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==Article purpose==
The purpose of this article is to
* briefly introduce the SDMMC peripheral and its main features
* indicate the level of security supported by this hardware block
* explain how each instance can be allocated to the three runtime contexts and linked to the corresponding software components
* explain, when necessary, how to configure the SDMMC peripheral.

==Peripheral overview==
The '''SDMMC''' peripheral is used to interconnect STM32 MPU to SD memory cards, SDIO and MMC devices.

===Features===
Refer to the [[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]] for the complete list of features, and to the software components, introduced below, to see which features are implemented.

===Security support===
SDMMC1/2/3 instances are either '''non-secure''' or '''secure''' peripherals (under [[ETZPC_internal_peripheral|ETZPC]] control).

{{Warning|
* When an SDMMC instance is secure internal, the DMA cannot be used to perform data transfers. 
* STMicroelectronics does not provide secure MMC driver (see below chapter)}}

==Peripheral usage and associated software==
===Boot time===
SDMMC1/2 instances can be used to support memory boot on SD or MMC Flash devices.

The SDMMC3 is not used at boot time.
{{Info | The SDMMC instances are ordered by address in the [[Device tree|device tree]] {{CodeSource | Linux kernel | arch/arm/boot/dts/stm32mp151.dtsi}} file:
 sdmmc3: sdmmc@48004000 {
 ...
 sdmmc1: sdmmc@58005000 {
 ...
 sdmmc2: sdmmc@58007000 {
By default, in [[OpenSTLinux distribution]], '''sdmmc3 is disabled''' so the sdmmc1 (SD card on [[STM32MP157x-EV1_-_hardware_description|Evaluation boards]] and [[STM32MP157x-DKx_-_hardware_description|Discovery kits]]) and sdmmc2 (eMMC on [[STM32MP157x-EV1_-_hardware_description|Evaluation boards]] and Wifi on [[STM32MP157x-DKx_-_hardware_description|Discovery kits]]) are respectively aliased to mmc0 and mmc1.<br>
'''If you enable sdmmc3''', it will take the mmc0 alias and the aliases above will shift, so don't forget to update the Linux kernel boot command accordingly!<br>
For instance, 'root&#61;/dev/mmcblk0p6' will become 'root&#61;/dev/mmcblk1p6' to mount the rootfs from the sdmmc1 (SD card) when sdmmc3 is enabled.}}

===Runtime===

====Overview====
SDMMC1/2/3 instances can be allocated to:
* the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-A7 non-secure core to be controlled in Linux<sup>&reg;</sup> by the [[MMC overview|MMC framework]]
or
* the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-M4 to be controlled in STM32Cube MPU Package by [[STM32CubeMP1 architecture|STM32Cube SDMMC driver]]
Chapter [[#Peripheral assignment]] describes which peripheral instance can be assigned to which context.

====Software frameworks====
{{:Internal_peripherals_software_table_template}}
 | Mass storage
 | [[SDMMC internal peripheral|SDMMC]]
 | 
 | [[MMC overview|Linux MMC framework]]
 | [[STM32CubeMP1 architecture|STM32Cube SDMMC driver]]
 |
 |-
 |}

====Peripheral configuration====
The configuration is applied by the firmware running in the context to which the peripheral is assigned. The configuration can be done alone via the [[STM32CubeMX]] tool for all internal peripherals, and then manually completed (particularly for external peripherals), according to the information given in the corresponding software framework article.

For Linux<sup>&reg;</sup> kernel configuration, please refer to [[SDMMC device tree configuration]].

====Peripheral assignment====
{{:Internal_peripherals_assignment_table_template}}
<onlyinclude>
 | rowspan="3" | Mass storage
 | rowspan="3" | [[SDMMC internal peripheral|SDMMC]]
 | SDMMC1
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 |
 |
 |-
 | SDMMC2
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | 
 |
 |-
 | SDMMC3
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
</onlyinclude>
 |}

==How to go further==

==References==
<references/>

<noinclude>
{{ArticleBasedOnModel | Internal peripheral article model}}
{{PublicationRequestId | 8316 | 2018-08-06 | AnneJ}}
[[Category:High speed interface peripherals]]
[[Category:Mass storage peripherals]]
</noinclude>