1 // SPDX-License-Identifier: GPL-2.0+
3 * Common ACPI functions for hot plug platforms
5 * Copyright (C) 2006 Intel Corporation
9 * Send feedback to <kristen.c.accardi@intel.com>
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>
22 #define MY_NAME "acpi_pcihp"
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)
29 #define METHOD_NAME__SUN "_SUN"
30 #define METHOD_NAME_OSHP "OSHP"
32 static bool debug_acpi;
34 /* acpi_run_oshp - get control of hotplug from the firmware
36 * @handle - the handle of the hotplug controller.
38 static acpi_status acpi_run_oshp(acpi_handle handle)
41 struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
43 acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
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);
52 dbg("%s:%s OSHP not found\n",
53 __func__, (char *)string.pointer);
55 pr_debug("%s:%s OSHP passes\n", __func__,
56 (char *)string.pointer);
58 kfree(string.pointer);
63 * acpi_get_hp_hw_control_from_firmware
64 * @dev: the pci_dev of the bridge that has a hotplug controller
66 * Attempt to take hotplug control from firmware.
68 int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
70 const struct pci_host_bridge *host;
71 const struct acpi_pci_root *root;
73 acpi_handle chandle, handle;
74 struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
77 * Per PCI firmware specification, we should run the ACPI _OSC
78 * method to get control of hotplug hardware before using it. If
79 * an _OSC is missing, we look for an OSHP to do the same thing.
80 * To handle different BIOS behavior, we look for _OSC on a root
81 * bridge preferentially (according to PCI fw spec). Later for
82 * OSHP within the scope of the hotplug controller and its parents,
83 * up to the host bridge under which this controller exists.
85 if (shpchp_is_native(pdev))
88 /* If _OSC exists, we should not evaluate OSHP */
91 * If there's no ACPI host bridge (i.e., ACPI support is compiled
92 * into the kernel but the hardware platform doesn't support ACPI),
93 * there's nothing to do here.
95 host = pci_find_host_bridge(pdev->bus);
96 root = acpi_pci_find_root(ACPI_HANDLE(&host->dev));
100 if (root->osc_support_set)
103 handle = ACPI_HANDLE(&pdev->dev);
106 * This hotplug controller was not listed in the ACPI name
107 * space at all. Try to get ACPI handle of parent PCI bus.
109 struct pci_bus *pbus;
110 for (pbus = pdev->bus; pbus; pbus = pbus->parent) {
111 handle = acpi_pci_get_bridge_handle(pbus);
118 acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
119 pci_info(pdev, "Requesting control of SHPC hotplug via OSHP (%s)\n",
120 (char *)string.pointer);
121 status = acpi_run_oshp(handle);
122 if (ACPI_SUCCESS(status))
124 if (acpi_is_root_bridge(handle))
127 status = acpi_get_parent(chandle, &handle);
128 if (ACPI_FAILURE(status))
132 pci_info(pdev, "Cannot get control of SHPC hotplug\n");
133 kfree(string.pointer);
136 pci_info(pdev, "Gained control of SHPC hotplug (%s)\n",
137 (char *)string.pointer);
138 kfree(string.pointer);
141 EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
143 static int pcihp_is_ejectable(acpi_handle handle)
146 unsigned long long removable;
147 if (!acpi_has_method(handle, "_ADR"))
149 if (acpi_has_method(handle, "_EJ0"))
151 status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
152 if (ACPI_SUCCESS(status) && removable)
158 * acpi_pcihp_check_ejectable - check if handle is ejectable ACPI PCI slot
159 * @pbus: the PCI bus of the PCI slot corresponding to 'handle'
160 * @handle: ACPI handle to check
162 * Return 1 if handle is ejectable PCI slot, 0 otherwise.
164 int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle)
166 acpi_handle bridge_handle, parent_handle;
168 bridge_handle = acpi_pci_get_bridge_handle(pbus);
171 if ((ACPI_FAILURE(acpi_get_parent(handle, &parent_handle))))
173 if (bridge_handle != parent_handle)
175 return pcihp_is_ejectable(handle);
177 EXPORT_SYMBOL_GPL(acpi_pci_check_ejectable);
180 check_hotplug(acpi_handle handle, u32 lvl, void *context, void **rv)
182 int *found = (int *)context;
183 if (pcihp_is_ejectable(handle)) {
185 return AE_CTRL_TERMINATE;
191 * acpi_pci_detect_ejectable - check if the PCI bus has ejectable slots
192 * @handle - handle of the PCI bus to scan
194 * Returns 1 if the PCI bus has ACPI based ejectable slots, 0 otherwise.
196 int acpi_pci_detect_ejectable(acpi_handle handle)
203 acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
204 check_hotplug, NULL, (void *)&found, NULL);
207 EXPORT_SYMBOL_GPL(acpi_pci_detect_ejectable);
209 module_param(debug_acpi, bool, 0644);
210 MODULE_PARM_DESC(debug_acpi, "Debugging mode for ACPI enabled or not");