[PATCH 03/13] dma: Document address_space_map/address_space_unmap() prototypes

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Add documentation based on address_space_map / address_space_unmap.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/sysemu/dma.h | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/include/sysemu/dma.h b/include/sysemu/dma.h
index 80c5bc3e02d..19bc9ad1b69 100644
--- a/include/sysemu/dma.h
+++ b/include/sysemu/dma.h
@@ -1,7 +1,7 @@
 /*
  * DMA helper functions
  *
- * Copyright (c) 2009 Red Hat
+ * Copyright (c) 2009, 2020 Red Hat
  *
  * This work is licensed under the terms of the GNU General Public License
  * (GNU GPL), version 2 or later.
@@ -125,6 +125,20 @@ static inline int dma_memory_write(AddressSpace *as, dma_addr_t addr,
 
 int dma_memory_set(AddressSpace *as, dma_addr_t addr, uint8_t c, dma_addr_t len);
 
+/**
+ * address_space_map: Map a physical memory region into a DMA controller
+ *                    virtual address
+ *
+ * May map a subset of the requested range, given by and returned in @plen.
+ * May return %NULL and set *@plen to zero(0), if resources needed to perform
+ * the mapping are exhausted.
+ * Use only for reads OR writes - not for read-modify-write operations.
+ *
+ * @as: #AddressSpace to be accessed
+ * @addr: address within that address space
+ * @len: pointer to length of buffer; updated on return
+ * @dir: indicates the transfer direction
+ */
 static inline void *dma_memory_map(AddressSpace *as,
                                    dma_addr_t addr, dma_addr_t *len,
                                    DMADirection dir)
@@ -138,6 +152,20 @@ static inline void *dma_memory_map(AddressSpace *as,
     return p;
 }
 
+/**
+ * address_space_unmap: Unmaps a memory region previously mapped
+ *                      by dma_memory_map()
+ *
+ * Will also mark the memory as dirty if @dir == %DMA_DIRECTION_FROM_DEVICE.
+ * @access_len gives the amount of memory that was actually read or written
+ * by the caller.
+ *
+ * @as: #AddressSpace used
+ * @buffer: host pointer as returned by address_space_map()
+ * @len: buffer length as returned by address_space_map()
+ * @dir: indicates the transfer direction
+ * @access_len: amount of data actually transferred
+ */
 static inline void dma_memory_unmap(AddressSpace *as,
                                     void *buffer, dma_addr_t len,
                                     DMADirection dir, dma_addr_t access_len)
-- 
2.26.2