forked from luck/tmp_suning_uos_patched
7589670f37
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>
89 lines
1.8 KiB
C
89 lines
1.8 KiB
C
#include <linux/kernel.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/device.h>
|
|
#include <linux/idr.h>
|
|
#include <linux/kdev_t.h>
|
|
#include <linux/err.h>
|
|
#include <linux/dca.h>
|
|
|
|
static struct class *dca_class;
|
|
static struct idr dca_idr;
|
|
static spinlock_t dca_idr_lock;
|
|
|
|
int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot)
|
|
{
|
|
struct class_device *cd;
|
|
|
|
cd = class_device_create(dca_class, dca->cd, MKDEV(0, slot + 1),
|
|
dev, "requester%d", slot);
|
|
if (IS_ERR(cd))
|
|
return PTR_ERR(cd);
|
|
return 0;
|
|
}
|
|
|
|
void dca_sysfs_remove_req(struct dca_provider *dca, int slot)
|
|
{
|
|
class_device_destroy(dca_class, MKDEV(0, slot + 1));
|
|
}
|
|
|
|
int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev)
|
|
{
|
|
struct class_device *cd;
|
|
int err = 0;
|
|
|
|
idr_try_again:
|
|
if (!idr_pre_get(&dca_idr, GFP_KERNEL))
|
|
return -ENOMEM;
|
|
spin_lock(&dca_idr_lock);
|
|
err = idr_get_new(&dca_idr, dca, &dca->id);
|
|
spin_unlock(&dca_idr_lock);
|
|
switch (err) {
|
|
case 0:
|
|
break;
|
|
case -EAGAIN:
|
|
goto idr_try_again;
|
|
default:
|
|
return err;
|
|
}
|
|
|
|
cd = class_device_create(dca_class, NULL, MKDEV(0, 0),
|
|
dev, "dca%d", dca->id);
|
|
if (IS_ERR(cd)) {
|
|
spin_lock(&dca_idr_lock);
|
|
idr_remove(&dca_idr, dca->id);
|
|
spin_unlock(&dca_idr_lock);
|
|
return PTR_ERR(cd);
|
|
}
|
|
dca->cd = cd;
|
|
return 0;
|
|
}
|
|
|
|
void dca_sysfs_remove_provider(struct dca_provider *dca)
|
|
{
|
|
class_device_unregister(dca->cd);
|
|
dca->cd = NULL;
|
|
spin_lock(&dca_idr_lock);
|
|
idr_remove(&dca_idr, dca->id);
|
|
spin_unlock(&dca_idr_lock);
|
|
}
|
|
|
|
int __init dca_sysfs_init(void)
|
|
{
|
|
idr_init(&dca_idr);
|
|
spin_lock_init(&dca_idr_lock);
|
|
|
|
dca_class = class_create(THIS_MODULE, "dca");
|
|
if (IS_ERR(dca_class)) {
|
|
idr_destroy(&dca_idr);
|
|
return PTR_ERR(dca_class);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void __exit dca_sysfs_exit(void)
|
|
{
|
|
class_destroy(dca_class);
|
|
idr_destroy(&dca_idr);
|
|
}
|
|
|