From 7589670f37736bcc119ebfbd69aafea6d585d1d4 Mon Sep 17 00:00:00 2001 From: Shannon Nelson Date: Tue, 16 Oct 2007 01:27:41 -0700 Subject: 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 Acked-by: David S. Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/dca.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 include/linux/dca.h (limited to 'include/linux/dca.h') diff --git a/include/linux/dca.h b/include/linux/dca.h new file mode 100644 index 000000000000..83eaecc6f8ab --- /dev/null +++ b/include/linux/dca.h @@ -0,0 +1,47 @@ +#ifndef DCA_H +#define DCA_H +/* DCA Provider API */ + +/* DCA Notifier Interface */ +void dca_register_notify(struct notifier_block *nb); +void dca_unregister_notify(struct notifier_block *nb); + +#define DCA_PROVIDER_ADD 0x0001 +#define DCA_PROVIDER_REMOVE 0x0002 + +struct dca_provider { + struct dca_ops *ops; + struct class_device *cd; + int id; +}; + +struct dca_ops { + int (*add_requester) (struct dca_provider *, struct device *); + int (*remove_requester) (struct dca_provider *, struct device *); + u8 (*get_tag) (struct dca_provider *, int cpu); +}; + +struct dca_provider *alloc_dca_provider(struct dca_ops *ops, int priv_size); +void free_dca_provider(struct dca_provider *dca); +int register_dca_provider(struct dca_provider *dca, struct device *dev); +void unregister_dca_provider(struct dca_provider *dca); + +static inline void *dca_priv(struct dca_provider *dca) +{ + return (void *)dca + sizeof(struct dca_provider); +} + +/* Requester API */ +int dca_add_requester(struct device *dev); +int dca_remove_requester(struct device *dev); +u8 dca_get_tag(int cpu); + +/* internal stuff */ +int __init dca_sysfs_init(void); +void __exit dca_sysfs_exit(void); +int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev); +void dca_sysfs_remove_provider(struct dca_provider *dca); +int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot); +void dca_sysfs_remove_req(struct dca_provider *dca, int slot); + +#endif /* DCA_H */ -- cgit v1.2.3-59-g8ed1b