Commit 576882ef authored by Chris Leech's avatar Chris Leech Committed by Greg Kroah-Hartman
Browse files

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: default avatarNilesh Javali <njavali@marvell.com>
Signed-off-by: default avatarChris Leech <cleech@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240205200137.138302-1-cleech@redhat.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0e439ba3

drivers/uio/uio.c

+47 −0
Original line number Diff line number Diff line
@@ -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;

	}

include/linux/uio_driver.h

+13 −0
Original line number Diff line number Diff line
@@ -28,19 +28,26 @@ struct uio_map; 
 *			logical, virtual, or physical & phys_addr_t

 *			should always be large enough to handle any of

 *			the address types)

 * @dma_addr:		DMA handle set by dma_alloc_coherent, used with

 *			UIO_MEM_DMA_COHERENT only (@addr should be the

 *			void * returned from the same dma_alloc_coherent call)

 * @offs:               offset of device memory within the page

 * @size:		size of IO (multiple of page size)

 * @memtype:		type of memory addr points to

 * @internal_addr:	ioremap-ped version of addr, for driver internal use

 * @dma_device:		device struct that was passed to dma_alloc_coherent,

 *			used with UIO_MEM_DMA_COHERENT only

 * @map:		for use by the UIO core only.

 */

struct uio_mem {

	const char		*name;

	phys_addr_t		addr;

	dma_addr_t		dma_addr;

	unsigned long		offs;

	resource_size_t		size;

	int			memtype;

	void __iomem		*internal_addr;

	struct device		*dma_device;

	struct uio_map		*map;

};
@@ -158,6 +165,12 @@ extern int __must_check 
#define UIO_MEM_LOGICAL	2

#define UIO_MEM_VIRTUAL 3

#define UIO_MEM_IOVA	4

/*

 * UIO_MEM_DMA_COHERENT exists for legacy drivers that had been getting by with

 * improperly mapping DMA coherent allocations through the other modes.

 * Do not use in new drivers.

 */

#define UIO_MEM_DMA_COHERENT	5



/* defines for uio_port->porttype */

#define UIO_PORT_NONE	0