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authorShannon Nelson <shannon.nelson@intel.com>2007-10-16 12:27:41 +0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-16 20:43:09 +0400
commit7589670f37736bcc119ebfbd69aafea6d585d1d4 (patch)
tree471f90dda6bcbcd59cc857b4f0130922bba88fc4 /drivers/dca/dca-sysfs.c
parent3e037454bcfa4b187e8293d2121bd8c0f5a5c31c (diff)
downloadlinux-7589670f37736bcc119ebfbd69aafea6d585d1d4.tar.xz
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>
Diffstat (limited to 'drivers/dca/dca-sysfs.c')
-rw-r--r--drivers/dca/dca-sysfs.c88
1 files changed, 88 insertions, 0 deletions
diff --git a/drivers/dca/dca-sysfs.c b/drivers/dca/dca-sysfs.c
new file mode 100644
index 000000000000..24a263b6844c
--- /dev/null
+++ b/drivers/dca/dca-sysfs.c
@@ -0,0 +1,88 @@
+#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);
+}
+