dt-bindings: dmaengine: dw-dmac: add protection control property

This patch for the DesignWare AHB Central
Direct Memory Access Controller adds the dma
protection control property:
	"snps,dma-protection-control"

as well as the properties specific values defines into
a new include file: include/dt-bindings/dma/dw-dmac.h

Note: The protection control signals are one-to-one
mapped to the AHB HPROT[1:3] signals for this controller.
The HPROT0 (Data Access) is always hardwired to 1.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/snps-dma.txt

@@ -27,6 +27,10 @@ Optional properties:
   general purpose DMA channel allocator. False if not passed.
 - multi-block: Multi block transfers supported by hardware. Array property with
   one cell per channel. 0: not supported, 1 (default): supported.
+- snps,dma-protection-control: AHB HPROT[3:1] protection setting.
+  The default value is 0 (for non-cacheable, non-buffered,
+  unprivileged data access).
+  Refer to include/dt-bindings/dma/dw-dmac.h for possible values.
 
 Example:
 

MAINTAINERS

@@ -14363,9 +14363,11 @@ SYNOPSYS DESIGNWARE DMAC DRIVER
 M:	Viresh Kumar <vireshk@kernel.org>
 R:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 S:	Maintained
+F:	Documentation/devicetree/bindings/dma/snps-dma.txt
+F:	drivers/dma/dw/
+F:	include/dt-bindings/dma/dw-dmac.h
 F:	include/linux/dma/dw.h
 F:	include/linux/platform_data/dma-dw.h
-F:	drivers/dma/dw/
 
 SYNOPSYS DESIGNWARE ENTERPRISE ETHERNET DRIVER
 M:	Jose Abreu <Jose.Abreu@synopsys.com>

include/dt-bindings/dma/dw-dmac.h

+/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
+
+#ifndef __DT_BINDINGS_DMA_DW_DMAC_H__
+#define __DT_BINDINGS_DMA_DW_DMAC_H__
+
+/*
+ * Protection Control bits provide protection against illegal transactions.
+ * The protection bits[0:2] are one-to-one mapped to AHB HPROT[3:1] signals.
+ */
+#define DW_DMAC_HPROT1_PRIVILEGED_MODE	(1 << 0)	/* Privileged Mode */
+#define DW_DMAC_HPROT2_BUFFERABLE	(1 << 1)	/* DMA is bufferable */
+#define DW_DMAC_HPROT3_CACHEABLE	(1 << 2)	/* DMA is cacheable */
+
+#endif /* __DT_BINDINGS_DMA_DW_DMAC_H__ */