dma-direct: provide generic support for uncached kernel segments
A few architectures support uncached kernel segments. In that case we get
an uncached mapping for a given physica address by using an offset in the
uncached segement. Implement support for this scheme in the generic
dma-direct code instead of duplicating it in arch hooks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/arch/Kconfig b/arch/Kconfig
index c47b328..e8d19c3 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -260,6 +260,14 @@
config ARCH_HAS_SET_DIRECT_MAP
bool
+#
+# Select if arch has an uncached kernel segment and provides the
+# uncached_kernel_address / cached_kernel_address symbols to use it
+#
+config ARCH_HAS_UNCACHED_SEGMENT
+ select ARCH_HAS_DMA_PREP_COHERENT
+ bool
+
# Select if arch init_task must go in the __init_task_data section
config ARCH_TASK_STRUCT_ON_STACK
bool