gpu: ipu-v3: Add ipu_idmac_get_current_buffer function

This function returns the currently active buffer (0 or 1)
of a double buffered IDMAC channel. It is to be used by the
CSI driver.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/ipu-v3/ipu-common.c

@@ -661,6 +661,15 @@ int ipu_module_disable(struct ipu_soc *ipu, u32 mask)
 }
 EXPORT_SYMBOL_GPL(ipu_module_disable);
 
+int ipu_idmac_get_current_buffer(struct ipuv3_channel *channel)
+{
+	struct ipu_soc *ipu = channel->ipu;
+	unsigned int chno = channel->num;
+
+	return (ipu_cm_read(ipu, IPU_CHA_CUR_BUF(chno)) & idma_mask(chno)) ? 1 : 0;
+}
+EXPORT_SYMBOL_GPL(ipu_idmac_get_current_buffer);
+
 void ipu_idmac_select_buffer(struct ipuv3_channel *channel, u32 buf_num)
 {
 	struct ipu_soc *ipu = channel->ipu;

include/video/imx-ipu-v3.h

@@ -103,6 +103,7 @@ int ipu_idmac_wait_busy(struct ipuv3_channel *channel, int ms);
 
 void ipu_idmac_set_double_buffer(struct ipuv3_channel *channel,
 		bool doublebuffer);
+int ipu_idmac_get_current_buffer(struct ipuv3_channel *channel);
 void ipu_idmac_select_buffer(struct ipuv3_channel *channel, u32 buf_num);
 
 /*