C++ sched_clock_register函数代码示例

static void __init intcp_init_early(void)
{
	cm_map = syscon_regmap_lookup_by_compatible("arm,core-module-integrator");
	if (IS_ERR(cm_map))
		return;
	sched_clock_register(intcp_read_sched_clock, 32, 24000000);
}

static int __init integrator_clocksource_init(unsigned long inrate,
					      void __iomem *base)
{
	u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC;
	unsigned long rate = inrate;
	int ret;

	if (rate >= 1500000) {
		rate /= 16;
		ctrl |= TIMER_CTRL_DIV16;
	}

	writel(0xffff, base + TIMER_LOAD);
	writel(ctrl, base + TIMER_CTRL);

	ret = clocksource_mmio_init(base + TIMER_VALUE, "timer2",
				    rate, 200, 16, clocksource_mmio_readl_down);
	if (ret)
		return ret;

	sched_clk_base = base;
	sched_clock_register(integrator_read_sched_clock, 16, rate);

	return 0;
}

static void __init bcm2708_timer_init(void)
{
	if (of_have_populated_dt()) {
		of_clk_init(NULL);
		clocksource_of_init();
		return;
	}

	/* init high res timer */
	bcm2708_clocksource_init();

	/*
	 * Make irqs happen for the system timer
	 */
	setup_irq(IRQ_TIMER3, &bcm2708_timer_irq);

	sched_clock_register(bcm2708_read_sched_clock, 32, STC_FREQ_HZ);

	timer0_clockevent.mult =
	    div_sc(STC_FREQ_HZ, NSEC_PER_SEC, timer0_clockevent.shift);
	timer0_clockevent.max_delta_ns =
	    clockevent_delta2ns(0xffffffff, &timer0_clockevent);
	timer0_clockevent.min_delta_ns =
	    clockevent_delta2ns(0xf, &timer0_clockevent);

	timer0_clockevent.cpumask = cpumask_of(0);
	clockevents_register_device(&timer0_clockevent);

	register_current_timer_delay(&bcm2708_delay_timer);
}

void __init iop_init_time(unsigned long tick_rate)
{
	u32 timer_ctl;

	sched_clock_register(iop_read_sched_clock, 32, tick_rate);

	ticks_per_jiffy = DIV_ROUND_CLOSEST(tick_rate, HZ);
	iop_tick_rate = tick_rate;

	timer_ctl = IOP_TMR_EN | IOP_TMR_PRIVILEGED |
			IOP_TMR_RELOAD | IOP_TMR_RATIO_1_1;

	/*
	 * Set up interrupting clockevent timer 0.
	 */
	write_tmr0(timer_ctl & ~IOP_TMR_EN);
	write_tisr(1);
	setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq);
	iop_clockevent.cpumask = cpumask_of(0);
	clockevents_config_and_register(&iop_clockevent, tick_rate,
					0xf, 0xfffffffe);

	/*
	 * Set up free-running clocksource timer 1.
	 */
	write_trr1(0xffffffff);
	write_tcr1(0xffffffff);
	write_tmr1(timer_ctl);
	clocksource_register_hz(&iop_clocksource, tick_rate);
}

static void __init arch_counter_register(unsigned type)
{
	u64 start_count;

	/* Register the CP15 based counter if we have one */
	if (type & ARCH_CP15_TIMER) {
		if (IS_ENABLED(CONFIG_ARM64) || arch_timer_use_virtual)
			arch_timer_read_counter = arch_counter_get_cntvct;
		else
			arch_timer_read_counter = arch_counter_get_cntpct;
	} else {
		arch_timer_read_counter = arch_counter_get_cntvct_mem;

		/* If the clocksource name is "arch_sys_counter" the
		 * VDSO will attempt to read the CP15-based counter.
		 * Ensure this does not happen when CP15-based
		 * counter is not available.
		 */
		clocksource_counter.name = "arch_mem_counter";
	}

	start_count = arch_timer_read_counter();
	clocksource_register_hz(&clocksource_counter, arch_timer_rate);
	cyclecounter.mult = clocksource_counter.mult;
	cyclecounter.shift = clocksource_counter.shift;
	timecounter_init(&timecounter, &cyclecounter, start_count);

