From b5d89905d0391de2f0e04b709ab60eee6cf76a6e Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Thu, 16 May 2019 11:31:34 +0300 Subject: [PATCH] dmaengine: axi-dmac: Sanity check memory mapped interface support The AXI-DMAC supports different types of interface for the data source and destination ports. Typically one of those ports is a memory-mapped interface while the other is some kind of streaming interface. The information about which kind of interface is used for each port is encoded in the devicetree. It is also possible in the driver to detect whether a port supports memory-mapped transfers or not. For streaming interfaces the address register is read-only and will always return 0. So in order to check if a port supports memory-mapped transfers write a non-zero value to the corresponding address register and check that the value read-back is still non zero. This allows to detect mismatches between the devicetree description and the actual hardware configuration. Unfortunately it is not possible to autodetect the interface types since there is no method to distinguish between the different streaming ports. So the best thing that can be done is to error out when a memory mapped port is described in the devicetree but none is detected in the hardware. Signed-off-by: Lars-Peter Clausen Signed-off-by: Alexandru Ardelean Signed-off-by: Vinod Koul --- drivers/dma/dma-axi-dmac.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c index 8e64b81c2d3c..0984ae6eb155 100644 --- a/drivers/dma/dma-axi-dmac.c +++ b/drivers/dma/dma-axi-dmac.c @@ -637,7 +637,7 @@ static int axi_dmac_parse_chan_dt(struct device_node *of_chan, return 0; } -static void axi_dmac_detect_caps(struct axi_dmac *dmac) +static int axi_dmac_detect_caps(struct axi_dmac *dmac) { struct axi_dmac_chan *chan = &dmac->chan; @@ -653,6 +653,24 @@ static void axi_dmac_detect_caps(struct axi_dmac *dmac) chan->max_length = axi_dmac_read(dmac, AXI_DMAC_REG_X_LENGTH); if (chan->max_length != UINT_MAX) chan->max_length++; + + axi_dmac_write(dmac, AXI_DMAC_REG_DEST_ADDRESS, 0xffffffff); + if (axi_dmac_read(dmac, AXI_DMAC_REG_DEST_ADDRESS) == 0 && + chan->dest_type == AXI_DMAC_BUS_TYPE_AXI_MM) { + dev_err(dmac->dma_dev.dev, + "Destination memory-mapped interface not supported."); + return -ENODEV; + } + + axi_dmac_write(dmac, AXI_DMAC_REG_SRC_ADDRESS, 0xffffffff); + if (axi_dmac_read(dmac, AXI_DMAC_REG_SRC_ADDRESS) == 0 && + chan->src_type == AXI_DMAC_BUS_TYPE_AXI_MM) { + dev_err(dmac->dma_dev.dev, + "Source memory-mapped interface not supported."); + return -ENODEV; + } + + return 0; } static int axi_dmac_probe(struct platform_device *pdev) @@ -728,7 +746,9 @@ static int axi_dmac_probe(struct platform_device *pdev) if (ret < 0) return ret; - axi_dmac_detect_caps(dmac); + ret = axi_dmac_detect_caps(dmac); + if (ret) + goto err_clk_disable; axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, 0x00);