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