	/* 56 bits minimum, so we assume worst case rollover */
	sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
}

static void __init omap2_gptimer_clocksource_init(int gptimer_id,
						  const char *fck_source,
						  const char *property)
{
	int res;

	clksrc.id = gptimer_id;
	clksrc.errata = omap_dm_timer_get_errata();

	res = omap_dm_timer_init_one(&clksrc, fck_source, property,
				     &clocksource_gpt.name,
				     OMAP_TIMER_NONPOSTED);
	BUG_ON(res);

	__omap_dm_timer_load_start(&clksrc,
				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0,
				   OMAP_TIMER_NONPOSTED);
	sched_clock_register(dmtimer_read_sched_clock, 32, clksrc.rate);

	if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
		pr_err("Could not register clocksource %s\n",
			clocksource_gpt.name);
	else
		pr_info("OMAP clocksource: %s at %lu Hz\n",
			clocksource_gpt.name, clksrc.rate);
}

static inline void setup_clksrc(u32 freq)
{
	struct clocksource *cs = &gpt_clocksource;
	struct gpt_device *dev = id_to_dev(GPT_CLKSRC_ID);
	struct timecounter *mt_timecounter;
	u64 start_count;

	pr_alert("setup_clksrc1: dev->base_addr=0x%lx GPT2_CON=0x%x\n",
		(unsigned long)dev->base_addr, __raw_readl(dev->base_addr));
	cs->mult = clocksource_hz2mult(freq, cs->shift);
	sched_clock_register(mt_read_sched_clock, 32, freq);

	setup_gpt_dev_locked(dev, GPT_FREE_RUN, GPT_CLK_SRC_SYS, GPT_CLK_DIV_1,
		0, NULL, 0);

	clocksource_register(cs);

	start_count = mt_read_sched_clock();
	mt_cyclecounter.mult = cs->mult;
	mt_cyclecounter.shift = cs->shift;
	mt_timecounter = arch_timer_get_timecounter();
	timecounter_init(mt_timecounter, &mt_cyclecounter, start_count);
	pr_alert("setup_clksrc1: mt_cyclecounter.mult=0x%x mt_cyclecounter.shift=0x%x\n",
		mt_cyclecounter.mult, mt_cyclecounter.shift);
	pr_alert("setup_clksrc2: dev->base_addr=0x%lx GPT2_CON=0x%x\n",
		(unsigned long)dev->base_addr, __raw_readl(dev->base_addr));
}

static void __init tango_clocksource_init(struct device_node *np)
{
	struct clk *clk;
	int xtal_freq, ret;

	xtal_in_cnt = of_iomap(np, 0);
	if (xtal_in_cnt == NULL) {
		pr_err("%s: invalid address\n", np->full_name);
		return;
	}

	clk = of_clk_get(np, 0);
	if (IS_ERR(clk)) {
		pr_err("%s: invalid clock\n", np->full_name);
		return;
	}

	xtal_freq = clk_get_rate(clk);
	delay_timer.freq = xtal_freq;
	delay_timer.read_current_timer = read_xtal_counter;

	ret = clocksource_register_hz(&tango_xtal, xtal_freq);
	if (ret != 0) {
		pr_err("%s: registration failed\n", np->full_name);
		return;
	}

	sched_clock_register(read_sched_clock, 32, xtal_freq);
	register_current_timer_delay(&delay_timer);
}

static int __init lpc32xx_clocksource_init(struct device_node *np)
{
	void __iomem *base;
	unsigned long rate;
	struct clk *clk;
	int ret;

	clk = of_clk_get_by_name(np, "timerclk");
	if (IS_ERR(clk)) {
		pr_err("clock get failed (%lu)\n", PTR_ERR(clk));
		return PTR_ERR(clk);
	}

	ret = clk_prepare_enable(clk);
	if (ret) {
		pr_err("clock enable failed (%d)\n", ret);
		goto err_clk_enable;
	}

	base = of_iomap(np, 0);
	if (!base) {
		pr_err("unable to map registers\n");
		ret = -EADDRNOTAVAIL;
		goto err_iomap;
	}

