stm32/pendsv: Remove preemptive keyboard interrupt feature.

dpgeorge · dpgeorge · commit f2f80c2b01ee · 2024-10-10T11:45:43.000+11:00
Signed-off-by: Damien George &lt;damien@micropython.org&gt;
diff --git a/ports/stm32/boards/common_isr_ram/common_isr.ld b/ports/stm32/boards/common_isr_ram/common_isr.ld
@@ -14,7 +14,7 @@
        flash (in main.c) along with the isr_vector above.
     */
     . = ALIGN(4);
-    *(.text.pendsv_kbd_intr)
+    *(.text.mp_sched_keyboard_interrupt)
     *(.text.pendsv_schedule_dispatch)
     *(.text.storage_systick_callback)
     *(.text.SysTick_Handler)
diff --git a/ports/stm32/pendsv.c b/ports/stm32/pendsv.c
@@ -31,13 +31,6 @@
 #include "pendsv.h"
 #include "irq.h"
 
-// This variable is used to save the exception object between a ctrl-C and the
-// PENDSV call that actually raises the exception.  It must be non-static
-// otherwise gcc-5 optimises it away.  It can point to the heap but is not
-// traced by GC.  This is okay because we only ever set it to
-// mp_kbd_exception which is in the root-pointer set.
-void *pendsv_object;
-
 #if defined(PENDSV_DISPATCH_NUM_SLOTS)
 uint32_t pendsv_dispatch_active;
 pendsv_dispatch_t pendsv_dispatch_table[PENDSV_DISPATCH_NUM_SLOTS];
@@ -51,24 +44,6 @@ void pendsv_init(void) {
     NVIC_SetPriority(PendSV_IRQn, IRQ_PRI_PENDSV);
 }
 
-// Call this function to raise a pending exception during an interrupt.
-// It will first try to raise the exception "softly" by setting the
-// mp_pending_exception variable and hoping that the VM will notice it.
-// If this function is called a second time (ie with the mp_pending_exception
-// variable already set) then it will force the exception by using the hardware
-// PENDSV feature.  This will wait until all interrupts are finished then raise
-// the given exception object using nlr_jump in the context of the top-level
-// thread.
-void pendsv_kbd_intr(void) {
-    if (MP_STATE_MAIN_THREAD(mp_pending_exception) == MP_OBJ_NULL) {
-        mp_sched_keyboard_interrupt();
-    } else {
-        MP_STATE_MAIN_THREAD(mp_pending_exception) = MP_OBJ_NULL;
-        pendsv_object = &MP_STATE_VM(mp_kbd_exception);
-        SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
-    }
-}
-
 #if defined(PENDSV_DISPATCH_NUM_SLOTS)
 void pendsv_schedule_dispatch(size_t slot, pendsv_dispatch_t f) {
     pendsv_dispatch_table[slot] = f;
@@ -90,10 +65,7 @@ void pendsv_dispatch_handler(void) {
 __attribute__((naked)) void PendSV_Handler(void) {
     // Handle a PendSV interrupt
     //
-    // For the case of an asynchronous exception, re-jig the
-    // stack so that when we return from this interrupt handler
-    // it returns instead to nlr_jump with argument pendsv_object
-    // note that stack has a different layout if DEBUG is enabled
+    // Calls any pending functions in pendsv_dispatch_table.
     //
     // For the case of a thread switch, swap stacks.
     //
@@ -132,27 +104,6 @@ __attribute__((naked)) void PendSV_Handler(void) {
         ".no_dispatch:\n"
         #endif
 
-        // Check if there is an active object to throw via nlr_jump
-        "ldr r1, pendsv_object_ptr\n"
-        "ldr r0, [r1]\n"
-        "cmp r0, #0\n"
-        "beq .no_obj\n"
-        #if defined(PENDSV_DEBUG)
-        "str r0, [sp, #8]\n"            // store to r0 on stack
-        #else
-        "str r0, [sp, #0]\n"            // store to r0 on stack
-        #endif
-        "mov r0, #0\n"
-        "str r0, [r1]\n"                // clear pendsv_object
-        "ldr r0, nlr_jump_ptr\n"
-        #if defined(PENDSV_DEBUG)
-        "str r0, [sp, #32]\n"           // store to pc on stack
-        #else
-        "str r0, [sp, #24]\n"           // store to pc on stack
-        #endif
-        "bx lr\n"                       // return from interrupt; will return to nlr_jump
-        ".no_obj:\n"                    // pendsv_object==NULL
-
         #if MICROPY_PY_THREAD
         // Do a thread context switch
         "push {r4-r11, lr}\n"
@@ -178,7 +129,5 @@ __attribute__((naked)) void PendSV_Handler(void) {
         #if defined(PENDSV_DISPATCH_NUM_SLOTS)
         "pendsv_dispatch_active_ptr: .word pendsv_dispatch_active\n"
         #endif
-        "pendsv_object_ptr: .word pendsv_object\n"
-        "nlr_jump_ptr: .word nlr_jump\n"
         );
 }
diff --git a/ports/stm32/pendsv.h b/ports/stm32/pendsv.h
@@ -51,7 +51,6 @@ enum {
 typedef void (*pendsv_dispatch_t)(void);
 
 void pendsv_init(void);
-void pendsv_kbd_intr(void);
 void pendsv_schedule_dispatch(size_t slot, pendsv_dispatch_t f);
 
 #endif // MICROPY_INCLUDED_STM32_PENDSV_H
diff --git a/ports/stm32/uart.c b/ports/stm32/uart.c
@@ -1229,7 +1229,7 @@ void uart_irq_handler(mp_uint_t uart_id) {
                 data &= self->char_mask;
                 if (self->attached_to_repl && data == mp_interrupt_char) {
                     // Handle interrupt coming in on a UART REPL
-                    pendsv_kbd_intr();
+                    mp_sched_keyboard_interrupt();
                 } else {
                     if (self->char_width == CHAR_WIDTH_9BIT) {
                         ((uint16_t *)self->read_buf)[self->read_buf_head] = data;
diff --git a/ports/stm32/usbd_cdc_interface.c b/ports/stm32/usbd_cdc_interface.c
@@ -315,7 +315,7 @@ int8_t usbd_cdc_receive(usbd_cdc_state_t *cdc_in, size_t len) {
     // copy the incoming data into the circular buffer
     for (const uint8_t *src = cdc->rx_packet_buf, *top = cdc->rx_packet_buf + len; src < top; ++src) {
         if (cdc->attached_to_repl && *src == mp_interrupt_char) {
-            pendsv_kbd_intr();
+            mp_sched_keyboard_interrupt();
         } else {
             uint16_t next_put = (cdc->rx_buf_put + 1) & (MICROPY_HW_USB_CDC_RX_DATA_SIZE - 1);
             if (next_put == cdc->rx_buf_get) {
