1/*
2 * Copyright (C) 2012 Intel Corporation
3 *    Author: Liu Jinsong <jinsong.liu@intel.com>
4 *    Author: Jiang Yunhong <yunhong.jiang@intel.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or (at
9 * your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
14 * NON INFRINGEMENT.  See the GNU General Public License for more
15 * details.
16 */
17
18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/init.h>
23#include <linux/types.h>
24#include <linux/cpu.h>
25#include <linux/acpi.h>
26#include <linux/uaccess.h>
27#include <acpi/processor.h>
28#include <xen/acpi.h>
29#include <xen/interface/platform.h>
30#include <asm/xen/hypercall.h>
31
32#define PREFIX "ACPI:xen_cpu_hotplug:"
33
34#define INSTALL_NOTIFY_HANDLER		0
35#define UNINSTALL_NOTIFY_HANDLER	1
36
37static acpi_status xen_acpi_cpu_hotadd(struct acpi_processor *pr);
38
39/* --------------------------------------------------------------------------
40				Driver Interface
41-------------------------------------------------------------------------- */
42
43static int xen_acpi_processor_enable(struct acpi_device *device)
44{
45	acpi_status status = 0;
46	unsigned long long value;
47	union acpi_object object = { 0 };
48	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
49	struct acpi_processor *pr;
50
51	pr = acpi_driver_data(device);
52	if (!pr) {
53		pr_err(PREFIX "Cannot find driver data\n");
54		return -EINVAL;
55	}
56
57	if (!strcmp(acpi_device_hid(device), ACPI_PROCESSOR_OBJECT_HID)) {
58		/* Declared with "Processor" statement; match ProcessorID */
59		status = acpi_evaluate_object(pr->handle, NULL, NULL, &buffer);
60		if (ACPI_FAILURE(status)) {
61			pr_err(PREFIX "Evaluating processor object\n");
62			return -ENODEV;
63		}
64
65		pr->acpi_id = object.processor.proc_id;
66	} else {
67		/* Declared with "Device" statement; match _UID */
68		status = acpi_evaluate_integer(pr->handle, METHOD_NAME__UID,
69						NULL, &value);
70		if (ACPI_FAILURE(status)) {
71			pr_err(PREFIX "Evaluating processor _UID\n");
72			return -ENODEV;
73		}
74
75		pr->acpi_id = value;
76	}
77
78	pr->id = xen_pcpu_id(pr->acpi_id);
79
80	if ((int)pr->id < 0)
81		/* This cpu is not presented at hypervisor, try to hotadd it */
82		if (ACPI_FAILURE(xen_acpi_cpu_hotadd(pr))) {
83			pr_err(PREFIX "Hotadd CPU (acpi_id = %d) failed.\n",
84					pr->acpi_id);
85			return -ENODEV;
86		}
87
88	return 0;
89}
90
91static int xen_acpi_processor_add(struct acpi_device *device)
92{
93	int ret;
94	struct acpi_processor *pr;
95
96	if (!device)
97		return -EINVAL;
98
99	pr = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
100	if (!pr)
101		return -ENOMEM;
102
103	pr->handle = device->handle;
104	strcpy(acpi_device_name(device), ACPI_PROCESSOR_DEVICE_NAME);
105	strcpy(acpi_device_class(device), ACPI_PROCESSOR_CLASS);
106	device->driver_data = pr;
107
108	ret = xen_acpi_processor_enable(device);
109	if (ret)
110		pr_err(PREFIX "Error when enabling Xen processor\n");
111
112	return ret;
113}
114
115static int xen_acpi_processor_remove(struct acpi_device *device)
116{
117	struct acpi_processor *pr;
118
119	if (!device)
120		return -EINVAL;
121
122	pr = acpi_driver_data(device);
123	if (!pr)
124		return -EINVAL;
125
126	kfree(pr);
127	return 0;
128}
129
130/*--------------------------------------------------------------
131		Acpi processor hotplug support
132--------------------------------------------------------------*/
133
134static int is_processor_present(acpi_handle handle)
135{
136	acpi_status status;
137	unsigned long long sta = 0;
138
139
140	status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
141
142	if (ACPI_SUCCESS(status) && (sta & ACPI_STA_DEVICE_PRESENT))
143		return 1;
144
145	/*
146	 * _STA is mandatory for a processor that supports hot plug
147	 */
148	if (status == AE_NOT_FOUND)
149		pr_info(PREFIX "Processor does not support hot plug\n");
150	else
151		pr_info(PREFIX "Processor Device is not present");
152	return 0;
