static ssize_t fake_master_read()

in bridges/vme_fake.c [516:613]

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

static ssize_t fake_master_read(struct vme_master_resource *image, void *buf,
		size_t count, loff_t offset)
{
	int retval;
	u32 aspace, cycle, dwidth;
	struct vme_bridge *fake_bridge;
	struct fake_driver *priv;
	int i;
	unsigned long long addr;
	unsigned int done = 0;
	unsigned int count32;

	fake_bridge = image->parent;

	priv = fake_bridge->driver_priv;

	i = image->number;

	addr = (unsigned long long)priv->masters[i].vme_base + offset;
	aspace = priv->masters[i].aspace;
	cycle = priv->masters[i].cycle;
	dwidth = priv->masters[i].dwidth;

	spin_lock(&image->lock);

	/* The following code handles VME address alignment. We cannot use
	 * memcpy_xxx here because it may cut data transfers in to 8-bit
	 * cycles when D16 or D32 cycles are required on the VME bus.
	 * On the other hand, the bridge itself assures that the maximum data
	 * cycle configured for the transfer is used and splits it
	 * automatically for non-aligned addresses, so we don't want the
	 * overhead of needlessly forcing small transfers for the entire cycle.
	 */
	if (addr & 0x1) {
		*(u8 *)buf = fake_vmeread8(priv, addr, aspace, cycle);
		done += 1;
		if (done == count)
			goto out;
	}
	if ((dwidth == VME_D16) || (dwidth == VME_D32)) {
		if ((addr + done) & 0x2) {
			if ((count - done) < 2) {
				*(u8 *)(buf + done) = fake_vmeread8(priv,
						addr + done, aspace, cycle);
				done += 1;
				goto out;
			} else {
				*(u16 *)(buf + done) = fake_vmeread16(priv,
						addr + done, aspace, cycle);
				done += 2;
			}
		}
	}

	if (dwidth == VME_D32) {
		count32 = (count - done) & ~0x3;
		while (done < count32) {
			*(u32 *)(buf + done) = fake_vmeread32(priv, addr + done,
					aspace, cycle);
			done += 4;
		}
	} else if (dwidth == VME_D16) {
		count32 = (count - done) & ~0x3;
		while (done < count32) {
			*(u16 *)(buf + done) = fake_vmeread16(priv, addr + done,
					aspace, cycle);
			done += 2;
		}
	} else if (dwidth == VME_D8) {
		count32 = (count - done);
		while (done < count32) {
			*(u8 *)(buf + done) = fake_vmeread8(priv, addr + done,
					aspace, cycle);
			done += 1;
		}

	}

	if ((dwidth == VME_D16) || (dwidth == VME_D32)) {
		if ((count - done) & 0x2) {
			*(u16 *)(buf + done) = fake_vmeread16(priv, addr + done,
					aspace, cycle);
			done += 2;
		}
	}
	if ((count - done) & 0x1) {
		*(u8 *)(buf + done) = fake_vmeread8(priv, addr + done, aspace,
				cycle);
		done += 1;
	}

out:
	retval = count;

	spin_unlock(&image->lock);

	return retval;
}