1. Article purpose[edit | edit source]
The purpose of this article is to:
- briefly introduce the SDMMC peripheral and its main features,
- indicate the peripheral instances assignment at boot time and their assignment at runtime (including whether instances can be allocated to secure contexts),
- list the software frameworks and drivers managing the peripheral,
- explain how to configure the peripheral.
2. Peripheral overview[edit | edit source]
The SDMMC peripheral is used to interconnect STM32 MPU to SD memory cards, SDIO and MMC devices.
Refer to the STM32 MPU reference manuals for the complete list of features, and to the software frameworks and drivers, introduced below, to see which features are implemented.
3. Peripheral usage[edit | edit source]
This chapter is applicable in the scope of the OpenSTLinux BSP running on the Arm® Cortex®-A processor(s), and the STM32CubeMPU Package running on the Arm® Cortex®-M processor.
3.1. Boot time assignment[edit | edit source]
By default, in OpenSTLinux distribution, SDMMC1 is the instance used to boot on SD memory cards when SDMMC2 is the instance used to boot on MMC Flash devices.
3.1.1. On STM32MP1 series[edit | edit source]
SDMMC1/2 instances can be used to support memory boot on SD or MMC Flash devices.
The SDMMC3 (only present on STM32MP15x lines 
) is not used at boot time.
 Information
|
| The SDMMC instances are ordered by address in the device tree arch/arm/boot/dts/stm32mp151.dtsi file for STM32MP15x lines :
sdmmc3: sdmmc@48004000 {
...
sdmmc1: sdmmc@58005000 {
...
sdmmc2: sdmmc@58007000 {
By default, in OpenSTLinux distribution, sdmmc3 is disabled so the sdmmc1 (SD card on Evaluation boards and Discovery kits) and sdmmc2 (eMMC on Evaluation boards and Wifi on Discovery kits) are respectively aliased to mmc0 and mmc1. |
Click on 
to expand or collapse the legend...
Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:
- ☐ means that the peripheral can be assigned to the given boot time context.
- ☑ means that the peripheral is assigned by default to the given boot time context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
- ⬚ means that the peripheral can be assigned to the given boot time context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
- ✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32 MPU reference manuals.
| Domain | Peripheral | Boot time allocation | Comment
| |||
|---|---|---|---|---|---|---|
| Instance | Cortex-A7 secure (ROM code) |
Cortex-A7 secure (TF-A BL2) |
Cortex-A7 non-secure (U-Boot) | |||
| Mass storage | SDMMC | SDMMC1 | ☐ | ☐ | ☐ | |
| SDMMC2 | ☐ | ☐ | ☐ | |||
3.1.2. On STM32MP2 series[edit | edit source]
Click on to expand or collapse the legend...
- ☐ means that the peripheral can be assigned to the given boot time context.
- ☑ means that the peripheral is assigned by default to the given boot time context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
- ⬚ means that the peripheral can be assigned to the given boot time context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
- ✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32MP25 reference manuals.
| Domain | Peripheral | Boot time allocation | Comment
| |||
|---|---|---|---|---|---|---|
| Instance | Cortex-A35 secure (ROM code) |
Cortex-A35 secure (TF-A BL2) |
Cortex-A35 non-secure (U-Boot) | |||
| Mass storage | SDMMC | SDMMC1 | ☐ | ☐ | ☐ | |
| SDMMC2 | ☐ | ☐ | ☐ | |||
| SDMMC3 | ☐ | |||||
3.2. Runtime assignment[edit | edit source]
3.2.1. On STM32MP13x lines [edit | edit source]
Click on to expand or collapse the legend...
Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:
- ☐ means that the peripheral can be assigned to the given runtime context.
- ☑ means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
- ⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
- ✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.
Refer to How to assign an internal peripheral to an execution context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32MP13 reference manuals.
| Domain | Peripheral | Runtime allocation | Comment
| ||
|---|---|---|---|---|---|
| Instance | Cortex-A7 secure (OP-TEE) |
Cortex-A7 non-secure (Linux) | |||
| Mass storage | SDMMC | SDMMC1 | ⬚ | ☐ | Assignment (single choice) |
| SDMMC2 | ⬚ | ☐ | Assignment (single choice) | ||
3.2.2. On STM32MP15x lines [edit | edit source]
Click on to expand or collapse the legend...
Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:
- ☐ means that the peripheral can be assigned to the given runtime context.
- ☑ means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
- ⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
- ✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.
Refer to How to assign an internal peripheral to an execution context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possiblities might be described in STM32MP15 reference manuals.
| Domain | Peripheral | Runtime allocation | Comment
| |||
|---|---|---|---|---|---|---|
| Instance | Cortex-A7 secure (OP-TEE) |
Cortex-A7 non-secure (Linux) |
Cortex-M4 (STM32Cube) | |||
| Mass storage | SDMMC | SDMMC1 | ☐ | |||
| SDMMC2 | ☐ | |||||
| SDMMC3 | ☐ | ☐ | Assignment (single choice) | |||
3.2.3. On STM32MP25x lines [edit | edit source]
Click on to expand or collapse the legend...
Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:
- ☐ means that the peripheral can be assigned to the given runtime context.
- ☑ means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
- ⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
- ✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32MP25 reference manuals.
| Domain | Peripheral | Runtime allocation | Comment
| |||||
|---|---|---|---|---|---|---|---|---|
| Instance | Cortex-A35 secure (OP-TEE / TF-A BL31) |
Cortex-A35 non-secure (Linux) |
Cortex-M33 secure (TF-M) |
Cortex-M33 non-secure (STM32Cube) |
Cortex-M0+ (STM32Cube) | |||
| Mass storage | SDMMC | SDMMC1 | ⬚OP-TEE | ☐ | ⬚ | ☐ | ||
| SDMMC2 | ⬚OP-TEE | ☐ | ⬚ | ☐ | ||||
| SDMMC3 | ⬚OP-TEE | ☐ | ⬚ | ☐ | ||||
4. Software frameworks and drivers[edit | edit source]
Below are listed the software frameworks and drivers managing the SDMMC peripheral for the embedded software components listed in the above tables.
- Linux®: Linux MMC framework
- STM32Cube: SDMMC HAL driver and header file of SD HAL module
- TF-A BL2: MMC framework (drivers/mmc/mmc.c ) and driver (drivers/st/mmc/stm32_sdmmc2.c )
- U-Boot: MMC framework (drivers/mmc/mmc.c ) and driver (drivers/mmc/stm32_sdmmc2.c )
5. How to assign and configure the peripheral[edit | edit source]
The peripheral assignment can be done via the STM32CubeMX graphical tool (and manually completed if needed).
This tool also helps to configure the peripheral:
- partial device trees (pin control and clock tree) generation for the OpenSTLinux software components,
- HAL initialization code generation for the STM32CubeMPU Package.
The configuration is applied by the firmware running in the context in which the peripheral is assigned.
For Linux® kernel configuration, please refer to SDMMC device tree configuration.
Arm® is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere. 
Arm® is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.