How to get a list of all available serial ports?

How to get a list of all available serial ports?

[Francisco M. Marzoa Alonso]

Hi,

Under Windows my program is able to perform an autodetection of the device 
with which it work. For that it takes a list of all available serial ports 
from Windows registry. 

Is there any manner to do the same under LiNUX that works on all 
distributions?

Thx.


-- 
Francisco M. Marzoa Alonso
Responsable de Software - Softrónica S.A.
http://www.softronica.org/
C/Herrerías, 14 - 28760 Tres Cantos (Madrid)
tfno. +34 918 038 600  fax. +34 918 032 297
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Re: How to get a list of all available serial ports?

[Jan-Benedict Glaw]

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On Thu, 2004-08-26 09:24:02 +0200, Francisco M. Marzoa Alonso <fmmarzoa@softronica.org>
wrote in message <200408260924.02123.fmmarzoa@softronica.org>:
> Under Windows my program is able to perform an autodetection of the device 
> with which it work. For that it takes a list of all available serial ports 
> from Windows registry. 
> 
> Is there any manner to do the same under LiNUX that works on all 
> distributions?

There are several solutions:

- opendir()/readdir()/closedir() "/dev/" and strncmp(ent->d_name, "ttyS", 4),
  then open all matches with O_NONBLOCK to see if you not get ENODEV
  from errno. This works on "traditional" systems not using something
  like devfs. Also, you'd better stat() all hits to not get false
  positives from things like symlinks.
- opendir/readdir/closedir "/dev/ttyS/" and iterate through all entries.
  These are solely serial ports, so not that much postprocessing
  involved. However, that would only work with devfs...
- open /proc/tty/driver/serial, check the format (first line), read all
  further lines and check if uart is != "unknown".

For sure, there are more techniques, like
	- if you're runnung with root privileges, you'd temporarily
	  create new device nodes for char devices, and mojor/minor
	  number from /proc/tty/drivers (the "^serial" lines).
	- check major/minor from /sys/class/tty/ttyS* (open() checking
	  for ENODEV in errno...), but that'd require creating temporary
	  device nodes and also having a 2.6.x kernel...

Personally, I don't like software that tries to "know better" than I do.
I'd like telling a program "use this device node and shut up!" and
possibly others would like to have it work that way, too...

MfG, JBG

-- 
Jan-Benedict Glaw       jbglaw@lug-owl.de    . +49-172-7608481             _ O _
"Eine Freie Meinung in  einem Freien Kopf    | Gegen Zensur | Gegen Krieg  _ _ O
 fuer einen Freien Staat voll Freier Bürger" | im Internet! |   im Irak!   O O O
ret = do_actions((curr | FREE_SPEECH) & ~(NEW_COPYRIGHT_LAW | DRM | TCPA));

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Re: How to get a list of all available serial ports?

[Salomon, Frank]

> Under Windows my program is able to perform an autodetection of the device 
> with which it work. For that it takes a list of all available serial ports 
> from Windows registry. 
> 
> Is there any manner to do the same under LiNUX that works on all 
> distributions?



hi,

cat /proc/ioports and serach serial

0000-001f : dma1
0020-003f : pic1
0040-005f : timer
0060-006f : keyboard
0070-007f : rtc
0080-008f : dma page reg
00a0-00bf : pic2
00c0-00df : dma2
00f0-00ff : fpu
02f8-02ff : serial(auto)
0340-0340 : HiSax hscx A fifo
03c0-03df : vga+
03f8-03ff : serial(auto)
0740-075f : HiSax hscx A
0b40-0b40 : HiSax hscx B fifo
0cf8-0cff : PCI conf1
0f40-0f5f : HiSax hscx B
1340-1340 : HiSax isac fifo
1740-175f : HiSax isac
1b40-1b47 : avm cfg
e800-e8ff : Adaptec AHA-2940U2/W
f0a0-f0bf : Intel Corp. 82371AB PIIX4 ACPI
f0c0-f0ff : Intel Corp. 82371AB PIIX4 ACPI
f400-f43f : Intel Corp. 82557 [Ethernet Pro 100]
   f400-f43f : eepro100
f800-f81f : Intel Corp. 82371AB PIIX4 USB
   f800-f81f : usb-uhci
fcf0-fcff : Intel Corp. 82371AB PIIX4 IDE
   fcf0-fcf7 : ide0
   fcf8-fcff : ide1

or cat /proc/tty/driver/serial

serinfo:1.0 driver:5.05c revision:2001-07-08
0: uart:16550A port:3F8 irq:4 baud:9600 tx:11 rx:0
1: uart:16550A port:2F8 irq:3 baud:9600 tx:11 rx:0

Frank

Re: How to get a list of all available serial ports?

[Jan-Benedict Glaw]

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On Thu, 2004-08-26 12:52:27 +0200, Salomon, Frank <frank.salomon@wincor-nixdorf.com>
wrote in message <412DC0EB.1090605@wincor-nixdorf.com>:
> hi,
> 
> cat /proc/ioports and serach serial
> 
[...]
> 02f8-02ff : serial(auto)
[...]
> 03f8-03ff : serial(auto)

That's *very* unreliable. There are a lot of UARTs that handle more than
one serial port within one I/O space or PCI bar, so you'd "miss" those.
To be honest, I think that quite a lot of the non-8250 UARTs will
actually handle more than one serial port...

> or cat /proc/tty/driver/serial
> 
> serinfo:1.0 driver:5.05c revision:2001-07-08
> 0: uart:16550A port:3F8 irq:4 baud:9600 tx:11 rx:0
> 1: uart:16550A port:2F8 irq:3 baud:9600 tx:11 rx:0

I actually think that this is one of the mest methods to find out about
serial ports from userspace (among letting the user specify the correct
device node for it:-)  Also (just as a hint), don't really worry about
I/O address, uart type (as long as it isn't "unknown") or IRQ. It's
somewhat architecture dependant (eg. Sparc64 used to show off vector
addresses instead of IRQ numbers, so you'd see an address instead...).

MfG, JBG

-- 
Jan-Benedict Glaw       jbglaw@lug-owl.de    . +49-172-7608481             _ O _
"Eine Freie Meinung in  einem Freien Kopf    | Gegen Zensur | Gegen Krieg  _ _ O
 fuer einen Freien Staat voll Freier Bürger" | im Internet! |   im Irak!   O O O
ret = do_actions((curr | FREE_SPEECH) & ~(NEW_COPYRIGHT_LAW | DRM | TCPA));

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