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(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 * @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(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;
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 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, 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