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dma-mapping: introduce DMA range map, supplanting dma_pfn_offset

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The new field 'dma_range_map' in struct device is used to facilitate the
use of single or multiple offsets between mapping regions of cpu addrs and
dma addrs.  It subsumes the role of "dev->dma_pfn_offset" which was only
capable of holding a single uniform offset and had no region bounds
checking.

The function of_dma_get_range() has been modified so that it takes a single
argument -- the device node -- and returns a map, NULL, or an error code.
The map is an array that holds the information regarding the DMA regions.
Each range entry contains the address offset, the cpu_start address, the
dma_start address, and the size of the region.

of_dma_configure() is the typical manner to set range offsets but there are
a number of ad hoc assignments to "dev->dma_pfn_offset" in the kernel
driver code.  These cases now invoke the function
dma_direct_set_offset(dev, cpu_addr, dma_addr, size).

Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
[hch: various interface cleanups]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
This commit is contained in:
Jim Quinlan 2020-09-17 18:43:40 +02:00 • committed by Christoph Hellwig
parent 6eb0233ec2
commit e0d072782c
22 changed files with 285 additions and 118 deletions
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4
include/linux/device.h
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@ -466,7 +466,7 @@ struct dev_links_info {
* such descriptors.
* @bus_dma_limit: Limit of an upstream bridge or bus which imposes a smaller
* DMA limit than the device itself supports.
* @dma_pfn_offset: offset of DMA memory range relatively of RAM
* @dma_range_map: map for DMA memory ranges relative to that of RAM
* @dma_parms: A low level driver may set these to teach IOMMU code about
* segment limitations.
* @dma_pools: Dma pools (if dma'ble device).
@ -561,7 +561,7 @@ struct device {
64 bit addresses for consistent
allocations such descriptors. */
u64 bus_dma_limit; /* upstream dma constraint */
unsigned long dma_pfn_offset;
const struct bus_dma_region *dma_range_map;
struct device_dma_parameters *dma_parms;