xref: /openbmc/linux/drivers/pci/hotplug/acpi_pcihp.c (revision 43395d9e)
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  */
acpi_run_oshp(acpi_handle handle)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  * @pdev: the pci_dev of the bridge that has a hotplug controller
65  *
66  * Attempt to take hotplug control from firmware.
67  */
acpi_get_hp_hw_control_from_firmware(struct pci_dev * pdev)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 
pcihp_is_ejectable(acpi_handle handle)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_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  */
acpi_pci_check_ejectable(struct pci_bus * pbus,acpi_handle handle)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
check_hotplug(acpi_handle handle,u32 lvl,void * context,void ** rv)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  */
acpi_pci_detect_ejectable(acpi_handle handle)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");
213