[PATCH 1/8] driver core: add a min_align_mask field to struct device_dma_parameters

Christoph Hellwig
2021-02-04T19:30:53Z

From: Jianxiong Gao <jxgao@google.com>

Some devices rely on the address offset in a page to function
correctly (NVMe driver as an example). These devices may use
a different page size than the Linux kernel. The address offset
has to be preserved upon mapping, and in order to do so, we
need to record the page_offset_mask first.

Signed-off-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/device.h | 1 +
include/linux/dma-mapping.h | 16 ++++++++++++++++
2 files changed, 17 insertions(+)

diff --git a/include/linux/device.h b/include/linux/device.h
index 1779f90eeb4cb4..7960bf516dd7fe 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -291,6 +291,7 @@ struct device_dma_parameters {
* sg limitations.
*/
unsigned int max_segment_size;
+ unsigned int min_align_mask;
unsigned long segment_boundary_mask;
};

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 2e49996a8f391a..9c26225754e719 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -500,6 +500,22 @@ static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask)
return -EIO;
}

+static inline unsigned int dma_get_min_align_mask(struct device *dev)
+{
+ if (dev->dma_parms)
+ return dev->dma_parms->min_align_mask;
+ return 0;
+}
+
+static inline int dma_set_min_align_mask(struct device *dev,
+ unsigned int min_align_mask)
+{
+ if (WARN_ON_ONCE(!dev->dma_parms))
+ return -EIO;
+ dev->dma_parms->min_align_mask = min_align_mask;
+ return 0;
+}
+
static inline int dma_get_cache_alignment(void)
{
#ifdef ARCH_DMA_MINALIGN
--
2.29.2