Add ability to debug the microcontroller

Makefile

@@ -65,6 +65,14 @@ assemble: compile $(OBJ_FILES)
 flash: $(BUILD_DIR)/$(TARGET).bin
 	st-flash --reset write $< 0x8000000
 
+.PHONY: gdb-server
+gdb-server:
+	sudo openocd -f stlink.cfg -f stm32f4x.cfg
+
+.PHONY: gdb-client
+gdb-client:
+	gdb --symbols $(BUILD_DIR)/$(TARGET).elf --init-eval-command="target extended-remote localhost:3333"
+
 .PHONY: clean
 clean:
 	rm -rf $(BUILD_DIR)

flake.nix

@@ -24,6 +24,8 @@
                   pkgs.gnumake
                   pkgs.gcc-arm-embedded
                   pkgs.stlink
+                  pkgs.gdb
+                  pkgs.openocd
                 ];
               };
             }

stlink.cfg

@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+#
+# STMicroelectronics ST-LINK/V1, ST-LINK/V2, ST-LINK/V2-1, STLINK-V3 in-circuit
+# debugger/programmer
+#
+
+adapter driver hla
+hla_layout stlink
+hla_device_desc "ST-LINK"
+hla_vid_pid 0x0483 0x3744 0x0483 0x3748 0x0483 0x374b 0x0483 0x374d 0x0483 0x374e 0x0483 0x374f 0x0483 0x3752 0x0483 0x3753 0x0483 0x3754
+
+# Optionally specify the serial number of ST-LINK/V2 usb device.  ST-LINK/V2
+# devices seem to have serial numbers with unreadable characters.  ST-LINK/V2
+# firmware version >= V2.J21.S4 recommended to avoid issues with adapter serial
+# number reset issues.
+# eg.
+# adapter serial "\xaa\xbc\x6e\x06\x50\x75\xff\x55\x17\x42\x19\x3f"

