linux-kernel - [PATCH] UIO: Let uio_pdrv_genirq support cached memory

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Date:   Wed, 04 May 2022 16:52:53 +0200
From:   Indan Zupancic <indan.zupancic@...-info.com>
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] UIO: Let uio_pdrv_genirq support cached memory

If 'cacheable' DT property exists, the memory mapping will be
done with UIO_MEM_IOVA instead of the default UIO_MEM_PHYS.
---
  Documentation/driver-api/uio-howto.rst | 3 ++-
  drivers/uio/uio_pdrv_genirq.c          | 8 ++++++--
  2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/Documentation/driver-api/uio-howto.rst 
b/Documentation/driver-api/uio-howto.rst
index 907ffa3b38f5..3cb48fc757d9 100644
--- a/Documentation/driver-api/uio-howto.rst
+++ b/Documentation/driver-api/uio-howto.rst
@@ -413,7 +413,8 @@ probed with the ``"of_id"`` module parameter set to 
the ``"compatible"``
  string of the node the driver is supposed to handle. By default, the
  node's name (without the unit address) is exposed as name for the
  UIO device in userspace. To set a custom name, a property named
-``"linux,uio-name"`` may be specified in the DT node.
+``"linux,uio-name"`` may be specified in the DT node. If a property
+named ``cacheable`` exists, the memory will be mapped cacheable.

  Using uio_dmem_genirq for platform devices
  ------------------------------------------
diff --git a/drivers/uio/uio_pdrv_genirq.c 
b/drivers/uio/uio_pdrv_genirq.c
index 63258b6accc4..269784ce0ba3 100644
--- a/drivers/uio/uio_pdrv_genirq.c
+++ b/drivers/uio/uio_pdrv_genirq.c
@@ -115,6 +115,7 @@ static int uio_pdrv_genirq_probe(struct 
platform_device *pdev)
  	struct uio_mem *uiomem;
  	int ret = -EINVAL;
  	int i;
+	int memtype = UIO_MEM_PHYS;

  	if (node) {
  		const char *name;
@@ -132,7 +133,10 @@ static int uio_pdrv_genirq_probe(struct 
platform_device *pdev)
  		else
  			uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
  						       "%pOFn", node);
-
+		if (of_get_property(node, "cacheable", NULL)) {
+			dev_info(&pdev->dev, "%s cacheable\n", uioinfo->name);
+			memtype = UIO_MEM_IOVA;
+		}
  		uioinfo->version = "devicetree";
  		/* Multiple IRQs are not supported */
  	}
@@ -204,7 +208,7 @@ static int uio_pdrv_genirq_probe(struct 
platform_device *pdev)
  			break;
  		}

-		uiomem->memtype = UIO_MEM_PHYS;
+		uiomem->memtype = memtype;
  		uiomem->addr = r->start & PAGE_MASK;
  		uiomem->offs = r->start & ~PAGE_MASK;
  		uiomem->size = (uiomem->offs + resource_size(r)
--