int hpet_alloc()

in hpet.c [835:957]

• 89 lines of code
• 14 McCabe index (conditional complexity)

int hpet_alloc(struct hpet_data *hdp)
{
	u64 cap, mcfg;
	struct hpet_dev *devp;
	u32 i, ntimer;
	struct hpets *hpetp;
	struct hpet __iomem *hpet;
	static struct hpets *last;
	unsigned long period;
	unsigned long long temp;
	u32 remainder;

	/*
	 * hpet_alloc can be called by platform dependent code.
	 * If platform dependent code has allocated the hpet that
	 * ACPI has also reported, then we catch it here.
	 */
	if (hpet_is_known(hdp)) {
		printk(KERN_DEBUG "%s: duplicate HPET ignored\n",
			__func__);
		return 0;
	}

	hpetp = kzalloc(struct_size(hpetp, hp_dev, hdp->hd_nirqs),
			GFP_KERNEL);

	if (!hpetp)
		return -ENOMEM;

	hpetp->hp_which = hpet_nhpet++;
	hpetp->hp_hpet = hdp->hd_address;
	hpetp->hp_hpet_phys = hdp->hd_phys_address;

	hpetp->hp_ntimer = hdp->hd_nirqs;

	for (i = 0; i < hdp->hd_nirqs; i++)
		hpetp->hp_dev[i].hd_hdwirq = hdp->hd_irq[i];

	hpet = hpetp->hp_hpet;

	cap = readq(&hpet->hpet_cap);

	ntimer = ((cap & HPET_NUM_TIM_CAP_MASK) >> HPET_NUM_TIM_CAP_SHIFT) + 1;

	if (hpetp->hp_ntimer != ntimer) {
		printk(KERN_WARNING "hpet: number irqs doesn't agree"
		       " with number of timers\n");
		kfree(hpetp);
		return -ENODEV;
	}

	if (last)
		last->hp_next = hpetp;
	else
		hpets = hpetp;

	last = hpetp;

	period = (cap & HPET_COUNTER_CLK_PERIOD_MASK) >>
		HPET_COUNTER_CLK_PERIOD_SHIFT; /* fs, 10^-15 */
	temp = 1000000000000000uLL; /* 10^15 femtoseconds per second */
	temp += period >> 1; /* round */
	do_div(temp, period);
	hpetp->hp_tick_freq = temp; /* ticks per second */

	printk(KERN_INFO "hpet%d: at MMIO 0x%lx, IRQ%s",
		hpetp->hp_which, hdp->hd_phys_address,
		hpetp->hp_ntimer > 1 ? "s" : "");
	for (i = 0; i < hpetp->hp_ntimer; i++)
		printk(KERN_CONT "%s %d", i > 0 ? "," : "", hdp->hd_irq[i]);
	printk(KERN_CONT "\n");

	temp = hpetp->hp_tick_freq;
	remainder = do_div(temp, 1000000);
	printk(KERN_INFO
		"hpet%u: %u comparators, %d-bit %u.%06u MHz counter\n",
		hpetp->hp_which, hpetp->hp_ntimer,
		cap & HPET_COUNTER_SIZE_MASK ? 64 : 32,
		(unsigned) temp, remainder);

	mcfg = readq(&hpet->hpet_config);
	if ((mcfg & HPET_ENABLE_CNF_MASK) == 0) {
		write_counter(0L, &hpet->hpet_mc);
		mcfg |= HPET_ENABLE_CNF_MASK;
		writeq(mcfg, &hpet->hpet_config);
	}

	for (i = 0, devp = hpetp->hp_dev; i < hpetp->hp_ntimer; i++, devp++) {
		struct hpet_timer __iomem *timer;

		timer = &hpet->hpet_timers[devp - hpetp->hp_dev];

		devp->hd_hpets = hpetp;
		devp->hd_hpet = hpet;
		devp->hd_timer = timer;

		/*
		 * If the timer was reserved by platform code,
		 * then make timer unavailable for opens.
		 */
		if (hdp->hd_state & (1 << i)) {
			devp->hd_flags = HPET_OPEN;
			continue;
		}

		init_waitqueue_head(&devp->hd_waitqueue);
	}

	hpetp->hp_delta = hpet_calibrate(hpetp);

/* This clocksource driver currently only works on ia64 */
#ifdef CONFIG_IA64
	if (!hpet_clocksource) {
		hpet_mctr = (void __iomem *)&hpetp->hp_hpet->hpet_mc;
		clocksource_hpet.archdata.fsys_mmio = hpet_mctr;
		clocksource_register_hz(&clocksource_hpet, hpetp->hp_tick_freq);
		hpetp->hp_clocksource = &clocksource_hpet;
		hpet_clocksource = &clocksource_hpet;
	}
#endif

	return 0;
}