Atmel introduced a "Device Service Unit" (DSU) that holds the CPU
in reset if TCK is low when srst (RESET_N) is deasserted.
Function is similar to SMAP in ATSAM4L, see http://openocd.zylin.com/2604
Atmel's EDBG adapter handles DSU reset correctly without this change.
An ordinary SWD adapter leaves TCK in its default state, low.
So without this change any use of sysresetreq or srst
locks the chip in reset state until power is cycled.
A new function dsu_reset_deassert is called as reset-deassert-post event handler.
It optionally prepares reset vector catch and DSU reset is released then.
Additionally SWD clock comment is fixed in at91samdXX.cfg and clock is
lowered a bit to ensure a margin for RC oscillator frequency deviation.
adapter_nsrst_delay 100 is commented out because is no more necessary after
http://openocd.zylin.com/2601
Change-Id: I42e99b1b245f766616c0a0d939f60612c29bd16c
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/2778
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
Prerequisites:
The users of OpenOCD as well as computer programs interacting with OpenOCD are expecting that certain commands
do the same thing across all the targets.
Rules to follow when writing scripts:
1. The configuration script should be defined such as , for example, the following sequences are working:
reset
flash info <bank>
and
reset
flash erase_address <start> <len>
and
reset init
load
In most cases this can be accomplished by specifying the default startup mode as reset_init (target command
in the configuration file).
2. If the target is correctly configured, flash must be writable without any other helper commands. It is
assumed that all write-protect mechanisms should be disabled.
3. The configuration scripts should be defined such as the binary that was written to flash verifies
(turn off remapping, checksums, etc...)
flash write_image [file] <parameters>
verify_image [file] <parameters>
4. adapter_khz sets the maximum speed (or alternatively RCLK). If invoked
multiple times only the last setting is used.
interface/xxx.cfg files are always executed *before* target/xxx.cfg
files, so any adapter_khz in interface/xxx.cfg will be overridden by
target/xxx.cfg. adapter_khz in interface/xxx.cfg would then, effectively,
set the default JTAG speed.
Note that a target/xxx.cfg file can invoke another target/yyy.cfg file,
so one can create target subtype configurations where e.g. only
amount of DRAM, oscillator speeds differ and having a single
config file for the default/common settings.
Tomas Vanek
751e2454bf