xref: /OK3568_Linux_fs/kernel/Documentation/arm/sa1100/serial_uart.rst (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593Smuzhiyun==================
2*4882a593SmuzhiyunSA1100 serial port
3*4882a593Smuzhiyun==================
4*4882a593Smuzhiyun
5*4882a593SmuzhiyunThe SA1100 serial port had its major/minor numbers officially assigned::
6*4882a593Smuzhiyun
7*4882a593Smuzhiyun  > Date: Sun, 24 Sep 2000 21:40:27 -0700
8*4882a593Smuzhiyun  > From: H. Peter Anvin <hpa@transmeta.com>
9*4882a593Smuzhiyun  > To: Nicolas Pitre <nico@CAM.ORG>
10*4882a593Smuzhiyun  > Cc: Device List Maintainer <device@lanana.org>
11*4882a593Smuzhiyun  > Subject: Re: device
12*4882a593Smuzhiyun  >
13*4882a593Smuzhiyun  > Okay.  Note that device numbers 204 and 205 are used for "low density
14*4882a593Smuzhiyun  > serial devices", so you will have a range of minors on those majors (the
15*4882a593Smuzhiyun  > tty device layer handles this just fine, so you don't have to worry about
16*4882a593Smuzhiyun  > doing anything special.)
17*4882a593Smuzhiyun  >
18*4882a593Smuzhiyun  > So your assignments are:
19*4882a593Smuzhiyun  >
20*4882a593Smuzhiyun  > 204 char        Low-density serial ports
21*4882a593Smuzhiyun  >                   5 = /dev/ttySA0               SA1100 builtin serial port 0
22*4882a593Smuzhiyun  >                   6 = /dev/ttySA1               SA1100 builtin serial port 1
23*4882a593Smuzhiyun  >                   7 = /dev/ttySA2               SA1100 builtin serial port 2
24*4882a593Smuzhiyun  >
25*4882a593Smuzhiyun  > 205 char        Low-density serial ports (alternate device)
26*4882a593Smuzhiyun  >                   5 = /dev/cusa0                Callout device for ttySA0
27*4882a593Smuzhiyun  >                   6 = /dev/cusa1                Callout device for ttySA1
28*4882a593Smuzhiyun  >                   7 = /dev/cusa2                Callout device for ttySA2
29*4882a593Smuzhiyun  >
30*4882a593Smuzhiyun
31*4882a593SmuzhiyunYou must create those inodes in /dev on the root filesystem used
32*4882a593Smuzhiyunby your SA1100-based device::
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun	mknod ttySA0 c 204 5
35*4882a593Smuzhiyun	mknod ttySA1 c 204 6
36*4882a593Smuzhiyun	mknod ttySA2 c 204 7
37*4882a593Smuzhiyun	mknod cusa0 c 205 5
38*4882a593Smuzhiyun	mknod cusa1 c 205 6
39*4882a593Smuzhiyun	mknod cusa2 c 205 7
40*4882a593Smuzhiyun
41*4882a593SmuzhiyunIn addition to the creation of the appropriate device nodes above, you
42*4882a593Smuzhiyunmust ensure your user space applications make use of the correct device
43*4882a593Smuzhiyunname. The classic example is the content of the /etc/inittab file where
44*4882a593Smuzhiyunyou might have a getty process started on ttyS0.
45*4882a593Smuzhiyun
46*4882a593SmuzhiyunIn this case:
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun- replace occurrences of ttyS0 with ttySA0, ttyS1 with ttySA1, etc.
49*4882a593Smuzhiyun
50*4882a593Smuzhiyun- don't forget to add 'ttySA0', 'console', or the appropriate tty name
51*4882a593Smuzhiyun  in /etc/securetty for root to be allowed to login as well.
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