	/*
	 * Disable and reset timer then set it to free running timer
	 * mode (CTCR) with no prescaler (PR) or match operations (MCR).
	 * After setup the timer is released from reset and enabled.
	 */
	writel_relaxed(LPC32XX_TIMER_TCR_CRST, base + LPC32XX_TIMER_TCR);
	writel_relaxed(0, base + LPC32XX_TIMER_PR);
	writel_relaxed(0, base + LPC32XX_TIMER_MCR);
	writel_relaxed(0, base + LPC32XX_TIMER_CTCR);
	writel_relaxed(LPC32XX_TIMER_TCR_CEN, base + LPC32XX_TIMER_TCR);

	rate = clk_get_rate(clk);
	ret = clocksource_mmio_init(base + LPC32XX_TIMER_TC, "lpc3220 timer",
				    rate, 300, 32, clocksource_mmio_readl_up);
	if (ret) {
		pr_err("failed to init clocksource (%d)\n", ret);
		goto err_clocksource_init;
	}

	clocksource_timer_counter = base + LPC32XX_TIMER_TC;
	sched_clock_register(lpc32xx_read_sched_clock, 32, rate);

	return 0;

err_clocksource_init:
	iounmap(base);
err_iomap:
	clk_disable_unprepare(clk);
err_clk_enable:
	clk_put(clk);
	return ret;
}

/* initialize the kernel jiffy timer source */
static int __init sirfsoc_prima2_timer_init(struct device_node *np)
{
    unsigned long rate;
    struct clk *clk;
    int ret;

    clk = of_clk_get(np, 0);
    if (IS_ERR(clk)) {
        pr_err("Failed to get clock");
        return PTR_ERR(clk);
    }

    ret = clk_prepare_enable(clk);
    if (ret) {
        pr_err("Failed to enable clock");
        return ret;
    }

    rate = clk_get_rate(clk);

    if (rate < PRIMA2_CLOCK_FREQ || rate % PRIMA2_CLOCK_FREQ) {
        pr_err("Invalid clock rate");
        return -EINVAL;
    }

    sirfsoc_timer_base = of_iomap(np, 0);
    if (!sirfsoc_timer_base) {
        pr_err("unable to map timer cpu registers\n");
        return -ENXIO;
    }

    sirfsoc_timer_irq.irq = irq_of_parse_and_map(np, 0);

    writel_relaxed(rate / PRIMA2_CLOCK_FREQ / 2 - 1,
                   sirfsoc_timer_base + SIRFSOC_TIMER_DIV);
    writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO);
    writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI);
    writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);

    ret = clocksource_register_hz(&sirfsoc_clocksource, PRIMA2_CLOCK_FREQ);
    if (ret) {
        pr_err("Failed to register clocksource");
        return ret;
    }

    sched_clock_register(sirfsoc_read_sched_clock, 64, PRIMA2_CLOCK_FREQ);

    ret = setup_irq(sirfsoc_timer_irq.irq, &sirfsoc_timer_irq);
    if (ret) {
        pr_err("Failed to setup irq");
        return ret;
    }

    sirfsoc_clockevent_init();

    return 0;
}

static int __init csky_mptimer_init(struct device_node *np)
{
	int ret, cpu, cpu_rollback;
	struct timer_of *to = NULL;

	/*
	 * Csky_mptimer is designed for C-SKY SMP multi-processors and
	 * every core has it's own private irq and regs for clkevt and
	 * clksrc.
	 *
	 * The regs is accessed by cpu instruction: mfcr/mtcr instead of
	 * mmio map style. So we needn't mmio-address in dts, but we still
	 * need to give clk and irq number.
	 *
	 * We use private irq for the mptimer and irq number is the same
	 * for every core. So we use request_percpu_irq() in timer_of_init.
	 */
	csky_mptimer_irq = irq_of_parse_and_map(np, 0);
	if (csky_mptimer_irq <= 0)
		return -EINVAL;

