+/* (CC-BY-NC-SA) ROBIN KRENS - ROBIN @ ROBINKRENS.NL
+ *
+ * $LOG$
+ * 2019/7/20 - ROBIN KRENS
+ * Initial version
+ *
+ * $DESCRIPTION$
+ * Set up of basic exceptions and interrupts. These interrupts
+ * don't do much, except for halting the system.
+ * ivt_set_gate(interrupt nr, function, priority) can be used
+ * later to define more appropriate handling. See timer (timer.c)
+ * or serial or (uart.c) handling for non-trivial examples.
+ *
+ * The actual code is not much, but there are a lot of details
+ * to consider. Besides that, in case more control is desired over
+ * entering and exiting interrupts (what is pushed on the stack)
+ * A so-called naked function can be used. See below for more
+ * details.
+ *
+ *
+ * */
+
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
-#include <stm32.h>
-#include <mmap.h>
+
+#include <sys/robsys.h>
+#include <sys/mmap.h>
+
+#include <lib/stdio.h>
+#include <lib/string.h>
+#include <lib/regfunc.h>
/*
* These values are pushed on the stack just before
* gives me a little bit more control over the caller
*
* The following register are pushed to the stack
- * in reverse order
+ * in reverse order:
*
* */
struct interrupt_frame {
/*
* Vector table, each entry contains an interrupt
- * service routine:
- *
+ * service routine:
* interrupt vector 1-15: processor exceptions
- * interrupt vector 16-64: irq0 - irq ..
+ * interrupt vector 16-92: irq0 - irq ..
+ * Vector table needs to be aligned in memory.
* */
+uint32_t __attribute__((aligned(0x100))) ivt[92];
-uint32_t ivt[64];
+/* Each message corresponds to each and every exception. */
+char * exception_message(uint8_t intnr) {
-/* each message corresponds to each and every exception.
- * We get the correct message by accessing
- * exception_message[interrupt_number]
- * exception_message[0] is not used (=MSP)*/
-unsigned char *exception_messages[] =
-{
+char * messages[] = {
"--",
"RESET",
"NMI",
"SVC",
"DEBUG MONITOR",
"RESERVED",
+ "RESERVED",
+ "RESERVED",
+ "RESERVED",
"PENDSV",
"SYSTICK",
"IRQ1",
// add more if needed
};
+if (intnr < 20) // TODO: strlen
+ return messages[intnr];
+ return NULL;
+}
+
void ivt_set_gate(unsigned char num, void * isr(), short pri) {
ivt[num] = (uint32_t) isr;
*NVIC_ISER0 = (1 << ((uint32_t)(num) & 0x1F));
- /* Priorities */
+ /* TODO: Priorities */
}
-/* Dummy interrupt */
-__attribute__ ((interrupt))
-void * dummy_isr(struct interrupt_frame * frame) {
-
+/* Dummy interrupt: comment out the comment to use a naked
+ * function */
- uint32_t * p = (volatile uint32_t *) 0x21000000;
+// __attribute__ ((interrupt))
+void * dummy_isr(/* struct interrupt_frame * frame */) {
- addrtohex(frame->r0);
- addrtohex(frame->r1);
- addrtohex(frame->r2);
- addrtohex(frame->r3);
- addrtohex(frame->r12);
- addrtohex(frame->lr);
- addrtohex(frame->pc);
- addrtohex(frame->psr);
+ uint8_t nr = *SCB_VTOR_ST & 0xFF;
- //__asm__ __volatile__ ("MRS r0, IPSR");
- //addrtohex(frame->r0);
- uart_puts("EXCEPTION X: SYSTEM HALTED\n");
+ cputs("EXCEPTION: ");
+ cputs(exception_message(nr));
+ cputs("\nSYSTEM HALTED\n");
for(;;);
}
/* Initialize interrupt vector */
void ivt_init() {
- /* clear entiry IVT, in SRAM location for SRAM + .data (in .bss section) */
- memset(&ivt, 0, (sizeof(uint32_t) * 87));
+ /* clear entire IVT location in memory */
+ memset(&ivt, 0, (sizeof(uint32_t) * 92));
- // stack top is loaded from the first entry table on boot/reset
- // don't need to relocate or init this here
+ /* The reset, NMI and hardfault handlers are originally
+ * defined in the assembly start up and can be
+ * reused or overwritten.
+ * */
extern void * reset, * nmi, * hardfault;
- for (int i = 1; i < 7; i++) {
+ // set dummy handlers
+ for (int i = 1; i <= 64 ; i++) {
ivt_set_gate(i, dummy_isr, 0);
}
- /* the vector table starts at 0x0. Since the address 0x0 point to
- * bootcode, it is on ROM or FLASH. The vector table can be
+ /* The vector table is intially at 0x0. The vector table can be
* relocated to other memory locations. We can do this by setting
* a register in the NVIC called the vector table offset register */
- //*SCB_VTOR = (volatile uint32_t) &ivt;
- regw_u32(SCB_VTOR, (uint32_t) &ivt, 0, 0x01);
+ regw_u32(SCB_VTOR, (uint32_t) &ivt, 0, OWRITE);
}