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 --- drivers/dca/dca-sysfs.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 drivers/dca/dca-sysfs.c (limited to 'drivers/dca/dca-sysfs.c') 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 +#include +#include +#include +#include +#include +#include + +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); +} + -- cgit v1.2.2