timer.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <timer.h>
#include <delay.h>
#include <device/mmio.h>
 
#include "dmtimer.h"
#include "clock.h"
 
struct am335x_dmtimer *dmtimer_2 = (struct am335x_dmtimer *)DMTIMER_2;
 
#define CLKSEL_M_OSC (0x01 << 0)
 
static uint32_t timer_raw_value(void)
{
        return read32(&dmtimer_2->tcrr);
}
 
void timer_monotonic_get(struct mono_time *mt)
{
        mono_time_set_usecs(mt, timer_raw_value() / M_OSC_MHZ);
}
 
void init_timer(void)
{
        write32(&am335x_cm_dpll->clksel_timer2_clk, CLKSEL_M_OSC);
 
        // Start the dmtimer in autoreload mode without any prescalers
        // With M_OSC at 24MHz, this gives a few minutes before the timer overflows
        write32(&dmtimer_2->tclr, TCLR_ST | TCLR_AR);
}