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-rw-r--r--kernel/dma/mapping.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index e323ca48f7..58db8fd704 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -793,6 +793,28 @@ int dma_set_coherent_mask(struct device *dev, u64 mask)
}
EXPORT_SYMBOL(dma_set_coherent_mask);
+/**
+ * dma_addressing_limited - return if the device is addressing limited
+ * @dev: device to check
+ *
+ * Return %true if the devices DMA mask is too small to address all memory in
+ * the system, else %false. Lack of addressing bits is the prime reason for
+ * bounce buffering, but might not be the only one.
+ */
+bool dma_addressing_limited(struct device *dev)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+
+ if (min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) <
+ dma_get_required_mask(dev))
+ return true;
+
+ if (unlikely(ops))
+ return false;
+ return !dma_direct_all_ram_mapped(dev);
+}
+EXPORT_SYMBOL_GPL(dma_addressing_limited);
+
size_t dma_max_mapping_size(struct device *dev)
{
const struct dma_map_ops *ops = get_dma_ops(dev);