MPC8xx: Using SCM/SCC and standard 16C550 Uarts together...

MPC8xx: Using SCM/SCC and standard 16C550 Uarts together...

[David Jander]

Hi all,

The situation is:
Our custom board needs to use SCM1 as console, and has an external quad uart 
chip (16C554) connected to the external bus, mapped at 0xf8100000.
I am using the ppclinux_2_4_devel tree from Denx.
I ioremapped that address space, and it seems to work. Right now I don't have 
the daughterboard with the quad-uarts working (as in hardware), so I can't 
fully test that.

The problem is:
Apparently arch/ppc/8xx_io/uart.c doesn't take into account other serial 
drivers that may initialize later, and uses a serial_state struct statically.
Shouldn't this be visible to the outside? Shouldn't there be a global 
serial_state structure somewhere that lists all serial ports?
Right now, I get this:

-----------------------------------
...
CPM UART driver version 0.04
ttyS0 at 0x0280 is on SMC1 using BRG1
ttyS1 at 0x0200 is on SCC3 using BRG2
ttyS2 at 0x0300 is on SCC4 using BRG3
pty: 256 Unix98 ptys configured
Serial driver version 5.05c (2001-07-08) with MANY_PORTS SHARE_IRQ enabled
...
VFS: Mounted root (jffs2 filesystem).
Mounted devfs on /dev
Freeing unused kernel memory: 56k init
------------------------------------

And then nothing more. I assume, at that point init opens /dev/console (ttyS0) 
and that device doesn't exist, since drivers/char/serial.c doesn't detect any 
uart at the moment.
If it did, maybe I would get console stuff out of the first 16c554 port.

Has anybody else tried this?
What would be the right way to fix this?

Greetings,

-- 
David Jander
Protonic Holland.

RE: MPC8xx: Using SCM/SCC and standard 16C550 Uarts together...

[Demke Torsten-atd012]

Hi David,

I dont know exactly the state of the DENX kernel, but in the standard
kernel the 8xx UART driver and the 16550 driver are using the same
device numbers (TTY_MAJOR) and device names (/dev/ttySx).
You have to change one of them.

Regards,
Torsten

> -----Original Message-----
> From: linuxppc-embedded-bounces@ozlabs.org
> [mailto:linuxppc-embedded-bounces@ozlabs.org]On Behalf Of David Jander
> Sent: Mittwoch, 12. Januar 2005 10:52
> To: linuxppc-embedded@ozlabs.org
> Subject: MPC8xx: Using SCM/SCC and standard 16C550 Uarts together...
> 
> 
> 
> Hi all,
> 
> The situation is:
> Our custom board needs to use SCM1 as console, and has an 
> external quad uart 
> chip (16C554) connected to the external bus, mapped at 0xf8100000.
> I am using the ppclinux_2_4_devel tree from Denx.
> I ioremapped that address space, and it seems to work. Right 
> now I don't have 
> the daughterboard with the quad-uarts working (as in 
> hardware), so I can't 
> fully test that.
> 
> The problem is:
> Apparently arch/ppc/8xx_io/uart.c doesn't take into account 
> other serial 
> drivers that may initialize later, and uses a serial_state 
> struct statically.
> Shouldn't this be visible to the outside? Shouldn't there be a global 
> serial_state structure somewhere that lists all serial ports?
> Right now, I get this:
> 
> -----------------------------------
> ...
> CPM UART driver version 0.04
> ttyS0 at 0x0280 is on SMC1 using BRG1
> ttyS1 at 0x0200 is on SCC3 using BRG2
> ttyS2 at 0x0300 is on SCC4 using BRG3
> pty: 256 Unix98 ptys configured
> Serial driver version 5.05c (2001-07-08) with MANY_PORTS 
> SHARE_IRQ enabled
> ...
> VFS: Mounted root (jffs2 filesystem).
> Mounted devfs on /dev
> Freeing unused kernel memory: 56k init
> ------------------------------------
> 
> And then nothing more. I assume, at that point init opens 
> /dev/console (ttyS0) 
> and that device doesn't exist, since drivers/char/serial.c 
> doesn't detect any 
> uart at the moment.
> If it did, maybe I would get console stuff out of the first 
> 16c554 port.
> 
> Has anybody else tried this?
> What would be the right way to fix this?
> 
> Greetings,
> 
> -- 
> David Jander
> Protonic Holland.
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
> 

Re: MPC8xx: Using SCM/SCC and standard 16C550 Uarts together...

[David Jander]

On Wednesday 12 January 2005 10:59, Demke Torsten-atd012 wrote:
> I dont know exactly the state of the DENX kernel, but in the standard
> kernel the 8xx UART driver and the 16550 driver are using the same
> device numbers (TTY_MAJOR) and device names (/dev/ttySx).
> You have to change one of them.

