FMC device tree configuration

Article purpose

本文介绍如何在将 FMC internal peripheral 分配给Linux^® 操作系统时对其进行配置。 在这种情况下，它由MTD framework控制。

使用device tree 机制执行配置，该机制提供STM32 FMC Linux驱动程序和MTD框架使用的FMC外设的硬件描述。

DT bindings documentation

FMC设备树绑定由以下组成：

• 通用MTD nand绑定 .

• FMC驱动程序绑定 .

DT configuration

该硬件描述是“STM32微处理器”设备树文件（扩展名为.dtsi）和“板子”设备树文件（扩展名为.dts）的组合。 有关设备树文件分割的说明，请参见Device tree。

STM32CubeMX可用于生成板卡设备树。 有关更多详细信息，请参考[[＃How_to_configure_the_DT_using_STM32CubeMX How to configure the DT using STM32CubeMX .

DT configuration (STM32 level)

FMC外设节点位于“ stm32mp157c.dtsi”中。文件。

   fmc: nand-controller@58002000 {                           Comments
       compatible = "st,stm32mp15-fmc2";
       reg = <0x58002000 0x1000>,                            --> First region contains the register location
             <0x80000000 0x1000>,                            --> Régions 2 to 4 respectively contain the data, command and address space for CS0
             <0x88010000 0x1000>,                            
             <0x88020000 0x1000>,                            
             <0x81000000 0x1000>,                            --> Régions 5 to 7 contain the same areas for CS1
             <0x89010000 0x1000>,                            
             <0x89020000 0x1000>;                            
       interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;        --> The interrupt number used
       dmas = <&mdma1 20 0x10 0x12000A02 0x0 0x0 0>,         --> DMA specifiers 
              <&mdma1 20 0x10 0x12000A08 0x0 0x0 0>,
              <&mdma1 21 0x10 0x12000A0A 0x0 0x0 0>;
       dma-names = "tx", "rx", "ecc";
       clocks = <&rcc FMC_K>;                  
       resets = <&rcc FMC_R>;                           
       status = "disabled";
   };

与STM32相关的设备树部分应保持原样，客户不应对其进行修改。

DT configuration (board level)

FMC外设可以连接到一个SLC NAND闪存（每个封装最多2个管芯）。

   &fmc {                                                    Comments     
       pinctrl-names = "default", "sleep";                   --> For pinctrl configuration, please refer to Pinctrl device tree configuration
       pinctrl-0 = <&fmc2_pins_a>;
       pinctrl-1 = <&fmc2_sleep_pins_a>;
       status = "okay";                                      --> Enable the node
       #address-cells = <1>;
       #size-cells = <0>;

       nand: nand@0 {
           reg = <0>;                                        --> Describe the CS line assigned to the NAND chip
           nand-on-flash-bbt;                                --> Store the bad block table on NAND Flash memory
           nand-ecc-strength = <8>;                          --> Number of bits to correct per ECC step
           nand-ecc-step-size = <512>;                       --> Number of data bytes that are covered by a single ECC step
           #address-cells = <1>;
           #size-cells = <1>;
       };
   };

支持的ECC强度和步长为：

• nand-ecc-strength = <1>, nand-ecc-step-size = <512> (HAMMING).
• nand-ecc-strength = <4>, nand-ecc-step-size = <512> (BCH4).
• nand-ecc-strength = <8>, nand-ecc-step-size = <512> (BCH8).

DT configuration examples

以下示例显示了在连接SLC 8位NAND闪存设备时（ECC要求：8位/ 512字节）如何配置FMC控制器.

   &fmc {                                              
       pinctrl-names = "default", "sleep";                  
       pinctrl-0 = <&fmc2_pins_a>;
       pinctrl-1 = <&fmc2_sleep_pins_a>;
       status = "okay";                                      
       #address-cells = <1>;
       #size-cells = <0>;

       nand: nand@0 {
           reg = <0>;                                       
           nand-on-flash-bbt;                                                   
           #address-cells = <1>;
           #size-cells = <1>;

           partition@0 {
               ...
           };
       };
   };

下例显示了连接SLC 8位NAND闪存设备时的FMC控制器配置（ECC要求：4位/ 512字节）.

   &fmc {                        
       pinctrl-names = "default", "sleep";            
       pinctrl-0 = <&fmc2_pins_a>;
       pinctrl-1 = <&fmc2_sleep_pins_a>;
       status = "okay";                                      
       #address-cells = <1>;
       #size-cells = <0>;

       nand: nand@0 {
           reg = <0>;                                       
           nand-on-flash-bbt;
           nand-ecc-strength = <4>;
           nand-ecc-step-size = <512>;                                                
           #address-cells = <1>;
           #size-cells = <1>;

           partition@0 {
               ...
           };
       };
   };

How to configure the DT using STM32CubeMX

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.

References

Please refer to the following links for full description:

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