Blackfin arch: Add DMA API to set curr descriptor address

This API is necessary for DMA descriptor array mode.
Signed-off-by: NSonic Zhang <sonic.zhang@analog.com>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>

arch/blackfin/kernel/bfin_dma_5xx.c

@@ -270,10 +270,23 @@ void set_dma_next_desc_addr(unsigned int channel, unsigned long addr)
 
 	dma_ch[channel].regs->next_desc_ptr = addr;
 	SSYNC();
-	pr_debug("set_dma_start_addr() : END\n");
+	pr_debug("set_dma_next_desc_addr() : END\n");
 }
 EXPORT_SYMBOL(set_dma_next_desc_addr);
 
+void set_dma_curr_desc_addr(unsigned int channel, unsigned long addr)
+{
+	pr_debug("set_dma_curr_desc_addr() : BEGIN \n");
+
+	BUG_ON(!(dma_ch[channel].chan_status != DMA_CHANNEL_FREE
+	       && channel < MAX_BLACKFIN_DMA_CHANNEL));
+
+	dma_ch[channel].regs->curr_desc_ptr = addr;
+	SSYNC();
+	pr_debug("set_dma_curr_desc_addr() : END\n");
+}
+EXPORT_SYMBOL(set_dma_curr_desc_addr);
+
 void set_dma_x_count(unsigned int channel, unsigned short x_count)
 {
 	BUG_ON(!(dma_ch[channel].chan_status != DMA_CHANNEL_FREE

include/asm-blackfin/dma.h

@@ -152,6 +152,7 @@ struct dma_channel {
 /* functions to set register mode */
 void set_dma_start_addr(unsigned int channel, unsigned long addr);
 void set_dma_next_desc_addr(unsigned int channel, unsigned long addr);
+void set_dma_curr_desc_addr(unsigned int channel, unsigned long addr);
 void set_dma_x_count(unsigned int channel, unsigned short x_count);
 void set_dma_x_modify(unsigned int channel, short x_modify);
 void set_dma_y_count(unsigned int channel, unsigned short y_count);