From: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx>
This patch adds dma bindings to support DMA/MDMA chaining transfer.
1 bit is to manage both DMA FIFO Threshold
1 bit is to manage DMA/MDMA Chaining features.
2 bits are used to specify SDRAM size to use for DMA/MDMA chaining.
The size in bytes of a certain order is given by the formula:
(2 ^ order) * PAGE_SIZE.
The order is given by those 2 bits.
For cyclic, whether chaining is chosen, any value above 1 can be set :
SRAM buffer size will rely on period size and not on this DT value.
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@xxxxxx>
---
Version history:
v3:
v2:
* rework content
v1:
* Initial
---
---
.../devicetree/bindings/dma/stm32-dma.txt | 27 +++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/dma/stm32-dma.txt b/Documentation/devicetree/bindings/dma/stm32-dma.txt
index c5f5190..2bac8c7 100644
--- a/Documentation/devicetree/bindings/dma/stm32-dma.txt
+++ b/Documentation/devicetree/bindings/dma/stm32-dma.txt
@@ -17,6 +17,12 @@ Optional properties:
- resets: Reference to a reset controller asserting the DMA controller
- st,mem2mem: boolean; if defined, it indicates that the controller supports
memory-to-memory transfer
+- dmas: A list of eight dma specifiers, one for each entry in dma-names.
+ Refer to stm32-mdma.txt for more details.
+- dma-names: should contain "ch0", "ch1", "ch2", "ch3", "ch4", "ch5", "ch6" and
+ "ch7" and represents each STM32 DMA channel connected to a STM32 MDMA one.
+- memory-region : phandle to a node describing memory to be used for
+ M2M intermediate transfer between DMA and MDMA.
Example:
@@ -36,6 +42,16 @@ Example:
st,mem2mem;
resets = <&rcc 150>;
dma-requests = <8>;
+ dmas = <&mdma1 8 0x10 0x1200000a 0x40026408 0x00000020 1>,
+ <&mdma1 9 0x10 0x1200000a 0x40026408 0x00000800 1>,
+ <&mdma1 10 0x10 0x1200000a 0x40026408 0x00200000 1>,
+ <&mdma1 11 0x10 0x1200000a 0x40026408 0x08000000 1>,
+ <&mdma1 12 0x10 0x1200000a 0x4002640C 0x00000020 1>,
+ <&mdma1 13 0x10 0x1200000a 0x4002640C 0x00000800 1>,
+ <&mdma1 14 0x10 0x1200000a 0x4002640C 0x00200000 1>,
+ <&mdma1 15 0x10 0x1200000a 0x4002640C 0x08000000 1>;
+ dma-names = "ch0", "ch1", "ch2", "ch3", "ch4", "ch5", "ch6", "ch7";
+ memory-region = <&sram_dmapool>;
};
* DMA client
@@ -68,7 +84,16 @@ channel: a phandle to the DMA controller plus the following four integer cells:
0x1: 1/2 full FIFO
0x2: 3/4 full FIFO
0x3: full FIFO
-
+ -bit 2: Intermediate M2M transfer from/to DDR to/from SRAM throughout MDMA
+ 0: MDMA not used to generate an intermediate M2M transfer
+ 1: MDMA used to generate an intermediate M2M transfer.
+ -bit 3-4: indicated SRAM Buffer size in (2^order)*PAGE_SIZE.
+ PAGE_SIZE is given by Linux at 4KiB: include/asm-generic/page.h.
+ Order is given by those 2 bits starting at 0.
+ Valid only whether Intermediate M2M transfer is set.
+ For cyclic, whether Intermediate M2M transfer is chosen, any value can
+ be set: SRAM buffer size will rely on period size and not on this DT
+ value.
Example:
--
2.7.4
