dt-bindings: dma: Document STM32 DMA3 controller bindings

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) <[email protected]>
Signed-off-by: Amelie Delaunay <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

Author: ADESTM

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 <[email protected]>
+
+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>;
+    };
+...