Template:ArticleBasedOnModel Template:ArticleMainWriter Template:ArticleApprovedVersion
1. Article purpose[edit source]
This article explains how to configure the FDCAN when it is assigned to the Linux® OS. In that case, it is controlled by the CAN framework for Bosch M_CAN controller.
The configuration is performed using the device tree mechanism that provides a hardware description of the FDCAN peripheral, used by the M_CAN Linux driver and by the NET/CAN framework.
2. DT bindings documentation[edit source]
M_CAN device tree bindings[1] describe all the required and optional properties.
3. DT configuration[edit source]
This hardware description is a combination of the STM32 microprocessor device tree files (.dtsi extension) and board device tree files (.dts extension). See the Device tree for an explanation of the device tree file split.
STM32CubeMX can be used to generate the board device tree. Refer to How to configure the DT using STM32CubeMX for more details.
3.1. DT configuration (STM32 level)[edit source]
All M_CAN nodes are described in stm32mp157c.dtsi [2] file with disabled status and required properties such as:
- Physical base address and size of the device register map
- Message RAM address and size (CAN SRAM)
- Host clock and CAN clock
- Message RAM configuration
This is a set of properties that may not vary for a given STM32 device.
m_can1: can@4400e000 {
compatible = "bosch,m_can";
reg = <0x4400e000 0x400>, <0x44011000 0x1400>; Template:Highlight
reg-names = "m_can", "message_ram";
interrupts = <GIC_SPI 19 IRQ_TYPE_LEVEL_HIGH>,
<GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
interrupt-names = "int0", "int1";
clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
clock-names = "hclk", "cclk";
bosch,mram-cfg = <0x0 0 0 32 0 0 2 2>;
status = "disabled";
};
m_can2: can@4400f000 {
compatible = "bosch,m_can";
reg = <0x4400f000 0x400>, <0x44011000 0x2800>; Template:Highlight
reg-names = "m_can", "message_ram";
interrupts = <GIC_SPI 20 IRQ_TYPE_LEVEL_HIGH>,
<GIC_SPI 22 IRQ_TYPE_LEVEL_HIGH>;
interrupt-names = "int0", "int1";
clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
clock-names = "hclk", "cclk";
bosch,mram-cfg = <0x1400 0 0 32 0 0 2 2>; Template:Highlight
status = "disabled";
};
The required and optional properties are fully described in the bindings files.
3.2. DT configuration (board level)[edit source]
Part of the device tree is used to describe the FDCAN hardware used on a given board. The DT node ("m_can") must be filled in:
- Enable the CAN block by setting status = "okay".
- Configure the pins in use via pinctrl, through pinctrl-0 (default pins), pinctrl-1 (sleep pins) and pinctrl-names.
3.3. DT configuration examples[edit source]
The example below shows how to configure and enable FDCAN1 instance at board level:
&m_can1 {
pinctrl-names = "default", "sleep"; Template:Highlight
pinctrl-0 = <&m_can1_pins_a>; Template:Highlight
pinctrl-1 = <&m_can1_sleep_pins_a>; Template:Highlight
status = "okay"; Template:Highlight
};
4. How to configure the DT using STM32CubeMX[edit source]
The STM32CubeMX tool can be used to configure the STM32MPU device and get the corresponding platform configuration device tree files.
The STM32CubeMX may not support all the properties described in the above DT bindings documentation paragraph. If so, the tool inserts user sections in the generated device tree. These sections can then be edited to add some properties and they are preserved from one generation to another. Refer to STM32CubeMX user manual for further information.
5. References[edit source]
Please refer to the following links for additional information:
- ↑ Template:CodeSource M_CAN device tree bindings
- ↑ Template:CodeSource, STM32MP157C device tree file