54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
#include "tb_cxxrtl_io.h"
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#define TIMER_INTERVAL 1000
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#define MAX_IRQ_COUNT 10
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#define __wfi() asm volatile ("wfi")
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#define __compiler_mb() asm volatile ("" ::: "memory")
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typedef struct {
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volatile uint32_t mtime;
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volatile uint32_t mtimeh;
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volatile uint32_t mtimecmp;
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volatile uint32_t mtimecmph;
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} timer_hw;
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timer_hw *const timer = (timer_hw*)(IO_BASE + 0x100);
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int irq_count;
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void __attribute__((interrupt)) isr_machine_timer() {
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__compiler_mb();
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++irq_count;
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__compiler_mb();
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tb_printf("IRQ %d\n", irq_count);
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// Disable timer IRQ via MTIE, or set the next timer IRQ
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if (irq_count >= MAX_IRQ_COUNT)
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asm ("csrc mie, %0" :: "r" (1u << 7));
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else
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timer->mtimecmp = timer->mtime + TIMER_INTERVAL;
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}
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int main() {
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irq_count = 0;
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__compiler_mb();
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// Per-IRQ enable for timer IRQ
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asm ("csrs mie, %0" :: "r" (1u << 7));
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tb_puts("Enabling IRQS...\n");
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// Global IRQ enable. Timer IRQ will fire immediately.
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asm ("csrsi mstatus, 0x8");
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// Count the number of sleep loop iterations to make sure the wfi waits
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int wait_spin_count;
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while (irq_count < MAX_IRQ_COUNT) {
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++wait_spin_count;
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__wfi();
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__compiler_mb();
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}
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tb_printf("Took %d IRQs, span %d times\n", irq_count, wait_spin_count);
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return irq_count != wait_spin_count + 1;
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}
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