bricks/_common/mphalport: use same file for EV3 and STM32

Move the STM32 mphalport.c to the common directory so that it can be
used for both the EV3 and STM32 ports. Eventually, all platforms should
use the same file. The EV3 clock driver had to have a small change to
make it work with the common mphalport.c.

Also clean up some duplication with regard to thumb assembly code files
while we are touching this.

Author: dlech

bricks/_common/arm_none_eabi.mk

@@ -253,24 +253,22 @@ PY_EXTRA_SRC_C += $(addprefix bricks/_common/,\
 	micropython.c \
 	)
 
-ifeq ($(PB_MCU_FAMILY),STM32)
-PY_EXTRA_SRC_C += $(addprefix bricks/_common_stm32/,\
+# TODO: NXT should eventually use the same mphalport.c as well.
+ifeq ($(PB_MCU_FAMILY),AT91SAM7)
+PY_EXTRA_SRC_C += $(addprefix bricks/nxt/,\
 	mphalport.c \
 	)
-
-ifeq ($(PB_MCU_SERIES),F0)
-SRC_S += shared/runtime/gchelper_thumb1.s
 else
-SRC_S += shared/runtime/gchelper_thumb2.s
-endif
-endif
-
-ifeq ($(PB_MCU_FAMILY),AT91SAM7)
-PY_EXTRA_SRC_C += $(addprefix bricks/nxt/,\
+PY_EXTRA_SRC_C += $(addprefix bricks/_common/,\
 	mphalport.c \
 	)
+endif
 
+# Not all MCUs support thumb2 instructions.
+ifeq ($(PB_MCU_SERIES),$(filter $(PB_MCU_SERIES),AT91SAM7 F0 TIAM1808))
 SRC_S += shared/runtime/gchelper_thumb1.s
+else
+SRC_S += shared/runtime/gchelper_thumb2.s
 endif
 
 # Skipping uart_irda_cir.c, gpio_v2.c, and hsi2c.c usbphyGS70.c, which
@@ -316,14 +314,6 @@ EV3_SRC_S = $(addprefix lib/pbio/platform/ev3/,\
 	start.S \
 	)
 
-ifeq ($(PB_MCU_FAMILY),TIAM1808)
-PY_EXTRA_SRC_C += $(addprefix bricks/ev3/,\
-	mphalport.c \
-	)
-
-SRC_S += shared/runtime/gchelper_thumb1.s
-endif
-
 # STM32 Bluetooth stack
 
 BLUENRG_SRC_C = $(addprefix lib/BlueNRG-MS/hci/,\

bricks/_common_stm32/mphalport.c renamed to bricks/_common/mphalport.c

@@ -1,10 +1,7 @@
-// SPDX-License-Identifier: MPL-1.0
+// SPDX-License-Identifier: MPL-1.0 AND MIT
 // Copyright (c) 2016 Tobias Schießl
-
-// SPDX-License-Identifier: MIT
 // Copyright (c) 2024 The Pybricks Authors
 
-
 #include <pbdrv/config.h>
 
 #if PBDRV_CONFIG_CLOCK_TIAM1808
@@ -35,7 +32,7 @@ static const uint32_t timer_us_division = auxclk_freq_hz / 1000000;
 /**
  * The current tick in milliseconds
  */
-volatile uint32_t systick_ms = 0;
+volatile uint32_t pbdrv_clock_ticks;
 
 /**
  * The systick interrupt service routine (ISR) which will be called every millisecond.
@@ -45,7 +42,7 @@ void systick_isr_C(void) {
     IntSystemStatusClear(SYS_INT_TINT12_0);
     TimerIntStatusClear(SOC_TMR_0_REGS, TMR_INTSTAT12_TIMER_NON_CAPT);
 
-    ++systick_ms;
+    pbdrv_clock_ticks++;
 
     etimer_request_poll();
     pbio_os_request_poll();
@@ -88,7 +85,7 @@ uint32_t pbdrv_clock_get_us(void) {
 }
 
 uint32_t pbdrv_clock_get_ms(void) {
-    return systick_ms;
+    return pbdrv_clock_ticks;
 }
 
 uint32_t pbdrv_clock_get_100us(void) {