# Re: Linuxppc-dev Digest, Vol 81, Issue 140

- From: Josh Boyer \<hidden\>
- Date: 2011-05-27 10:34:18 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2011/05/9464742
- Thread: https://ratatoskr.run/linuxppc-dev/2011/05/9464741/t.md

```text
On Fri, May 27, 2011 at 12:26:20PM +0500, Muhammad Waseem wrote:
>I have developed a simple polling based serial device driver for PC's serial
>port (COM1: 0x3F8) which works fine. Now I want to implement the same on
>UART # 1 of PPC440EPx (Sequoia board).
>
>By changing the base address 0x3F8 to UART# 1 base address (0xEF600400) in
>Sequoia it does not work and return all the registers contents
>from 0xEF600400 to 0xEF600407 as 0xFF.
>
>Whereas existing ttyS1 driver works for UART# 1.
>
>How can I access the UART# 1 registers in a custom serial driver under
>kernel space.

If you post your driver code, we can review it.

josh
```