AM335x如何使用timer（Kernel 4.4）

自己写驱动，对底层的硬件寄存器进行操作

我从e2e上找到个例子，用的plat/dmtimer.h的API，不知道对不对

/****************************************************************/
/* PWM Timer Driver used to trig A/D convert                    */
/****************************************************************/

int timer_pwm_init(struct as_platform_data *as_data)
{
    struct omap_dm_timer *timer_pwm_ptr;

    int ret = 1;
    int timer_reload;
    struct clk *timer_clk;

    if (as_data == NULL)
    {
        printk(KERN_ERR "timer_pwm_init got NULL as_data.\n");
        return(-1);
    }

    timer_pwm_ptr = as_data->timer_pwm;

    /* Set the Clock source to the System Clock */
    ret = omap_dm_timer_set_source(timer_pwm_ptr, OMAP_TIMER_SRC_SYS_CLK);

    /* Determine what IRQ the timer triggers */
    as_data->timer_pwm_irq = omap_dm_timer_get_irq(timer_pwm_ptr);

    /* Get the Clock rate in Hz */
    timer_clk = omap_dm_timer_get_fclk(timer_pwm_ptr);
    as_data->timer_pwm_rate = clk_get_rate(timer_clk);

    /* calc 50Hz * 512 initial rate */
    as_data->timer_pwm_clks_per_cycle = as_data->timer_pwm_rate / (50 * 512);
    /* calc reload value, maybe +1 is needed if output freq is not accurate */
    timer_reload = 0xFFFFFFFF - as_data->timer_pwm_clks_per_cycle; // +1

    /* Setup the Output for the Timer pin */
    /* Setup to toggle on the overflow and the compare match event */
    omap_dm_timer_set_pwm(timer_pwm_ptr, 0, 1, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE);

    /* Enable the Timer */
    /* Needs to be done before we can write to the counter */
    omap_dm_timer_enable(timer_pwm_ptr);

    /* Set the initial Count */
    /* According to section 20.1.3.5 Pulse-Width Modulation, an overflow or match be used to toggle when a compare condition occurs*/
    /* Therefore it we will trigger the overflow event almost immediately to ensure our toggle will be generated quickly */
    omap_dm_timer_write_counter(timer_pwm_ptr, (0xFFFFFFFF - 5));

    /* Setup the Load Register */
    /* Setup as autoload to set the the counter back to 0 on an overflow */
    omap_dm_timer_set_load(timer_pwm_ptr, 1, timer_reload);

    /* Set the the compare register to half of cycle */
    omap_dm_timer_set_match(timer_pwm_ptr, 1, timer_reload + 5);

    /* Start the timer */
    ret = omap_dm_timer_start(timer_pwm_ptr);


    printk(KERN_INFO "PWM timer started. CLK = %u Cycle = %u\n", \
            as_data->timer_pwm_rate, as_data->timer_pwm_clks_per_cycle);
    /*
    * A non 0 returns means the call to init_modules failed; module can't be loaded
    */
    return 0;
}

你好，请问后来你找到解决问题的方法了么？我现在也需要做个硬件的定时器驱动，3.2的内核。可不可以给个指导

请问能不能麻烦你把链接发出来呢，我想查看完整的代码

hrtimer 在高负载的时候不准很正常，就是kernel中的关中断的临界区