5 files changed, 84 insertions, 21 deletions
diff --git a/ports/mimxrt/board_init.c b/ports/mimxrt/board_init.c
index 9222b302b..88de27ea7 100644
--- a/ports/mimxrt/board_init.c
+++ b/ports/mimxrt/board_init.c
@@ -39,6 +39,7 @@
 
 #include CLOCK_CONFIG_H
 #include "modmachine.h"
+#include "irq.h"
 
 const uint8_t dcd_data[] = { 0x00 };
 
@@ -63,7 +64,7 @@ void board_init(void) {
 
     // 1ms tick timer
     SysTick_Config(SystemCoreClock / 1000);
-    NVIC_SetPriority(SysTick_IRQn, NVIC_EncodePriority(NVIC_PRIORITYGROUP_4, 0, 0));
+    NVIC_SetPriority(SysTick_IRQn, IRQ_PRI_SYSTICK);
 
     // USB0
     usb_phy0_init(0b0111, 0b0110, 0b0110);  // Configure nominal values for D_CAL and TXCAL45DP/DN
diff --git a/ports/mimxrt/irq.h b/ports/mimxrt/irq.h
new file mode 100644
index 000000000..b83eb49ff
--- /dev/null
+++ b/ports/mimxrt/irq.h
@@ -0,0 +1,80 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2023 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_MIMXRT_IRQ_H
+#define MICROPY_INCLUDED_MIMXRT_IRQ_H
+
+#define NVIC_PRIORITYGROUP_4    ((uint32_t)0x00000003)
+
+static inline uint32_t query_irq(void) {
+    return __get_PRIMASK();
+}
+
+static inline uint32_t raise_irq_pri(uint32_t pri) {
+    uint32_t basepri = __get_BASEPRI();
+    // If non-zero, the processor does not process any exception with a
+    // priority value greater than or equal to BASEPRI.
+    // When writing to BASEPRI_MAX the write goes to BASEPRI only if either:
+    //   - Rn is non-zero and the current BASEPRI value is 0
+    //   - Rn is non-zero and less than the current BASEPRI value
+    pri <<= (8 - __NVIC_PRIO_BITS);
+    __ASM volatile ("msr basepri_max, %0" : : "r" (pri) : "memory");
+    return basepri;
+}
+
+// "basepri" should be the value returned from raise_irq_pri
+static inline void restore_irq_pri(uint32_t basepri) {
+    __set_BASEPRI(basepri);
+}
+
+// IRQ priority definitions.
+//
+// Lower number implies higher interrupt priority.
+//
+// The default priority grouping used in this port is NVIC_PRIORITYGROUP_4.
+// This corresponds to 4 bits for the priority field and 0 bits for the
+// sub-priority field (which means that for all intents and purposes the
+// sub-priorities below are ignored).
+//
+// While a given interrupt is being processed, only higher priority (lower number)
+// interrupts will preempt a given interrupt. If sub-priorities are active
+// then the sub-priority determines the order that pending interrupts of
+// a given priority are executed. This is only meaningful if 2 or more
+// interrupts of the same priority are pending at the same time.
+//
+// The following interrupts are arranged from highest priority to lowest
+// priority to make it a bit easier to figure out.
+
+#define IRQ_PRI_SYSTICK         NVIC_EncodePriority(NVIC_PRIORITYGROUP_4, 0, 0)
+
+#define IRQ_PRI_OTG_HS          NVIC_EncodePriority(NVIC_PRIORITYGROUP_4, 6, 0)
+
+#define IRQ_PRI_EXTINT          NVIC_EncodePriority(NVIC_PRIORITYGROUP_4, 14, 0)
+
+// PENDSV should be at the lowst priority so that other interrupts complete
+// before exception is raised.
+#define IRQ_PRI_PENDSV          NVIC_EncodePriority(NVIC_PRIORITYGROUP_4, 15, 0)
+
+#endif // MICROPY_INCLUDED_MIMXRT_IRQ_H
diff --git a/ports/mimxrt/mpconfigport.h b/ports/mimxrt/mpconfigport.h
index 9dccebc1f..fb4acede5 100644
--- a/ports/mimxrt/mpconfigport.h
+++ b/ports/mimxrt/mpconfigport.h
@@ -152,23 +152,6 @@ __attribute__((always_inline)) static inline uint32_t disable_irq(void) {
     return state;
 }
 
-static inline uint32_t raise_irq_pri(uint32_t pri) {
-    uint32_t basepri = __get_BASEPRI();
-    // If non-zero, the processor does not process any exception with a
-    // priority value greater than or equal to BASEPRI.
-    // When writing to BASEPRI_MAX the write goes to BASEPRI only if either:
-    //   - Rn is non-zero and the current BASEPRI value is 0
-    //   - Rn is non-zero and less than the current BASEPRI value
-    pri <<= (8 - __NVIC_PRIO_BITS);
-    __ASM volatile ("msr basepri_max, %0" : : "r" (pri) : "memory");
-    return basepri;
-}
-
-// "basepri" should be the value returned from raise_irq_pri
-static inline void restore_irq_pri(uint32_t basepri) {
-    __set_BASEPRI(basepri);
-}
-
 #define MICROPY_BEGIN_ATOMIC_SECTION()     disable_irq()
 #define MICROPY_END_ATOMIC_SECTION(state)  enable_irq(state)
 
diff --git a/ports/mimxrt/mphalport.h b/ports/mimxrt/mphalport.h
index 1813a9834..36eb38779 100644
--- a/ports/mimxrt/mphalport.h
+++ b/ports/mimxrt/mphalport.h
@@ -31,6 +31,7 @@
 #include "ticks.h"
 #include "py/ringbuf.h"
 #include "pin.h"
+#include "irq.h"
 #include "fsl_clock.h"
 
 #define MICROPY_HAL_VERSION             "2.8.0"
diff --git a/ports/mimxrt/pendsv.c b/ports/mimxrt/pendsv.c
index 11f2ef5e1..46d13a5ac 100644
--- a/ports/mimxrt/pendsv.c
+++ b/ports/mimxrt/pendsv.c
@@ -28,9 +28,7 @@
 
 #include "py/runtime.h"
 #include "pendsv.h"
-
-#define NVIC_PRIORITYGROUP_4    ((uint32_t)0x00000003)
-#define IRQ_PRI_PENDSV          NVIC_EncodePriority(NVIC_PRIORITYGROUP_4, 15, 0)
+#include "irq.h"
 
 #if defined(PENDSV_DISPATCH_NUM_SLOTS)
 pendsv_dispatch_t pendsv_dispatch_table[PENDSV_DISPATCH_NUM_SLOTS];