	ret = request_percpu_irq(csky_mptimer_irq, csky_timer_interrupt,
				 "csky_mp_timer", &csky_to);
	if (ret)
		return -EINVAL;

	for_each_possible_cpu(cpu) {
		to = per_cpu_ptr(&csky_to, cpu);
		ret = timer_of_init(np, to);
		if (ret)
			goto rollback;
	}

	clocksource_register_hz(&csky_clocksource, timer_of_rate(to));
	sched_clock_register(sched_clock_read, 32, timer_of_rate(to));

	ret = cpuhp_setup_state(CPUHP_AP_CSKY_TIMER_STARTING,
				"clockevents/csky/timer:starting",
				csky_mptimer_starting_cpu,
				csky_mptimer_dying_cpu);
	if (ret)
		return -EINVAL;

	return 0;

rollback:
	for_each_possible_cpu(cpu_rollback) {
		if (cpu_rollback == cpu)
			break;

		to = per_cpu_ptr(&csky_to, cpu_rollback);
		timer_of_cleanup(to);
	}
	return -EINVAL;
}

static int __init pit_clocksource_init(unsigned long rate)
{
    /* set the max load value and start the clock source counter */
    __raw_writel(0, clksrc_base + PITTCTRL);
    __raw_writel(~0UL, clksrc_base + PITLDVAL);
    __raw_writel(PITTCTRL_TEN, clksrc_base + PITTCTRL);

    sched_clock_register(pit_read_sched_clock, 32, rate);
    return clocksource_mmio_init(clksrc_base + PITCVAL, "vf-pit", rate,
                                 300, 32, clocksource_mmio_readl_down);
}

static inline void setup_clksrc(void)
{
    struct clocksource *cs = &mt6582_gpt.clocksource;
    struct gpt_device *dev = id_to_dev(GPT_CLKSRC_ID);

    cs->mult = clocksource_hz2mult(SYS_CLK_RATE, cs->shift);

    setup_gpt_dev_locked(dev, GPT_FREE_RUN, GPT_CLK_SRC_SYS, GPT_CLK_DIV_1,
                0, NULL, 0);
    sched_clock_register((void *)mt_read_sched_clock, 32, SYS_CLK_RATE);
}

static void __init versatile_sched_clock_init(struct device_node *node)
{
	void __iomem *base = of_iomap(node, 0);

	if (!base)
		return;

	versatile_sys_24mhz = base + SYS_24MHZ;

	sched_clock_register(versatile_sys_24mhz_read, 32, 24000000);
}

static void __init sun4i_timer_init(struct device_node *node)
{
	unsigned long rate = 0;
	struct clk *clk;
	int ret, irq;
	u32 val;

	timer_base = of_iomap(node, 0);
	if (!timer_base)
		panic("Can't map registers");

	irq = irq_of_parse_and_map(node, 0);
	if (irq <= 0)
		panic("Can't parse IRQ");

	clk = of_clk_get(node, 0);
	if (IS_ERR(clk))
		panic("Can't get timer clock");
	clk_prepare_enable(clk);

	rate = clk_get_rate(clk);

	writel(~0, timer_base + TIMER_INTVAL_REG(1));
	writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
	       TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
	       timer_base + TIMER_CTL_REG(1));

	sched_clock_register(sun4i_timer_sched_read, 32, rate);
	clocksource_mmio_init(timer_base + TIMER_CNTVAL_REG(1), node->name,
			      rate, 350, 32, clocksource_mmio_readl_down);

	ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);

	writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
	       timer_base + TIMER_CTL_REG(0));

	/* Make sure timer is stopped before playing with interrupts */
	sun4i_clkevt_time_stop(0);

	ret = setup_irq(irq, &sun4i_timer_irq);
	if (ret)
		pr_warn("failed to setup irq %d\n", irq);

	/* Enable timer0 interrupt */
	val = readl(timer_base + TIMER_IRQ_EN_REG);
	writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);

	sun4i_clockevent.cpumask = cpu_possible_mask;
	sun4i_clockevent.irq = irq;

	clockevents_config_and_register(&sun4i_clockevent, rate,
					TIMER_SYNC_TICKS, 0xffffffff);
}