board: tt_blackhole: minor cleanup of SRST workaround

Add a minor cleanup of the SRST workaround, bringing variables out to
Kconfig. It makes the SRST workaround optional, but enabled by default.

By doing so, we preserve the previous functionality, which will also
work when only one JTAG adapter is present for SMC. This will work
unmodified for P100, but requires the SRST (BH_RESET) signal is brought
out to the debug header for other Blackhole cards such as P100A, as
well as P150 and P300 variants.

Signed-off-by: Chris Friedt <[email protected]>

Author: Chris Friedt

boards/tenstorrent/tt_blackhole/Kconfig

@@ -7,3 +7,44 @@ config BOARD_INIT_PRIORITY
 	help
 	  Board initialization priority. Should be greater than flash
 	  initialization priority
+
+if BOARD_TT_BLACKHOLE_TT_BLACKHOLE_SMC
+
+config TT_SRST_ASSIST
+	bool "Enable TT SRST assist"
+	default y
+	help
+	  It's safe to enable this option always, but it is mainly required when using JTAG to control
+	  Blackhole cards. It requires both a JTAG debugger attached to the SMC as well as an SWD
+	  debugger attached to the BMC.
+
+if TT_SRST_ASSIST
+
+config TT_SRST_ASSIST_ADDR
+	hex "Address to write to toggle SRST pin(s)"
+	# this is the same address on all P100a+ boards
+	default 0x50000418
+	help
+	  This is the address of the GPIO control register on the BMC that controls the SRST pin(s).
+
+config TT_SRST_ASSIST_SET
+	hex "Value to write to set SRST pin(s)"
+	# GPIOB pins 0 and 1
+	default 0x30000 if BOARD_P300
+	# GPIOB pin 0
+	default 0x10000
+	help
+	  This is the value to write to the GPIO control register on the BMC to set the SRST pin(s).
+
+config TT_SRST_ASSIST_CLR
+	hex "Value to write to set SRST pin(s)"
+	# GPIOB pins 0 and 1
+	default 0x3 if BOARD_P300
+	# GPIOB pin 0
+	default 0x1
+	help
+	  This is the value to write to the GPIO control register on the BMC to set the SRST pin(s).
+
+endif
+
+endif

boards/tenstorrent/tt_blackhole/board.cmake

@@ -14,24 +14,16 @@ if(CONFIG_ARM)
   board_runner_args(stm32cubeprogrammer "--port=swd" "--reset-mode=hw")
 endif()
 
-if(CONFIG_SOC_TT_BLACKHOLE_SMC)
-  set(BMC_VARS "# Autogenerated file with variables to reset BH core. Don't edit!\n")
+set(BMC_VARS "# Autogenerated file with variables to reset SMC. Don't edit!\n")
+if(CONFIG_TT_SRST_ASSIST)
   string(APPEND BMC_VARS "set OPENOCD ${OPENOCD}\n")
   string(APPEND BMC_VARS "set OPENOCD_DEFAULT_PATH ${OPENOCD_DEFAULT_PATH}\n")
   string(APPEND BMC_VARS "set BMC_CFG ${CMAKE_CURRENT_LIST_DIR}/support/tt_blackhole_bmc.cfg\n")
-  if(CONFIG_BOARD_REVISION MATCHES "p300.*")
-    # P300 has two reset GPIOs, on GPIOB pin 0 and 1
-    string(APPEND BMC_VARS "set RST_GPIO_REG 0x50000418\n")
-    string(APPEND BMC_VARS "set RST_GPIO_SET_MASK 0x30000\n")
-    string(APPEND BMC_VARS "set RST_GPIO_CLR_MASK 0x3\n")
-  else()
-    # All other Blackhole cards have RST pin on GPIOB, pin 0
-    string(APPEND BMC_VARS "set RST_GPIO_REG 0x50000418\n")
-    string(APPEND BMC_VARS "set RST_GPIO_SET_MASK 0x10000\n")
-    string(APPEND BMC_VARS "set RST_GPIO_CLR_MASK 0x1\n")
-  endif()
-  file(WRITE ${CMAKE_CURRENT_LIST_DIR}/support/bmc-reset-vars.cfg ${BMC_VARS})
+  string(APPEND BMC_VARS "set RST_GPIO_REG ${CONFIG_TT_SRST_ASSIST_ADDR}\n")
+  string(APPEND BMC_VARS "set RST_GPIO_SET_MASK ${CONFIG_TT_SRST_ASSIST_SET}\n")
+  string(APPEND BMC_VARS "set RST_GPIO_CLR_MASK ${CONFIG_TT_SRST_ASSIST_CLR}\n")
 endif()
+file(WRITE ${CMAKE_CURRENT_LIST_DIR}/support/bmc-reset-vars.cfg ${BMC_VARS})
 
 # Include debugger templates below (order is important)
 include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)

boards/tenstorrent/tt_blackhole/support/tt_blackhole_smc.cfg

@@ -14,8 +14,7 @@ set _dbgbase [expr {$_coreid << 13}]
 
 set _CHIPNAME arc-em
 
-# Override the init_reset procedure
-proc init_reset {mode} {
+proc toggle_srst {} {
 	global OPENOCD
 	global OPENOCD_DEFAULT_PATH
 	global BMC_CFG
@@ -24,9 +23,26 @@ proc init_reset {mode} {
 	global RST_GPIO_SET_MASK
 
 	echo "Resetting blackhole SOC"
-	exec $OPENOCD -s $OPENOCD_DEFAULT_PATH -f $BMC_CFG -c "init; mww $RST_GPIO_REG $RST_GPIO_SET_MASK; exit"
+
+	# This method works for all Blackhole cards but requires an SWD adapter on BMC
+	if {[info exists BMC_CFG]} {
+		exec $OPENOCD -s $OPENOCD_DEFAULT_PATH -f $BMC_CFG -c "init; mww $RST_GPIO_REG $RST_GPIO_SET_MASK; exit"
+		sleep 10
+		exec $OPENOCD -s $OPENOCD_DEFAULT_PATH -f $BMC_CFG -c "init; mww $RST_GPIO_REG $RST_GPIO_CLR_MASK; exit"
+		return
+	}
+
+	# This method may be used as a fallback when no SWD adapter is available.
+	# It does require that the SRST pin is brought out to the SMC debug interface.
+	reset_config srst_only
+	adapter assert srst
 	sleep 10
-	exec $OPENOCD -s $OPENOCD_DEFAULT_PATH -f $BMC_CFG -c "init; mww $RST_GPIO_REG $RST_GPIO_CLR_MASK; exit"
+	adapter deassert srst
+}
+
+# Override the init_reset procedure
+proc init_reset {mode} {
+	toggle_srst
 	# Without this delay, the jtag scan fails
 	sleep 100
 	jtag arp_init