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author | Shannon Nelson <shannon.nelson@intel.com> | 2007-10-16 01:27:41 -0700 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 09:43:09 -0700 |
commit | 7589670f37736bcc119ebfbd69aafea6d585d1d4 (patch) | |
tree | 471f90dda6bcbcd59cc857b4f0130922bba88fc4 /drivers/dca/dca-sysfs.c | |
parent | 3e037454bcfa4b187e8293d2121bd8c0f5a5c31c (diff) | |
download | kernel_samsung_tuna-7589670f37736bcc119ebfbd69aafea6d585d1d4.zip kernel_samsung_tuna-7589670f37736bcc119ebfbd69aafea6d585d1d4.tar.gz kernel_samsung_tuna-7589670f37736bcc119ebfbd69aafea6d585d1d4.tar.bz2 |
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.c | 88 |
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 0000000..24a263b --- /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); +} + |