COMMAND_QUEUE_PORT
writel(cmd->cmd_hi, master->regs + COMMAND_QUEUE_PORT);
writel(cmd->cmd_lo, master->regs + COMMAND_QUEUE_PORT);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[0]);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[1]);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[2]);
pio_reg_write(COMMAND_QUEUE_PORT, xfer->cmd_desc[3]);