Merge branch 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6

[pandora-kernel.git] / include / linux / virtio_ring.h

diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index ac69e7b..abe481e 100644 (file)
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -15,9 +15,13 @@
 /* This marks a buffer as write-only (otherwise read-only). */
 #define VRING_DESC_F_WRITE     2
 
-/* This means don't notify other side when buffer added. */
+/* The Host uses this in used->flags to advise the Guest: don't kick me when
+ * you add a buffer.  It's unreliable, so it's simply an optimization.  Guest
+ * will still kick if it's out of buffers. */
 #define VRING_USED_F_NO_NOTIFY 1
-/* This means don't interrupt guest when buffer consumed. */
+/* The Guest uses this in avail->flags to advise the Host: don't interrupt me
+ * when you consume a buffer.  It's unreliable, so it's simply an
+ * optimization.  */
 #define VRING_AVAIL_F_NO_INTERRUPT     1
 
 /* Virtio ring descriptors: 16 bytes.  These can chain together via "next". */
@@ -67,7 +71,7 @@ struct vring {
 };
 
 /* The standard layout for the ring is a continuous chunk of memory which looks
- * like this.  The used fields will be aligned to a "num+1" boundary.
+ * like this.  We assume num is a power of 2.
  *
  * struct vring
  * {
@@ -79,8 +83,8 @@ struct vring {
  *     __u16 avail_idx;
  *     __u16 available[num];
  *
- *     // Padding so a correctly-chosen num value will cache-align used_idx.
- *     char pad[sizeof(struct vring_desc) - sizeof(avail_flags)];
+ *     // Padding to the next page boundary.
+ *     char pad[];
  *
  *     // A ring of used descriptor heads with free-running index.
  *     __u16 used_flags;
@@ -88,18 +92,21 @@ struct vring {
  *     struct vring_used_elem used[num];
  * };
  */
-static inline void vring_init(struct vring *vr, unsigned int num, void *p)
+static inline void vring_init(struct vring *vr, unsigned int num, void *p,
+                             unsigned long pagesize)
 {
        vr->num = num;
        vr->desc = p;
-       vr->avail = p + num*sizeof(struct vring);
-       vr->used = p + (num+1)*(sizeof(struct vring) + sizeof(__u16));
+       vr->avail = p + num*sizeof(struct vring_desc);
+       vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + pagesize-1)
+                           & ~(pagesize - 1));
 }
 
-static inline unsigned vring_size(unsigned int num)
+static inline unsigned vring_size(unsigned int num, unsigned long pagesize)
 {
-       return (num + 1) * (sizeof(struct vring_desc) + sizeof(__u16))
-               + sizeof(__u32) + num * sizeof(struct vring_used_elem);
+       return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
+                + pagesize - 1) & ~(pagesize - 1))
+               + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num;
 }
 
 #ifdef __KERNEL__
@@ -111,7 +118,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
                                      struct virtio_device *vdev,
                                      void *pages,
                                      void (*notify)(struct virtqueue *vq),
-                                     bool (*callback)(struct virtqueue *vq));
+                                     void (*callback)(struct virtqueue *vq));
 void vring_del_virtqueue(struct virtqueue *vq);
 
 irqreturn_t vring_interrupt(int irq, void *_vq);