target: restructure dap support

- add 'dap create' command to create dap instances
- move all dap subcmmand into the dap instance commands
- keep 'dap info' for convenience
- change all armv7 and armv8 targets to take a dap
  instance instead of a jtag chain position
- restructure tap/dap/target relations, jtag tap no
  longer references the dap, daps are now independently
  created and initialized.
- clean up swd connect
- re-initialize DAP also on JTAG errors (e.g. after reset,
  power cycle)
- update documentation
- update target files

Change-Id: I322cf3969b5407c25d1d3962f9d9b9bc1df067d9
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>
Reviewed-on: http://openocd.zylin.com/4468
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

tcl/target/amdm37x.cfg

@@ -86,8 +86,8 @@ source [find target/icepick.cfg]
 
 # Secondary TAP: DAP is closest to the TDO output
 # The TAP enable event also needs to be described
-jtag newtap $_CHIPNAME dap -irlen 4 -ircapture 0x1 -irmask 0xf -disable
-jtag configure $_CHIPNAME.dap -event tap-enable \
+jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -disable
+jtag configure $_CHIPNAME.cpu -event tap-enable \
    "icepick_c_tapenable $_CHIPNAME.jrc 3"
 
 # These taps are only present in the DM37x series.
@@ -141,7 +141,8 @@ jtag configure $_CHIPNAME.jrc -event setup "jtag tapenable $_CHIPNAME.dap"
 
 # Create the CPU target to be used with GDB:  Cortex-A8, using DAP
 set _TARGETNAME $_CHIPNAME.cpu
-target create $_TARGETNAME cortex_a -chain-position $_CHIPNAME.dap
+dap create $_CHIPNAME.dap -chain-position $_CHIPNAME.cpu
+target create $_TARGETNAME cortex_a -dap $_CHIPNAME.dap
 
 # The DM37x has 64K of SRAM starting at address 0x4020_0000.  Allow the first
 # 16K to be used as a scratchpad for OpenOCD.