[PATCH 2/2] dma: add dma_sync nop stubs for PBL

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

We can implement dma_sync functions as compiler barriers when we are
certain that the buffers are in coherent/uncached memory, e.g. because
MMU is only enabled in barebox_arm_entry which hasn't run yet.

This will come in handy when doing mailbox communication in PBL on the
Raspberry Pi.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
Please replace equally-named patch in next with this.
Should fix breakage for !MMU SoCFPGA
---
 include/dma.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/dma.h b/include/dma.h
index 2a271044f61c..2c4bdfc98fb5 100644
--- a/include/dma.h
+++ b/include/dma.h
@@ -56,6 +56,7 @@ static inline int dma_mapping_error(struct device_d *dev, dma_addr_t dma_addr)
 		(dev->dma_mask && dma_addr > dev->dma_mask);
 }
 
+#ifndef __PBL__
 /* streaming DMA - implement the below calls to support HAS_DMA */
 #ifndef dma_sync_single_for_cpu
 void dma_sync_single_for_cpu(dma_addr_t address, size_t size,
@@ -66,6 +67,27 @@ void dma_sync_single_for_cpu(dma_addr_t address, size_t size,
 void dma_sync_single_for_device(dma_addr_t address, size_t size,
 				enum dma_data_direction dir);
 #endif
+#else
+#ifndef dma_sync_single_for_cpu
+/*
+ * assumes buffers are in coherent/uncached memory, e.g. because
+ * MMU is only enabled in barebox_arm_entry which hasn't run yet.
+ */
+static inline void dma_sync_single_for_cpu(dma_addr_t address, size_t size,
+			     enum dma_data_direction dir)
+{
+	barrier_data((void *)address);
+}
+#endif
+
+#ifndef dma_sync_single_for_device
+static inline void dma_sync_single_for_device(dma_addr_t address, size_t size,
+				enum dma_data_direction dir)
+{
+	barrier_data((void *)address);
+}
+#endif
+#endif
 
 #ifndef dma_alloc_coherent
 void *dma_alloc_coherent(size_t size, dma_addr_t *dma_handle);
-- 
2.30.2


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