Functional Description
Table 11-20. Example Access Allowed
Register
Value
Description
EER
0x0000 0000
Value in EER to begin with.
(offset 0x1020)
EESR
0xFF00 FF00
Value attempted to be written to shadow region 7's EESR. This is done by an EDMA3
(offset 0x2E30)
programmer with a privilege level of User and Privilege ID of 0.
MPPA[7]
0x0000 04B3
Memory Protection Filter AID = 1, UW = 1, UR = 1, SW = 1, SR = 1.
(offset 0x082C)
√
Access allowed.
↓
DRAE[7]
0x9FF0 0FC2
DMA Region Access Enable Filter
(offset 0x0378)
↓
EESR
0x8BC0 0102
Value written to shadow region 7's EESR. This is done by an EDMA3 programmer
(offset 0x2E30)
↓
with a privilege level of User and a Privilege ID of 0.
EER
↓
Final value of EER.
(offset 0x1020)
0xBC0 0102
11.3.10.2 Proxy Memory Protection
Proxy memory protection allows an EDMA3 transfer programmed by a given EDMA3 programmer to have
its permissions travel with the transfer through the EDMA3TC. The permissions travel along with the read
transactions to the source and the write transactions to the destination endpoints. The PRIV bit and
PRIVID bit in the channel options parameter (OPT) is set with the EDMA3 programmer's PRIV value and
PRIVID values, respectively, when any part of the PaRAM set is written.
The PRIV is the privilege level (i.e., user vs. supervisor). The PRIVID refers to a privilege ID with a
number that is associated with an EDMA3 programmer.
See the data manual for the PRIVIDs that are associated with potential EDMA3 programmers.
These options are part of the TR that are submitted to the transfer controller. The transfer controller uses
the above values on their respective read and write command bus so that the target endpoints can
perform memory protection checks based on these values.
Consider a parameter set that is programmed by a CPU in user privilege level for a simple transfer with
the source buffer on an L2 page and the destination buffer on an L1D page. The PRIV is 0 for user-level
and the CPU has a PRIVID of 0.
The PaRAM set is shown in
910
Enhanced Direct Memory Access (EDMA)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated