static int intel_qep_spike_filter_ns_write()

in intel-qep.c [275:322]

• 38 lines of code
• 6 McCabe index (conditional complexity)

static int intel_qep_spike_filter_ns_write(struct counter_device *counter,
					   struct counter_count *count,
					   u64 length)
{
	struct intel_qep *qep = counter_priv(counter);
	u32 reg;
	bool enable;
	int ret = 0;

	/*
	 * Spike filter length is (MAX_COUNT + 2) clock periods.
	 * Disable filter when userspace writes 0, enable for valid
	 * nanoseconds values and error out otherwise.
	 */
	do_div(length, INTEL_QEP_CLK_PERIOD_NS);
	if (length == 0) {
		enable = false;
		length = 0;
	} else if (length >= 2) {
		enable = true;
		length -= 2;
	} else {
		return -EINVAL;
	}

	if (length > INTEL_QEPFLT_MAX_COUNT(length))
		return -ERANGE;

	mutex_lock(&qep->lock);
	if (qep->enabled) {
		ret = -EBUSY;
		goto out;
	}

	pm_runtime_get_sync(qep->dev);
	reg = intel_qep_readl(qep, INTEL_QEPCON);
	if (enable)
		reg |= INTEL_QEPCON_FLT_EN;
	else
		reg &= ~INTEL_QEPCON_FLT_EN;
	intel_qep_writel(qep, INTEL_QEPFLT, length);
	intel_qep_writel(qep, INTEL_QEPCON, reg);
	pm_runtime_put(qep->dev);

out:
	mutex_unlock(&qep->lock);
	return ret;
}