omap3530: target reset/init improvements

Now I can issue "reset halt" and have everything act smoothly;
the vector_catch hardware is obviously not kicking in, but the
rest of the reset sequence acts sanely.

 - TAP "setup" event enables the DAP, not omap3_dbginit
   (resolving a chicken/egg bug I noted a while back)
 - Remove stuff from omap3_dbginit which should never be
   used in event handlers
 - Cope better with slow clocking during reset

Also, stop hard-wiring the target name: use the input params in
the standard way, and set up $_TARGETNAME as an output param.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

tcl/target/omap3530.cfg

@@ -34,28 +34,38 @@ if { [info exists JRC_TAPID ] } {
 jtag newtap $_CHIPNAME jrc -irlen 6 -ircapture 0x1 -irmask 0x3f \
 	-expected-id $_JRC_TAPID
 
+# GDB target:  Cortex-A8, using DAP
+set _TARGETNAME $_CHIPNAME.cpu
+target create $_TARGETNAME cortex_a8 -chain-position $_CHIPNAME.dap
+
+###################
+
+# the reset sequence is event-driven
+# and kind of finicky...
+
+# some TCK tycles are required to activate the DEBUG power domain
 jtag configure $_CHIPNAME.jrc -event post-reset "runtest 100"
 
-# GDB target:  Cortex-A8, using DAP
-target create omap3.cpu cortex_a8 -chain-position $_CHIPNAME.dap
+# have the DAP "always" be active
+jtag configure $_CHIPNAME.jrc -event setup "jtag tapenable $_CHIPNAME.dap"
 
-# FIXME much of this should be in reset event handlers
-proc omap3_dbginit { } {
-     poll off
-     sleep 100
-
-     jtag tapenable omap3530.dap
-     targets
+proc omap3_dbginit {target} {
      # General Cortex A8 debug initialisation
      cortex_a8 dbginit
      # Enable DBGU signal for OMAP353x
-     omap3.cpu mww 0x5401d030 0x00002000
-     poll on
+     $target mww 0x5401d030 0x00002000
 }
 
+# be absolutely certain the JTAG clock will work with the worst-case
+# 16.8MHz/2 = 8.4MHz core clock, even before a bootloader kicks in.
+# OK to speed up *after* PLL and clock tree setup.
+jtag_rclk 1000
+$_TARGETNAME configure -event "reset-start" { jtag_rclk 1000 }
+
+# REVISIT This assumes that SRST is unavailable, so we must assert reset
+# ourselves using PRM_RSTCTRL.  RST_GS (2) is a warm reset, like ICEpick
+# would issue.  RST_DPLL3 (4) is a cold reset.
 set PRM_RSTCTRL 0x48307250
+$_TARGETNAME configure -event reset-assert-pre "$_TARGETNAME mww $PRM_RSTCTRL 2"
 
-omap3.cpu configure -event reset-start "omap3.cpu mww $PRM_RSTCTRL 2"
-omap3.cpu configure -event reset-assert-pre "omap3_dbginit"
-
-
+$_TARGETNAME configure -event reset-assert-post "omap3_dbginit $_TARGETNAME"