
RM0453 Rev 2
485/1454
RM0453
DMA request multiplexer (DMAMUX)
497
14.4.4
DMAMUX secure/non-secure channels
The DMAMUX is a security-aware peripheral , partitioning all its resources so that they exist
in one of the two worlds: the secure world and the normal/non-secure world, at any given
time.
The DMAMUX security is controlled by software at channel level. Any DMAMUX channel is
in secure or non-secure state, as configured by the secure register bit of the associated
channel of the DMA controller(s).
Note:
A DMA controller(s) channel must be first configured as secure or non-secure, before the
configuration of the connected DMAMUX channel.
Note:
A secure software is able to access any DMAMUX register, whatever secure or non-secure.
A non-secure software is restricted to access only non-secure DMAMUX register or
non-secure register fields.
A secure read/write access is a read/write transaction on AHB slave with the signal
HNONSEC = 0 (at the clock cycle of the address sampling). On the contrary, a non-secure
read/write access is a read/write transaction on AHB slave with the signal HNONSEC = 1.
When a channel is configured in secure mode, its configuration register fields become
secure resources, meaning that:
•
A non-secure read access to a (secure register) field is forced to return 0.
•
A non-secure write access to a (secure register) field has no impact.
Additionally, an illegal access signal is generated, as a pulse, to the secure interrupt
controller, when a non-secure software attempts to access a secure DMAMUX register:
•
DMAMUX_CxCR if the request multiplexer channel x is secure.
•
DMAMUX_RGxCR if the request generator channel x is secure.
Note:
The secure illegal access signal is never asserted on a non-secure access to the global
interrupt status and clear registers, even despite all the DMAMUX channels are set as
secure.
14.4.5
DMAMUX privileged / unprivileged channels
The DMAMUX is aware of the privileged or unprivileged state of a given DMA connected
channel, and manages consequently its DMAMUX requested channel.
Note:
A DMA controller(s) channel must be first configured as privileged or unprivileged, before
the configuration of the connected DMAMUX channel.
Note:
A privileged software is able to access any DMAMUX register, privileged or unprivileged. An
unprivileged software is restricted to access only unprivileged DMAMUX register or register
fields.
When a privileged software configures a DMA channel x either as privileged, an
unprivileged software is not able to access (write is ignored, read returns zero) the related
DMAMUX channel registers or register fields.
14.4.6
DMAMUX request line multiplexer
The DMAMUX request multiplexer with its multiple channels ensures the actual routing of
DMA request/acknowledge control signals, named DMA request lines.
Each DMA request line is connected in parallel to all the channels of the DMAMUX request
line multiplexer.