in devices/ipoctal.c [60:68]
static void ipoctal_reset_channel(struct ipoctal_channel *channel)
{
iowrite8(CR_DISABLE_RX | CR_DISABLE_TX, &channel->regs->w.cr);
channel->rx_enable = 0;
iowrite8(CR_CMD_RESET_RX, &channel->regs->w.cr);
iowrite8(CR_CMD_RESET_TX, &channel->regs->w.cr);
iowrite8(CR_CMD_RESET_ERR_STATUS, &channel->regs->w.cr);
iowrite8(CR_CMD_RESET_MR, &channel->regs->w.cr);
}