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authorChris Leech <cleech@redhat.com>2024-02-05 12:01:37 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2024-03-07 21:52:59 +0000
commit576882ef5e7fce030b65c92b508a0f84ea5a81c2 (patch)
tree5fa1cdf6c13a80a6b3ca2498721d77ff99e25f1b /drivers/uio
parent0e439ba38e615e505404b3935585f1898bafaea9 (diff)
uio: introduce UIO_MEM_DMA_COHERENT type
Add a UIO memtype specifically for sharing dma_alloc_coherent memory with userspace, backed by dma_mmap_coherent. This is mainly for the bnx2/bnx2x/bnx2i "cnic" interface, although there are a few other uio drivers which map dma_alloc_coherent memory and will be converted to use dma_mmap_coherent as well. Signed-off-by: Nilesh Javali <njavali@marvell.com> Signed-off-by: Chris Leech <cleech@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20240205200137.138302-1-cleech@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/uio')
-rw-r--r--drivers/uio/uio.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 2d572f6c8ec8..bb77de6fa067 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -24,6 +24,7 @@
#include <linux/kobject.h>
#include <linux/cdev.h>
#include <linux/uio_driver.h>
+#include <linux/dma-mapping.h>
#define UIO_MAX_DEVICES (1U << MINORBITS)
@@ -759,6 +760,49 @@ static int uio_mmap_physical(struct vm_area_struct *vma)
vma->vm_page_prot);
}
+static int uio_mmap_dma_coherent(struct vm_area_struct *vma)
+{
+ struct uio_device *idev = vma->vm_private_data;
+ struct uio_mem *mem;
+ void *addr;
+ int ret = 0;
+ int mi;
+
+ mi = uio_find_mem_index(vma);
+ if (mi < 0)
+ return -EINVAL;
+
+ mem = idev->info->mem + mi;
+
+ if (mem->addr & ~PAGE_MASK)
+ return -ENODEV;
+ if (mem->dma_addr & ~PAGE_MASK)
+ return -ENODEV;
+ if (!mem->dma_device)
+ return -ENODEV;
+ if (vma->vm_end - vma->vm_start > mem->size)
+ return -EINVAL;
+
+ dev_warn(mem->dma_device,
+ "use of UIO_MEM_DMA_COHERENT is highly discouraged");
+
+ /*
+ * UIO uses offset to index into the maps for a device.
+ * We need to clear vm_pgoff for dma_mmap_coherent.
+ */
+ vma->vm_pgoff = 0;
+
+ addr = (void *)mem->addr;
+ ret = dma_mmap_coherent(mem->dma_device,
+ vma,
+ addr,
+ mem->dma_addr,
+ vma->vm_end - vma->vm_start);
+ vma->vm_pgoff = mi;
+
+ return ret;
+}
+
static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
{
struct uio_listener *listener = filep->private_data;
@@ -806,6 +850,9 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
case UIO_MEM_VIRTUAL:
ret = uio_mmap_logical(vma);
break;
+ case UIO_MEM_DMA_COHERENT:
+ ret = uio_mmap_dma_coherent(vma);
+ break;
default:
ret = -EINVAL;
}