tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
DCA: Add Direct Cache Access driver
Direct Cache Access (DCA) is a method for warming the CPU cache before data
is used, with the intent of lessening the impact of cache misses. This
patch adds a manager and interface for matching up client requests for DCA
services with devices that offer DCA services.
In order to use DCA, a module must do bus writes with the appropriate tag
bits set to trigger a cache read for a specific CPU. However, different
CPUs and chipsets can require different sets of tag bits, and the methods
for determining the correct bits may be simple hardcoding or may be a
hardware specific magic incantation. This interface is a way for DCA
clients to find the correct tag bits for the targeted CPU without needing
to know the specifics.
[Dave Miller] use DEFINE_SPINLOCK()
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
authored by
Shannon Nelson
and committed by
Linus Torvalds
7589670f
3e037454
+351
+2
drivers/Kconfig
+2
drivers/Kconfig
+1
drivers/Makefile
+1
drivers/Makefile
+11
drivers/dca/Kconfig
+11
drivers/dca/Kconfig
+200
drivers/dca/dca-core.c
+200
drivers/dca/dca-core.c
···
1
+
/*
2
+
* Copyright(c) 2007 Intel Corporation. All rights reserved.
3
+
*
4
+
* This program is free software; you can redistribute it and/or modify it
5
+
* under the terms of the GNU General Public License as published by the Free
6
+
* Software Foundation; either version 2 of the License, or (at your option)
7
+
* any later version.
8
+
*
9
+
* This program is distributed in the hope that it will be useful, but WITHOUT
10
+
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11
+
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12
+
* more details.
13
+
*
14
+
* You should have received a copy of the GNU General Public License along with
15
+
* this program; if not, write to the Free Software Foundation, Inc., 59
16
+
* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17
+
*
18
+
* The full GNU General Public License is included in this distribution in the
19
+
* file called COPYING.
20
+
*/
21
+
22
+
/*
23
+
* This driver supports an interface for DCA clients and providers to meet.
24
+
*/
25
+
26
+
#include <linux/kernel.h>
27
+
#include <linux/notifier.h>
28
+
#include <linux/device.h>
29
+
#include <linux/dca.h>
30
+
31
+
MODULE_LICENSE("GPL");
32
+
33
+
/* For now we're assuming a single, global, DCA provider for the system. */
34
+
35
+
static DEFINE_SPINLOCK(dca_lock);
36
+
37
+
static struct dca_provider *global_dca = NULL;
38
+
39
+
/**
40
+
* dca_add_requester - add a dca client to the list
41
+
* @dev - the device that wants dca service
42
+
*/
43
+
int dca_add_requester(struct device *dev)
44
+
{
45
+
int err, slot;
46
+
47
+
if (!global_dca)
48
+
return -ENODEV;
49
+
50
+
spin_lock(&dca_lock);
51
+
slot = global_dca->ops->add_requester(global_dca, dev);
52
+
spin_unlock(&dca_lock);
53
+
if (slot < 0)
54
+
return slot;
55
+
56
+
err = dca_sysfs_add_req(global_dca, dev, slot);
57
+
if (err) {
58
+
spin_lock(&dca_lock);
59
+
global_dca->ops->remove_requester(global_dca, dev);
60
+
spin_unlock(&dca_lock);
61
+
return err;
62
+
}
63
+
64
+
return 0;
65
+
}
66
+
EXPORT_SYMBOL_GPL(dca_add_requester);
67
+
68
+
/**
69
+
* dca_remove_requester - remove a dca client from the list
70
+
* @dev - the device that wants dca service
71
+
*/
72
+
int dca_remove_requester(struct device *dev)
73
+
{
74
+
int slot;
75
+
if (!global_dca)
76
+
return -ENODEV;
77
+
78
+
spin_lock(&dca_lock);
79
+
slot = global_dca->ops->remove_requester(global_dca, dev);
80
+
spin_unlock(&dca_lock);
