[PATCH 4.19 26/80] dmaengine: xilinx_dma: program hardware supported buffer length

[PATCH 4.19 26/80] dmaengine: xilinx_dma: program hardware supported buffer length

[Greg Kroah-Hartman]

From: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>

[ Upstream commit ae809690b46a71dc56cda5b3b8884c8c41a0df15 ]

AXI-DMA IP supports configurable (c_sg_length_width) buffer length
register width, hence read buffer length (xlnx,sg-length-width) DT
property and ensure that driver doesn't program buffer length
exceeding the supported limit. For VDMA and CDMA there is no change.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Andrea Merello <andrea.merello@gmail.com> [rebase, reword]
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Stable-dep-of: 596b53ccc36a ("dmaengine: xilinx_dma: call of_node_put() when breaking out of for_each_child_of_node()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/xilinx/xilinx_dma.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index e4ea94b93400..6687cee26843 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -164,7 +164,9 @@
 #define XILINX_DMA_REG_BTT		0x28
 
 /* AXI DMA Specific Masks/Bit fields */
-#define XILINX_DMA_MAX_TRANS_LEN	GENMASK(22, 0)
+#define XILINX_DMA_MAX_TRANS_LEN_MIN	8
+#define XILINX_DMA_MAX_TRANS_LEN_MAX	23
+#define XILINX_DMA_V2_MAX_TRANS_LEN_MAX	26
 #define XILINX_DMA_CR_COALESCE_MAX	GENMASK(23, 16)
 #define XILINX_DMA_CR_CYCLIC_BD_EN_MASK	BIT(4)
 #define XILINX_DMA_CR_COALESCE_SHIFT	16
@@ -2634,7 +2636,7 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 	struct xilinx_dma_device *xdev;
 	struct device_node *child, *np = pdev->dev.of_node;
 	struct resource *io;
-	u32 num_frames, addr_width;
+	u32 num_frames, addr_width, len_width;
 	int i, err;
 
 	/* Allocate and initialize the DMA engine structure */
@@ -2666,10 +2668,24 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 
 	/* Retrieve the DMA engine properties from the device tree */
 	xdev->has_sg = of_property_read_bool(node, "xlnx,include-sg");
-	xdev->max_buffer_len = XILINX_DMA_MAX_TRANS_LEN;
+	xdev->max_buffer_len = GENMASK(XILINX_DMA_MAX_TRANS_LEN_MAX - 1, 0);
 
-	if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA)
+	if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) {
 		xdev->mcdma = of_property_read_bool(node, "xlnx,mcdma");
+		if (!of_property_read_u32(node, "xlnx,sg-length-width",
+					  &len_width)) {
+			if (len_width < XILINX_DMA_MAX_TRANS_LEN_MIN ||
+			    len_width > XILINX_DMA_V2_MAX_TRANS_LEN_MAX) {
+				dev_warn(xdev->dev,
+					 "invalid xlnx,sg-length-width property value. Using default width\n");
+			} else {
+				if (len_width > XILINX_DMA_MAX_TRANS_LEN_MAX)
+					dev_warn(xdev->dev, "Please ensure that IP supports buffer length > 23 bits\n");
+				xdev->max_buffer_len =
+					GENMASK(len_width - 1, 0);
+			}
+		}
+	}
 
 	if (xdev->dma_config->dmatype == XDMA_TYPE_VDMA) {
 		err = of_property_read_u32(node, "xlnx,num-fstores",
-- 
2.39.0