[RFC][PATCH 1/2] dma: imx-sdma: Add device to device support

[Nicolin Chen <nicoleotsuka@gmail.com>]

This patch adds DEV_TO_DEV support for i.MX SDMA driver to support data
tranfer between two peripheral FIFOs. The per_2_per script requires two
peripheral addresses and two DMA requests. So this patch also adds them
into private structure.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
 drivers/dma/imx-sdma.c                | 40 ++++++++++++++++++++++++++++++-----
 include/linux/platform_data/dma-imx.h |  1 +
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 85561dc..5af1a69 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -258,8 +258,9 @@ struct sdma_channel {
 	struct sdma_buffer_descriptor	*bd;
 	dma_addr_t			bd_phys;
 	unsigned int			pc_from_device, pc_to_device;
+	unsigned int			device_to_device;
 	unsigned long			flags;
-	dma_addr_t			per_address;
+	dma_addr_t			per_address, per_address2;
 	unsigned long			event_mask[2];
 	unsigned long			watermark_level;
 	u32				shp_addr, per_addr;
@@ -696,6 +697,7 @@ static void sdma_get_pc(struct sdma_channel *sdmac,
 
 	sdmac->pc_from_device = 0;
 	sdmac->pc_to_device = 0;
+	sdmac->device_to_device = 0;
 
 	switch (peripheral_type) {
 	case IMX_DMATYPE_MEMORY:
@@ -770,6 +772,7 @@ static void sdma_get_pc(struct sdma_channel *sdmac,
 
 	sdmac->pc_from_device = per_2_emi;
 	sdmac->pc_to_device = emi_2_per;
+	sdmac->device_to_device = per_2_per;
 }
 
 static int sdma_load_context(struct sdma_channel *sdmac)
@@ -782,11 +785,12 @@ static int sdma_load_context(struct sdma_channel *sdmac)
 	int ret;
 	unsigned long flags;
 
-	if (sdmac->direction == DMA_DEV_TO_MEM) {
+	if (sdmac->direction == DMA_DEV_TO_MEM)
 		load_address = sdmac->pc_from_device;
-	} else {
+	else if (sdmac->direction == DMA_DEV_TO_DEV)
+		load_address = sdmac->device_to_device;
+	else
 		load_address = sdmac->pc_to_device;
-	}
 
 	if (load_address < 0)
 		return load_address;
@@ -850,6 +854,12 @@ static int sdma_config_channel(struct sdma_channel *sdmac)
 		sdma_event_enable(sdmac, sdmac->event_id0);
 	}
 
+	if (sdmac->event_id1) {
+		if (sdmac->event_id1 >= sdmac->sdma->drvdata->num_events)
+			return -EINVAL;
+		sdma_event_enable(sdmac, sdmac->event_id1);
+	}
+
 	switch (sdmac->peripheral_type) {
 	case IMX_DMATYPE_DSP:
 		sdma_config_ownership(sdmac, false, true, true);
@@ -880,7 +890,12 @@ static int sdma_config_channel(struct sdma_channel *sdmac)
 		/* Watermark Level */
 		sdmac->watermark_level |= sdmac->watermark_level;
 		/* Address */
-		sdmac->shp_addr = sdmac->per_address;
+		if (sdmac->direction == DMA_DEV_TO_DEV) {
+			sdmac->shp_addr = sdmac->per_address2;
+			sdmac->per_addr = sdmac->per_address;
+		} else {
+			sdmac->shp_addr = sdmac->per_address;
+		}
 	} else {
 		sdmac->watermark_level = 0; /* FIXME: M3_BASE_ADDRESS */
 	}
@@ -974,6 +989,7 @@ static int sdma_alloc_chan_resources(struct dma_chan *chan)
 
 	sdmac->peripheral_type = data->peripheral_type;
 	sdmac->event_id0 = data->dma_request;
+	sdmac->event_id1 = data->dma_request2;
 
 	clk_enable(sdmac->sdma->clk_ipg);
 	clk_enable(sdmac->sdma->clk_ahb);
@@ -1213,6 +1229,19 @@ static int sdma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
 			sdmac->watermark_level = dmaengine_cfg->src_maxburst *
 						dmaengine_cfg->src_addr_width;
 			sdmac->word_size = dmaengine_cfg->src_addr_width;
+		} else if (dmaengine_cfg->direction == DMA_DEV_TO_DEV) {
+			sdmac->per_address = dmaengine_cfg->src_addr;
+			sdmac->per_address2 = dmaengine_cfg->dst_addr;
+			/*
+			 * For per_2_per sciprt, register r7 requires two
+			 * watermark levels: the lower placed at bits [0-7]
+			 * and the higher one placed at bits [16-23].
+			 */
+			sdmac->watermark_level =
+				dmaengine_cfg->src_maxburst & 0xff;
+			sdmac->watermark_level |=
+				(dmaengine_cfg->dst_maxburst & 0xff) << 16;
+			sdmac->word_size = dmaengine_cfg->dst_addr_width;
 		} else {
 			sdmac->per_address = dmaengine_cfg->dst_addr;
 			sdmac->watermark_level = dmaengine_cfg->dst_maxburst *
@@ -1433,6 +1462,7 @@ static struct dma_chan *sdma_xlate(struct of_phandle_args *dma_spec,
 	data.dma_request = dma_spec->args[0];
 	data.peripheral_type = dma_spec->args[1];
 	data.priority = dma_spec->args[2];
+	data.dma_request2 = 0;
 
 	return dma_request_channel(mask, sdma_filter_fn, &data);
 }
diff --git a/include/linux/platform_data/dma-imx.h b/include/linux/platform_data/dma-imx.h
index 7aa0e89..6a1357d 100644
--- a/include/linux/platform_data/dma-imx.h
+++ b/include/linux/platform_data/dma-imx.h
@@ -51,6 +51,7 @@ enum imx_dma_prio {
 
 struct imx_dma_data {
 	int dma_request; /* DMA request line */
+	int dma_request2; /* secondary DMA request line */
 	enum sdma_peripheral_type peripheral_type;
 	int priority;
 };
-- 
1.8.4