From: M'boumba Cedric Madianga <[email protected]> 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 <[email protected]> --- 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
