static long d7s_ioctl()

in char/display7seg.c [102:153]

• 37 lines of code
• 9 McCabe index (conditional complexity)

static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct d7s *p = d7s_device;
	u8 regs = readb(p->regs);
	int error = 0;
	u8 ireg = 0;

	if (D7S_MINOR != iminor(file_inode(file)))
		return -ENODEV;

	mutex_lock(&d7s_mutex);
	switch (cmd) {
	case D7SIOCWR:
		/* assign device register values we mask-out D7S_FLIP
		 * if in sol_compat mode
		 */
		if (get_user(ireg, (int __user *) arg)) {
			error = -EFAULT;
			break;
		}
		if (sol_compat) {
			if (regs & D7S_FLIP)
				ireg |= D7S_FLIP;
			else
				ireg &= ~D7S_FLIP;
		}
		writeb(ireg, p->regs);
		break;

	case D7SIOCRD:
		/* retrieve device register values
		 * NOTE: Solaris implementation returns D7S_FLIP bit
		 * as toggled by user, even though it does not honor it.
		 * This driver will not misinform you about the state
		 * of your hardware while in sol_compat mode
		 */
		if (put_user(regs, (int __user *) arg)) {
			error = -EFAULT;
			break;
		}
		break;

	case D7SIOCTM:
		/* toggle device mode-- flip display orientation */
		regs ^= D7S_FLIP;
		writeb(regs, p->regs);
		break;
	}
	mutex_unlock(&d7s_mutex);

	return error;
}