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authorAlan Cox <alan@linux.intel.com>2010-03-29 19:38:00 +0200
committerJesse Barnes <jbarnes@virtuousgeek.org>2010-05-11 12:01:10 -0700
commit8b6d043b7ee2d1b819dc833d677ea2aead71a0c0 (patch)
tree757e0be31fc4951d6e0688191a929542751d6e49 /kernel
parentd19f61f098ae9315b76a97962007f687683916d4 (diff)
resource: shared I/O region support
SuperIO devices share regions and use lock/unlock operations to chip select. We therefore need to be able to request a resource and wait for it to be freed by whichever other SuperIO device currently hogs it. Right now you have to poll which is horrible. Add a MUXED field to IO port resources. If the MUXED field is set on the resource and on the request (via request_muxed_region) then we block until the previous owner of the muxed resource releases their region. This allows us to implement proper resource sharing and locking for superio chips using code of the form enable_my_superio_dev() { request_muxed_region(0x44, 0x02, "superio:watchdog"); outb() ..sequence to enable chip } disable_my_superio_dev() { outb() .. sequence of disable chip release_region(0x44, 0x02); } Signed-off-by: Giel van Schijndel <me@mortis.eu> Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/resource.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index 9c358e263534..7b36976e5dea 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -15,6 +15,7 @@
#include <linux/spinlock.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
+#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/pfn.h>
@@ -681,6 +682,8 @@ resource_size_t resource_alignment(struct resource *res)
* release_region releases a matching busy region.
*/
+static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait);
+
/**
* __request_region - create a new busy resource region
* @parent: parent resource descriptor
@@ -693,6 +696,7 @@ struct resource * __request_region(struct resource *parent,
resource_size_t start, resource_size_t n,
const char *name, int flags)
{
+ DECLARE_WAITQUEUE(wait, current);
struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL);
if (!res)
@@ -717,7 +721,15 @@ struct resource * __request_region(struct resource *parent,
if (!(conflict->flags & IORESOURCE_BUSY))
continue;
}
-
+ if (conflict->flags & flags & IORESOURCE_MUXED) {
+ add_wait_queue(&muxed_resource_wait, &wait);
+ write_unlock(&resource_lock);
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule();
+ remove_wait_queue(&muxed_resource_wait, &wait);
+ write_lock(&resource_lock);
+ continue;
+ }
/* Uhhuh, that didn't work out.. */
kfree(res);
res = NULL;
@@ -791,6 +803,8 @@ void __release_region(struct resource *parent, resource_size_t start,
break;
*p = res->sibling;
write_unlock(&resource_lock);
+ if (res->flags & IORESOURCE_MUXED)
+ wake_up(&muxed_resource_wait);
kfree(res);
return;
}