static int quad8_function_write()

in 104-quad-8.c [240:300]

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

static int quad8_function_write(struct counter_device *counter,
				struct counter_count *count,
				enum counter_function function)
{
	struct quad8 *const priv = counter_priv(counter);
	const int id = count->id;
	unsigned int *const quadrature_mode = priv->quadrature_mode + id;
	unsigned int *const scale = priv->quadrature_scale + id;
	unsigned int *const synchronous_mode = priv->synchronous_mode + id;
	const int base_offset = priv->base + 2 * id + 1;
	unsigned long irqflags;
	unsigned int mode_cfg;
	unsigned int idr_cfg;

	spin_lock_irqsave(&priv->lock, irqflags);

	mode_cfg = priv->count_mode[id] << 1;
	idr_cfg = priv->index_polarity[id] << 1;

	if (function == COUNTER_FUNCTION_PULSE_DIRECTION) {
		*quadrature_mode = 0;

		/* Quadrature scaling only available in quadrature mode */
		*scale = 0;

		/* Synchronous function not supported in non-quadrature mode */
		if (*synchronous_mode) {
			*synchronous_mode = 0;
			/* Disable synchronous function mode */
			outb(QUAD8_CTR_IDR | idr_cfg, base_offset);
		}
	} else {
		*quadrature_mode = 1;

		switch (function) {
		case COUNTER_FUNCTION_QUADRATURE_X1_A:
			*scale = 0;
			mode_cfg |= QUAD8_CMR_QUADRATURE_X1;
			break;
		case COUNTER_FUNCTION_QUADRATURE_X2_A:
			*scale = 1;
			mode_cfg |= QUAD8_CMR_QUADRATURE_X2;
			break;
		case COUNTER_FUNCTION_QUADRATURE_X4:
			*scale = 2;
			mode_cfg |= QUAD8_CMR_QUADRATURE_X4;
			break;
		default:
			/* should never reach this path */
			spin_unlock_irqrestore(&priv->lock, irqflags);
			return -EINVAL;
		}
	}

	/* Load mode configuration to Counter Mode Register */
	outb(QUAD8_CTR_CMR | mode_cfg, base_offset);

	spin_unlock_irqrestore(&priv->lock, irqflags);

	return 0;
}