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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/dma/st,stm32-dma.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: STMicroelectronics STM32 DMA Controller
description: |
The STM32 DMA is a general-purpose direct memory access controller capable of
supporting 8 independent DMA channels. Each channel can have up to 8 requests.
DMA clients connected to the STM32 DMA controller must use the format
described in the dma.txt file, using a four-cell specifier for each
channel: a phandle to the DMA controller plus the following four integer cells:
1. The channel id
2. The request line number
3. A 32bit mask specifying the DMA channel configuration which are device
dependent:
-bit 9: Peripheral Increment Address
0x0: no address increment between transfers
0x1: increment address between transfers
-bit 10: Memory Increment Address
0x0: no address increment between transfers
0x1: increment address between transfers
-bit 15: Peripheral Increment Offset Size
0x0: offset size is linked to the peripheral bus width
0x1: offset size is fixed to 4 (32-bit alignment)
-bit 16-17: Priority level
0x0: low
0x1: medium
0x2: high
0x3: very high
4. A 32bit bitfield value specifying DMA features which are device dependent:
-bit 0-1: DMA FIFO threshold selection
0x0: 1/4 full FIFO
0x1: 1/2 full FIFO
0x2: 3/4 full FIFO
0x3: full FIFO
-bit 2: DMA direct mode
0x0: FIFO mode with threshold selectable with bit 0-1
0x1: Direct mode: each DMA request immediately initiates a transfer
from/to the memory, FIFO is bypassed.
-bit 4: alternative DMA request/acknowledge protocol
0x0: Use standard DMA ACK management, where ACK signal is maintained
up to the removal of request and transfer completion
0x1: Use alternative DMA ACK management, where ACK de-assertion does
not wait for the de-assertion of the REQuest, ACK is only managed
by transfer completion. This must only be used on channels
managing transfers for STM32 USART/UART.
maintainers:
- Amelie Delaunay <amelie.delaunay@foss.st.com>
allOf:
- $ref: dma-controller.yaml#
properties:
"#dma-cells":
const: 4
compatible:
const: st,stm32-dma
reg:
maxItems: 1
clocks:
maxItems: 1
interrupts:
maxItems: 8
description: Should contain all of the per-channel DMA
interrupts in ascending order with respect to the
DMA channel index.
resets:
maxItems: 1
st,mem2mem:
$ref: /schemas/types.yaml#/definitions/flag
description: if defined, it indicates that the controller
supports memory-to-memory transfer
required:
- compatible
- reg
- clocks
- interrupts
unevaluatedProperties: false
examples:
- |
#include <dt-bindings/interrupt-controller/arm-gic.h>
#include <dt-bindings/clock/stm32mp1-clks.h>
#include <dt-bindings/reset/stm32mp1-resets.h>
dma-controller@40026400 {
compatible = "st,stm32-dma";
reg = <0x40026400 0x400>;
interrupts = <56>,
<57>,
<58>,
<59>,
<60>,
<68>,
<69>,
<70>;
clocks = <&clk_hclk>;
#dma-cells = <4>;
st,mem2mem;
resets = <&rcc 150>;
dma-requests = <8>;
};
...
|
