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 #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
  32 static 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  */
  38 static 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  */
  68 int 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;
 137 got_one:
 138         pci_info(pdev, "Gained control of SHPC hotplug (%s)\n",
 139                  (char *)string.pointer);
 140         kfree(string.pointer);
 141         return 0;
 142 }
 143 EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
 144
 145 static 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  */
 166 int 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 }
 179 EXPORT_SYMBOL_GPL(acpi_pci_check_ejectable);
 180
 181 static acpi_status
 182 check_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  */
 198 int 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 }
 209 EXPORT_SYMBOL_GPL(acpi_pci_detect_ejectable);
 210
 211 module_param(debug_acpi, bool, 0644);
 212 MODULE_PARM_DESC(debug_acpi, "Debugging mode for ACPI enabled or not");