1/* hvapi.c: Hypervisor API management.
2 *
3 * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
4 */
5#include <linux/kernel.h>
6#include <linux/module.h>
7#include <linux/init.h>
8#include <linux/slab.h>
9
10#include <asm/hypervisor.h>
11#include <asm/oplib.h>
12#include <asm/sstate.h>
13
14/* If the hypervisor indicates that the API setting
15 * calls are unsupported, by returning HV_EBADTRAP or
16 * HV_ENOTSUPPORTED, we assume that API groups with the
17 * PRE_API flag set are major 1 minor 0.
18 */
19struct api_info {
20	unsigned long group;
21	unsigned long major;
22	unsigned long minor;
23	unsigned int refcnt;
24	unsigned int flags;
25#define FLAG_PRE_API		0x00000001
26};
27
28static struct api_info api_table[] = {
29	{ .group = HV_GRP_SUN4V,	.flags = FLAG_PRE_API	},
30	{ .group = HV_GRP_CORE,		.flags = FLAG_PRE_API	},
31	{ .group = HV_GRP_INTR,					},
32	{ .group = HV_GRP_SOFT_STATE,				},
33	{ .group = HV_GRP_PCI,		.flags = FLAG_PRE_API	},
34	{ .group = HV_GRP_LDOM,					},
35	{ .group = HV_GRP_SVC_CHAN,	.flags = FLAG_PRE_API	},
36	{ .group = HV_GRP_NCS,		.flags = FLAG_PRE_API	},
37	{ .group = HV_GRP_NIAG_PERF,	.flags = FLAG_PRE_API	},
38	{ .group = HV_GRP_FIRE_PERF,				},
39	{ .group = HV_GRP_DIAG,		.flags = FLAG_PRE_API	},
40};
41
42static DEFINE_SPINLOCK(hvapi_lock);
43
44static struct api_info *__get_info(unsigned long group)
45{
46	int i;
47
48	for (i = 0; i < ARRAY_SIZE(api_table); i++) {
49		if (api_table[i].group == group)
50			return &api_table[i];
51	}
52	return NULL;
53}
54
55static void __get_ref(struct api_info *p)
56{
57	p->refcnt++;
58}
59
60static void __put_ref(struct api_info *p)
61{
62	if (--p->refcnt == 0) {
63		unsigned long ignore;
64
65		sun4v_set_version(p->group, 0, 0, &ignore);
66		p->major = p->minor = 0;
67	}
68}
69
70/* Register a hypervisor API specification.  It indicates the
71 * API group and desired major+minor.
72 *
73 * If an existing API registration exists '0' (success) will
74 * be returned if it is compatible with the one being registered.
75 * Otherwise a negative error code will be returned.
76 *
77 * Otherwise an attempt will be made to negotiate the requested
78 * API group/major/minor with the hypervisor, and errors returned
79 * if that does not succeed.
80 */
81int sun4v_hvapi_register(unsigned long group, unsigned long major,
82			 unsigned long *minor)
83{
84	struct api_info *p;
85	unsigned long flags;
86	int ret;
87
88	spin_lock_irqsave(&hvapi_lock, flags);
89	p = __get_info(group);
90	ret = -EINVAL;
91	if (p) {
92		if (p->refcnt) {
93			ret = -EINVAL;
94			if (p->major == major) {
95				*minor = p->minor;
96				ret = 0;
97			}
98		} else {
99			unsigned long actual_minor;
100			unsigned long hv_ret;
101
102			hv_ret = sun4v_set_version(group, major, *minor,
103						   &actual_minor);
104			ret = -EINVAL;
105			if (hv_ret == HV_EOK) {
106				*minor = actual_minor;
107				p->major = major;
108				p->minor = actual_minor;
109				ret = 0;
110			} else if (hv_ret == HV_EBADTRAP ||
111				   hv_ret == HV_ENOTSUPPORTED) {
112				if (p->flags & FLAG_PRE_API) {
113					if (major == 1) {
114						p->major = 1;
115						p->minor = 0;
116						*minor = 0;
117						ret = 0;
118					}
119				}
120			}
121		}
122
123		if (ret == 0)
124			__get_ref(p);
125	}
126	spin_unlock_irqrestore(&hvapi_lock, flags);
127
128	return ret;
129}
130EXPORT_SYMBOL(sun4v_hvapi_register);
131
132void sun4v_hvapi_unregister(unsigned long group)
133{
134	struct api_info *p;
135	unsigned long flags;
136
137	spin_lock_irqsave(&hvapi_lock, flags);
138	p = __get_info(group);
139	if (p)
140		__put_ref(p);
141	spin_unlock_irqrestore(&hvapi_lock, flags);
142}
143EXPORT_SYMBOL(sun4v_hvapi_unregister);
144
145int sun4v_hvapi_get(unsigned long group,
146		    unsigned long *major,
147		    unsigned long *minor)
148{
149	struct api_info *p;
150	unsigned long flags;
151	int ret;
152
153	spin_lock_irqsave(&hvapi_lock, flags);
154	ret = -EINVAL;
155	p = __get_info(group);
156	if (p && p->refcnt) {
157		*major = p->major;
158		*minor = p->minor;
159		ret = 0;
160	}
161	spin_unlock_irqrestore(&hvapi_lock, flags);
162
163	return ret;
164}
165EXPORT_SYMBOL(sun4v_hvapi_get);
166
167void __init sun4v_hvapi_init(void)
168{
169	unsigned long group, major, minor;
170
171	group = HV_GRP_SUN4V;
172	major = 1;
173	minor = 0;
174	if (sun4v_hvapi_register(group, major, &minor))
175		goto bad;
176
177	group = HV_GRP_CORE;
178	major = 1;
179	minor = 1;
180	if (sun4v_hvapi_register(group, major, &minor))
181		goto bad;
182
183	sun4v_sstate_init();
184
185	return;
186
187bad:
188	prom_printf("HVAPI: Cannot register API group "
189		    "%lx with major(%u) minor(%u)\n",
190		    group, major, minor);
191	prom_halt();
192}
193