You are right! What now? I cannot go around and change TTY_MAJOR!
Is it true then, that you normally cannot have a mix of non-16550 uarts and 
16550 uarts on the same system, without doing nonstandard things with major 
numbers?
Should maybe arch/ppc/8xx_io/uart.c use another major number?

Greetings,

-- 
David Jander
Protonic Holland.

Re: MPC8xx: Using SCM/SCC and standard 16C550 Uarts together...

[Yuli Barcohen]

>>>>> David Jander writes:

    David> On Wednesday 12 January 2005 10:59, Demke Torsten-atd012
    David> wrote:

    Demke> I dont know exactly the state of the DENX kernel, but in the
    Demke> standard kernel the 8xx UART driver and the 16550 driver are
    Demke> using the same device numbers (TTY_MAJOR) and device names
    Demke> (/dev/ttySx).  You have to change one of them.

    David> You are right! What now? I cannot go around and change
    David> TTY_MAJOR!  Is it true then, that you normally cannot have a
    David> mix of non-16550 uarts and 16550 uarts on the same system,
    David> without doing nonstandard things with major numbers?

We've got such a mix but we use completely different MPC8xx support
infrastructure. Our SCC/SMC UART driver takes care of possible external
UARTs (it uses the same major number but configurable minor).

    David> Should maybe arch/ppc/8xx_io/uart.c use another major number?

Then you'll have to change all applications using standard device names
(ttySx).

-- 
========================================================================
 Yuli Barcohen       | Phone +972-9-765-1788 |  Software Project Leader
 yuli@arabellasw.com | Fax   +972-9-765-7494 | Arabella Software, Israel
========================================================================

RE: MPC8xx: Using SCM/SCC and standard 16C550 Uarts together...

[Demke Torsten-atd012]

Hello David,
> 
> On Wednesday 12 January 2005 10:59, Demke Torsten-atd012 wrote:
> > I dont know exactly the state of the DENX kernel, but in 
> the standard
> > kernel the 8xx UART driver and the 16550 driver are using the same
> > device numbers (TTY_MAJOR) and device names (/dev/ttySx).
> > You have to change one of them.
> 
> You are right! What now? I cannot go around and change TTY_MAJOR!
> Is it true then, that you normally cannot have a mix of 
> non-16550 uarts and 
> 16550 uarts on the same system, without doing nonstandard 
> things with major 
> numbers?
> Should maybe arch/ppc/8xx_io/uart.c use another major number?
Yes, indeed I changed the major device number and the name in 
8xx_io/uart.c. I used the same numbers and names that are used
in the 2.6 kernel (TTY_CPM_MAJOR=42, name= "ttyCPM"). Of course
you have to change all applications that use the 8xx UART then.

See pseudo-patch:

+#ifdef CONFIG_SERIAL_CONSOLE
 static struct console sercons = {
-	name:		"ttyS",
+	name:		"ttyCPM",
 	write:		serial_console_write,
 	device:		serial_console_device,
 	setup:		serial_console_setup,
 	flags:		CON_PRINTBUFFER,
 	index:		CONFIG_SERIAL_CONSOLE_PORT,
 };
+#endif

...

 static kdev_t serial_console_device(struct console *c)
 {
+#ifdef CONFIG_SERIAL
+	return MKDEV(TTY_CPM_MAJOR, 42 + c->index);
+#else
 	return MKDEV(TTY_MAJOR, 64 + c->index);
+#endif
 }

...

 	serial_driver.magic = TTY_DRIVER_MAGIC;
 	serial_driver.driver_name = "serial";
+#ifdef CONFIG_SERIAL
+/* use different numbers if "standard" serial driver is enabled */
+	serial_driver.driver_name = "serialCPM";
+#ifdef CONFIG_DEVFS_FS
+	serial_driver.name = "tts/%d";
+#else
+	serial_driver.name = "ttyCPM";
+#endif
+	serial_driver.major = TTY_CPM_MAJOR;
+	serial_driver.minor_start = 42;
+#else
+	serial_driver.driver_name = "serial";
 #ifdef CONFIG_DEVFS_FS
 	serial_driver.name = "tts/%d";
 #else
@@ -2553,6 +2585,7 @@ int __init rs_8xx_init(void)
 #endif
 	serial_driver.major = TTY_MAJOR;
 	serial_driver.minor_start = 64;
+#endif /* CONFIG_SERIAL */
 	serial_driver.num = NR_PORTS;
 	serial_driver.type = TTY_DRIVER_TYPE_SERIAL;
 	serial_driver.subtype = SERIAL_TYPE_NORMAL;

Greetings,
Torsten

> 
> Greetings,
> 
> -- 
> David Jander
> Protonic Holland.
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
>