STM32MP13 RNG internal peripheral

Applicable for

1. Article purpose[edit source]

The purpose of this article is to:

briefly introduce the RNG 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 how to configure the RNG peripheral.

2. Peripheral overview[edit source]

The RNG peripheral is used to provide 32-bit random numbers.

2.1. Features[edit source]

Refer to STM32MP15 reference manuals for the complete list of features, and to the software components, introduced below, to know which features are really implemented.

2.2. Security support[edit source]

RNG1 is a secure peripheral (under ETZPC control).
RNG2 is a non-secure peripheral.

3. Peripheral usage and associated software[edit source]

3.1. Boot time[edit source]

RNG instances are not used as boot devices.

3.2. Runtime[edit source]

3.2.1. Overview[edit source]

RNG instances can be allocated to:

the Arm^® Cortex^®-A7 secure core to be controlled in OP-TEE with OP-TEE RNG driver

or

the Arm^® Cortex^®-A7 non-secure core to be controlled in Linux^® by the Linux hardware random framework

or

the Arm^® Cortex^®-M4 to be controlled in STM32Cube MPU Package by STM32Cube RNG driver

Chapter #Peripheral assignment exposes which instance can be assigned to which context.

3.2.2. Software frameworks[edit source]

Internal peripherals software table template

| Security
| RNG
| OP-TEE RNG driver
| Linux hardware random framework
| STM32Cube RNG driver
|
|-
|}

3.2.3. Peripheral configuration[edit source]

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.

3.2.4. Peripheral assignment[edit source]

Internal peripherals assignment table template

| rowspan="2" | Security
| rowspan="2" | RNG
| RNG1
| ☐
| ☐
| 
| Assignment (single choice)
|-
| RNG2
| 
| 
| ☐
| 
|-

|}

4. How to go further[edit source]

Not applicable.