platform/vexpress-a15/timer.c

/*
 * Copyright (c) 2008-2012 Travis Geiselbrecht
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#include <debug.h>
#include <err.h>
#include <kernel/thread.h>
#include <platform.h>
#include <platform/interrupts.h>
#include <platform/timer.h>
#include <platform/vexpress-a15.h>
#include <sys/types.h>
#include "platform_p.h"

#define TIMREG(reg) (*REG32(TIMER0 + (reg)))

#define LOADVAL (0x00)
#define VAL (0x04)
#define CONTROL (0x08)
#define INTCLEAR (0x0c)
#define RAWINTSTAT (0x10)
#define MASKEDINTSTAT (0x14)

static platform_timer_callback t_callback;

static volatile uint ticks = 0;
static lk_time_t periodic_interval;

status_t platform_set_periodic_timer(platform_timer_callback callback,
                                     void* arg,
                                     lk_time_t interval) {
    enter_critical_section();

    t_callback = callback;

    periodic_interval = interval;
    TIMREG(LOADVAL) = periodic_interval * 1000; /* timer is running at 1Mhz */

    TIMREG(CONTROL) |= (1 << 7);  // enable

    unmask_interrupt(TIMER01_INT);

    exit_critical_section();

    return NO_ERROR;
}

lk_bigtime_t current_time_hires(void) {
    lk_bigtime_t time;

    time = ticks * periodic_interval * 1000ULL;

    return time;
}

lk_time_t current_time(void) {
    lk_time_t time;

    time = ticks * periodic_interval;

    return time;
}

static enum handler_return platform_tick(void* arg) {
    ticks++;
    TIMREG(INTCLEAR) = 1;
    if (t_callback) {
        return t_callback(arg, current_time());
    } else {
        return INT_NO_RESCHEDULE;
    }
}

void platform_init_timer(void) {
    /* disable timer */
    TIMREG(CONTROL) = 0;

    /* periodic mode, ints enabled, 32bit, wrapping */
    TIMREG(CONTROL) = (1 << 6) | (1 << 5) | (1 << 1);

    register_int_handler(TIMER01_INT, &platform_tick, NULL);
}