timer.c

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/* SPDX-License-Identifier: BSD-3-Clause */
 
#include <delay.h>
#include <soc/iomap.h>
#include <soc/ipq_timer.h>
#include <timer.h>
 
/*
 * DGT runs at 25 MHz / 4, or 6.25 ticks per microsecond
 */
#define DGT_MHZ_NUM     25
#define DGT_MHZ_DEN     4
 
#define TIMER_TICKS(us) ((DGT_MHZ_NUM*(us) + (DGT_MHZ_DEN - 1)) / DGT_MHZ_DEN)
#define TIMER_USECS(ticks) (DGT_MHZ_DEN*(ticks) / DGT_MHZ_NUM)
 
/* Clock divider values for the timer. */
#define DGT_CLK_DIV_1   0
#define DGT_CLK_DIV_2   1
#define DGT_CLK_DIV_3   2
#define DGT_CLK_DIV_4   3
 
/**
 * init_timer - initialize timer
 */
void init_timer(void)
{
        /* disable timer */
        writel_i(0, DGT_ENABLE);
 
        /* DGT uses TCXO source which is 25MHz.
         * The timer should run at 1/4th the frequency of TCXO
         * according to clock plan.
         * Set clock divider to 4.
         */
        writel_i(DGT_CLK_DIV_4, DGT_CLK_CTL);
 
        /* Enable timer */
        writel_i(0, DGT_CLEAR);
        writel_i(DGT_ENABLE_EN, DGT_ENABLE);
}
 
/**
 * udelay -  generates micro second delay.
 * @param usec: delay duration in microseconds
 */
void udelay(unsigned int usec)
{
        uint32_t now;
        uint32_t last;
        uint32_t ticks;
        uint32_t curr_ticks = 0;
 
        /* Calculate number of ticks required. */
        ticks = TIMER_TICKS(usec);
 
        /* Obtain the current timer value. */
        last = readl_i(DGT_COUNT_VAL);
 
        /* Loop until the right number of ticks. */
        while (curr_ticks < ticks) {
                now = readl_i(DGT_COUNT_VAL);
                curr_ticks += now - last;
                last = now;
        }
}
 
void timer_monotonic_get(struct mono_time *mt)
{
        mono_time_set_usecs(mt, TIMER_USECS(readl_i(DGT_COUNT_VAL)));
}