153}
154
155static int xen_apic_id(acpi_handle handle)
156{
157	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
158	union acpi_object *obj;
159	struct acpi_madt_local_apic *lapic;
160	int apic_id;
161
162	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_MAT", NULL, &buffer)))
163		return -EINVAL;
164
165	if (!buffer.length || !buffer.pointer)
166		return -EINVAL;
167
168	obj = buffer.pointer;
169	if (obj->type != ACPI_TYPE_BUFFER ||
170	    obj->buffer.length < sizeof(*lapic)) {
171		kfree(buffer.pointer);
172		return -EINVAL;
173	}
174
175	lapic = (struct acpi_madt_local_apic *)obj->buffer.pointer;
176
177	if (lapic->header.type != ACPI_MADT_TYPE_LOCAL_APIC ||
178	    !(lapic->lapic_flags & ACPI_MADT_ENABLED)) {
179		kfree(buffer.pointer);
180		return -EINVAL;
181	}
182
183	apic_id = (uint32_t)lapic->id;
184	kfree(buffer.pointer);
185	buffer.length = ACPI_ALLOCATE_BUFFER;
186	buffer.pointer = NULL;
187
188	return apic_id;
189}
190
191static int xen_hotadd_cpu(struct acpi_processor *pr)
192{
193	int cpu_id, apic_id, pxm;
194	struct xen_platform_op op;
195
196	apic_id = xen_apic_id(pr->handle);
197	if (apic_id < 0) {
198		pr_err(PREFIX "Failed to get apic_id for acpi_id %d\n",
199				pr->acpi_id);
200		return -ENODEV;
201	}
202
203	pxm = xen_acpi_get_pxm(pr->handle);
204	if (pxm < 0) {
205		pr_err(PREFIX "Failed to get _PXM for acpi_id %d\n",
206				pr->acpi_id);
207		return pxm;
208	}
209
210	op.cmd = XENPF_cpu_hotadd;
211	op.u.cpu_add.apic_id = apic_id;
212	op.u.cpu_add.acpi_id = pr->acpi_id;
213	op.u.cpu_add.pxm = pxm;
214
215	cpu_id = HYPERVISOR_dom0_op(&op);
216	if (cpu_id < 0)
217		pr_err(PREFIX "Failed to hotadd CPU for acpi_id %d\n",
218				pr->acpi_id);
219
220	return cpu_id;
221}
222
223static acpi_status xen_acpi_cpu_hotadd(struct acpi_processor *pr)
224{
225	if (!is_processor_present(pr->handle))
226		return AE_ERROR;
227
228	pr->id = xen_hotadd_cpu(pr);
229	if ((int)pr->id < 0)
230		return AE_ERROR;
231
232	/*
233	 * Sync with Xen hypervisor, providing new /sys/.../xen_cpuX
234	 * interface after cpu hotadded.
235	 */
236	xen_pcpu_hotplug_sync();
237
238	return AE_OK;
239}
240
241static int acpi_processor_device_remove(struct acpi_device *device)
242{
243	pr_debug(PREFIX "Xen does not support CPU hotremove\n");
244
245	return -ENOSYS;
246}
247
248static void acpi_processor_hotplug_notify(acpi_handle handle,
249					  u32 event, void *data)
250{
251	struct acpi_processor *pr;
252	struct acpi_device *device = NULL;
253	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
254	int result;
255
256	acpi_scan_lock_acquire();
257
258	switch (event) {
259	case ACPI_NOTIFY_BUS_CHECK:
260	case ACPI_NOTIFY_DEVICE_CHECK:
261		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
262			"Processor driver received %s event\n",
263			(event == ACPI_NOTIFY_BUS_CHECK) ?
264			"ACPI_NOTIFY_BUS_CHECK" : "ACPI_NOTIFY_DEVICE_CHECK"));
265
266		if (!is_processor_present(handle))
267			break;
268
269		acpi_bus_get_device(handle, &device);
270		if (acpi_device_enumerated(device))
271			break;
272
273		result = acpi_bus_scan(handle);
274		if (result) {
275			pr_err(PREFIX "Unable to add the device\n");
276			break;
277		}
278		device = NULL;
279		acpi_bus_get_device(handle, &device);
280		if (!acpi_device_enumerated(device)) {
281			pr_err(PREFIX "Missing device object\n");
282			break;
283		}
284		ost_code = ACPI_OST_SC_SUCCESS;
285		break;
286
287	case ACPI_NOTIFY_EJECT_REQUEST:
288		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
289				  "received ACPI_NOTIFY_EJECT_REQUEST\n"));
290
291		if (acpi_bus_get_device(handle, &device)) {
292			pr_err(PREFIX "Device don't exist, dropping EJECT\n");
293			break;
294		}
295		pr = acpi_driver_data(device);
296		if (!pr) {
297			pr_err(PREFIX "Driver data is NULL, dropping EJECT\n");
298			break;
299		}
300
301		/*
302		 * TBD: implement acpi_processor_device_remove if Xen support
303		 * CPU hotremove in the future.
