dmaengine: axi-dmac: check cache coherency register

Marking the DMA as cache coherent (dma-coherent in devicetree) is only
safe with versions of axi_dmac that have this feature enabled.

Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Vinod Koul <vkoul@kernel.org>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Mathias Tausen <mta@satlab.com>
Link: https://lore.kernel.org/r/20220726140213.786939-1-mta@satlab.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c
index 5161b73..f30dabc 100644 (file)
--- a/drivers/dma/dma-axi-dmac.c
+++ b/drivers/dma/dma-axi-dmac.c
@@ -18,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_dma.h>
+#include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
@@ -55,6 +56,9 @@
 #define   AXI_DMAC_DMA_DST_TYPE_GET(x) FIELD_GET(AXI_DMAC_DMA_DST_TYPE_MSK, x)
 #define   AXI_DMAC_DMA_DST_WIDTH_MSK   GENMASK(3, 0)
 #define   AXI_DMAC_DMA_DST_WIDTH_GET(x)        FIELD_GET(AXI_DMAC_DMA_DST_WIDTH_MSK, x)
+#define AXI_DMAC_REG_COHERENCY_DESC    0x14
+#define   AXI_DMAC_DST_COHERENT_MSK    BIT(0)
+#define   AXI_DMAC_DST_COHERENT_GET(x) FIELD_GET(AXI_DMAC_DST_COHERENT_MSK, x)
 
 #define AXI_DMAC_REG_IRQ_MASK          0x80
 #define AXI_DMAC_REG_IRQ_PENDING       0x84
@@ -979,6 +983,18 @@ static int axi_dmac_probe(struct platform_device *pdev)
 
        axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, 0x00);
 
+       if (of_dma_is_coherent(pdev->dev.of_node)) {
+               ret = axi_dmac_read(dmac, AXI_DMAC_REG_COHERENCY_DESC);
+
+               if (version < ADI_AXI_PCORE_VER(4, 4, 'a') ||
+                   !AXI_DMAC_DST_COHERENT_GET(ret)) {
+                       dev_err(dmac->dma_dev.dev,
+                               "Coherent DMA not supported in hardware");
+                       ret = -EINVAL;
+                       goto err_clk_disable;
+               }
+       }
+
        ret = dma_async_device_register(dma_dev);
        if (ret)
                goto err_clk_disable;