ARM: DaVinci: Clear an EDMA event

Adds edma_clear_event API support to EDMA.

There has been a change to the MMC interface on TI's DA830/OMAP-L137
architecture that requires setting the DMATRIG bit to trigger
the first read data transfer when doing a read operation using
the CPU, but it has the unintended consequence causing a DMA
event.  Because of this, the next DMA read from the MMC/SD will
fail with an Event Miss. This API will be used to clear the ER.
Signed-off-by: David Griego <dgriego@mvista.com>
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-davinci/dma.c

@@ -95,6 +95,8 @@
 #define EDMA_CCSTAT	0x0640
 
 #define EDMA_M		0x1000	/* global channel registers */
+#define EDMA_ECR	0x1008
+#define EDMA_ECRH	0x100C
 #define EDMA_SHADOW0	0x2000	/* 4 regions shadowing global channels */
 #define EDMA_PARM	0x4000	/* 128 param entries */
 
@@ -987,6 +989,22 @@ void edma_clean_channel(unsigned channel)
 }
 EXPORT_SYMBOL(edma_clean_channel);
 
+/*
+ * edma_clear_event - clear an outstanding event on the DMA channel
+ * Arguments:
+ *	channel - channel number
+ */
+void edma_clear_event(unsigned channel)
+{
+	if (channel >= num_channels)
+		return;
+	if (channel < 32)
+		edma_write(EDMA_ECR, 1 << channel);
+	else
+		edma_write(EDMA_ECRH, 1 << (channel - 32));
+}
+EXPORT_SYMBOL(edma_clear_event);
+
 /*-----------------------------------------------------------------------*/
 
 static int __init edma_probe(struct platform_device *pdev)

arch/arm/mach-davinci/include/mach/edma.h

@@ -205,6 +205,7 @@ void edma_read_slot(unsigned slot, struct edmacc_param *params);
 int edma_start(unsigned channel);
 void edma_stop(unsigned channel);
 void edma_clean_channel(unsigned channel);
+void edma_clear_event(unsigned channel);
 void edma_pause(unsigned channel);
 void edma_resume(unsigned channel);