304		 */
305		acpi_processor_device_remove(device);
306		break;
307
308	default:
309		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
310				  "Unsupported event [0x%x]\n", event));
311
312		/* non-hotplug event; possibly handled by other handler */
313		goto out;
314	}
315
316	(void) acpi_evaluate_ost(handle, event, ost_code, NULL);
317
318out:
319	acpi_scan_lock_release();
320}
321
322static acpi_status is_processor_device(acpi_handle handle)
323{
324	struct acpi_device_info *info;
325	char *hid;
326	acpi_status status;
327
328	status = acpi_get_object_info(handle, &info);
329	if (ACPI_FAILURE(status))
330		return status;
331
332	if (info->type == ACPI_TYPE_PROCESSOR) {
333		kfree(info);
334		return AE_OK;	/* found a processor object */
335	}
336
337	if (!(info->valid & ACPI_VALID_HID)) {
338		kfree(info);
339		return AE_ERROR;
340	}
341
342	hid = info->hardware_id.string;
343	if ((hid == NULL) || strcmp(hid, ACPI_PROCESSOR_DEVICE_HID)) {
344		kfree(info);
345		return AE_ERROR;
346	}
347
348	kfree(info);
349	return AE_OK;	/* found a processor device object */
350}
351
352static acpi_status
353processor_walk_namespace_cb(acpi_handle handle,
354			    u32 lvl, void *context, void **rv)
355{
356	acpi_status status;
357	int *action = context;
358
359	status = is_processor_device(handle);
360	if (ACPI_FAILURE(status))
361		return AE_OK;	/* not a processor; continue to walk */
362
363	switch (*action) {
364	case INSTALL_NOTIFY_HANDLER:
365		acpi_install_notify_handler(handle,
366					    ACPI_SYSTEM_NOTIFY,
367					    acpi_processor_hotplug_notify,
368					    NULL);
369		break;
370	case UNINSTALL_NOTIFY_HANDLER:
371		acpi_remove_notify_handler(handle,
372					   ACPI_SYSTEM_NOTIFY,
373					   acpi_processor_hotplug_notify);
374		break;
375	default:
376		break;
377	}
378
379	/* found a processor; skip walking underneath */
380	return AE_CTRL_DEPTH;
381}
382
383static
384void acpi_processor_install_hotplug_notify(void)
385{
386	int action = INSTALL_NOTIFY_HANDLER;
387	acpi_walk_namespace(ACPI_TYPE_ANY,
388			    ACPI_ROOT_OBJECT,
389			    ACPI_UINT32_MAX,
390			    processor_walk_namespace_cb, NULL, &action, NULL);
391}
392
393static
394void acpi_processor_uninstall_hotplug_notify(void)
395{
396	int action = UNINSTALL_NOTIFY_HANDLER;
397	acpi_walk_namespace(ACPI_TYPE_ANY,
398			    ACPI_ROOT_OBJECT,
399			    ACPI_UINT32_MAX,
400			    processor_walk_namespace_cb, NULL, &action, NULL);
401}
402
403static const struct acpi_device_id processor_device_ids[] = {
404	{ACPI_PROCESSOR_OBJECT_HID, 0},
405	{ACPI_PROCESSOR_DEVICE_HID, 0},
406	{"", 0},
407};
408MODULE_DEVICE_TABLE(acpi, processor_device_ids);
409
410static struct acpi_driver xen_acpi_processor_driver = {
411	.name = "processor",
412	.class = ACPI_PROCESSOR_CLASS,
413	.ids = processor_device_ids,
414	.ops = {
415		.add = xen_acpi_processor_add,
416		.remove = xen_acpi_processor_remove,
417		},
418};
419
420static int __init xen_acpi_processor_init(void)
421{
422	int result = 0;
423
424	if (!xen_initial_domain())
425		return -ENODEV;
426
427	/* unregister the stub which only used to reserve driver space */
428	xen_stub_processor_exit();
429
430	result = acpi_bus_register_driver(&xen_acpi_processor_driver);
431	if (result < 0) {
432		xen_stub_processor_init();
433		return result;
434	}
435
436	acpi_processor_install_hotplug_notify();
437	return 0;
438}
439
440static void __exit xen_acpi_processor_exit(void)
441{
442	if (!xen_initial_domain())
443		return;
444
445	acpi_processor_uninstall_hotplug_notify();
446
447	acpi_bus_unregister_driver(&xen_acpi_processor_driver);
448
449	/*
450	 * stub reserve space again to prevent any chance of native
451	 * driver loading.
452	 */
453	xen_stub_processor_init();
454	return;
455}
456
457module_init(xen_acpi_processor_init);
458module_exit(xen_acpi_processor_exit);
459ACPI_MODULE_NAME("xen-acpi-cpuhotplug");
460MODULE_AUTHOR("Liu Jinsong <jinsong.liu@intel.com>");
461MODULE_DESCRIPTION("Xen Hotplug CPU Driver");
462MODULE_LICENSE("GPL");
463