static int __init at91sam926x_pit_dt_init()

in timer-atmel-pit.c [166:262]

• 71 lines of code
• 8 McCabe index (conditional complexity)

static int __init at91sam926x_pit_dt_init(struct device_node *node)
{
	unsigned long   pit_rate;
	unsigned        bits;
	int             ret;
	struct pit_data *data;

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->base = of_iomap(node, 0);
	if (!data->base) {
		pr_err("Could not map PIT address\n");
		ret = -ENXIO;
		goto exit;
	}

	data->mck = of_clk_get(node, 0);
	if (IS_ERR(data->mck)) {
		pr_err("Unable to get mck clk\n");
		ret = PTR_ERR(data->mck);
		goto exit;
	}

	ret = clk_prepare_enable(data->mck);
	if (ret) {
		pr_err("Unable to enable mck\n");
		goto exit;
	}

	/* Get the interrupts property */
	data->irq = irq_of_parse_and_map(node, 0);
	if (!data->irq) {
		pr_err("Unable to get IRQ from DT\n");
		ret = -EINVAL;
		goto exit;
	}

	/*
	 * Use our actual MCK to figure out how many MCK/16 ticks per
	 * 1/HZ period (instead of a compile-time constant LATCH).
	 */
	pit_rate = clk_get_rate(data->mck) / 16;
	data->cycle = DIV_ROUND_CLOSEST(pit_rate, HZ);
	WARN_ON(((data->cycle - 1) & ~AT91_PIT_PIV) != 0);

	/* Initialize and enable the timer */
	at91sam926x_pit_reset(data);

	/*
	 * Register clocksource.  The high order bits of PIV are unused,
	 * so this isn't a 32-bit counter unless we get clockevent irqs.
	 */
	bits = 12 /* PICNT */ + ilog2(data->cycle) /* PIV */;
	data->clksrc.mask = CLOCKSOURCE_MASK(bits);
	data->clksrc.name = "pit";
	data->clksrc.rating = 175;
	data->clksrc.read = read_pit_clk;
	data->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
	
	ret = clocksource_register_hz(&data->clksrc, pit_rate);
	if (ret) {
		pr_err("Failed to register clocksource\n");
		goto exit;
	}

	/* Set up irq handler */
	ret = request_irq(data->irq, at91sam926x_pit_interrupt,
			  IRQF_SHARED | IRQF_TIMER | IRQF_IRQPOLL,
			  "at91_tick", data);
	if (ret) {
		pr_err("Unable to setup IRQ\n");
		clocksource_unregister(&data->clksrc);
		goto exit;
	}

	/* Set up and register clockevents */
	data->clkevt.name = "pit";
	data->clkevt.features = CLOCK_EVT_FEAT_PERIODIC;
	data->clkevt.shift = 32;
	data->clkevt.mult = div_sc(pit_rate, NSEC_PER_SEC, data->clkevt.shift);
	data->clkevt.rating = 100;
	data->clkevt.cpumask = cpumask_of(0);

	data->clkevt.set_state_shutdown = pit_clkevt_shutdown;
	data->clkevt.set_state_periodic = pit_clkevt_set_periodic;
	data->clkevt.resume = at91sam926x_pit_resume;
	data->clkevt.suspend = at91sam926x_pit_suspend;
	clockevents_register_device(&data->clkevt);

	return 0;

exit:
	kfree(data);
	return ret;
}