QUADSPI device tree configuration

1 Article purpose[edit]

This article explains how to configure the QUADSPI internal peripheral when it is assigned to the Linux® OS. In that case, it is controlled by the MTD framework.

The configuration is performed using the device tree mechanism that provides a hardware description of the QUADSPI peripheral, used by the STM32 QUADSPI Linux driver and by the MTD framework.

2 DT bindings documentation[edit]

The QUADSPI device tree bindings are composed by:

  • generic SPI-NOR / SPI-NAND Flash memory bindings [1].
  • QUADSPI driver bindings [2].

In next chapters, SPI-NAND bindings are only compatible with ecosystem release ≥ v1.1.0 More info.png.

3 DT configuration[edit]

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]

The QUADSPI peripheral node is located in stm32mp157c.dtsi[3] file.

   qspi: spi@58003000 {                                      Comments
       compatible = "st,stm32f469-qspi";
       reg = <0x58003000 0x1000>,                            --> Register location
             <0x70000000 0x10000000>;                        --> Memory mapping address
       reg-names = "qspi", "qspi_mm";
       interrupts = <GIC_SPI 92 IRQ_TYPE_LEVEL_HIGH>;        --> The interrupt number used
       dmas = <&mdma1 22 0x10 0x100002 0x0 0x0 0x0>,         --> DMA specifiers [4]
              <&mdma1 22 0x10 0x100008 0x0 0x0 0x0>;
       dma-names = "tx", "rx";
       clocks = <&rcc QSPI_K>;
       resets = <&rcc QSPI_R>;   
       status = "disabled";
   };

Warning.png This device tree part related to the STM32 should be kept as is, the customer should not modify it.

3.2 DT configuration (board level)[edit]

The QUADSPI peripheral may connect a maximum of 2 SPI-NOR Flash memories.

SPI-NOR Flash memory nodes [1] must be children of the QUADSPI peripheral node.

   &qspi {                                                   Comments
       pinctrl-names = "default", "sleep";                   --> For pinctrl configuration, please refer to Pinctrl device tree configuration
       pinctrl-0 = <&qspi_clk_pins_a &qspi_bk1_pins_a &qspi_bk2_pins_a>;
       pinctrl-1 = <&qspi_clk_sleep_pins_a &qspi_bk1_sleep_pins_a &qspi_bk2_sleep_pins_a>;
       reg = <0x58003000 0x1000>,
             <0x70000000 0x4000000>;                         --> Overwrite the memory map to the Flash device size, avoid the waste of virtual memory that will not be used
       #address-cells = <1>;
       #size-cells = <0>;
       status = "okay";                                      --> Enable the node
flash0: mx66l51235l@0 { compatible = "jdec,spi-nor"; reg = <0>; --> Chip select number spi-rx-bus-width = <4>; --> The bus width (number of data wires used) spi-max-frequency = <108000000>; --> Maximum SPI clocking speed of device in Hz #address-cells = <1>; #size-cells = <1>; }; };

3.3 DT configuration example[edit]

The below example shows how to configure the QUADSPI peripheral when 1 SPI-NAND Flash and 1 SPI-NOR Flash memories are connected.

   &qspi {                                                    
       pinctrl-names = "default", "sleep";                    
       pinctrl-0 = <&qspi_clk_pins_a &qspi_bk1_pins_a &qspi_bk2_pins_a>;
       pinctrl-1 = <&qspi_clk_sleep_pins_a &qspi_bk1_sleep_pins_a &qspi_bk2_sleep_pins_a>;
       reg = <0x58003000 0x1000>,
             <0x70000000 0x4000000>;                          
       #address-cells = <1>;
       #size-cells = <0>;
       status = "okay";
flash0: mx66l51235l@0 { compatible = "jdec,spi-nor"; reg = <0>; spi-rx-bus-width = <4>; spi-max-frequency = <108000000>; #address-cells = <1>; #size-cells = <1>; };
flash1: mt29f2g01abagd@1 { compatible = "spi-nand"; reg = <1>; spi-rx-bus-width = <4>; spi-tx-bus-width = <4>; spi-max-frequency = <133000000>; #address-cells = <1>; #size-cells = <1>; }; };

4 How to configure the DT using STM32CubeMX[edit]

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]

Please refer to the following links for full description:



Operating System

Memory Technology Device

Device Tree

Serial Peripheral Interface

Flash memories combine high density and cost effectiveness of EPROMs with the electrical erasability of EEPROMs.

Generic Interrupt Controller

Direct Memory Access

Attachments

Discussions