static int __init global_timer_of_register()

in arm_global_timer.c [345:438]

• 75 lines of code
• 12 McCabe index (conditional complexity)

static int __init global_timer_of_register(struct device_node *np)
{
	struct clk *gt_clk;
	static unsigned long gt_clk_rate;
	int err = 0;

	/*
	 * In A9 r2p0 the comparators for each processor with the global timer
	 * fire when the timer value is greater than or equal to. In previous
	 * revisions the comparators fired when the timer value was equal to.
	 */
	if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9
	    && (read_cpuid_id() & 0xf0000f) < 0x200000) {
		pr_warn("global-timer: non support for this cpu version.\n");
		return -ENOSYS;
	}

	gt_ppi = irq_of_parse_and_map(np, 0);
	if (!gt_ppi) {
		pr_warn("global-timer: unable to parse irq\n");
		return -EINVAL;
	}

	gt_base = of_iomap(np, 0);
	if (!gt_base) {
		pr_warn("global-timer: invalid base address\n");
		return -ENXIO;
	}

	gt_clk = of_clk_get(np, 0);
	if (!IS_ERR(gt_clk)) {
		err = clk_prepare_enable(gt_clk);
		if (err)
			goto out_unmap;
	} else {
		pr_warn("global-timer: clk not found\n");
		err = -EINVAL;
		goto out_unmap;
	}

	gt_clk_rate = clk_get_rate(gt_clk);
	gt_target_rate = gt_clk_rate / CONFIG_ARM_GT_INITIAL_PRESCALER_VAL;
	gt_clk_rate_change_nb.notifier_call =
		gt_clk_rate_change_cb;
	err = clk_notifier_register(gt_clk, &gt_clk_rate_change_nb);
	if (err) {
		pr_warn("Unable to register clock notifier\n");
		goto out_clk;
	}

	gt_evt = alloc_percpu(struct clock_event_device);
	if (!gt_evt) {
		pr_warn("global-timer: can't allocate memory\n");
		err = -ENOMEM;
		goto out_clk_nb;
	}

	err = request_percpu_irq(gt_ppi, gt_clockevent_interrupt,
				 "gt", gt_evt);
	if (err) {
		pr_warn("global-timer: can't register interrupt %d (%d)\n",
			gt_ppi, err);
		goto out_free;
	}

	/* Register and immediately configure the timer on the boot CPU */
	err = gt_clocksource_init();
	if (err)
		goto out_irq;
	
	err = cpuhp_setup_state(CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
				"clockevents/arm/global_timer:starting",
				gt_starting_cpu, gt_dying_cpu);
	if (err)
		goto out_irq;

	gt_delay_timer_init();

	return 0;

out_irq:
	free_percpu_irq(gt_ppi, gt_evt);
out_free:
	free_percpu(gt_evt);
out_clk_nb:
	clk_notifier_unregister(gt_clk, &gt_clk_rate_change_nb);
out_clk:
	clk_disable_unprepare(gt_clk);
out_unmap:
	iounmap(gt_base);
	WARN(err, "ARM Global timer register failed (%d)\n", err);

	return err;
}