split startup.tcl file across modules

Moves definitions for each layer into their own file, eliminating
layering violations in the built-in TCL code.  Updates src/Makefile.am
rules to include all files in the final startup.tcl input file, and
others Makefile.am rules to distribute the new files in our packages.

src/jtag/Makefile.am

@@ -94,4 +94,6 @@ noinst_HEADERS = \
 	rlink/st7.h \
 	minidummy/jtag_minidriver.h
 
+EXTRA_DIST = startup.tcl
+
 MAINTAINERCLEANFILES = $(srcdir)/Makefile.in

src/jtag/startup.tcl

@@ -0,0 +1,41 @@
+# Defines basic Tcl procs for OpenOCD JTAG module
+
+# Executed during "init". Can be overridden
+# by board/target/... scripts
+proc jtag_init {} {
+	if {[catch {jtag arp_init} err]!=0} {
+		# try resetting additionally
+		init_reset startup
+	}
+}
+
+#########
+
+# TODO: power_restore and power_dropout are currently neither
+# documented nor supported except on ZY1000.
+
+proc power_restore {} {
+	puts "Sensed power restore."
+	reset init
+}
+
+add_help_text power_restore "Overridable procedure run when power restore is detected. Runs 'reset init' by default."
+
+proc power_dropout {} {
+	puts "Sensed power dropout."
+}
+
+#########
+
+# TODO: srst_deasserted and srst_asserted are currently neither
+# documented nor supported except on ZY1000.
+
+proc srst_deasserted {} {
+	puts "Sensed nSRST deasserted."
+	reset init
+}
+add_help_text srst_deasserted "Overridable procedure run when srst deassert is detected. Runs 'reset init' by default."
+
+proc srst_asserted {} {
+	puts "Sensed nSRST asserted."
+}