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Subject: Re: [RFC] powerpc: experimental of serial port driver
From: David Woodhouse <dwmw2@infradead.org>
To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
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Date: Sat, 09 Dec 2006 17:39:10 +0000
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Cc: cbe-oss-dev@ozlabs.org, Arnd Bergmann <arnd@arndb.de>,
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On Sat, 2006-12-09 at 19:44 +0300, Sergei Shtylyov wrote:
> Then it should be something like "nc16750\0ns16550\0ns16450\08250". 

Those aren't particularly interesting distinctions -- they're dead easy
to probe for. The really interesting one is the type of SuperIO chip
it's compatible with -- which specifies how you get baud rates above
115200. For some chips (SMSC iirc) you have a 'magic multiplier'; by
setting the divisor to 0x8001 or 0x8002 you get 230400/460800 baud resp.
For NatSemi type chips you have baud rate divisors in an alternate bank,
and you get a higher baud_base if you use those but if you use the
registers in bank zero it reverts to 115200, etc. 

-- 
dwmw2