no_control;
  94
  95         handle = ACPI_HANDLE(&pdev->dev);
  96         if (!handle) {
  97                 /*
  98                  * This hotplug controller was not listed in the ACPI name
  99                  * space at all. Try to get ACPI handle of parent PCI bus.
 100                  */
 101                 struct pci_bus *pbus;
 102                 for (pbus = pdev->bus; pbus; pbus = pbus->parent) {
 103                         handle = acpi_pci_get_bridge_handle(pbus);
 104                         if (handle)
 105                                 break;
 106                 }
 107         }
 108
 109         while (handle) {
 110                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
 111                 pci_info(pdev, "Requesting control of SHPC hotplug via OSHP (%s)\n",
 112                          (char *)string.pointer);
 113                 status = acpi_run_oshp(handle);
 114                 if (ACPI_SUCCESS(status))
 115                         goto got_one;
 116                 if (acpi_is_root_bridge(handle))
 117                         break;
 118                 chandle = handle;
 119                 status = acpi_get_parent(chandle, &handle);
 120                 if (ACPI_FAILURE(status))
 121                         break;
 122         }
 123 no_control:
 124         pci_info(pdev, "Cannot get control of SHPC hotplug\n");
 125         kfree(string.pointer);
 126         return -ENODEV;
 127 got_one:
 128         pci_info(pdev, "Gained control of SHPC hotplug (%s)\n",
 129                  (char *)string.pointer);
 130         kfree(string.pointer);
 131         return 0;
 132 }
 133 EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
 134
 135 static int pcihp_is_ejectable(acpi_handle handle)
 136 {
 137         acpi_status status;
 138         unsigned long long removable;
 139         if (!acpi_has_method(handle, "_ADR"))
 140                 return 0;
 141         if (acpi_has_method(handle, "_EJ0"))
 142                 return 1;
 143         status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
 144         if (ACPI_SUCCESS(status) && removable)
 145                 return 1;
 146         return 0;
 147 }
 148
 149 /**
 150  * acpi_pcihp_check_ejectable - check if handle is ejectable ACPI PCI slot
 151  * @pbus: the PCI bus of the PCI slot corresponding to 'handle'
 152  * @handle: ACPI handle to check
 153  *
 154  * Return 1 if handle is ejectable PCI slot, 0 otherwise.
 155  */
 156 int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle)
 157 {
 158         acpi_handle bridge_handle, parent_handle;
 159
 160         bridge_handle = acpi_pci_get_bridge_handle(pbus);
 161         if (!bridge_handle)
 162                 return 0;
 163         if ((ACPI_FAILURE(acpi_get_parent(handle, &parent_handle))))
 164                 return 0;
 165         if (bridge_handle != parent_handle)
 166                 return 0;
 167         return pcihp_is_ejectable(handle);
 168 }
 169 EXPORT_SYMBOL_GPL(acpi_pci_check_ejectable);
 170
 171 static acpi_status
 172 check_hotplug(acpi_handle handle, u32 lvl, void *context, void **rv)
 173 {
 174         int *found = (int *)context;
 175         if (pcihp_is_ejectable(handle)) {
 176                 *found = 1;
 177                 return AE_CTRL_TERMINATE;
 178         }
 179         return AE_OK;
 180 }
 181
 182 /**
 183  * acpi_pci_detect_ejectable - check if the PCI bus has ejectable slots
 184  * @handle - handle of the PCI bus to scan
 185  *
 186  * Returns 1 if the PCI bus has ACPI based ejectable slots, 0 otherwise.
 187  */
 188 int acpi_pci_detect_ejectable(acpi_handle handle)
 189 {
 190         int found = 0;
 191
 192         if (!handle)
 193                 return found;
 194
 195         acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
 196                             check_hotplug, NULL, (void *)&found, NULL);
 197         return found;
 198 }
 199 EXPORT_SYMBOL_GPL(acpi_pci_detect_ejectable);
 200
 201 module_param(debug_acpi, bool, 0644);
 202 MODULE_PARM_DESC(debug_acpi, "Debugging mode for ACPI enabled or not");