81
+
if (slot < 0)
82
+
return slot;
83
+
84
+
dca_sysfs_remove_req(global_dca, slot);
85
+
return 0;
86
+
}
87
+
EXPORT_SYMBOL_GPL(dca_remove_requester);
88
+
89
+
/**
90
+
* dca_get_tag - return the dca tag for the given cpu
91
+
* @cpu - the cpuid as returned by get_cpu()
92
+
*/
93
+
u8 dca_get_tag(int cpu)
94
+
{
95
+
if (!global_dca)
96
+
return -ENODEV;
97
+
return global_dca->ops->get_tag(global_dca, cpu);
98
+
}
99
+
EXPORT_SYMBOL_GPL(dca_get_tag);
100
+
101
+
/**
102
+
* alloc_dca_provider - get data struct for describing a dca provider
103
+
* @ops - pointer to struct of dca operation function pointers
104
+
* @priv_size - size of extra mem to be added for provider's needs
105
+
*/
106
+
struct dca_provider *alloc_dca_provider(struct dca_ops *ops, int priv_size)
107
+
{
108
+
struct dca_provider *dca;
109
+
int alloc_size;
110
+
111
+
alloc_size = (sizeof(*dca) + priv_size);
112
+
dca = kzalloc(alloc_size, GFP_KERNEL);
113
+
if (!dca)
114
+
return NULL;
115
+
dca->ops = ops;
116
+
117
+
return dca;
118
+
}
119
+
EXPORT_SYMBOL_GPL(alloc_dca_provider);
120
+
121
+
/**
122
+
* free_dca_provider - release the dca provider data struct
123
+
* @ops - pointer to struct of dca operation function pointers
124
+
* @priv_size - size of extra mem to be added for provider's needs
125
+
*/
126
+
void free_dca_provider(struct dca_provider *dca)
127
+
{
128
+
kfree(dca);
129
+
}
130
+
EXPORT_SYMBOL_GPL(free_dca_provider);
131
+
132
+
static BLOCKING_NOTIFIER_HEAD(dca_provider_chain);
133
+
134
+
/**
135
+
* register_dca_provider - register a dca provider
136
+
* @dca - struct created by alloc_dca_provider()
137
+
* @dev - device providing dca services
138
+
*/
139
+
int register_dca_provider(struct dca_provider *dca, struct device *dev)
140
+
{
141
+
int err;
142
+
143
+
if (global_dca)
144
+
return -EEXIST;
145
+
err = dca_sysfs_add_provider(dca, dev);
146
+
if (err)
147
+
return err;
148
+
global_dca = dca;
149
+
blocking_notifier_call_chain(&dca_provider_chain,
150
+
DCA_PROVIDER_ADD, NULL);
151
+
return 0;
152
+
}
153
+
EXPORT_SYMBOL_GPL(register_dca_provider);
154
+
155
+
/**
156
+
* unregister_dca_provider - remove a dca provider
157
+
* @dca - struct created by alloc_dca_provider()
158
+
*/
159
+
void unregister_dca_provider(struct dca_provider *dca)
160
+
{
161
+
if (!global_dca)
162
+
return;
163
+
blocking_notifier_call_chain(&dca_provider_chain,
164
+
DCA_PROVIDER_REMOVE, NULL);
165
+
global_dca = NULL;
166
+
dca_sysfs_remove_provider(dca);
167
+
}
168
+
EXPORT_SYMBOL_GPL(unregister_dca_provider);
169
+
170
+
/**
171
+
* dca_register_notify - register a client's notifier callback
172
+
*/
173
+
void dca_register_notify(struct notifier_block *nb)
174
+
{
175
+
blocking_notifier_chain_register(&dca_provider_chain, nb);
176
+
}
177
+
EXPORT_SYMBOL_GPL(dca_register_notify);
178
+
179
+
/**
180
+
* dca_unregister_notify - remove a client's notifier callback
181
+
*/
182
+
void dca_unregister_notify(struct notifier_block *nb)
183
+
{
184
+
blocking_notifier_chain_unregister(&dca_provider_chain, nb);
185
+
}
186
+
EXPORT_SYMBOL_GPL(dca_unregister_notify);
187
+
188
+
static int __init dca_init(void)
189
+
{
190
+
return dca_sysfs_init();
191
+
}
192
+
193
+
static void __exit dca_exit(void)
194
+
{
195
+
dca_sysfs_exit();
196
+
}
197
+
198
+
module_init(dca_init);
199
+
module_exit(dca_exit);
200
+
+88
drivers/dca/dca-sysfs.c
+88
drivers/dca/dca-sysfs.c
···
1
+
#include <linux/kernel.h>
2
+
#include <linux/spinlock.h>
3
+
#include <linux/device.h>
4
+
#include <linux/idr.h>
5
+
#include <linux/kdev_t.h>
6
+
#include <linux/err.h>
7
+
