1 files changed, 102 insertions, 9 deletions

diff --git a/arch/arm/mach-ep93xx/include/mach/dma.h b/arch/arm/mach-ep93xx/include/mach/dma.h
index 3a5961d3f3b1..5e31b2b25da9 100644
--- a/arch/arm/mach-ep93xx/include/mach/dma.h
+++ b/arch/arm/mach-ep93xx/include/mach/dma.h
@@ -1,5 +1,13 @@
-/*
- * arch/arm/mach-ep93xx/include/mach/dma.h
+/**
+ * DOC: EP93xx DMA M2P memory to peripheral and peripheral to memory engine
+ *
+ * The EP93xx DMA M2P subsystem handles DMA transfers between memory and
+ * peripherals. DMA M2P channels are available for audio, UARTs and IrDA.
+ * See chapter 10 of the EP93xx users guide for full details on the DMA M2P
+ * engine.
+ *
+ * See sound/soc/ep93xx/ep93xx-pcm.c for an example use of the DMA M2P code.
+ *
  */
 
 #ifndef __ASM_ARCH_DMA_H
@@ -8,12 +16,34 @@
 #include <linux/list.h>
 #include <linux/types.h>
 
+/**
+ * struct ep93xx_dma_buffer - Information about a buffer to be transferred
+ * using the DMA M2P engine
+ *
+ * @list: Entry in DMA buffer list
+ * @bus_addr: Physical address of the buffer
+ * @size: Size of the buffer in bytes
+ */
 struct ep93xx_dma_buffer {
         struct list_head        list;
         u32                     bus_addr;
         u16                     size;
 };
 
+/**
+ * struct ep93xx_dma_m2p_client - Information about a DMA M2P client
+ *
+ * @name: Unique name for this client
+ * @flags: Client flags
+ * @cookie: User data to pass to callback functions
+ * @buffer_started: Non NULL function to call when a transfer is started.
+ *                      The arguments are the user data cookie and the DMA
+ *                      buffer which is starting.
+ * @buffer_finished: Non NULL function to call when a transfer is completed.
+ *                      The arguments are the user data cookie, the DMA buffer
+ *                      which has completed, and a boolean flag indicating if
+ *                      the transfer had an error.
+ */
 struct ep93xx_dma_m2p_client {
         char                    *name;
         u8                      flags;
@@ -24,10 +54,11 @@ struct ep93xx_dma_m2p_client {
                                         struct ep93xx_dma_buffer *buf,
                                         int bytes, int error);
 
-        /* Internal to the DMA code.  */
+        /* private: Internal use only */
         void                    *channel;
 };
 
+/* DMA M2P ports */
 #define EP93XX_DMA_M2P_PORT_I2S1        0x00
 #define EP93XX_DMA_M2P_PORT_I2S2        0x01
 #define EP93XX_DMA_M2P_PORT_AAC1        0x02
@@ -39,18 +70,80 @@ struct ep93xx_dma_m2p_client {
 #define EP93XX_DMA_M2P_PORT_UART3       0x08
 #define EP93XX_DMA_M2P_PORT_IRDA        0x09
 #define EP93XX_DMA_M2P_PORT_MASK        0x0f
-#define EP93XX_DMA_M2P_TX               0x00
-#define EP93XX_DMA_M2P_RX               0x10
-#define EP93XX_DMA_M2P_ABORT_ON_ERROR   0x20
-#define EP93XX_DMA_M2P_IGNORE_ERROR     0x40
-#define EP93XX_DMA_M2P_ERROR_MASK       0x60
 
-int  ep93xx_dma_m2p_client_register(struct ep93xx_dma_m2p_client *m2p);
+/* DMA M2P client flags */
+#define EP93XX_DMA_M2P_TX               0x00    /* Memory to peripheral */
+#define EP93XX_DMA_M2P_RX               0x10    /* Peripheral to memory */
+
+/*
+ * DMA M2P client error handling flags. See the EP93xx users guide
+ * documentation on the DMA M2P CONTROL register for more details
+ */
+#define EP93XX_DMA_M2P_ABORT_ON_ERROR   0x20    /* Abort on peripheral error */
+#define EP93XX_DMA_M2P_IGNORE_ERROR     0x40    /* Ignore peripheral errors */
+#define EP93XX_DMA_M2P_ERROR_MASK       0x60    /* Mask of error bits */
+
+/**
+ * ep93xx_dma_m2p_client_register - Register a client with the DMA M2P
+ * subsystem
+ *
+ * @m2p: Client information to register
+ * returns 0 on success
+ *
+ * The DMA M2P subsystem allocates a channel and an interrupt line for the DMA
+ * client
+ */
+int ep93xx_dma_m2p_client_register(struct ep93xx_dma_m2p_client *m2p);
+
+/**
+ * ep93xx_dma_m2p_client_unregister - Unregister a client from the DMA M2P
+ * subsystem
+ *
+ * @m2p: Client to unregister
+ *
+ * Any transfers currently in progress will be completed in hardware, but
+ * ignored in software.
+ */
 void ep93xx_dma_m2p_client_unregister(struct ep93xx_dma_m2p_client *m2p);
+
+/**
+ * ep93xx_dma_m2p_submit - Submit a DMA M2P transfer
+ *
+ * @m2p: DMA Client to submit the transfer on
+ * @buf: DMA Buffer to submit
+ *
+ * If the current or next transfer positions are free on the M2P client then
+ * the transfer is started immediately. If not, the transfer is added to the
+ * list of pending transfers. This function must not be called from the
+ * buffer_finished callback for an M2P channel.
+ *
+ */
 void ep93xx_dma_m2p_submit(struct ep93xx_dma_m2p_client *m2p,
                            struct ep93xx_dma_buffer *buf);
+
+/**
+ * ep93xx_dma_m2p_submit_recursive - Put a DMA transfer on the pending list
+ * for an M2P channel
+ *
+ * @m2p: DMA Client to submit the transfer on
+ * @buf: DMA Buffer to submit
+ *
+ * This function must only be called from the buffer_finished callback for an
+ * M2P channel. It is commonly used to add the next transfer in a chained list
+ * of DMA transfers.
+ */
 void ep93xx_dma_m2p_submit_recursive(struct ep93xx_dma_m2p_client *m2p,
                                      struct ep93xx_dma_buffer *buf);
+
+/**
+ * ep93xx_dma_m2p_flush - Flush all pending transfers on a DMA M2P client
+ *
+ * @m2p: DMA client to flush transfers on
+ *
+ * Any transfers currently in progress will be completed in hardware, but
+ * ignored in software.
+ *
+ */
 void ep93xx_dma_m2p_flush(struct ep93xx_dma_m2p_client *m2p);
 
 #endif /* __ASM_ARCH_DMA_H */