stm32f4x.cfg

@@ -0,0 +1,148 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# script for stm32f4x family
+
+#
+# stm32f4 devices support both JTAG and SWD transports.
+#
+source [find target/swj-dp.tcl]
+source [find mem_helper.tcl]
+
+if { [info exists CHIPNAME] } {
+   set _CHIPNAME $CHIPNAME
+} else {
+   set _CHIPNAME stm32f4x
+}
+
+set _ENDIAN little
+
+# Work-area is a space in RAM used for flash programming
+# By default use 32kB (Available RAM in smallest device STM32F410)
+if { [info exists WORKAREASIZE] } {
+   set _WORKAREASIZE $WORKAREASIZE
+} else {
+   set _WORKAREASIZE 0x8000
+}
+
+#jtag scan chain
+if { [info exists CPUTAPID] } {
+   set _CPUTAPID $CPUTAPID
+} else {
+   if { [using_jtag] } {
+      # See STM Document RM0090
+      # Section 38.6.3 - corresponds to Cortex-M4 r0p1
+      set _CPUTAPID 0x4ba00477
+   } {
+      set _CPUTAPID 0x2ba01477
+   }
+}
+
+swj_newdap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_CPUTAPID
+dap create $_CHIPNAME.dap -chain-position $_CHIPNAME.cpu
+
+if {[using_jtag]} {
+   jtag newtap $_CHIPNAME bs -irlen 5
+}
+
+set _TARGETNAME $_CHIPNAME.cpu
+target create $_TARGETNAME cortex_m -endian $_ENDIAN -dap $_CHIPNAME.dap
+
+$_TARGETNAME configure -work-area-phys 0x20000000 -work-area-size $_WORKAREASIZE -work-area-backup 0
+
+set _FLASHNAME $_CHIPNAME.flash
+flash bank $_FLASHNAME stm32f2x 0 0 0 0 $_TARGETNAME
+
+flash bank $_CHIPNAME.otp stm32f2x 0x1fff7800 0 0 0 $_TARGETNAME
+
+if { [info exists QUADSPI] && $QUADSPI } {
+   set a [llength [flash list]]
+   set _QSPINAME $_CHIPNAME.qspi
+   flash bank $_QSPINAME stmqspi 0x90000000 0 0 0 $_TARGETNAME 0xA0001000
+}
+
+# JTAG speed should be <= F_CPU/6. F_CPU after reset is 16MHz, so use F_JTAG = 2MHz
+#
+# Since we may be running of an RC oscilator, we crank down the speed a
+# bit more to be on the safe side. Perhaps superstition, but if are
+# running off a crystal, we can run closer to the limit. Note
+# that there can be a pretty wide band where things are more or less stable.
+adapter speed 2000
+
+adapter srst delay 100
+if {[using_jtag]} {
+ jtag_ntrst_delay 100
+}
+
+reset_config srst_nogate
+
+if {![using_hla]} {
+   # if srst is not fitted use SYSRESETREQ to
+   # perform a soft reset
+   cortex_m reset_config sysresetreq
+}
+
+$_TARGETNAME configure -event examine-end {
+	# Enable debug during low power modes (uses more power)
+	# DBGMCU_CR |= DBG_STANDBY | DBG_STOP | DBG_SLEEP
+	mmw 0xE0042004 0x00000007 0
+
+	# Stop watchdog counters during halt
+	# DBGMCU_APB1_FZ |= DBG_IWDG_STOP | DBG_WWDG_STOP
+	mmw 0xE0042008 0x00001800 0
+}
+
+tpiu create $_CHIPNAME.tpiu -dap $_CHIPNAME.dap -ap-num 0 -baseaddr 0xE0040000
+
+lappend _telnet_autocomplete_skip _proc_pre_enable_$_CHIPNAME.tpiu
+proc _proc_pre_enable_$_CHIPNAME.tpiu {_chipname} {
+	targets $_chipname.cpu
+
+	if { [$_chipname.tpiu cget -protocol] eq "sync" } {
+		switch [$_chipname.tpiu cget -port-width] {
+			1 {
+				# Set TRACE_IOEN; TRACE_MODE to sync 1 bit; GPIOE[2-3] to AF0
+				mmw 0xE0042004 0x00000060 0x000000c0
+				mmw 0x40021020 0x00000000 0x0000ff00
+				mmw 0x40021000 0x000000a0 0x000000f0
+				mmw 0x40021008 0x000000f0 0x00000000
+			  }
+			2 {
+				# Set TRACE_IOEN; TRACE_MODE to sync 2 bit; GPIOE[2-4] to AF0
+				mmw 0xE0042004 0x000000a0 0x000000c0
+				mmw 0x40021020 0x00000000 0x000fff00
+				mmw 0x40021000 0x000002a0 0x000003f0
+				mmw 0x40021008 0x000003f0 0x00000000
+			  }
+			4 {
+				# Set TRACE_IOEN; TRACE_MODE to sync 4 bit; GPIOE[2-6] to AF0
+				mmw 0xE0042004 0x000000e0 0x000000c0
+				mmw 0x40021020 0x00000000 0x0fffff00
+				mmw 0x40021000 0x00002aa0 0x00003ff0
+				mmw 0x40021008 0x00003ff0 0x00000000
+			  }
+		}
+	} else {
+		# Set TRACE_IOEN; TRACE_MODE to async
+		mmw 0xE0042004 0x00000020 0x000000c0
+	}
+}
+
+$_CHIPNAME.tpiu configure -event pre-enable "_proc_pre_enable_$_CHIPNAME.tpiu $_CHIPNAME"
+
+$_TARGETNAME configure -event reset-init {
+	# Configure PLL to boost clock to HSI x 4 (64 MHz)
+	mww 0x40023804 0x08012008   ;# RCC_PLLCFGR 16 Mhz /8 (M) * 128 (N) /4(P)
+	mww 0x40023C00 0x00000102   ;# FLASH_ACR = PRFTBE | 2(Latency)
+	mmw 0x40023800 0x01000000 0 ;# RCC_CR |= PLLON
+	sleep 10                    ;# Wait for PLL to lock
+	mmw 0x40023808 0x00001000 0 ;# RCC_CFGR |= RCC_CFGR_PPRE1_DIV2
+	mmw 0x40023808 0x00000002 0 ;# RCC_CFGR |= RCC_CFGR_SW_PLL
+
+	# Boost JTAG frequency
+	adapter speed 8000
+}
+
+$_TARGETNAME configure -event reset-start {
+	# Reduce speed since CPU speed will slow down to 16MHz with the reset
+	adapter speed 2000
+}