#include <linux/dca.h>
8
+
9
+
static struct class *dca_class;
10
+
static struct idr dca_idr;
11
+
static spinlock_t dca_idr_lock;
12
+
13
+
int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot)
14
+
{
15
+
struct class_device *cd;
16
+
17
+
cd = class_device_create(dca_class, dca->cd, MKDEV(0, slot + 1),
18
+
dev, "requester%d", slot);
19
+
if (IS_ERR(cd))
20
+
return PTR_ERR(cd);
21
+
return 0;
22
+
}
23
+
24
+
void dca_sysfs_remove_req(struct dca_provider *dca, int slot)
25
+
{
26
+
class_device_destroy(dca_class, MKDEV(0, slot + 1));
27
+
}
28
+
29
+
int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev)
30
+
{
31
+
struct class_device *cd;
32
+
int err = 0;
33
+
34
+
idr_try_again:
35
+
if (!idr_pre_get(&dca_idr, GFP_KERNEL))
36
+
return -ENOMEM;
37
+
spin_lock(&dca_idr_lock);
38
+
err = idr_get_new(&dca_idr, dca, &dca->id);
39
+
spin_unlock(&dca_idr_lock);
40
+
switch (err) {
41
+
case 0:
42
+
break;
43
+
case -EAGAIN:
44
+
goto idr_try_again;
45
+
default:
46
+
return err;
47
+
}
48
+
49
+
cd = class_device_create(dca_class, NULL, MKDEV(0, 0),
50
+
dev, "dca%d", dca->id);
51
+
if (IS_ERR(cd)) {
52
+
spin_lock(&dca_idr_lock);
53
+
idr_remove(&dca_idr, dca->id);
54
+
spin_unlock(&dca_idr_lock);
55
+
return PTR_ERR(cd);
56
+
}
57
+
dca->cd = cd;
58
+
return 0;
59
+
}
60
+
61
+
void dca_sysfs_remove_provider(struct dca_provider *dca)
62
+
{
63
+
class_device_unregister(dca->cd);
64
+
dca->cd = NULL;
65
+
spin_lock(&dca_idr_lock);
66
+
idr_remove(&dca_idr, dca->id);
67
+
spin_unlock(&dca_idr_lock);
68
+
}
69
+
70
+
int __init dca_sysfs_init(void)
71
+
{
72
+
idr_init(&dca_idr);
73
+
spin_lock_init(&dca_idr_lock);
74
+
75
+
dca_class = class_create(THIS_MODULE, "dca");
76
+
if (IS_ERR(dca_class)) {
77
+
idr_destroy(&dca_idr);
78
+
return PTR_ERR(dca_class);
79
+
}
80
+
return 0;
81
+
}
82
+
83
+
void __exit dca_sysfs_exit(void)
84
+
{
85
+
class_destroy(dca_class);
86
+
idr_destroy(&dca_idr);
87
+
}
88
+
+47
include/linux/dca.h
+47
include/linux/dca.h
···
1
+
#ifndef DCA_H
2
+
#define DCA_H
3
+
/* DCA Provider API */
4
+
5
+
/* DCA Notifier Interface */
6
+
void dca_register_notify(struct notifier_block *nb);
7
+
void dca_unregister_notify(struct notifier_block *nb);
8
+
9
+
#define DCA_PROVIDER_ADD 0x0001
10
+
#define DCA_PROVIDER_REMOVE 0x0002
11
+
12
+
struct dca_provider {
13
+
struct dca_ops *ops;
14
+
struct class_device *cd;
15
+
int id;
16
+
};
17
+
18
+
struct dca_ops {
19
+
int (*add_requester) (struct dca_provider *, struct device *);
20
+
int (*remove_requester) (struct dca_provider *, struct device *);
21
+
u8 (*get_tag) (struct dca_provider *, int cpu);
22
+
};
23
+
24
+
struct dca_provider *alloc_dca_provider(struct dca_ops *ops, int priv_size);
25
+
void free_dca_provider(struct dca_provider *dca);
26
+
int register_dca_provider(struct dca_provider *dca, struct device *dev);
27
+
void unregister_dca_provider(struct dca_provider *dca);
28
+
29
+
static inline void *dca_priv(struct dca_provider *dca)
30
+
{
31
+
return (void *)dca + sizeof(struct dca_provider);
32
+
}
33
+
34
+
/* Requester API */
35
+
int dca_add_requester(struct device *dev);
36
+
int dca_remove_requester(struct device *dev);
37
+
u8 dca_get_tag(int cpu);
38
+
39
+
/* internal stuff */
40
+
int __init dca_sysfs_init(void);
41
+
void __exit dca_sysfs_exit(void);
42
+
int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev);
43
+
void dca_sysfs_remove_provider(struct dca_provider *dca);
44
+
int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot);
45
+
void dca_sysfs_remove_req(struct dca_provider *dca, int slot);
46
+
47
+
#endif /* DCA_H */