[PATCH 4/4][Doc] Document pci_iomap()

[Rolf Eike Beer <eike-kernel@sf-tec.de>]

This useful interface is hardly mentioned anywhere in the in-tree
documentation.

Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de>

---
commit 2cb2450818804edcbcb1486a4df0db06e5d49969
tree 2c53fbd2e0be832767446a8684561200b437a695
parent 288a3f1fd00365669ed9ad725b15ff67004cee0a
author Rolf Eike Beer <eike-kernel@sf-tec.de> Mon, 14 Aug 2006 14:20:30 +0200
committer Rolf Eike Beer <eike-kernel@sf-tec.de> Mon, 14 Aug 2006 14:20:30 +0200

 Documentation/DocBook/deviceiobook.tmpl |    1 +
 include/asm-i386/io.h                   |    3 +++
 lib/iomap.c                             |   15 ++++++++++++++-
 3 files changed, 18 insertions(+), 1 deletions(-)

diff --git a/Documentation/DocBook/deviceiobook.tmpl b/Documentation/DocBook/deviceiobook.tmpl
index 90ed23d..4f85515 100644
--- a/Documentation/DocBook/deviceiobook.tmpl
+++ b/Documentation/DocBook/deviceiobook.tmpl
@@ -317,6 +317,7 @@ CPU B:  spin_unlock_irqrestore(&amp;dev_lock, flags)
   <chapter id="pubfunctions">
      <title>Public Functions Provided</title>
 !Einclude/asm-i386/io.h
+!Elib/iomap.c
   </chapter>
 
 </book>
diff --git a/include/asm-i386/io.h b/include/asm-i386/io.h
index b3724fe..e176483 100644
--- a/include/asm-i386/io.h
+++ b/include/asm-i386/io.h
@@ -112,6 +112,9 @@ extern void __iomem * __ioremap(unsigned long offset, unsigned long size, unsign
  * writew/writel functions and the other mmio helpers. The returned
  * address is not guaranteed to be usable directly as a virtual
  * address. 
+ *
+ * If the area you are trying to map is a PCI BAR you should have a
+ * look on pci_iomap().
  */
 
 static inline void __iomem * ioremap(unsigned long offset, unsigned long size)
diff --git a/lib/iomap.c b/lib/iomap.c
index 55689c5..8de891d 100644
--- a/lib/iomap.c
+++ b/lib/iomap.c
@@ -202,7 +202,20 @@ void ioport_unmap(void __iomem *addr)
 EXPORT_SYMBOL(ioport_map);
 EXPORT_SYMBOL(ioport_unmap);
 
-/* Create a virtual mapping cookie for a PCI BAR (memory or IO) */
+/**
+ * pci_iomap - create a virtual mapping cookie for a PCI BAR
+ * @dev: PCI device that owns the BAR
+ * @bar: BAR number
+ * @maxlen: length of the memory to map
+ *
+ * Using this function you will get a __iomem address to your device BAR.
+ * You can access it using ioread*() and iowrite*(). These functions hide 
+ * the details if this is a MMIO or PIO address space and will just do what 
+ * you expect from them in the correct way.
+ *
+ * @maxlen specifies the maximum length to map. If you want to get access to 
+ * the complete BAR without checking for their length first pass %0 here.
+ **/
 void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
 {
 	unsigned long start = pci_resource_start(dev, bar);