[PATCH v4 04/12] dt-bindings: dma: Document STM32 DMA3 controller bindings
From: Amelie Delaunay
Date: Fri May 31 2024 - 11:09:01 EST
The STM32 DMA3 is a Direct Memory Access controller with different features
depending on its hardware configuration.
The channels have not the same capabilities, some have a larger FIFO, so
their performance is higher.
This patch describes STM32 DMA3 bindings, used to select a channel that
fits client requirements, and to pre-configure the channel depending on
the client needs.
Reviewed-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxxxxxxx>
---
v3:
- add Rob's Reviewed-by after fixing lines length at 80 and useless '|'
v2:
- DMA controller specific information description has been moved and
added as description of #dma-cells property
- description has been added to interrupts property specifying the
expected format for channel interrupts
- compatible has been updated to st,stm32mp25-dma3 (SoC specific)
---
.../bindings/dma/stm32/st,stm32-dma3.yaml | 135 ++++++++++++++++++
1 file changed, 135 insertions(+)
create mode 100644 Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml
diff --git a/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml
new file mode 100644
index 000000000000..7fdc44b2e646
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml
@@ -0,0 +1,135 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/stm32/st,stm32-dma3.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STMicroelectronics STM32 DMA3 Controller
+
+description: |
+ The STM32 DMA3 is a direct memory access controller with different features
+ depending on its hardware configuration.
+ It is either called LPDMA (Low Power), GPDMA (General Purpose) or HPDMA (High
+ Performance).
+ Its hardware configuration registers allow to dynamically expose its features.
+
+ GPDMA and HPDMA support 16 independent DMA channels, while only 4 for LPDMA.
+ GPDMA and HPDMA support 256 DMA requests from peripherals, 8 for LPDMA.
+
+ Bindings are generic for these 3 STM32 DMA3 configurations.
+
+ DMA clients connected to the STM32 DMA3 controller must use the format
+ described in "#dma-cells" property description below, using a three-cell
+ specifier for each channel.
+
+maintainers:
+ - Amelie Delaunay <amelie.delaunay@xxxxxxxxxxx>
+
+allOf:
+ - $ref: /schemas/dma/dma-controller.yaml#
+
+properties:
+ compatible:
+ const: st,stm32mp25-dma3
+
+ reg:
+ maxItems: 1
+
+ interrupts:
+ minItems: 4
+ maxItems: 16
+ description:
+ Should contain all of the per-channel DMA interrupts in ascending order
+ with respect to the DMA channel index.
+
+ clocks:
+ maxItems: 1
+
+ resets:
+ maxItems: 1
+
+ power-domains:
+ maxItems: 1
+
+ "#dma-cells":
+ const: 3
+ description: |
+ Specifies the number of cells needed to provide DMA controller specific
+ information.
+ The first cell is the request line number.
+ The second cell is a 32-bit mask specifying the DMA channel requirements:
+ -bit 0-1: The priority level
+ 0x0: low priority, low weight
+ 0x1: low priority, mid weight
+ 0x2: low priority, high weight
+ 0x3: high priority
+ -bit 4-7: The FIFO requirement for queuing source/destination transfers
+ 0x0: no FIFO requirement/any channel can fit
+ 0x2: FIFO of 8 bytes (2^2+1)
+ 0x4: FIFO of 32 bytes (2^4+1)
+ 0x6: FIFO of 128 bytes (2^6+1)
+ 0x7: FIFO of 256 bytes (2^7+1)
+ The third cell is a 32-bit mask specifying the DMA transfer requirements:
+ -bit 0: The source incrementing burst
+ 0x0: fixed burst
+ 0x1: contiguously incremented burst
+ -bit 1: The source allocated port
+ 0x0: port 0 is allocated to the source transfer
+ 0x1: port 1 is allocated to the source transfer
+ -bit 4: The destination incrementing burst
+ 0x0: fixed burst
+ 0x1: contiguously incremented burst
+ -bit 5: The destination allocated port
+ 0x0: port 0 is allocated to the destination transfer
+ 0x1: port 1 is allocated to the destination transfer
+ -bit 8: The type of hardware request
+ 0x0: burst
+ 0x1: block
+ -bit 9: The control mode
+ 0x0: DMA controller control mode
+ 0x1: peripheral control mode
+ -bit 12-13: The transfer complete event mode
+ 0x0: at block level, transfer complete event is generated at the end
+ of a block
+ 0x2: at LLI level, the transfer complete event is generated at the end
+ of the LLI transfer
+ including the update of the LLI if any
+ 0x3: at channel level, the transfer complete event is generated at the
+ end of the last LLI
+
+required:
+ - compatible
+ - reg
+ - interrupts
+ - clocks
+ - "#dma-cells"
+
+unevaluatedProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/interrupt-controller/arm-gic.h>
+ #include <dt-bindings/clock/st,stm32mp25-rcc.h>
+ dma-controller@40400000 {
+ compatible = "st,stm32mp25-dma3";
+ reg = <0x40400000 0x1000>;
+ interrupts = <GIC_SPI 33 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 35 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 36 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 38 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 39 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 41 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 42 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 43 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 46 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 47 IRQ_TYPE_LEVEL_HIGH>,
+ <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&rcc CK_BUS_HPDMA1>;
+ #dma-cells = <3>;
+ };
+...
--
2.25.1