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

STM32CubeMX 工具可用于配置STM32MPU设备并获取相应的platform configuration device tree 文件。
STM32CubeMX可能不支持以上DT bindings documentation 段中描述的所有属性。 如果是这样，该工具会在生成的设备树中插入用户部分。 然后可以编辑这些部分以添加某些属性，并将它们代代相传。 有关详细信息，请参阅STM32CubeMX 用户手册。

References

有关完整说明，请参阅以下链接：