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(object: handle, ACPI_FULL_PATHNAME, ret_path_ptr: &string);
44
45 /* run OSHP */
46 status = acpi_evaluate_object(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(objp: string.pointer);
59 return status;
60}
61
62/**
63 * acpi_get_hp_hw_control_from_firmware
64 * @pdev: 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(bus: 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(object: handle, ACPI_FULL_PATHNAME, ret_path_ptr: &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(object: chandle, out_handle: &handle);
130 if (ACPI_FAILURE(status))
131 break;
132 }
133
134 pci_info(pdev, "Cannot get control of SHPC hotplug\n");
135 kfree(objp: string.pointer);
136 return -ENODEV;
137got_one:
138 pci_info(pdev, "Gained control of SHPC hotplug (%s)\n",
139 (char *)string.pointer);
140 kfree(objp: 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, name: "_ADR"))
150 return 0;
151 if (acpi_has_method(handle, name: "_EJ0"))
152 return 1;
153 status = acpi_evaluate_integer(handle, pathname: "_RMV", NULL, data: &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 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, start_object: handle, max_depth: 1,
206 descending_callback: check_hotplug, NULL, context: (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