Add an extension to the character device interface that allows character

device drivers to use arbitrary VM objects to satisfy individual mmap()
requests.
- A new d_mmap_single(cdev, &foff, objsize, &object, prot) callback is
  added to cdevsw.  This function is called for each mmap() request.
  If it returns ENODEV, then the mmap() request will fall back to using
  the device's device pager object and d_mmap().  Otherwise, the method
  can return a VM object to satisfy this entire mmap() request via
  *object.  It can also modify the starting offset into this object via
  *foff.  This allows device drivers to use the file offset as a cookie
  to identify specific VM objects.
- vm_mmap_vnode() has been changed to call vm_mmap_cdev() directly when
  mapping V_CHR vnodes.  This avoids duplicating all the cdev mmap
  handling code and simplifies some of vm_mmap_vnode().
- D_VERSION has been bumped to D_VERSION_02.  Older device drivers
  using D_VERSION_01 are still supported.

MFC after:	1 month

1 files changed, 6 insertions, 2 deletions

diff --git a/sys/sys/conf.h b/sys/sys/conf.h
index 05c4bb5..457e127 100644
--- a/sys/sys/conf.h
+++ b/sys/sys/conf.h
@@ -103,6 +103,7 @@ struct thread;
 struct uio;
 struct knote;
 struct clonedevs;
+struct vm_object;
 struct vnode;
 
 /*
@@ -136,6 +137,8 @@ typedef int d_poll_t(struct cdev *dev, int events, struct thread *td);
 typedef int d_kqfilter_t(struct cdev *dev, struct knote *kn);
 typedef int d_mmap_t(struct cdev *dev, vm_offset_t offset, vm_paddr_t *paddr,
    		     int nprot);
+typedef int d_mmap_single_t(struct cdev *cdev, vm_ooffset_t *offset,
+    vm_size_t size, struct vm_object **object, int nprot);
 typedef void d_purge_t(struct cdev *dev);
 
 typedef int d_spare2_t(struct cdev *dev);
@@ -175,7 +178,8 @@ typedef int dumper_t(
  */
 #define D_VERSION_00	0x20011966
 #define D_VERSION_01	0x17032005	/* Add d_uid,gid,mode & kind */
-#define D_VERSION	D_VERSION_01
+#define D_VERSION_02	0x28042009	/* Add d_mmap_single */
+#define D_VERSION	D_VERSION_02
 
 /*
  * Flags used for internal housekeeping
@@ -201,7 +205,7 @@ struct cdevsw {
 	dumper_t		*d_dump;
 	d_kqfilter_t		*d_kqfilter;
 	d_purge_t		*d_purge;
-	d_spare2_t		*d_spare2;
+	d_mmap_single_t		*d_mmap_single;
 	uid_t			d_uid;
 	gid_t			d_gid;
 	mode_t			d_mode;