static int arc_pmu_device_probe()

in kernel/perf_event.c [723:829]

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

static int arc_pmu_device_probe(struct platform_device *pdev)
{
	struct arc_reg_pct_build pct_bcr;
	struct arc_reg_cc_build cc_bcr;
	int i, has_interrupts, irq = -1;
	int counter_size;	/* in bits */

	union cc_name {
		struct {
			u32 word0, word1;
			char sentinel;
		} indiv;
		char str[ARCPMU_EVENT_NAME_LEN];
	} cc_name;


	READ_BCR(ARC_REG_PCT_BUILD, pct_bcr);
	if (!pct_bcr.v) {
		pr_err("This core does not have performance counters!\n");
		return -ENODEV;
	}
	BUILD_BUG_ON(ARC_PERF_MAX_COUNTERS > 32);
	if (WARN_ON(pct_bcr.c > ARC_PERF_MAX_COUNTERS))
		return -EINVAL;

	READ_BCR(ARC_REG_CC_BUILD, cc_bcr);
	if (WARN(!cc_bcr.v, "Counters exist but No countable conditions?"))
		return -EINVAL;

	arc_pmu = devm_kzalloc(&pdev->dev, sizeof(struct arc_pmu), GFP_KERNEL);
	if (!arc_pmu)
		return -ENOMEM;

	arc_pmu->n_events = cc_bcr.c;

	if (arc_pmu_raw_alloc(&pdev->dev))
		return -ENOMEM;

	has_interrupts = is_isa_arcv2() ? pct_bcr.i : 0;

	arc_pmu->n_counters = pct_bcr.c;
	counter_size = 32 + (pct_bcr.s << 4);

	arc_pmu->max_period = (1ULL << counter_size) / 2 - 1ULL;

	pr_info("ARC perf\t: %d counters (%d bits), %d conditions%s\n",
		arc_pmu->n_counters, counter_size, cc_bcr.c,
		has_interrupts ? ", [overflow IRQ support]" : "");

	cc_name.str[ARCPMU_EVENT_NAME_LEN - 1] = 0;
	for (i = 0; i < PERF_COUNT_ARC_HW_MAX; i++)
		arc_pmu->ev_hw_idx[i] = -1;

	/* loop thru all available h/w condition indexes */
	for (i = 0; i < cc_bcr.c; i++) {
		write_aux_reg(ARC_REG_CC_INDEX, i);
		cc_name.indiv.word0 = le32_to_cpu(read_aux_reg(ARC_REG_CC_NAME0));
		cc_name.indiv.word1 = le32_to_cpu(read_aux_reg(ARC_REG_CC_NAME1));

		arc_pmu_map_hw_event(i, cc_name.str);
		arc_pmu_add_raw_event_attr(i, cc_name.str);
	}

	arc_pmu_events_attr_gr.attrs = arc_pmu->attrs;
	arc_pmu->attr_groups[ARCPMU_ATTR_GR_EVENTS] = &arc_pmu_events_attr_gr;
	arc_pmu->attr_groups[ARCPMU_ATTR_GR_FORMATS] = &arc_pmu_format_attr_gr;

	arc_pmu->pmu = (struct pmu) {
		.pmu_enable	= arc_pmu_enable,
		.pmu_disable	= arc_pmu_disable,
		.event_init	= arc_pmu_event_init,
		.add		= arc_pmu_add,
		.del		= arc_pmu_del,
		.start		= arc_pmu_start,
		.stop		= arc_pmu_stop,
		.read		= arc_pmu_read,
		.attr_groups	= arc_pmu->attr_groups,
	};

	if (has_interrupts) {
		irq = platform_get_irq(pdev, 0);
		if (irq >= 0) {
			int ret;

			arc_pmu->irq = irq;

			/* intc map function ensures irq_set_percpu_devid() called */
			ret = request_percpu_irq(irq, arc_pmu_intr, "ARC perf counters",
						 this_cpu_ptr(&arc_pmu_cpu));

			if (!ret)
				on_each_cpu(arc_cpu_pmu_irq_init, &irq, 1);
			else
				irq = -1;
		}

	}

	if (irq == -1)
		arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;

	/*
	 * perf parser doesn't really like '-' symbol in events name, so let's
	 * use '_' in arc pct name as it goes to kernel PMU event prefix.
	 */
	return perf_pmu_register(&arc_pmu->pmu, "arc_pct", PERF_TYPE_RAW);
}